Acute Appendicitis PDF

The Appendix By: Zaid Haydar Introduction and anatomy: The function of the appendix is not entirely clear, but it may have important roles in both immune function and maintaining the gut microbiota. The putative role of the appendix in the pathogenesis of ulcerative colitis (appendice...

The Appendix By: Zaid Haydar Introduction and anatomy: The function of the appendix is not entirely clear, but it may have important roles in both immune function and maintaining the gut microbiota. The putative role of the appendix in the pathogenesis of ulcerative colitis (appendicectomy seems to be protective) for example, may be explained by its interaction with the intestinal flora and gut immune function. The vermiform appendix is a blind muscular tube with mucosal, submucosal, muscular and serosal layers. The position of the appendix is variable in humans:  The position of the base of the appendix is constant, being found at the confluence of the three taeniae coli of the caecum. At operation, use can be made of this to find an elusive appendix, as gentle traction on the taeniae coli, particularly the anterior taenia, will lead the operator to the base of the appendix.  The average length of the appendix is between 7.5 and 10 cm. Blood supply: Appendicular artery (branch of the lower division of the ileocolic artery). An accessory appendicular artery may be present but, in most people, the appendicular artery is an ‘end-artery’, thrombosis of which results in necrosis of the appendix. Lymphatic drainage: 4, 6, or more lymphatic channels traverse the mesoappendix to empty into the ileocecal lymph nodes. Nerve supply: derived from sympathetic elements contributed by the superior mesenteric plexus (T10-L1) Acute appendicitis Epidemiology: Acute appendicitis is the most common cause of an ‘acute abdomen’ in young adults. Appendicectomy is the most frequently performed urgent abdominal operation. Acute appendicitis is relatively rare in infants and becomes increasingly common in childhood and early adult life, reaching a peak incidence in the teens and early 20s. After middle age, the risk of developing appendicitis is quite small. The incidence of appendicitis is equal among males and females before puberty. In teenagers and young adults, the male–female ratio increases to 3:2 at age 25; thereafter, the greater incidence in males declines. Etiology: There is no unifying hypothesis regarding the etiology of acute appendicitis, but there are predisposing factors: 1. Obstruction: (most important factor). It is usually due to faecolith (hard feces) or swelling of lymphoid in response to viral infection. It may also be due to stricture (due to past appendicitis that resolved spontaneously), parasites, particularly Oxyuris vermicularis (pinworm), FBs, undigested seeds, or tumors of appendix or cecum (especially in middle aged and elderly patients). 2. Anatomical factors: A narrow lumen & its wall is rich in lymphoid follicles. 3. Diet: Decreased dietary fiber and increased consumption of refined carbohydrates may be important.  A faecolith (AKA appendicolith) is composed of inspissated fecal material, calcium phosphates, bacteria and epithelial debris. The incidental finding of a faecolith is a relative indication for prophylactic appendicectomy or an interval appendicetomy in a patient treated conservatively. No single organism is responsible for acute appendicitis. A mixed growth of aerobic and anaerobic organisms is usual. A fibrotic stricture of the appendix usually indicates previous appendicitis that resolved without surgical intervention. Pathology Obstruction of the appendiceal lumen seems to be essential for the development of appendiceal gangrene and perforation. However, in many cases of early appendicitis, the appendix lumen is patent despite the presence of mucosal inflammation and lymphoid hyperplasia. Occasional clustering of cases among children and young adults suggests an infective agent, possibly viral, which initiates an inflammatory response. Seasonal variation in the incidence is also observed. Once obstruction occurs, continued mucus secretion and inflammatory exudation increase intraluminal pressure, obstructing lymphatic drainage. Edema and mucosal ulceration develop with bacterial translocation to the submucosa. Resolution may occur at this point either spontaneously or in response to antibiotic therapy.  