Chapter 23: The Acute Abdomen PDF

EUROPEAN UNIVERSITY CYPRUS Access Provided by: Current Diagnosis & Treatment: Surgery, 15e Chapter 23: The Acute Abdomen Sameer Hirji; Reza Askari INTRODUCTION An “acute abdomen” denotes any sudden, spontaneous, nontraumatic, severe abdominal pain, typically of less than 24 hours in duration. The acute abdomen requires rapid and specific diagnosis because several etiologies demand urgent operative intervention. Because there is frequently a progressive underlying intraabdominal disorder, undue delay in diagnosis and treatment may adversely affect outcome. Therefore, understanding the clinical presentation, associated laboratory and diagnostic imaging findings, and various facets of preoperative evaluation of acute abdomen is essential. The approach to a patient with an acute abdomen must be systematic and thorough yet efficient to minimize delay. An acute abdomen should be suspected even in a patient with only mild or atypical presentations. Increasingly, certain patient populations present with atypical complaints, including the immunocompromised, elderly, and bariatric patients. The complete history and physical examination often suggest the probable cause (Table 23–1), allow for timely formation of a differential diagnosis, and guide the choice of appropriate initial diagnostic studies. Table 23–1. Common causes of the acute abdomen.1 Gastrointestinal tract disorders *Nonspecific abdominal pain *Appendicitis *Small and large bowel obstruction *Perforated peptic ulcer Incarcerated hernia Bowel perforation Meckel diverticulitis Boerhaave syndrome *Diverticulitis Inflammatory bowel disorders MalloryWeiss syndrome Gastroenteritis Downloaded 2024129 1:8 A Your IP is 82.116.202.56 gastritis Chapter Acute 23: The Acute Abdomen, Sameer Hirji; Reza Askari ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Mesenteric adenitis Page 1 / 19 Inflammatory bowel disorders MalloryWeiss syndrome EUROPEAN UNIVERSITY CYPRUS Access Provided by: Gastroenteritis Acute gastritis Mesenteric adenitis Parasitic infections Liver, spleen, and biliary tract disorders *Acute cholecystitis Acute cholangitis Hepatic abscess Ruptured hepatic tumor Spontaneous rupture of the spleen Splenic infarct Biliary colic Acute hepatitis Pancreatic disorders *Acute pancreatitis Urinary tract disorders *Ureteral or renal colic Acute pyelonephritis Acute cystitis Renal infarct Gynecologic disorders Ruptured ectopic pregnancy Twisted ovarian tumor Ruptured ovarian follicle cyst *Acute salpingitis Dysmenorrhea Endometriosis Downloaded 2024129 1:8 A Your IP is 82.116.202.56 Vascular Chapter 23: Thedisorders Acute Abdomen, Sameer Hirji; Reza Askari ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Ruptured aortic and visceral aneurysms Page 2 / 19 *Acute salpingitis EUROPEAN UNIVERSITY CYPRUS Dysmenorrhea Access Provided by: Endometriosis Vascular disorders Ruptured aortic and visceral aneurysms Acute ischemic colitis Mesenteric thrombosis Portal vein Thrombosis Peritoneal disorders Intraabdominal abscesses Primary peritonitis Tuberculous peritonitis Retroperitoneal disorders Retroperitoneal hemorrhage 1The most common causes are marked with an asterisk (*). Conditions in italic type often require urgent operation. Please see specific chapters for management. Depending on the degree of clinical suspicion and status of the patient, the clinician must then decide if inhospital observation is warranted, if additional tests are needed, if early operation is indicated, or if nonoperative treatment would be more suitable. If unclear or when in doubt, it is always appropriate to be a little aggressive and pursue additional tests, if needed. This chapter provides important insights and a useful framework to efficiently diagnose and manage a patient with an acute abdomen. HISTORY Abdominal Pain Despite availability of advanced imaging techniques, the fundamental aspect of evaluation is history taking and physical exam. Taking a patient history is an active process whereby a large number of diagnostic possibilities are considered simultaneously and systematically eliminated based on their pretest probability or likelihood of occurrence. Pain is the most common and predominant presenting feature of an acute abdomen, but as often is the case, it can be variable in nature. Thus, careful consideration of the location, severity, mode of onset and progression, and character of the pain will suggest a preliminary list of diagnoses, which can be further explored. A. Location of Pain Determining the location of pain is the initial step but serves only as a rough guide to the diagnosis; “typical” descriptions are reported in only two thirds of cases. This variability is due to atypical pain patterns, a shift of maximum intensity away from the primary site, advanced or severe disease, or acute on chronic pain. In patients presenting with diffuse peritonitis, generalized pain may completely obscure the precipitating event. Fortunately, some general patterns do emerge that provide clues to diagnosis and narrow the differential of the acute abdomen. Pain confined to either upper quadrant may be evaluated by anatomic consideration of acute conditions affecting underlying organs. The same approach applies to the lower quadrants. Because of the complex dual visceral and parietal sensory networks innervating the abdominal area, pain is not as precisely localized in the abdomen Downloaded 2024129 1:8 Asensation Your IP is ismediated 82.116.202.56 as in the extremities. Visceral primarily by afferent C fibers located in the walls of hollow viscera and in the capsules of solid Page 3 / 19 Chapter 23: The Acute Abdomen, Sameer Hirji; Reza Askari organs. Unlike cutaneous pain, visceral pain is elicited by distention, inflammation or ischemia stimulating the receptor neurons, or direct ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility involvement (eg, malignant infiltration) of sensory nerves. Visceral pain is a centrally perceived sensation that is generally slow in onset, dull, poorly localized, and protracted. The pain may be due to increased wall tension or luminal distention or forceful smooth muscle contraction (colic) producing acute on chronic pain. In patients presenting with diffuse peritonitis, generalized pain may completely obscure the precipitating event. Fortunately, EUROPEAN UNIVERSITY CYPRUS some general patterns do emerge that provide clues to diagnosis and narrow the differential of the acute abdomen. Pain confined to either upper Access Provided by: quadrant may be evaluated by anatomic consideration of acute conditions affecting underlying organs. The same approach applies to the lower quadrants. Because of the complex dual visceral and parietal sensory networks innervating the abdominal area, pain is not as precisely localized in the abdomen as in the extremities. Visceral sensation is mediated primarily by afferent C fibers located in the walls of hollow viscera and in the capsules of solid organs. Unlike cutaneous pain, visceral pain is elicited by distention, inflammation or ischemia stimulating the receptor neurons, or direct involvement (eg, malignant infiltration) of sensory nerves. Visceral pain is a centrally perceived sensation that is generally slow in onset, dull, poorly localized, and protracted. The pain may be due to increased wall tension or luminal distention or forceful smooth muscle contraction (colic) producing diffuse, deepseated pain. Visceral pain is most often felt in the midline because of the bilateral sensory supply to the spinal cord. Because different visceral structures are associated with different sensory levels in the spine (Table 23–2), visceral pain may be felt in the midepigastrium, periumbilical area, lower abdomen, or flank areas (Figure 23–1) depending on the organ involved. Table 23–2. Sensory levels associated with visceral structures. Structures Nervous System Pathways Sensory Level Liver, spleen, and central part of diaphragm Phrenic nerve C35 Peripheral diaphragm, stomach, pancreas, gallbladder, and small bowel Celiac plexus and greater splanchnic nerve T69 Appendix, colon, and pelvic viscera Mesenteric plexus and lesser splanchnic nerve T1011 Sigmoid colon, rectum, kidney, ureters, and testes Lowest splanchnic nerve T11L1 Bladder and rectosigmoid Hypogastric plexus S24 Figure 23–1. Visceral pain sites. By contrast, parietal pain is mediated by both C and A delta nerve fibers, the latter being responsible for the transmission of more acute, sharper, better localized pain sensation. Direct irritation of the somatically innervated parietal peritoneum by pus, bile, urine, or gastrointestinal secretions leads to a more precisely localized pain. Parietal pain is more easily localized than visceral pain because the somatic afferent fibers are directed to only one side of the nervous system. The cutaneous distribution of parietal pain corresponds to the T6L1 areas. Abdominal parietal pain is conventionally described as occurring in one of the four abdominal quadrants or in the epigastric or central abdominal area. Abdominal pain may be referred or may shift to sites removed from the primarily affected organs (Figure 23–2). Referred pain denotes noxious (usually cutaneous) sensations perceived at a site distant from that of a strong primary stimulus. Distorted central perception of the site of pain is due to the confluence of afferent nerve fibers from disparate areas within the posterior horn of the spinal cord. For example, pain due to subdiaphragmatic Downloaded 2024129 1:8 A Your IP is 82.116.202.56 irritation by air, fluid, blood, or a mass lesionAskari is referred to the shoulder via the C4mediated (phrenic) nerve. Pain may also be referred Page 4 /to19 Chapter 23: Theperitoneal Acute Abdomen, Sameer Hirji; Reza the shoulder from supradiaphragmatic lesions suchofasUse pleurisy or lower lobe pneumonia. Although more often perceived in the right scapular region, ©2024 McGraw Hill. All Rights Reserved. Terms Privacy Policy Notice Accessibility referred biliary pain may mimic angina pectoris if it is perceived in the anterior chest or left shoulder areas. one side of the nervous system. The cutaneous distribution of parietal pain corresponds to the T6L1 