Acute Appendicitis PDF

Bowel Disorders Part 2 ACUTE APPENDICITIS as the inflammatory process continues, the appendiceal serosa and adjacent structures EPIDEMIOLOGY...

Bowel Disorders Part 2 ACUTE APPENDICITIS as the inflammatory process continues, the appendiceal serosa and adjacent structures EPIDEMIOLOGY become inflamed. This inflammation triggers the somatic pain fibers, which innervate the While reports on the stability of the incidence peritoneal structures, typically localizing the of acute appendicitis vary, the incidence of pain in the right lower quadrant. This explains appendectomy appears to be declining due to the migration of pain from the periumbilical more accurate preoperative diagnosis. Still, area to the right lower quadrant, classically despite the introduction of newer imaging associated with acute appendicitis. techniques, acute appendicitis can be extremely difficult to diagnose. However, there are many exceptions to the classic presentation. These exceptions are often PATHOPHYSIOLOGY due to the variability of the anatomic location of the appendix. In a study of 71,000 human Acute appendicitis is thought to begin with an appendix specimens removed over a 40-year obstruction of the lumen. The obstruction can period, 26 percent were retrocecal, and 4 result from food matter, adhesions, or lymphoid percent were located in the right upper hyperplasia. Despite the obstruction, mucosal quadrant. With the retrocecal appendix, the secretion continues, leading to an increase in pain of acute appendicitis may localize to the intraluminal pressure. This pressure eventually flank rather than the right lower quadrant. will exceed capillary perfusion pressure and Similarly, in pregnant patients, the gravid will obstruct venous and lymphatic drainage. uterus may displace the appendix, leading to a With such vascular compromise, the epithelial presentation of right upper quadrant or flank mucosa begins to break down, allowing pain. In male patients, a retroileal appendicitis bacterial invasion by bowel flora. The may irritate the ureter, causing pain in the subsequent inflammatory response and edema testicle. A pelvic appendix may irritate the further exacerbate the increased intraluminal bladder or rectum and cause suprapubic pain, pressure. Eventually, this increased pressure pain with urination, or the feeling of a need to leads to arterial stasis and tissue infarction. The defecate. These anatomically based variations end result is perforation and spillage of the in presentation help to explain the difficulty in infected appendiceal contents into the making the diagnosis of acute appendicitis. peritoneum. CLINICAL FEATURES In order to understand the clinical presentation and the clinical progression of acute History appendicitis, it is important to consider the innervation and anatomic variability of the The primary symptom in acute appendicitis is appendix. Presumably, the initial luminal abdominal pain. In approximately one-half to distension triggers the visceral afferent pain two-thirds of patients with appendicitis, the fibers from the appendix, which enter the spinal pain evolves in a classic pattern. Beginning in cord at the tenth thoracic vertebra. As is the epigastrium or periumbilical region early in characteristic of visceral afferent innervation, the illness, the pain is vague initially and this pain is generally vague and poorly difficult to localize. Patients may describe their localized. Based on the anatomic level of these discomfort as indigestion or as a feeling of the afferent fibers at the tenth thoracic level, the need to defecate or pass flatus. In the classic pain generally is perceived by the patient at the presentation, periumbilical pain is followed by periumbilical or epigastric region. Eventually, anorexia, nausea, and vomiting. As the illness W:\Academy EMS\ACP yr1(ICP)\ACP Year One 2014-2015\Module 3 Resp_Gastro_BLS Recert\Day 9 Gastroenterology\Gastroenterology_Handouts\Acute Appendicitis.doc progresses, the pain becomes more localized, Additional components of the physical typically in the right lower quadrant. In one examination that may help in the diagnosis meta-analysis, right lower quadrant pain was 81 include rebound tenderness, voluntary percent sensitive and 53 percent specific for the guarding, local muscular rigidity over the diagnosis of acute appendicitis. Similarly, inflamed area (involuntary guarding), and migration of the pain from initial periumbilical tenderness on rectal examination. pain to the right lower quadrant was 64 percent sensitive and 82 percent specific for the Special manoeuvres that can aid in the diagnosis of acute appendicitis. diagnosis of acute appendicitis include the psoas sign and the obturator sign. The In addition to abdominal pain, the classic examiner checks for a psoas sign by placing the symptoms in appendicitis include anorexia, patient in the left lateral decubitus position and nausea, and vomiting. In acute appendicitis, extending the right leg at the hip. If an these symptoms typically appear after the onset inflamed appendix is overlying the psoas of vague abdominal pain. Anorexia is the most muscle, this manoeuvre will cause an increase common of these symptoms, with 68 percent in the patient’s pain, thereby eliciting a positive sensitivity and 36 percent specificity. Vomiting psoas sign. The obturator sign is evaluated by is more variable in acute appendicitis, occurring passively flexing the right hip and knee and in about half of patients with acute appendicitis. internally rotating the hip. This action will The significance of the temporal relationship stretch the obturator muscle. An inflamed