If the condition progresses, further distension of the appendix may cause venous obstruction and ischemia of the appendix wall. With ischemia, bacterial invasion occurs through the muscularis propria and submucosa, producing acute appendicitis. Finally, ischemic necrosis of the appendix wall produces gangrenous appendicitis, with free bacterial contamination of the peritoneal cavity. Alternatively, the greater omentum and loops of small bowel become adherent to the inflamed appendix, walling off the spread of peritoneal contamination and resulting in a phlegmonous mass or paracecal abscess. Rarely, appendiceal inflammation resolves, leaving a distended mucus-filled organ termed a mucocele of the appendix. It is the potential for diffuse peritonitis that is the great threat of acute appendicitis. Peritonitis occurs as a result of free migration of bacteria through an ischemic appendicular wall, frank perforation of a gangrenous appendix or delayed perforation of an appendix abscess. Risk factors for perforation of appendix: 1. Extremes of age 2. Immunosuppression 3. Diabetes mellitus 4. Faecolith obstruction 5. Pelvic appendix 6. Previous abdominal surgery Clinical features Symptoms: Poorly localized periumbilical pain Pain shifting to the right iliac fossa Anorexia Nausea & vomiting Fever Murphy’s triad: abdominal pain + N&V + fever Notes: Why does the pain begin as a poorly localized pain, maximum in the periumbilical region? It’s poorly localized because inflammation and obstruction of the appendix causes visceral pain (visceral pain is poorly localized.) It’s maximum in the periumbilical region because afferent sensory fibers from the appendix are carried on the sympathetic nerve fibers to enter the spinal cord at T10, which corresponds to the umbilical dermatome. This pain is similar to, but less intense than, the colic of small bowel obstruction. Why does the pain later shift to the RIF? With progressive inflammation of the appendix, the parietal peritoneum in the RIF becomes irritated, producing more intense, constant and localized somatic pain. Patients often report this as an abdominal pain that has shifted and changed in character. The classic visceral–somatic sequence of pain is present in only about half of those patients subsequently proven to have acute appendicitis. Atypical presentations include pain that is predominantly somatic or visceral and poorly localized. Atypical pain is more common in the elderly, in whom localization to the right iliac fossa is unusual.  Typically, coughing or sudden movement exacerbates the RIF pain. Anorexia is a useful and constant clinical feature, particularly in children. It usually precedes the pain. The patient often gives a history of similar discomfort that settled spontaneously. A family history is also useful as up to one-third of children with appendicitis have a first-degree relative with a similar history. Vomiting occurs once or twice and after the pain. If it is persistent, it indicates complications.  Typically, two clinical syndromes of acute appendicitis can be discerned, acute catarrhal (non-obstructive) appendicitis and acute obstructive appendicitis, the latter characterised by a more acute course. The onset of symptoms is abrupt and there may be generalised abdominal pain from the start. The temperature may be normal and vomiting is common, so the clinical picture may mimic acute intestinal obstruction. * Non obstructive Signs: Low grade pyrexia: During the first 6 hours, there is rarely any alteration in temperature or pulse rate. After that, slight pyrexia (37.2–37.7ºC) with an increase in the pulse rate to 80 or 90 is usual. However, in 20% of patients there is no pyrexia or tachycardia in the early stages. In children, a temperature greater than 38.5ºC suggests other causes (e.g. mesenteric adenitis Localised tenderness in the right iliac fossa Muscle guarding (over the point of maximum tenderness, classically McBurney’s point), and limitation of respiratory movement in the lower abdomen. Rebound tenderness (Blumberg’s sign) Signs to elicit in appendicitis: Pointing sign: patient is asked to point to where the pain began and where it moved. Rovsing’s sign: Deep palpation of the LIF may cause pain in the RIF. Psoas sign: Pt. will lie with the right hip flexed for pain relief, and hyperextension of the right hip will cause abdominal pain. This sign occurs because an inflamed appendix occasionally lies on the psoas muscle, causing its spasm. Obturator sign: flexion and int. rotation of the hip will cause pain in the hypogastrium. This sign occurs because an inflamed appendix occasionally lies on the obturator internus muscle, causing its spasm. Cutaneous hyperesthesia (in the sheren’s triangle) may be demonstrable in the RIF, but is rarely of diagnostic value. Special clinical features, according to position of the appendix Retrocecal: Rigidity is often absent, and even application of deep pressure may fail to elicit tenderness (silent appendix), the reason being that the caecum, distended with gas, prevents the pressure exerted by the hand from reaching the inflamed structure. However, deep tenderness is often present in the loin, and rigidity of the quadratus lumborum may be in evidence. Psoas sign indicates that the appendix is retrocecal. Pelvic: Occasionally, early diarrhea results from an inflamed appendix being in contact with the rectum. An inflamed appendix in contact with the bladder may cause frequency of micturition. This is more common in children. When the appendix lies entirely within the pelvis, there is usually complete absence of rigidity, and tenderness over McBurney’s point is also lacking. In some instances, deep tenderness can be made out just above and to the right of the symphysis pubis. In either event, a rectal examination reveals tenderness in the rectovesical pouch or the pouch of Douglas, especially on the right side. (This is the basis for the