areas. Abdominal parietal pain is conventionally EUROPEAN UNIVERSITY CYPRUS described as occurring in one of the four abdominal quadrants or in the epigastric or central abdominal area. Access Provided by: Abdominal pain may be referred or may shift to sites removed from the primarily affected organs (Figure 23–2). Referred pain denotes noxious (usually cutaneous) sensations perceived at a site distant from that of a strong primary stimulus. Distorted central perception of the site of pain is due to the confluence of afferent nerve fibers from disparate areas within the posterior horn of the spinal cord. For example, pain due to subdiaphragmatic irritation by air, peritoneal fluid, blood, or a mass lesion is referred to the shoulder via the C4mediated (phrenic) nerve. Pain may also be referred to the shoulder from supradiaphragmatic lesions such as pleurisy or lower lobe pneumonia. Although more often perceived in the right scapular region, referred biliary pain may mimic angina pectoris if it is perceived in the anterior chest or left shoulder areas. Figure 23–2. Referred pain (Top) and shifting pain (Bottom) in the acute abdomen. Solid circles indicate the site of maximum pain; dashed circles indicate sites of lesser pain. Spreading or shifting pain parallels the course of the underlying condition. The site of pain at onset should be distinguished from the site at presentation. The chronology of a patient’s pain may be as important as the location itself. For example, in a patient with acute appendicitis, the initial visceral pain begins classically in the epigastric or periumbilical region and then shifts to become sharper parietal pain localized in the right lower quadrant when the overlying peritoneum becomes directly inflamed (Figure 23–2). With a perforated peptic ulcer, pain almost always begins in the epigastrium, but as leaked gastric contents track down the right paracolic gutter, pain may descend and become prominent in the right lower quadrant. Thus, localized pain often suggests progression of disease and warrants prompt intervention. B. Mode of Onset and Progression of Pain The duration, acuity, and progression of pain should be assessed at initial presentation, and assessment should be repeated as often as necessary. The mode of onset of pain reflects the nature and severity of the underlying process. Onset may be acute (within seconds), rapidly progressive (within 12 hours), or insidious (gradually over several hours). One must also determine the time course of the pain (constant, intermittent, decreasing, or increasing) because this will help prioritize the next steps. For instance, sudden, unheralded, excruciating, increasing generalized pain suggests an ongoing intraabdominal catastrophe such as a perforated viscus or rupture of an aneurysm, ectopic pregnancy, or abscess. Accompanying systemic signs (tachycardia, sweating, tachypnea, shock) soon supersede the abdominal disturbances and underscore the need for rapid resuscitation and laparotomy. In some cases, portal vein hypertension can progress over time into abdominal pain and distension, and ultimately manifest as acute abdomen if there is sudden obstruction of venous blood flow. A less dramatic clinical picture is steady, mild pain that becomes intensely localized in a welldefined area within a few (12) hours. Any of the above conditions may present in this manner, but this is more typical of acute cholecystitis, acute pancreatitis, strangulated bowel, mesenteric infarction, renal or ureteral colic, and proximal small bowel obstruction. Finally, some patients initially have slight—at times only vague—abdominal discomfort that is fleetingly present diffusely throughout the abdomen. It may be unclear whether these patients even have an acute abdomen or whether the illness is likely to be a matter for medical rather than surgical attention. Associated gastrointestinal symptoms are infrequent at first, and systemic symptoms are often absent. Eventually, the pain and abdominal findings become more pronounced, become either colicky or steady, and localize to a smaller area. This gradual onset pattern leading to a more Downloaded 2024129 1:8 A Your IP is 82.116.202.56 localized pain may reflect a slowly developing condition or the body’s defensive efforts to cordon off an acute process. Page 5 / 19 Chapter 23: The Acute Abdomen, Sameer Hirji; Reza Askari ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility C. Character of Pain renal or ureteral colic, and proximal small bowel obstruction. EUROPEAN UNIVERSITY CYPRUS Access Provided by: Finally, some patients initially have slight—at times only vague—abdominal discomfort that is fleetingly present diffusely throughout the abdomen. It may be unclear whether these patients even have an acute abdomen or whether the illness is likely to be a matter for medical rather than surgical attention. Associated gastrointestinal symptoms are infrequent at first, and systemic symptoms are often absent. Eventually, the pain and abdominal findings become more pronounced, become either colicky or steady, and localize to a smaller area. This gradual onset pattern leading to a more localized pain may reflect a slowly developing condition or the body’s defensive efforts to cordon off an acute process. C. Character of Pain The nature, severity, and periodicity of pain provide useful clues to the underlying pathology (Figure 23–3). Pain may be continual or intermittent. Steady pain is more common and often indicates a process that will inevitably lead to peritoneal inflammation. It may be constant in severity or fluctuate, but it is always present. Sharp, superficial, constant pain due to peritoneal irritation (often presenting as focal peritonitis) is typical of perforated ulcer or a ruptured appendix, ovarian cyst, or ectopic pregnancy. Intermittent, crampy pain (colic) may occur for short or long periods but is punctuated by painfree intervals and is most characteristic of obstruction of a hollow viscus. The gripping, mounting pain of small bowel obstruction (and occasionally early pancreatitis) is usually intermittent, vague, deepseated, and crescendo at first, but becomes sharper, unremitting, and better localized with time. Unlike the disquieting but bearable pain associated with bowel obstruction, pain caused by lesions occluding smaller conduits (bile ducts, uterine tubes, and ureters) rapidly becomes unbearably intense. The painfree intervals reflect intermittent smooth muscle relaxation. In the strict sense, the term biliary colic is a misnomer because biliary pain does not remit because bile ducts do not have peristaltic movements. Figure 23–3. The location and character of pain are helpful in the differential diagnosis of the acute abdomen. The quality of a patient’s pain leads to the use of certain descriptors to describe different types of pain and may be typical of certain pathologies. The “aching discomfort” of ulcer pain, the “stabbing, breathtaking” pain of acute pancreatitis and mesenteric infarction, the “gripping” pain of a bowel obstruction, and the “tearing” pain of ruptured aortic aneurysm remain apt descriptions. Despite the use of such descriptive terms, the quality of visceral pain is not a reliable clue to its cause because it is often subjective. The intensity of a patient’s pain may relate to the severity of the insult. Agonizing pain denotes serious or advanced disease. Colicky pain is usually promptly alleviated by analgesics. Ischemic pain due to strangulated bowel or mesenteric thrombosis is only slightly assuaged even by narcotics. Nonspecific abdominal pain is usually mild, but mild pain may also be found with perforated ulcers that have become localized and in mild acute pancreatitis. An occasional patient will deny pain but complain of a vague feeling of abdominal fullness that feels as though it might be relieved by a bowel movement. This visceral sensation (gas stoppage sign) is due to reflex ileus induced by an inflammatory lesion walled off from the free peritoneal cavity, as in retrocecal appendicitis. In addition, previous pain episodes and factors that aggravate or relieve pain should be noted. Pain caused by localized peritonitis, especially when it affects upper abdominal organs, tends to be exacerbated by movement or deep breathing. Other Symptoms Associated With Abdominal Pain Anorexia, fever, nausea and vomiting, constipation/obstipation, and diarrhea often accompany abdominal pain but are nonspecific symptoms and have limited diagnostic value. However, these symptoms should be managed promptly while the formal diagnosis is sought. A. Vomiting 2024129 1:8 A Your IP is 82.116.202.56 Downloaded Page 6 / 19 Chapter 23: The Acute Abdomen, Sameer Hirji; Reza Askari ©2024 McGraw Hill. All Rights Terms afferent of Use fibers, Privacy Policy Notice Accessibility When sufficiently stimulated by Reserved. secondary visceral the medullary vomiting centers activate efferent fibers to induce reflex vomiting. Hence, pain in the acute surgical abdomen usually precedes vomiting, whereas the reverse holds true in medical conditions. Vomiting is a prominent symptom in upper gastrointestinal diseases such as Boerhaave syndrome, MalloryWeiss syndrome, acute gastritis, and acute pancreatitis. Severe, Other Symptoms Associated With Abdominal Pain EUROPEAN UNIVERSITY CYPRUS Access Provided by: Anorexia, fever, nausea and vomiting, constipation/obstipation, and diarrhea often accompany abdominal pain but are nonspecific symptoms and have limited diagnostic value. However, these symptoms should be managed promptly while the formal diagnosis is sought. A. Vomiting When sufficiently stimulated by secondary visceral afferent fibers, the medullary vomiting centers activate efferent fibers to induce reflex vomiting. Hence, pain in the acute surgical abdomen usually precedes vomiting, whereas the reverse holds true in medical conditions. Vomiting is a prominent symptom in upper gastrointestinal diseases such as Boerhaave syndrome, MalloryWeiss syndrome, acute gastritis, and acute pancreatitis. Severe, uncontrollable retching provides temporary pain relief in moderate attacks of pancreatitis. The absence of bile in the vomitus is a feature of pyloric stenosis or gastric outlet