between abdominal pain and onset of vomiting appendix may irritate the obturator muscle, and as a predictor of acute appendicitis has not yet this manoeuvre will increase pain, indicating a been established. positive obturator sign. Physical Examination Fever is another relatively late physical finding in acute appendicitis. At the onset of pain, the Like the history, the findings on physical patient’s temperature probably will be normal. examination of a patient with acute appendicitis If the temperature is taken frequently during the depend on the duration of the illness prior to the progression of the illness, it will usually rise 1 examination. Early in the course of acute to 2 degrees C. Temperatures above 39oC appendicitis, the patient may not have localized (102.2oF) are uncommon in the first 24 hours of tenderness. As the illness progresses, the the illness but not uncommon after rupture of patient typically develops tenderness, especially an appendix. to deep palpation, over McBurney’s point. This is a point just below the middle of a line DIAGNOSIS connecting the umbilicus and the anterosuperior iliac spine. Pain in the right lower quadrant The diagnosis of acute appendicitis should be with palpation of the left lower quadrant suspected in any individual with epigastric, (Rovsing sign) also may be elicited. As with periumbilical, right flank, or right-sided the subjective pain, the localization of abdominal pain who has not had an tenderness varies with the anatomic position of appendectomy. Women of childbearing age the appendix. If the patient has a pelvic should have a pelvic examination and appendix, the patient’s tenderness may be most pregnancy test to exclude gynaecologic causes pronounced on rectal examination. With a of pain. Additional studies including a retrocecal appendix, tenderness to palpation complete blood count (CBC), urinalysis (UA), may be attenuated by the overlying cecum or and imaging studies are often needed to help may be most pronounced in the right flank. make the diagnosis. Clinical observation is another common diagnostic modality. W:\Academy EMS\ACP yr1(ICP)\ACP Year One 2014-2015\Module 3 Resp_Gastro_BLS Recert\Day 9 Gastroenterology\Gastroenterology_Handouts\Acute Appendicitis.doc Special Populations used to aid in diagnosis, particularly in differentiating obstetric causes of pain from Certain groups of patients (e.g., very young, appendicitis. very old, pregnant, AIDS patients) present atypically and more often have delayed Patients with AIDS are particularly susceptible diagnosis as a result, with a concomitant to complications from appendicitis. Although increase in complications, such as appendiceal symptoms are no different for appendicitis in perforation. Very young patients present this population, diagnosis can be delayed insidiously. The rate of misdiagnosis is high, because of the baseline frequency of with a consequent increase in the perforation gastrointestinal symptoms unrelated to rate, particularly in children under 5 years of appendicitis and the occurrence of non-surgical age. Diagnosis in children can be confounded opportunistic pathologic conditions with similar by difficulty with communication and atypical presentations. One study noted a higher symptoms, including concurrent respiratory incidence of perforation in this population, symptoms or suspected gastroenteritis. possibly related to the delay in presentation or Peritonitis in children can present with varied to the immunocompromised state. One clear signs such as lethargy, inactivity, and difference in management relates to the WBC, hypothermia. A high index of suspicion and which is generally not elevated even in acute early surgical consultation are recommended appendicitis. for children. Ultrasound and CT scan also can be used to assist in diagnosis. Misdiagnosis rates in the elderly can exceed 50 TREATMENT percent, with a high incidence of perforation ranging from 40 to 70 percent. Mortality rates Appendectomy is the standard of care for acute for patients over age 70 with acute appendicitis appendicitis. Patients who are being prepared approach 30 percent. In addition to late for appendectomy should be given nothing by presentation with an advanced course, anatomic mouth, have intravenous (IV) fluid changes in the appendix involving the vascular resuscitation, and be given preoperative bed and reduced mural thickness are thought to antibiotics. Antibiotics are most effective when contribute to the fulminant course of given prior to surgery. In patients with appendicitis seen in the elderly. One study uncomplicated appendicitis, antibiotics found that the most significant predictors of decrease the incidence of postoperative wound acute appendicitis ain the aged were tenderness, infections. In patients with perforation, early rigidity, pain at diagnosis, fever, and previous antibiotics have been shown to decrease abdominal surgery. Since extensive laboratory postoperative abscess formation. studies may obscure the diagnosis in patients with other concurrent medical problems, a high index of clinical suspicion is needed in management of the elderly. Appendicitis remains the most common extra- uterine surgical emergency in pregnancy, and fetal mortality rates can be four times higher if the appendicitis is complicated by perforation and peritonitis. Consequently, the diagnosis of appendicitis must be entertained in any gravid patient presenting with abdominal pain and gastrointestinal symptoms. Ultrasound can be W:\Academy EMS\ACP yr1(ICP)\ACP Year One 2014-2015\Module 3 Resp_Gastro_BLS Recert\Day 9 Gastroenterology\Gastroenterology_Handouts\Acute Appendicitis.doc