recommendation that a DRE should be performed on every patient who presents with acute lower abdominal pain) Spasm of the psoas and obturator internus muscles may be present when the appendix is in this position. Postileal: It presents the greatest difficulty in diagnosis because the pain may not shift, diarrhea is a feature and marked retching may occur. Tenderness, if any, is ill defined, although it may be present immediately to the right of the umbilicus. Special clinical features, according to age Infants: Patient is unable to give a history, so the diagnosis is often delayed, and thus the incidence of perforation and morbidity is higher. Diffuse peritonitis can develop rapidly because of the underdeveloped greater omentum, which is unable to localize the infection. Children: It is rare to find a child with appendicitis who has no anorexia and vomiting. The elderly: They have higher mortality for the following reasons: Gangrene and perforation occur much more frequently in elderly patients. Elderly patients with a lax abdominal wall or obesity may harbor a gangrenous appendix with little evidence of it, and clinical picture may simulate subacute intestinal obstruction. Coincident medical conditions The obese: Obesity can obscure the local signs of acute appendicitis and the clinician may have to rely on imaging to establish the diagnosis. Laparoscopy is particularly useful as it may obviate the need for a large abdominal incision. Pregnancy: Appendicitis is the most common extrauterine acute abdominal condition in pregnancy, with a frequency of 1:1500–2000 pregnancies. Diagnosis can be delayed as early symptoms are often attributed to the pregnancy. The caecum and appendix are pushed to the RUQ of the abdomen as pregnancy develops. However, pain in the RLQ remains the cardinal feature of appendicitis in pregnancy. Fetal loss occurs in 3–5% of cases, increasing to 20% if perforation is found at operation. Differential diagnosis of acute appendicitis: The differential diagnosis differs in patients of different ages: *The diseases most commonly mistaken for acute appendicitis in children are acute gastroenteritis and mesenteric lymphadenitis.  Key point… Diagnosis of appendicitis is essentially clinical. However, a decision to operate based on clinical suspicion alone can lead to removal of a normal appendix in 15–30% of cases. A number of scoring systems have been devised to assist diagnosis. The most widely used is the Alvarado score. Interpretation: Score < 3: Low likelihood of appendicitis 4–6: Consider further imaging (CT or US) ≥ 7: High likelihood of appendicitis US is more useful in children and thin adults, particularly if gynecological pathology is suspected, with a diagnostic accuracy > 90%. CT is both sensitive and specific (approximately 95%) in the diagnosis of acute appendicitis.  Typical US findings in appendicitis include:  Non-compressible appendix (> 6mm in diameter)  Appendicolith within the appendix  Wall thickening (≥ 3mm) with associated hyperemia CT has been shown to reduce the rate of negative appendicectomy without an associated increased perforation rate (due to delay in diagnosis) and may be cost-effective due to shorter hospital stay.  Radiation exposure and the theoretical carcinogenic effect are a concern in CT scans. Low-dose protocols, which reduce the radiation dose to the patient by up to 80%, can be as reliable as standard dose scanning and may be more appropriate in the younger adult. Contrast-enhanced standard dose CT is especially useful in patients in whom there is diagnostic uncertainty, particularly older patients, where acute diverticulitis, intestinal obstruction and neoplasm are likely differential diagnoses. Investigations: Treatment Non-operative management: While surgery remains the standard teaching, there is an emerging body of literature to support a trial of conservative management in patients with uncomplicated (absence of appendicolith, perforation or abscess) appendicitis. Treatment is bowel rest and IV antibiotics, often metronidazole and 3rd generation cephalosporin. More recently, ertapenem has been used in this setting and has the benefit of broad antimicrobial cover administered as a single daily dose. The available data indicate initial successful outcomes in more than 90% of Patients. However, approximately 25% of patients initially treated conservatively will require surgery within 1 year for recurrent appendicitis. Subsequent surgery, if needed, tends to be uncomplicated. This approach may be considered in the well patient with limited signs or those with high operative risk (multiple co-morbidities). Patients over the age of 40 should be followed up to ensure there is no underlying malignancy. Operative management The traditional treatment for acute appendicitis is appendicectomy, preceded by a short period of intensive preoperative preparation by IV fluids and ABs (in addition to salicylates in the case of hyperpyrexia in children). a single peroperative dose of ABs reduces the incidence of postoperative wound infection. When peritonitis is suspected, therapeutic IV ABs to cover gram-negative bacilli as well as anaerobic cocci should be given. With appropriate use of IV fluids and ABs, a policy of deferring appendicectomy after midnight to the first case on the following morning does not increase morbidity. However, when acute obstructive appendicitis is recognized, operation should not be deferred longer than it takes to optimize the patient’s condition.  