obstruction. Where associated findings suggest bowel obstruction, the onset and character of vomiting may indicate the level of the lesion. Recurrent vomiting of bilestained fluid is typical of proximal small bowel obstruction. In distal small or large bowel obstruction, prolonged nausea precedes vomiting, which may become feculent in late cases. Although vomiting may present in either acute appendicitis or nonspecific abdominal pain, coexisting nausea and anorexia are more suggestive of the former condition. B. Constipation Reflex ileus is often induced by visceral afferent fibers stimulating efferent fibers of the sympathetic autonomic nervous system (splanchnic nerves) to reduce intestinal peristalsis. Hence, paralytic ileus undermines the value of constipation in the differential diagnosis of an acute abdomen. Constipation itself is hardly an absolute indicator of intestinal obstruction and often nonspecific. However, obstipation (the absence of passage of both stool and flatus) strongly suggests mechanical bowel obstruction if there is progressive painful abdominal distention or repeated vomiting. Clinical history in terms of onset and duration of pain should help provide further clinical context. C. Diarrhea Copious watery diarrhea is characteristic of gastroenteritis and other medical causes of an acute abdomen. Bloodstained diarrhea suggests ulcerative colitis, Crohn disease, or bacillary or amebic dysentery. A recent travel or food intake history should be elicited. It is also found with ischemic colitis but often absent in intestinal infarction due to superior mesenteric artery occlusion. D. Fever Fever is a marker of inflammation and may be present in a variety of medical and surgical conditions in the abdomen if they are allowed to progress. The sensitivity of this finding is low because the ability of many patient populations to mount a fever is compromised (eg, immunocompromised patients) and, for most diseases leading to acute abdomen, fever is low grade or absent. E. Other Specific Symptoms The following findings are extremely helpful if present. Significant weight loss may suggest a chronic condition such as cancer or chronic mesenteric ischemia. Jaundice suggests hepatobiliary disorders (both benign and malignant). Hematochezia or hematemesis may suggest a gastroduodenal lesion or MalloryWeiss syndrome; melena may suggest a lower gastrointestinal bleed or colonic ischemia; and hematuria may suggest ureteral colic or cystitis. The passage of blood clots or necrotic mucosal debris may be the sole evidence of advanced intestinal ischemia. Other Relevant Aspects of the History A. Past Medical History A complete past medical history is crucial to identify both medical conditions related to the presentation of the acute abdomen as well as conditions of associated pulmonary, renal, and cardiac systems that may mimic the acute abdomen in their presentation. Many chronic medical conditions complicate the patient’s presentation and increase the patient’s overall surgical risk. An assessment of the patient’s cardiovascular and pulmonary status should always be done before proceeding to the operating room. Particular attention should be paid to elderly and frail patients. Liver disease should be noted because it increases risk for gastrointestinal bleeding and, in severe disease, may be complicated by ascites and spontaneous bacterial peritonitis. In patients with vascular disease or atrial fibrillation, mesenteric ischemia should be included in the differential and correlated with clinical symptoms. Inflammatory bowel disease can cause severe abdominal pain (or “attacks”) that is often treated medically but may be complicated by processes requiring more emergent intervention including intraabdominal abscess, stricture, obstruction, or perforation. A patient should also be asked about any history of recent trauma. This could be either blunt or penetrating trauma. Delayed splenic bleeding is one of the more common examples of Your traumatic presenting in delayed fashion. Downloaded 2024129 1:8 A IP is injuries 82.116.202.56 Chapter 23: The Acute Abdomen, Sameer Hirji; Reza Askari B. Surgical History ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Page 7 / 19 Any history of a previous abdominal, groin, vascular, or thoracic operation is relevant to the current illness and must be obtained. Particular attention bacterial peritonitis. In patients with vascular disease or atrial fibrillation, mesenteric ischemia should be included in the differential and correlated EUROPEAN UNIVERSITY CYPRUS with clinical symptoms. Inflammatory bowel disease can cause severe abdominal pain (or “attacks”) that is often treated medically but may be Access Provided by: complicated by processes requiring more emergent intervention including intraabdominal abscess, stricture, obstruction, or perforation. A patient should also be asked about any history of recent trauma. This could be either blunt or penetrating trauma. Delayed splenic bleeding is one of the more common examples of traumatic injuries presenting in delayed fashion. B. Surgical History Any history of a previous abdominal, groin, vascular, or thoracic operation is relevant to the current illness and must be obtained. Particular attention to the mode of operation (laparoscopic, open, endovascular, transabdominal [eg, biopsies]) and any anatomic reconstructions may clarify aspects of the current complaint. History of foreign implants (eg, meshes, bone implants) should also be taken. If possible within the time constraints imposed by the urgency of the current problem, operative notes and pathology reports should be obtained and reviewed. C. Gynecologic History The menstrual history (duration, chronicity, timing) is crucial to the diagnosis of ectopic pregnancy, mittelschmerz (due to a ruptured ovarian follicle), and endometriosis. A history of vaginal discharge or dysmenorrhea may denote pelvic inflammatory disease. A complete sexual history should be performed if indicated, and all women of childbearing age should be evaluated for possibility of pregnancy. If the patient has been previously pregnant, information regarding the nature of delivery (particularly cesarean section) is also relevant. D. Medication History In the current era, polypharmacy is increasingly common but equally important to consider when evaluating patients. Medications of interest include anticoagulants, antiplatelets, and immunosuppression medications. For instance, nonsteroidal antiinflammatory drug (NSAIDs) or aspirin use could explain the etiology of gastric or duodenal ulcer. Anticoagulants have been implicated in retroperitoneal and intramural duodenal and jejunal hematomas. Additionally, patients who are anticoagulated or are on antiplatelet therapy may require correction or further consideration prior to operative management. Oral contraceptives have been implicated in the formation of benign hepatic adenomas and in mesenteric venous infarction. Corticosteroids or other chemotherapeutics and immunosuppressive medications may mask the clinical signs of even advanced peritonitis. Alcohol use should be interrogated because it can be associated with liver disease, ulcers, gastritis, and pancreatitis. E. Family History Family history often provides the best information about medical or hereditary causes of an acute abdomen. F. Travel History Travel history may raise the possibility of amebic liver abscess or hydatid cyst, malarial spleen, tuberculosis, Salmonella typhi infection of the ileocecal area, or dysentery. FORMING A DIFFERENTIAL DIAGNOSIS LIST The age, gender, and clinical history of the patient should assist in guiding the development of the differential diagnosis and should be correlated with the history and physical examination. Mesenteric adenitis mimics acute appendicitis in the young, gynecologic disorders complicate the evaluation of abdominal pain in women of childbearing age, and malignant and vascular diseases are more common in the elderly. Knowledge of the common causes of abdominal pain and their incidence in various populations is also helpful. Acute cholecystitis, appendicitis, bowel obstruction, cancer, and vascular conditions are the common causes of a surgical acute abdomen in older patients. In children, appendicitis accounts for onethird of all abdominal pain and nonspecific abdominal pain for much of the remainder. Causes of an acute abdomen reflect disease patterns of the indigenous population, and awareness of common causes within the physician’s locale improves diagnostic accuracy. PHYSICAL EXAMINATION The tendency to concentrate on the abdomen should be resisted in favor of a methodical and complete physical examination. Examination should begin with an initial assessment of the patient’s vital signs, and if hemodynamically unstable or with signs of systemic shock, the patient must be resuscitated aggressively. The patient should be evaluated concurrently with a physical exam in an efficient manner. A more “focused” assessment may be appropriate in timesensitive situations if it delays a subsequent intervention. The abdominal exam should be done with the patient in the supine position. A systematic approach to the abdominal examination (Table 23–3) is key Downloaded 2024129 1:8 A Your IP is 82.116.202.56 to success. physical exam allows the clinician to search for specific signs that confirm or rule out differential diagnostic possibilities (Table Page23–4). 8 / 19 Chapter 23:The The Acute Abdomen, Sameer Hirji; Reza Askari ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility 1. General inspection. General observation affords a fairly reliable indication of the severity of the clinical situation. Most patients, although uncomfortable, remain calm. The writhing of patients with visceral pain (eg, intestinal or ureteral colic) contrasts with the rigidly motionless The tendency to concentrate on the abdomen should be resisted in favor of a methodical and complete physical examination. Examination should EUROPEAN UNIVERSITY CYPRUS begin with an initial assessment of the patient’s vital signs, and if hemodynamically unstable or with signs of systemic shock, the patient must be Access Provided by: resuscitated aggressively. The patient should be evaluated concurrently with a physical exam in an efficient manner. A more “focused” assessment may be appropriate in timesensitive situations if it delays a subsequent intervention. The abdominal exam should be done with the patient in the supine position. A systematic approach to the abdominal examination (Table 23–3) is key to success. The physical exam allows the clinician to search for specific signs that confirm or rule out differential diagnostic possibilities (Table 23–4). 1. General inspection. General observation affords a fairly reliable indication of the severity of the clinical situation. Most patients, although uncomfortable, remain calm. The writhing of patients with visceral pain (eg, intestinal or ureteral colic) contrasts with the rigidly motionless bearing of those with parietal pain (eg, acute appendicitis, generalized peritonitis). Diminished responsiveness or an altered sensorium is suggestive of more advance or significant disease and may herald imminent cardiopulmonary collapse. 2. Assessing systemic signs. Systemic signs usually accompany rapidly progressive or advanced disorders of the acute abdomen. Extreme pallor, hypotension, hypothermia, tachycardia, tachypnea, and diaphoresis are some of the hard signs suggestive of major intraabdominal hemorrhage (eg, ruptured aortic aneurysm or tubal pregnancy). These findings warrant immediate attention and rapid diagnostic tests to rule out extra abdominal pathology. If extraabdominal pathology is excluded, these are markers of severe or rapidly progressive intraabdominal pathology and are indications for emergent laparotomy. 3. Fever. Constant lowgrade fever is common in inflammatory conditions such as diverticulitis, acute cholecystitis, and appendicitis. High fever with lower abdominal tenderness in a young woman without signs of systemic illness suggests acute salpingitis. Disorientation or extreme lethargy combined with a very high fever (> 39°C) or fever with chills and rigors signifies impending septic shock. This is most often due to advanced peritonitis, acute cholangitis, or pyelonephritis. However, fever is often mild or absent in elderly, chronically ill, or immunosuppressed patients despite a serious acute abdomen. 4. Examination of the acute abdomen a. Inspection. The abdomen should be thoughtfully inspected before palpation. One should look for old surgical scars, hernias, evidence of trauma, stigmata of liver disease, obvious masses, distension, and signs of peritonitis. A tensely distended abdomen with an old surgical scar suggests both the presence and the cause (adhesions) of small bowel obstruction. A scaphoid contracted abdomen is seen with perforated ulcer; visible peristalsis occurs in thin patients with advanced bowel obstruction; and soft doughy fullness is seen in early paralytic ileus or mesenteric thrombosis. b. Auscultation. Auscultation of the abdomen should also precede palpation. Peristaltic rushes synchronous with colic are heard in midsmall bowel obstruction and in early acute pancreatitis. They differ from the highpitched hyperperistaltic sounds unrelated to the crampy pain of gastroenteritis, dysentery, and fulminant ulcerative colitis. An abdomen that is silent except for infrequent tinkly or squeaky sounds characterizes late bowel obstruction or diffuse peritonitis. Except for these more extreme patterns, the many auscultatory variants heard in abdominal conditions render them largely useless for specific diagnosis. c. Percussion. Percussion serves several purposes. Tenderness on percussion is akin to eliciting rebound tenderness; both reflect peritoneal irritation and parietal pain. With a perforated viscus, free air accumulating under the diaphragm may efface normal liver dullness. Tympany near the midline in a distended abdomen denotes air trapped within distended bowel loops. Free peritoneal fluid may be detected by demonstrating shifting dullness. d. Palpation. Palpation is performed with the patient resting in a comfortable supine position. Incisional and periumbilical hernias are noted. Tenderness that connotes localized peritoneal inflammation is the most important finding in patients with an acute abdomen. Its extent and severity are determined first by one or twofinger palpation, beginning away from the area of cough tenderness and gradually advancing toward it. Tenderness is usually well demarcated in acute cholecystitis, appendicitis, diverticulitis, and acute salpingitis. If there is poorly localized tenderness unaccompanied by guarding, one should suspect gastroenteritis or some other inflammatory intestinal process without peritonitis. Compared with the degree of pain, unexpectedly little or vaguely localized tenderness is elicited in uncomplicated hollow viscus obstruction, walledoff or deepseated perforations (eg, retrocecal appendicitis or diverticular phlegmons), and very obese patients. In these instances, use of additional imaging may help to localize the source of the problem. Severe pain out of proportion to exam is a hallmark for mesenteric ischemia, but these patients often have concurrent history of atrial fibrillation or stigmata of severe peripheral vascular disease. Rebound tenderness is elicited by applying deep gentle pressure to the area of concern and then releasing the pressure rapidly. It is a marker of peritoneal inflammation, but its usefulness may be confounded if the patient is startled by the abrupt release and interprets that as pain. Rebound tenderness may also be elicited with a bed bump or by lightly shaking the abdominal wall. Guarding is assessed placing hands over the abdominal muscles and depressing the fingers gently. Properly performed, this Downloaded 2024129 1:8 AbyYour IP isboth 82.116.202.56 Page 9the / 19 Chaptermaneuver 23: The Acute Abdomen, Sameer Hirji; Reza Askari spasm, the muscle will be felt to relax when the patient inhales deeply through is comforting to the patient. If there is voluntary ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility mouth. With true involuntary spasm, however, the muscle will remain taut and rigid (“boardlike”) throughout respiration. Except for rare neurologic disorders—and, for unknown reasons, renal colic—only peritoneal inflammation produces rectus muscle rigidity. Unlike peritonitis, mesenteric ischemia, but these patients often have concurrent history of atrial fibrillation or stigmata of severe peripheral vascular disease. EUROPEAN UNIVERSITY CYPRUS Rebound tenderness is elicited by applying deep gentle pressure to the area of concern and then releasing the pressure rapidly. It is a marker Access Provided by: of peritoneal inflammation, but its usefulness may be confounded if the patient is startled by the abrupt release and interprets that as pain. Rebound tenderness may also be elicited with a bed bump or by lightly shaking the abdominal wall. Guarding is assessed by placing both hands over the abdominal muscles and depressing the fingers gently. Properly performed, this maneuver is comforting to the patient. If there is voluntary spasm, the muscle will be felt to relax when the patient inhales deeply through the mouth. With true involuntary spasm, however, the muscle will remain taut and rigid (“boardlike”) throughout respiration. Except for rare neurologic disorders—and, for unknown reasons, renal colic—only peritoneal inflammation produces rectus muscle rigidity. Unlike peritonitis, renal colic induces spasm confined to the ipsilateral rectus muscle. When the patient raises his or her head from the bed, the abdominal muscles will be tensed. Tenderness persists in abdominal wall conditions (eg, rectus hematoma), whereas deeper peritoneal pain due to intraperitoneal disease is lessened (Carnett test). Hyperesthesia may be demonstrable in abdominal wall disorders or localized peritonitis, but it is more prominent in herpes zoster, spinal root compression, and other neuromuscular problems. Trigger point sensitivity, lateral costal rib tip tenderness, and pain exacerbated by spinal motion reflect parietal abdominal wall conditions that subside dramatically after infiltration with local anesthetic agents. Abdominal masses are usually detected by deep palpation. Superficial lesions such as a distended gallbladder or appendiceal abscess are often tender and have discrete borders. Deeper masses may be adherent to the posterior or lateral abdominal wall and are often partially walled off by overlying omentum and small bowel. As a result, their borders are illdefined, and only dull pain may be elicited by palpation. Examples include pancreatic phlegmon and ruptured aortic aneurysm. e. Maneuvers. Even if a mass cannot be directly felt, its presence may be inferred by other maneuvers. A large psoas abscess may cause pain when the hip is passively extended or actively flexed against resistance (iliopsoas sign). Internal and external rotation of the flexed thigh may exert painful pressure (obturator sign) on a loop of the small bowel entrapped within the obturator canal (obturator hernia). Bump tenderness over the lower costal ribs indicates an inflammatory condition affecting the diaphragm, liver, spleen, or its adjacent structures. Referred pain to McBurney point from the left lower quadrant (Rovsing sign) is associated with acute appendicitis. If one suspects abdominal guarding is masking an acutely inflamed gallbladder, the right subcostal area should be palpated while the patient inhales deeply. Inspiration will be arrested abruptly by pain (Murphy sign), or the gallbladder fundus may be felt as it strikes the examining fingers during descent of the diaphragm. Pain in the shoulder indicates irritation of the diaphragm by fluid such as blood, pus, gastric contents, or stool. Kehr sign is left shoulder pain associated with hemoperitoneum. Costovertebral angle tenderness is common in acute pyelonephritis. Because they are not invariably present, these special signs are helpful in conjunction with a compatible history and related physical findings. f. Inguinal and femoral rings; male genitalia. The inguinal and femoral rings in both sexes and the genitalia in male patients should be examined as needed, especially if there is suspicion for incarcerated bowel causing an acute abdomen. g. Rectal examination. A rectal examination should be performed in most patients with an acute abdomen. Diffuse tenderness is nonspecific, but rightsided rectal tenderness accompanied by lower abdominal rebound tenderness is indicative of peritoneal irritation due to pelvic appendicitis or abscess. Other useful findings include a rectal tumor, bloodstained stool, or occult blood (detected by guaiac testing). h. Pelvic examination. An acute abdomen is incorrectly diagnosed more often in women than in men, particularly in younger age groups. A pelvic examination is vital in women with vaginal discharge, dysmenorrhea, menorrhagia, or left lower quadrant pain. A properly performed pelvic examination is invaluable in differentiating among acute pelvic inflammatory diseases that do not require operation and acute appendicitis, twisted ovarian cyst, or tuboovarian abscess. Almost always, these patients undergo additional imaging to further delineate the cause of the pain. Table 23–3. Steps in physical examination of the acute abdomen. 