Appendicectomy should be performed under GA with the patient supine on the operating table and may be undertaken using either an open or laparoscopic approach. Advantages of laparoscopy include:  Allows the diagnosis to be established and may reduce the negative appendicectomy rate.  Quicker recovery  Rate of wound infection is lower  The incidence of postoperative pelvic collection does not appear to be increased. Types of incisions: Gridiron incision: made at right angles to a line joining the ASIS to the umbilicus, its center being along the line at McBurney’s point. Rutherford Morison incision: essentially an oblique muscle-cutting incision with its lower end over McBurney’s point and extending obliquely upwards and laterally as necessary. Its used when better access is required, as it is possible to convert the gridiron to a Rutherford Morison incision. It’s useful if the appendix is para- or retrocecal and fixed. Transverse skin crease (Lanz) incision: better exposure and easier extension. Its made approximately 2 cm below the umbilicus centred on the midclavicular– mid-inguinal line. When necessary, the incision may be extended medially, with retraction or suitable division of the rectus abdominis muscle.  When the diagnosis is in doubt, particularly in the presence of intestinal obstruction, a lower midline abdominal incision is to be preferred over a right lower paramedian incision. The latter, although widely practised in the past, is difficult to extend, more difficult to close and provides poorer access to the pelvis and peritoneal cavity. Problems encountered during appendicectomy A normal appendix is found This demands careful exclusion of other possible diagnoses, particularly terminal ileitis, Meckel’s diverticulitis and tubal or ovarian causes in women. It is usual to remove the appendix to avoid future diagnostic difficulties, even though the appendix is macroscopically normal, particularly if a skin crease or gridiron incision has been made. A case can be made for preserving the macroscopically normal appendix seen at diagnostic laparoscopy, although approximately one-quarter of seemingly normal appendices show microscopic evidence of inflammation. The appendix cannot be found The caecum should be mobilized, and the taeniae coli should be traced to their confluence on the caecum before the diagnosis of ‘absent appendix’ is made. An appendicular tumor is found Small tumors (under 2 cm in diameter) can be removed by appendicectomy; larger tumors should be treated by a right hemicolectomy. Appendicitis complicating Crohn’s disease Occasionally, a patient undergoing surgery for acute appendicitis is found to have concomitant Crohn’s disease of the ileocaecal region. Providing that the cecal wall is healthy at the base of the appendix, appendicectomy can be performed without increasing the risk of an enterocutaneous fistula. Rarely, the appendix is involved with the Crohn’s disease. In this situation, a conservative approach may be used, and a trial of IV corticosteroids and ABs can be used to resolve the acute inflammatory process. Complications of appendicitis: I. Appendicular Mass (Phlegmonous mass): Mechanism: In non obstructive type → gives time for the greater omentum , cecum , loops of intestine and adhesions to surround the inflamed appendix. This occurs on the 3rd day after the onset of the condition. Fate of Appendicular Mass: 1. Usually it resolves within few weeks. 2. Or there may be perforation inside the mass → appendicular abscess. Clinical features: History suggests acute appendicitis 2-3 days ago. High temperature > 38°C. Firm tender mass in the right iliac fossa ,with overlying muscle guarding, therefore it is usually diagnosed only by exam. under anesthesia in the operating theater before the operation. Treatment: The standard treatment is the conservative Ochsner–Sherren regime. This strategy is based on the premise that the inflammatory process is already localized and that inadvertent surgery is difficult and may be dangerous; It may be impossible to find the appendix and, occasionally, a fecal fistula may form. Ochsner-sherren regime: 1. Rest 2. NG tube, gastric suction, NPO & IV fluid until nausea subsides, then start oral feeding gradually. 3. Antibiotics 4. After confirming diagnosis, analgesics can be prescribed for pain. 5. Close observation Antibiotics used: Combination of ampicillin, aminoglycoside & metronidazole (Triple therapy). Given first IV then oral. This regime should be followed by an interval appendectomy 8-12 weeks later.  