1. Global Assessment, Vital Signs 2. Inspection 3. Auscultation 4. Percussion 5. Palpation Guarding or rigidity Local palpation Downloaded 2024129 1:8 A Your IP is 82.116.202.56 Rebound Chapter 23: The Acutetenderness Abdomen, Sameer Hirji; Reza Askari Deep ©2024 McGraw Hill.tenderness All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Bump tenderness Masses Page 10 / 19 pelvic examination is vital in women with vaginal discharge, dysmenorrhea, menorrhagia, or left lower quadrant pain. A properly performed EUROPEAN UNIVERSITY CYPRUS pelvic examination is invaluable in differentiating among acute pelvic inflammatory diseases that do not require operation and acute Access Provided by: appendicitis, twisted ovarian cyst, or tuboovarian abscess. Almost always, these patients undergo additional imaging to further delineate the cause of the pain. Table 23–3. Steps in physical examination of the acute abdomen. 1. Global Assessment, Vital Signs 2. Inspection 3. Auscultation 4. Percussion 5. Palpation Guarding or rigidity Local palpation Rebound tenderness Deep tenderness Bump tenderness Masses 6. Special signs 7. External hernias and male genitalia 8. Rectal examination 9. Pelvic examination Table 23–4. Physical findings in various causes of acute abdomen. Condition Helpful Signs Perforated viscus Scaphoid, tense abdomen; diminished bowel sounds (late); loss of liver dullness; guarding or rigidity. Peritonitis Motionless; absent bowel sounds (late); cough and rebound tenderness; guarding or rigidity. Inflamed mass or Tender mass (abdominal, rectal, or pelvic); bump tenderness; special signs (Murphy, psoas, or obturator). abscess Intestinal obstruction Distention; visible peristalsis (late); hyperperistalsis (early) or quiet abdomen (late); diffuse pain without rebound tenderness; hernia or rectal mass (some). Paralytic ileus Distention; minimal bowel sounds; no localized tenderness. Ischemic or strangulated Not distended (until late); bowel sounds variable; severe pain but little tenderness; rectal bleeding (some). bowel Bleeding Pallor, shock; distention; pulsatile (aneurysm) or tender (eg, ectopic pregnancy) mass; rectal bleeding (some). INVESTIGATIVE STUDIES History and physical examination by themselves remain pivotal in establishing a diagnosis of an acute abdomen. However, adjuncts such as laboratory and diagnostic imaging can help confirm the diagnosis, exclude medical causes not treated by operation, and help in preoperative planning, especially in patients with complex or prior abdominal surgery. In the current era, diagnostic studies can be obtained relatively quickly and improve clinical decision making. Downloaded 2024129 1:8 A Your IP is 82.116.202.56 Page 11 / 19 Chapter 23: The Acute Abdomen, Sameer Hirji; Reza Askari However, the availability and reliability of certain studies vary in different hospitals. When selecting a study, the invasiveness, risk, and cost ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility effectiveness should be considered. Test results must be interpreted within the clinical context of each case. Basic studies should be obtained in all but the most desperately ill patients, while other less vital tests may be requested later as indicated. INVESTIGATIVE STUDIES EUROPEAN UNIVERSITY CYPRUS Access Provided by: History and physical examination by themselves remain pivotal in establishing a diagnosis of an acute abdomen. However, adjuncts such as laboratory and diagnostic imaging can help confirm the diagnosis, exclude medical causes not treated by operation, and help in preoperative planning, especially in patients with complex or prior abdominal surgery. In the current era, diagnostic studies can be obtained relatively quickly and improve clinical decision making. However, the availability and reliability of certain studies vary in different hospitals. When selecting a study, the invasiveness, risk, and cost effectiveness should be considered. Test results must be interpreted within the clinical context of each case. Basic studies should be obtained in all but the most desperately ill patients, while other less vital tests may be requested later as indicated. Laboratory Investigations A. Blood Studies Hemoglobin, hematocrit, white blood cell, and differential counts taken on admission are highly informative. Both a rising or marked leukocytosis (> 13,000/µL) and leukopenia (< 5000/µL) are indicative of serious infection. The differential counts should be reviewed because the presence of increased neutrophils (“left shift”) may suggest the presence of infection, even when the white blood cell count is normal. Additionally, the presence of bands may indicate severe infection. Serum electrolytes, urea nitrogen, and creatinine are important, especially if hypovolemia is expected (eg, due to shock, copious vomiting or diarrhea, or delay in presentation). Creatinine is considered imperative prior to obtaining radiographic imaging with iodized contrast agents due to potential renal injury. It should also be obtained in patients with existing or prior history of renal disease. Arterial blood gas with lactate should be obtained in patients with hypotension, generalized peritonitis, pancreatitis, possible ischemic bowel, and septicemia. Elevated serum lactate may indicate bowel ischemia due to the correlation with anaerobic metabolism; however, this is nonspecific and may be elevated in other clinical scenarios, such as dehydration, cocaine use, or liver failure. Unsuspected metabolic acidosis may be the first clue to serious disease. A raised serum amylase or more specifically lipase level corroborates a clinical diagnosis of acute pancreatitis. Moderately elevated amylase values must be interpreted with caution because abnormal levels frequently accompany strangulated or ischemic bowel, twisted ovarian cyst, or perforated ulcer. Lipase is more specific to pancreatitis. In patients with suspected hepatobiliary disease, liver function tests (serum bilirubin, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, albumin, and globulin) are useful to differentiate medical from surgical hepatic disorders and to gauge the severity of underlying parenchymal disease. Clotting studies (platelet counts, prothrombin time, and partial thromboplastin time) may be obtained in certain patients in anticipation of surgical intervention. They should be evaluated in patients on anticoagulants such as warfarin to ensure therapeutic levels or alert the clinician that correction is needed prior to surgical intervention. Prothrombin time is also a marker of the synthetic function of the liver in those with advanced liver disease. A peripheral blood smear should be considered if the history hints at a hematologic abnormality (eg, cirrhosis, petechiae). The erythrocyte sedimentation rate, often nonspecifically raised in the acute abdomen, is of dubious diagnostic value; a normal value does not exclude serious surgical illness. A specimen of clotted blood for crossmatching should be sent whenever urgent surgery is anticipated or there is suspicion of hemorrhage. Beta human chorionic gonadotropin serum testing is routinely performed at many institutions in lieu of urine testing. This should be performed on all women of childbearing age. B. Urine Tests Urinalysis is easily performed and may reveal useful information. Dark urine or a raised specific gravity reflects mild dehydration in patients with normal renal function. Hyperbilirubinemia may give rise to teacolored urine that froths when shaken. Microscopic hematuria or pyuria can confirm ureteral colic or urinary tract infection and obviate a needless operation. Dipstick testing (for albumin, bilirubin, glucose, and ketones) may reveal a medical cause of an acute abdomen. Pregnancy tests must be ordered on all women of childbearing age if serum testing was not performed. C. Stool Tests Gastrointestinal bleeding is not a common feature of the acute abdomen. Nonetheless, testing for occult fecal blood should be performed on a case bycase basis. A positive test points to a mucosal lesion that may be responsible for large bowel obstruction or chronic anemia, or it may reflect an unsuspected carcinoma. Downloaded 2024129 1:8 A Your IP is 82.116.202.56 Stool samples for culture should be taken in patients with suspected gastroenteritis, dysentery, or cholera. Clostridium difficile should bePage on the 12 / 19 Chapter 23: The Acute Abdomen, Sameer Hirji; Reza Askari differential of anyone with a recent course of antibiotic therapy. ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Imaging Studies C. Stool Tests EUROPEAN UNIVERSITY CYPRUS Access Provided by: Gastrointestinal bleeding is not a common feature of the acute abdomen. Nonetheless, testing for occult fecal blood should be performed on a case bycase basis. A positive test points to a mucosal lesion that may be responsible for large bowel obstruction or chronic anemia, or it may reflect an unsuspected carcinoma. Stool samples for culture should be taken in patients with suspected gastroenteritis, dysentery, or cholera. Clostridium difficile should be on the differential of anyone with a recent course of antibiotic therapy. Imaging Studies Radiographic imaging is now routinely used to aid in the diagnosis and even treatment of the acute abdomen. It is of utmost importance that the surgeon, who is familiar with the clinical scenario of the patient, reviews all images. It should be remembered that patients in distress with concern for abdominal catastrophe may be moved to the operating room without any confirmatory imaging. A. Plain Chest XRay Studies An upright chest xray is essential in all cases of an acute abdomen. Not only is it vital for preoperative assessment, but it may also demonstrate supradiaphragmatic conditions that simulate an acute abdomen (eg, lower lobe pneumonia or ruptured esophagus). An elevated hemidiaphragm or pleural effusion may direct attention to subphrenic inflammatory lesions. Subdiaphragmatic air, if present, suggests perforated viscous and may forego the need for additional imaging. An upright chest radiograph is more sensitive than abdominal plain films for free intraperitoneal air. B. Plain Abdominal XRay Studies Plain supine films of the abdomen should be obtained only selectively, especially if the facility does not have a computed tomography (CT) scanner. In general, erect (or lateral decubitus) views contribute little additional information except in suspected intestinal obstruction, and they rarely eliminate the need for further imaging. Plain films are indicated in patients with signs and symptoms of intestinal obstruction or in patients with suspected foreign body ingestion. They are inappropriate in pregnant patients, unstable individuals in whom clear physical signs mandating laparotomy already exist, or patients with only mild, resolving, nonspecific pain. When looking at plain radiographs, one should observe the gas pattern of the hollow viscera; an abnormal bowel gas pattern suggests paralytic ileus, mechanical bowel obstruction, or pseudoobstruction. Bowel obstructions are usually accompanied by findings of gaseous distention, airfluid levels, distended cecum, and a paucity of air in the rectum. Colonic dilatation is seen in toxic megacolon or volvulus (see Figures 32–16 and 32–18). “Thumbprint” impressions on the colonic wall are noted in about half of patients with ischemic colitis. Radiopaque densities may be seen with biliary, renal, or ureteral calculi, as well as in the case of foreign bodies. Free air under the hemidiaphragm suggests a perforated viscous, although it does not identify the source. Its presence in approximately 80% of perforated ulcers corroborates the clinical diagnosis. Massive pneumoperitoneum is observed in free colonic perforations. Biliary tree air designates a biliaryenteric communication, such as a gallstone ileus. Air delineating the portal venous system characterizes pylephlebitis. C. Ultrasonography The role of ultrasonography is becoming increasingly important in the early evaluation of abdominal pain because it is often used bedside by a trained physician. It is one of the first exams for right upper quadrant pain that is biliary in nature. Ultrasonography has a diagnostic sensitivity of about 80% for acute appendicitis and is most useful in pregnant patients due its safe modality and lower cost. It becomes technically difficult in the third trimester due to the large gravid uterus and is also difficult in obese patients. Ultrasound also plays a role in evaluating a variety of gynecologic causes of abdominal pain. Color Doppler studies can distinguish avascular cysts and twisted masses from inflammatory and infectious processes. Ultrasound with Doppler may also be useful in evaluating for flow through the mesenteric vessels. The bedside test can also be helpful in quickly assessing unstable patients where transfer for CT might not be possible. The focused assessment with sonography for trauma (FAST) is a limited ultrasound examination directed at identifying presence of free intraperitoneal fluid, especially in the trauma setting. D. Computed Tomography Scan CT scan of the abdomen has proved extremely useful in the evaluation of abdominal complaints for patients who do not already have clear indications for laparotomy or laparoscopy. CT provides excellent diagnostic accuracy and is often readily available. Whether contrast is used should be carefully weighed on an individual basis. Intravenous (IV) contrast administration may be limited by creatinine impairment. Oral contrast is useful to distinguish bowel from remaining abdominal contents and also to diagnose bowel perforations or anastomotic leaks. It can be administered orally or rectally, but oral administration adds significant time to obtaining imaging and may not be appropriate in severely ill patients. CT scans should be used sparingly in Downloaded 2024129 Your IP poses is 82.116.202.56 pregnancy because of the1:8 riskAradiation to the fetus, especially in the first trimester. Ultrasound and magnetic resonance imaging (MRI) are Page 13 / 19 Chapter 23: The Acute Abdomen, Sameer Hirji; Reza Askari preferred imaging techniques in pregnancy. ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility CT can identify small amounts of free intraperitoneal gas and sites of inflammatory diseases that may prompt (appendicitis, tuboovarian abscess) or postpone (noncomplicated diverticulitis, pancreatitis, hepatic abscess) operation. It should not replace or delay operation in a patient for whom the EUROPEAN CYPRUS CT scan of the abdomen has proved extremely useful in the evaluation of abdominal complaints for patients who do not alreadyUNIVERSITY have clear indications Access Provided by: for laparotomy or laparoscopy. CT provides excellent diagnostic accuracy and is often readily available. Whether contrast is used should be carefully weighed on an individual basis. Intravenous (IV) contrast administration may be limited by creatinine impairment. Oral contrast is useful to distinguish bowel from remaining abdominal contents and also to diagnose bowel perforations or anastomotic leaks. It can be administered orally or rectally, but oral administration adds significant time to obtaining imaging and may not be appropriate in severely ill patients. CT scans should be used sparingly in pregnancy because of the risk radiation poses to the fetus, especially in the first trimester. Ultrasound and magnetic resonance imaging (MRI) are preferred imaging techniques in pregnancy. CT can identify small amounts of free intraperitoneal gas and sites of inflammatory diseases that may prompt (appendicitis, tuboovarian abscess) or postpone (noncomplicated diverticulitis, pancreatitis, hepatic abscess) operation. It should not replace or delay operation in a patient for whom the findings will not change the decision to operate. CT has proven helpful in the diagnosis of appendicitis, especially where exam and laboratory data may not be clear, and is recommended in females, in whom other pelvic pathology may explain the presence of right lower quadrant pain. E. Angiography CT angiography (CTA), percutaneous invasive angiographic studies, or magnetic resonance angiography (MRA) is indicated if intestinal ischemia or ongoing hemorrhage is suspected. They should precede any gastrointestinal contrast study that might obscure film interpretation. Selective visceral angiography is a reliable method of diagnosing mesenteric infarction. Emergency angiography may be diagnostic (eg, confirm a ruptured liver adenoma or carcinoma or an aneurysm of the splenic artery or other visceral artery) as well as therapeutic (eg, for coiling or embolizing aneurysmal disease). In patients with massive lower gastrointestinal bleeding, angiography may identify the bleeding site, suggest the likely diagnosis (eg, vascular ectasia, polyarteritis nodosa), and be therapeutic if embolization can be performed. Angiography is of little value in ruptured aortic aneurysm or if frank peritoneal findings (peritonitis) are present. It is contraindicated in unstable patients with severe shock or sepsis and seldom warranted if other findings or tests already dictate the need for laparotomy or laparoscopy. A patient’s renal function should be considered before contrast is administered. MRA is useful when a patient is unable to undergo IV contrast administration (due to either renal impairment or contrast dye allergy). It is additionally used as an alternative imaging modality in pregnancy. F. Gastrointestinal Contrast XRay Studies Gastrointestinal contrast studies should not be requested routinely or be regarded as screening studies. They are helpful only if a specific condition being considered can be verified or treated by a contrast xray examination. For suspected perforations of the esophagus or gastroduodenal area without pneumoperitoneum, a watersoluble contrast medium (eg, meglumine diatrizoate [Gastrografin]) is preferred. If there is no clinical evidence of bowel perforation, a barium enema may identify the level of a large bowel obstruction or even reduce a sigmoid volvulus or intussusception. Upper gastrointestinal contrast studies can also be helpful in the bariatric patient population to evaluate for leak or gastric pouch emptying. G. Radionuclide Scans The utility of radionuclide scans has been greatly decreased by the routine availability of urgent CT scans. Liverspleen scans, hepatobiliary iminodiacetic acid (HIDA) scans, and gallium scans may be useful for localizing intraabdominal abscesses in rare cases. Radionuclide blood pool or Tc sulfur colloid scans may identify sources of slow or intermittent intestinal bleeding. Technetium pertechnetate scans may reveal ectopic gastric mucosa in Meckel diverticulum. Endoscopy Proctosigmoidoscopy is indicated in any patient with suspected large bowel obstruction, grossly bloody stools, or a rectal mass. Minimal air should be used for bowel insufflation to minimize iatrogenic bowel perforation. Besides reducing a sigmoid volvulus, colonoscopy may also locate the source of bleeding in cases of lower gastrointestinal hemorrhage that has subsided. Gastroduodenoscopy and endoscopic retrograde cholangiopancreatography (ERCP) are usually done electively to evaluate less urgent inflammatory conditions (eg, gastritis, peptic disease) in patients without alarming abdominal signs. However, urgent ERCP may be