Recording of the patient’s condition and the extent of the mass should be made and the abdomen regularly examined. It is helpful to mark the limits of the mass by a skin pencil. Temperature and pulse rate should be recorded 4-hourly and a fluid balance record maintained. Contrast CT abdomen should also be performed. Clinical improvement is usually evident within 24–48 hours. Using this regime, approximately 90% of cases resolve without incident. Failure of the mass to resolve should raise suspicion of a carcinoma or Crohn’s disease. Criteria for stopping conservative treatment of an appendix mass 1. A rising pulse rate 2. Increasing or spreading abdominal pain 3. Increasing size of the mass II. Appendicular abscess Clinical features: History suggests acute appendicitis 5-10 days ago. Progressive fever, hectic fever & tachycardia. Tense cystic tender swelling in the right iliac fossa. Pain increases and becomes throbbing with persistent vomiting. US confirms the diagnosis by presence of fluid inside the mass. Treatment: Same as for an appendicular mass + US-guided percutaneous drainage. Rarely this is unsuccessful and laparotomy though a midline incision is indicated. III. Pelvic abscess an occasional complication of appendicitis and can occur irrespective of the position of the appendix. The most common presentation is a spiking pyrexia several days after appendicitis; indeed, the patient may already have been discharged from hospital. Pelvic pressure or discomfort associated with loose stool or tenesmus is common. DRE reveals a boggy mass in the pelvis, anterior to the rectum. US or CT will confirm. Traditionally, treatment has been through transrectal drainage under general anesthetic; however, increasing availability of radiologically guided percutaneous drainage has reduced the need considerably. IV. Perforation and peritonitis (discussed on slide 13) Post-op complications: I. Wound infection: most common postoperative complication, occurring in 5–10% of patients. Presents on the 4th or 5th post-op day, soon after hospital discharge. Treatment is by wound drainage and antibiotics. The organisms responsible are usually a mixt of gram-negative bacilli and anaerobic bacteria, predominantly Bacteroides and anaerobic streptococci. II. Adhesive intestinal obstruction: commonest late complication of appendicectomy. At operation, a single band adhesion is often found to be responsible. Occasionally, chronic pain in the RIF is attributed to adhesion formation after appendicectomy. In such cases, laparoscopy is of value in confirming the diagnosis and allowing division. III. Intra-abdominal abscess: incidence of 8%. In an era of hospital discharge 24–48 hours following appendectomy, patients should be advised prior to discharge that a spiking fever, malaise and anorexia developing 5–7 days after operation is suggestive of an intraperitoneal collection and that urgent medical advice should be obtained. Interloop, paracolic, pelvic and subphrenic sites should be considered. US and CT allow diagnosis and percutaneous drainage. Laparotomy should be considered in patients suspected of having intra-abdominal sepsis but in whom imaging fails to show a collection, particularly those with continuing ileus. IV. Ileus: A period of adynamic ileus is to be expected after appendicectomy, and this may last a number of days following removal of a gangrenous appendix. Ileus persisting for more than 4 or 5 days, particularly in the presence of a fever, is indicative of continuing intra-abdominal sepsis and should prompt further investigation. Rarely, early during post-op recovery, a Richter’s type of hernia may occur at the site of a laparoscopic port insertion and may be confused with a postoperative ileus. A CT scan is usually definitive. V. Respiratory: In the absence of concurrent pulmonary disease, respiratory complications are rare following appendicectomy. Adequate postoperative analgesia and physiotherapy reduce the incidence. VI. Venous thrombosis and embolism: rare, except in the elderly and in women taking oral contraceptive pills. VII. Portal pyaemia (pylephlebitis): a rare but very serious complication of gangrenous appendicitis associated with high fever, rigors and jaundice. It is caused by septicemia in the portal venous system and leads to the development of intrahepatic abscesses (often multiple). Treatment is with antibiotics and percutaneous drainage. A screen for underlying thrombophilia should be considered. VIII. Fecal fistula: Leakage from the appendicular stump occurs rarely, but may follow if the encircling stitch has been put in too deeply or if the cecal wall was involved by edema or inflammation. Occasionally, a fistula may result following appendicectomy in Crohn’s disease. Recurrent acute appendicitis: Rarely, inflammation of the appendix may present as a chronic condition characterized by recurrent episodes of lower abdominal pain. It is thought to arise as a consequence of incomplete self- limiting obstruction of the appendix lumen. The attacks vary in intensity and may occur every few months, and the majority of cases ultimately culminate in severe acute appendicitis. If a careful history is taken from patients with acute appendicitis, many remember having had milder but similar attacks of pain. The appendix in these cases is thickened and shows fibrosis indicative of previous inflammation.  The Anki deck for this lecture will be available on the telegram channel!