indicated in cases of suspected cholangitis. Paracentesis Although performing paracentesis is becoming increasingly rare, it is important to understand that in patients with free peritoneal fluid, aspiration of blood, bile, or bowel contents is a strong indication for laparotomy. On the other hand, infected ascitic fluid may establish a diagnosis in spontaneous bacterial peritonitis, tuberculous peritonitis, or chylous ascites, which rarely require surgery. Laparoscopy Downloaded 2024129 1:8 A Your IP is 82.116.202.56 Laparoscopy is a therapeutic as well as diagnostic modality. The role of laparoscopy has broadened to be a useful modality in the treatment of 14 / 19 Page Chapter 23: The Acute Abdomen, Sameer Hirji; Reza Askari abdominal emergencies. In certain cases, it has been associated with decreased pain and faster recovery times. Its use is dependent on surgeon ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility experience and hospital and operating room equipment and staffing. Although performing paracentesis is becoming increasingly rare, it is important to understand that in patients with free peritoneal fluid, aspiration of EUROPEAN UNIVERSITY CYPRUS blood, bile, or bowel contents is a strong indication for laparotomy. On the other hand, infected ascitic fluid may establish a diagnosis in spontaneous Access Provided by: bacterial peritonitis, tuberculous peritonitis, or chylous ascites, which rarely require surgery. Laparoscopy Laparoscopy is a therapeutic as well as diagnostic modality. The role of laparoscopy has broadened to be a useful modality in the treatment of abdominal emergencies. In certain cases, it has been associated with decreased pain and faster recovery times. Its use is dependent on surgeon experience and hospital and operating room equipment and staffing. In cases of unclear diagnosis, laparoscopy helps guide surgical planning and avoid unneeded laparotomies. In young women, it may distinguish a nonsurgical problem (ruptured graafian follicle, pelvic inflammatory disease, tuboovarian disease) from appendicitis. In obese patients, it may allow for a smaller, less morbid incision. In obtunded, elderly, or critically ill patients, who often have deceptive manifestations of an acute abdomen, it may facilitate earlier treatment in those with positive findings while eliminating the added morbidity of a laparotomy in negative cases. Any patient undergoing laparoscopy must be suited to tolerate conversion to an open procedure when necessary. This aspect must be communicated with the patient and discussed prior to proceeding to the operating room. DIAGNOSTIC UNCERTAINTY As the surgeon gathers data, the differential diagnosis is narrowed and associated with a clear direction of plan. The plan of action should focus on whether the patient will need to: Go directly to the operating room Be admitted for surgical observation and expected operative intervention Be admitted for surgical observation or further diagnostics Be admitted to medical service for nonoperative abdominal pain Several patient populations may fall out of the expected presentation of the patient with an acute abdomen. The clinical picture in early cases is often unclear. The following observations should be borne in mind: 1. Acute abdominal pain persisting for over 6 hours should be regarded as indicating a surgical problem requiring inhospital evaluation. Well localized pain and tenderness usually indicate a surgical condition. Systemic hypoperfusion with generalized abdominal pain is seldom nonsurgical. 2. Acute appendicitis and intestinal obstruction (usually small bowel) are the most frequent final diagnoses in cases erroneously believed at first to be nonsurgical. Appendicitis should remain a foremost concern if sepsis or an inflammatory lesion is suspected. It is the most common cause of bizarre peritoneal findings producing ileus or intestinal obstruction. Pelvic appendicitis, with mild abdominal pain, vomiting, and frequent loose stools, simulates gastroenteritis. Atypical presentations of appendicitis are encountered during pregnancy. 3. Salpingitis, dysmenorrhea, ovarian lesions, and urinary tract infections complicate the evaluation of the acute abdomen in young women. Diagnostic errors can be avoided by taking a careful gynecologic history and performing a pelvic examination and urinalysis. Always consider a pregnancy test. CT scan can help confirm the diagnosis. 4. Unusual types or atypical manifestations of intestinal obstruction are easily missed. Emesis, abdominal distention, and airfluid levels on xray may be negligible in Richter hernia, proximal or closedloop small bowel obstructions, and early cecal volvulus. Intestinal obstruction in an elderly woman who has not had a previous operation suggests an incarcerated femoral hernia or, rarely, an obturator hernia or gallstone ileus. 5. Elderly or cardiac patients with severe unrelenting diffuse abdominal pain but no peritoneal signs may have intestinal ischemia. Arterial blood pH and lactate should be measured and visceral angiography or CTA performed expediently. 6. Medical causes of the acute abdomen should be considered and excluded if possible before exploratory laparotomy is planned (Table 23–5). Upper abdominal pain may be encountered in myocardial infarction, acute pulmonary conditions, pancreatitis, and acute hepatitis. Generalized or migratory abdominal discomfort may be felt in acute rheumatic fever, polyarteritis nodosa, and other vasculitides. Acute bursitis and hip joint disorders can produce pain radiating into the lower quadrants. 7. Beware of acute cholecystitis, acute appendicitis, and perforated peptic ulcer in patients already hospitalized for an illness affecting another organ system. Always perform a systematic evaluation as previously emphasized. Downloaded 2024129 1:8 A Your IP is 82.116.202.56 Page 15 / 19 Chapter 23: The Acute Abdomen, Sameer Hirji; Reza Askari Table 23–5. ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Medical causes of an acute abdomen for which surgery is not indicated. abdominal pain may be encountered in myocardial infarction, acute pulmonary conditions, pancreatitis, and acute hepatitis. Generalized or EUROPEAN UNIVERSITY CYPRUS migratory abdominal discomfort may be felt in acute rheumatic fever, polyarteritis nodosa, and other vasculitides. Acute bursitis and hip joint Access Provided by: disorders can produce pain radiating into the lower quadrants. 7. Beware of acute cholecystitis, acute appendicitis, and perforated peptic ulcer in patients already hospitalized for an illness affecting another organ system. Always perform a systematic evaluation as previously emphasized. Table 23–5. Medical causes of an acute abdomen for which surgery is not indicated. Endocrine and metabolic disorders Infections and inflammatory disorders Uremia Tabes dorsalis Diabetic crisis Herpes zoster Addisonian crisis Acute rheumatic fever Acute intermittent porphyria HenochSchönlein purpura Acute hyperlipoproteinemia Systemic lupus erythematosus Hereditary Mediterranean fever Hematologic disorders Sickle cell crisis Polyarteritis nodosa Referred pain Thoracic region Acute leukemia Myocardial infarction Other dyscrasias Acute pericarditis Toxins and drugs Pneumonia Lead and other heavy metal poisoning Pleurisy Narcotic withdrawal Pulmonary embolus Black widow spider poisoning Pneumothorax Empyema Hip and back SPECIAL POPULATIONS Elderly Physicians are increasingly exposed to elderly patients given the rising population of older patients. Most often, elderly patients presenting with an acute abdomen are more likely to require surgical intervention. However, the presence of comorbidities adds complexity to their presentation and overall risk of surgical intervention. For example, patients with cardiovascular disease, whether known or unknown, will be more likely to present with acute mesenteric ischemia as a cause of abdominal pain. One of the most frequent causes of acute abdominal pain in the elderly is bowel obstruction. The etiology of these bowel obstructions will differ from younger populations, with malignancy and hernias higher on the differential. Elderly patients tend to present later in their course of illness. Many will have past surgical history, which can make operative intervention technically challenging. Bariatrics Obesity is increasingly prevalent in the United States, and weightloss surgery (either gastric bypass surgery or sleeve gastrectomy) has become relatively common. This patient population presents both its own differential for the acute abdomen and its own anatomic challenge to the surgeon. Physical exam findings may be vague due to the patient’s body habitus. Tachycardia is an ominous sign that should not be dismissed. Common causes of acute abdomen in the bariatric population include marginal ulcers, obstruction due to internal hernias or adhesions, and gastric band complications. Due to the common formation of gallstones following rapid weight loss, cholecystitis is another frequent cause of the acute abdomen in postbypass patients. These patients almost always need a CT scan for further evaluation. Pregnancy Prompt diagnosis and management of acute abdomen in pregnant women can be particularly challenging, as they often present with confounding symptoms. Normal pregnancy may be associated with nausea and vomiting or mild leukocytosis. Physical exam may also be misleading due to the shift in organs secondary to their enlarged uterus. Thus, importantly, abdominal pain problems must be dealt with immediately because delay may be detrimental to both the mother and the fetus. The most common cause of the acute abdomen in pregnancy is appendicitis. Appendicitis in pregnancy may present with pain in 1:8 atypical locations due to displacement by the uterus. As the gravid uterus pushes the appendix cephalad and often Downloaded 2024129 A Your IP is 82.116.202.56 16 / 19 Chapter 23: The Acute Abdomen, Sameer Hirji; posteriorly, right lower quadrant pain remains theReza mostAskari consistent symptom in any trimester. Pain may also be present in the right upper Page quadrant, or ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility if the appendix is pushed posteriorly, patients may not demonstrate peritoneal pain. One way to differentiate pain due to appendicitis from uterine pain is with the help of the Adler sign: if the point of maximal tenderness shifts medially with repositioning on the left lateral side, then the etiology is Pregnancy EUROPEAN UNIVERSITY CYPRUS Provided by: with confounding Prompt diagnosis and management of acute abdomen in pregnant women can be particularly challenging, as theyAccess often present symptoms. Normal pregnancy may be associated with nausea and vomiting or mild leukocytosis. Physical exam may also be misleading due to the shift in organs secondary to their enlarged uterus. Thus, importantly, abdominal pain problems must be dealt with immediately because delay may be detrimental to both the mother and the fetus. The most common cause of the acute abdomen in pregnancy is appendicitis. Appendicitis in pregnancy may present with pain in atypical locations due to displacement by the uterus. As the gravid uterus pushes the appendix cephalad and often posteriorly, right lower quadrant pain remains the most consistent symptom in any trimester. Pain may also be present in the right upper quadrant, or if the appendix is pushed posteriorly, patients may not demonstrate peritoneal pain. One way to differentiate pain due to appendicitis from uterine pain is with the help of the Adler sign: if the point of maximal tenderness shifts medially with repositioning on the left lateral side, then the etiology is usually (not always) due to adnexa or uterine. It should be noted that guarding and rebound tenderness may not manifest in the third trimester given the relative laxity of the abdominal wall muscles. Once diagnosed, early operative intervention is indicated because ruptured appendicitis leads to increased risk of fetal loss. However, it should be noted that the risk of spontaneous abortion at operation tends to be highest in the first trimester. If the patient is hemodynamically stable and the appendix is not ruptured, treatment with IV antibiotics may be appropriate in certain scenarios, although nonoperative management of acute appendicitis is associated with higher rate of recurrence. These risks should be weighed against the benefits of the procedure itself at the time of evaluation. Immunocompromised Immunosuppressed patients present a unique challenge, because their immune response will not mount the same presentation as an otherwise healthy patient. This population includes patients with HIV/AIDS, diabetics, patients on chemotherapy, transplant patients, and patients on steroid therapy. Immunosuppressed patients have a wider differential including many obscure medical etiologies, such as various opportunistic infections. Due to the lack of inflammatory response, physical exam may present as not concerning. The examiner should be wary of a “benign exam” in light of an otherwise concerning clinical picture. These patients often do not mount an expected leukocytosis. Delayed diagnosis may be devastating because patients often present with advanced disease, shock, or peritonitis, with limited reserve. INDICATIONS FOR SURGICAL EXPLORATION The need for operation is apparent when the diagnosis is certain, but surgery sometimes must be undertaken before a precise diagnosis is reached. Table 23–6 lists some indications for urgent laparotomy or laparoscopy. Among patients with acute abdominal pain, those over age 65 more often require operation (33%) than do younger patients (15%). Table 23–6. Indications for urgent operation in patients with an acute abdomen. Physical findings Involuntary guarding or rigidity, especially if spreading Increasing or severe localized tenderness Tense or progressive distention Tender abdominal or rectal mass with high fever or hypotension Rectal bleeding with shock or acidosis Equivocal abdominal findings along with septicemia (high fever, marked or rising leukocytosis, mental changes, or increasing glucose intolerance in a diabetic patient) Bleeding (unexplained shock or acidosis, falling hematocrit) Suspected ischemia (acidosis, fever, tachycardia) Deterioration on conservative treatment Downloaded 2024129 1:8 A Your IP is 82.116.202.56 Chapter 23: The Acute Abdomen, Sameer Hirji; Reza Askari Radiologic findings ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Pneumoperitoneum Page 17 / 19 INDICATIONS FOR SURGICAL EXPLORATION EUROPEAN UNIVERSITY CYPRUS The need for operation is apparent when the diagnosis is certain, but surgery sometimes must be undertaken before a precise diagnosis is reached. Access Provided by: Table 23–6 lists some indications for urgent laparotomy or laparoscopy. Among patients with acute abdominal pain, those over age 65 more often require operation (33%) than do younger patients (15%). Table 23–6. Indications for urgent operation in patients with an acute abdomen. Physical findings Involuntary guarding or rigidity, especially if spreading Increasing or severe localized tenderness Tense or progressive distention Tender abdominal or rectal mass with high fever or hypotension Rectal bleeding with shock or acidosis Equivocal abdominal findings along with septicemia (high fever, marked or rising leukocytosis, mental changes, or increasing glucose intolerance in a diabetic patient) Bleeding (unexplained shock or acidosis, falling hematocrit) Suspected ischemia (acidosis, fever, tachycardia) Deterioration on conservative treatment Radiologic findings Pneumoperitoneum Gross or progressive bowel distention Free extravasation of contrast material Spaceoccupying lesion on scan, with fever Mesenteric occlusion on angiography Endoscopic findings Perforated or uncontrollably bleeding lesion A liberal policy of exploration is advisable in patients with inconclusive but persistent right lower quadrant tenderness. Pain in the left upper quadrant infrequently requires urgent laparotomy, and its cause can usually await elective confirmatory studies. PREOPERATIVE MANAGEMENT After initial assessment, parenteral analgesics for pain relief should not be withheld. In moderate doses, analgesics neither obscure useful physical findings nor mask their subsequent development. Indeed, abdominal masses may become obvious once rectus spasm is relieved. Pain that persists despite adequate doses of narcotics suggests a serious condition often requiring operative correction. Resuscitation of acutely ill patients should proceed based on their intravascular fluid deficits and systemic diseases. Medications should be restricted to essential requirements. Particular care should be given to use of cardiac drugs and corticosteroids and to control of diabetes. Antibiotics are indicated for some infectious as prophylaxis in the perioperative period. They should be immediately initiated if sepsis due to perforated Downloaded 2024129 1:8 Aconditions Your IP isor82.116.202.56 Page 18 / 19 Chapter 23: The Acute Abdomen, Sameer Hirji; Reza Askari viscous is suspected. ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility A nasogastric tube should be inserted in patients with hematemesis or copious vomiting, suspected bowel obstruction, or severe paralytic ileus. This precaution may prevent aspiration in patients suffering from drug overdose or alcohol intoxication, patients who are comatose or debilitated, or After initial assessment, parenteral analgesics for pain relief should not be withheld. In moderate doses, analgesics neither obscure useful physical findings nor mask their subsequent development. Indeed, abdominal masses may become obvious once rectus spasm is relieved. Pain that persists EUROPEAN UNIVERSITY CYPRUS despite adequate doses of narcotics suggests a serious condition often requiring operative correction. Access Provided by: Resuscitation of acutely ill patients should proceed based on their intravascular fluid deficits and systemic diseases. Medications should be restricted to essential requirements. Particular care should be given to use of cardiac drugs and corticosteroids and to control of diabetes. Antibiotics are indicated for some infectious conditions or as prophylaxis in the perioperative period. They should be immediately initiated if sepsis due to perforated viscous is suspected. A nasogastric tube should be inserted in patients with hematemesis or copious vomiting, suspected bowel obstruction, or severe paralytic ileus. This precaution may prevent aspiration in patients suffering from drug overdose or alcohol intoxication, patients who are comatose or debilitated, or elderly patients with impaired cough reflexes. A urinary catheter should be placed in patients with systemic hypoperfusion. In some elderly patients, it eliminates the cause of pain (acute bladder distention) or unmasks relevant abdominal signs. Informed consent for surgery may be difficult to obtain when the diagnosis is uncertain. It is prudent to discuss with the patient and family the possibility of multiple staged operations, temporary or permanent stomal openings, impotence or sterility, and postoperative mechanical ventilation. Whenever the exact diagnosis is uncertain—especially in young, frail, or severely ill patients—a frank preoperative discussion of the diagnostic dilemma and reasons for laparotomy or laparoscopy will reduce postoperative anxieties and misunderstanding. Discussing goals of care, especially in frail and elderly patients, is also key. REFERENCES Flum D: Acute appendicitis: appendectomy or the “antibiotics first” strategy. N Engl J Med. 2015;372:1937–1943. [PubMed: 25970051] Gans S, Pols M, Stoker J, et al: Guideline for the diagnostic pathway in patients with acute abdominal pain. Dig Surg. 2015;32(1):23–31. [PubMed: 25659265] Lewis K, Takenaka K, Luber S: Acute abdominal pain in the bariatric surgery patient. Emerg Med Clin. 2016;34:387–407. Spangler R, Van Pham T, Khoujah D, et al: Abdominal emergencies in the geriatric patient. Int J Emerg Med. 2014;7:43. [PubMed: 25635203] Strasberg S: Acute calculous cholecystitis. N Engl J Med. 2008;358:2804–2811. [PubMed: 18579815] Downloaded 2024129 1:8 A Your IP is 82.116.202.56 Chapter 23: The Acute Abdomen, Sameer Hirji; Reza Askari ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility Page 19 / 19

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