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appendicitis

Etiology: 1) appendiceal lumenal obstruction resulting in vascular congestion, edema & inflammation a) appendicolith - consists of fecal material - most common etiology (40%) - appendicoliths are associated with more inflammation & higher risk for abscess &/or perforation [31] b) calculi c) inspissated barium from previous contrast study d) Helminths - pinworms, tapeworms, roundworms e) carcinoma f) carcinoid g) submucosal lymphoid hyperplasia secondary to viral infection 2) immunocompromised patients a) tuberculosis b) cytomegalovirus c) Cryptosporidium d) Kaposi's sarcoma Epidemiology: - incidence of appendicitis increases with increasing temperature, independent of season [34] Clinical manifestations: 1) classic symptoms are infrequent 2) abdominal pain a) initially, poorly localized periumbilical pain (4-6 hr) b) right lower quadrant pain with rebound tenderness 1] McBurney's point is the point of maximal tenderness in the classic presentation 2] if pain subsides temporarily, suspect perforation 3) nausea/vomiting 4) anorexia 5) low-grade fever, consider perforation if T > 101 F 6) hyperesthesia may be present 7) a mass in the right lower quadrant suggests a periappendiceal abscess 8) right-sided tenderness on rectal examination Laboratory: 1) complete blood count (CBC) a) leukocytosis generally 10,00-20,000/mm3 with band forms b) WBC > 20,000/mm3 should raise suspicion of perforation c) WBC may be normal in immunocompromised hosts 2) peripheral blood smear for toxic granulation 3) urinalysis: microscopic hematuria or pyuria may occur if inflamed appendix abuts bladder 4) urine pregnancy test in women of child-bearing age 5) stool guaiac Radiology: 1) multidetector computed tomography* (CT) [8] a) sensitivity, 98.5% b) specificity, 98.0%; c) negative predictive value, 99.5% d) positive predictive value, 93.9%. 2) computed tomography (CT) with rectal contrast a) presence of inflammatory mass b) abscess c) appendicolith d) thickened appendiceal wall may enhance with contrast e) sensitivity 99%, specificity 95%, positive-predictive value 93%, negative-predicitive value 99% [4] f) low-dose CT as good as standard CT [10,23] g) addition of oral contrast to IV contrast does not improve accuracy [14] 3) plain abdominal film a) appendicolith b) blurring of right psoas margin c) lumbar scoliosis with convexity to the right d) sentinel loop of bowel in right-lower quadrant e) gas-containing abscess or pneumoperitoneum with perforation 4) graded-compression ultrasound a) appendix appears fluid-filled, non-compressible & > 6 mm in diameter b) radiographic exam of choice in women of child-bearing age c) first examination in children [26] d) sensitivity of ultrasound increases with symptom duration - 81% for < 12 hours versus 96% for 49-71 hours e) specificity of ultrasound: 80%-86% [11] 5) cross-sectional magnetic resonance imaging if ultrasound inconclusive & radiation exposure from CT to be avoided [12] i.e. pregnancy - MRI for appendicitis s 92%, specificity was 98% - heterogeneity among studies is high for sensitivity [25] 6) barium enema: complete opacification of the appendix excludes the diagnosis * clinical scoring systems perform as well as physician gestalt in predicting appendicitis; they do not obviate the need for imaging when a physician deems it necessary [20] Differential diagnosis: 1) cholecystitis 2) diverticulitis - including Meckel's diverticulitis 3) gastroenteritis 4) ectopic pregnancy 5) acute salpingitis 6) tubo-ovarian abscess 7) mittelschmerz 8) ovarian torsion 9) ruptured ovarian cyst 10) ureteral calculus 11) pyelonephritis 12) perinephric abscess 13) Crohn's disease 14) Yersinia enterocolitis 15) mesenteric adenitis 16) psoas abscess 17) torsion of an undescended testicle 18) perforated duodenal ulcer 19) omental torsion 20) mucocele 21) strangulated inguinal hernia 22) Mycobacterium avium intracellulare in patients with AIDS 23) intussusception 24) volvulus Complications: 1) perforation 2) periappendiceal abscess 3) 4-fold increase in colorectal cancer with 1 year [35] Management: 1) pelvic examination on all women 2) hospitalization 3) antibiotics coverage for gram-negative aerobic bacilli (E. coli), obligate anaerobes (Bacteroides sp.), & enteric Streptococci (S. milleri) a) antibiotic treatment as an alternative to surgery is controversial [16] - may be a reasonable alternative [16] - feasible for the initial treatment of uncomplicated appendicitis in adults [24] - fever of > 38 C, diameter of appendix > 14 mm or presence of an appendicolith predict failure of antibiotic therapy [32,33] - amoxicillin-clavulanate alone may prevent need for surgery in 68% of patients [7,9] - 10 days of antibiotics [29] - recurrence rate is 27% [16] - slightly higher appendectomy rate with oral antibiotic monotherapy [38] b) appendectomy remains standard of care [7,9] c) at 7 years, quality of life similar with antibiotics vs appendectomy, but satisfaction higher with appendectomy [27] d) nonoperative treatment fails during the index hospital admission in 15% [37] - 25% undergo later appendectomy, generally within 1 year - 60% without appendectomy after 25 years [37] 4) mild to moderate infections: a) cefoxitin, moxifloxacin [30], or ticarcillin-clavulanic acid, or b) metronidazole plus cefazolin, cefuroxime, ceftriaxone, cefotaxime, ciprofloxacin, or levofloxacin c) anti-pseudomonal or anti-enterococcal activity not needed 5) high risk (elderly, immunocompromised) or severe infection: a) imipenem-cilastatin, meropenem, doripenem, or piperacillin-tazobactam, or b) combination of metronidazole plus cefepime, ceftazidime, ciprofloxacin, or levofloxacin c) Enterococcal coverage recommended 6) pregnancy - see appendicitis in pregnant patients - surgery should not be delayed because of pregnancy (imaging first) 7) pediatrics: a) ertapenem, meropenem, imipenem-cilastatin, ticarcillin-clavulanate, or piperacillin-tazobactam, or b) combination of metronidazole plus ceftriaxone, cefotaxime, cefepime, or ceftazidime, or c) combination of gentamicin or tobramycin plus metronidazole or clindamycin, with or without ampicillin d) cefoxitin may be as effective as piperacillin-tazobactam [19] e) selected uncomplicated cases may be treated successfully with antibiotics alone (without surgery) [13,28] f) failure rate for surgery less than antibiotics alone especially if appendicolith (1% vs 10%) [21,33] 8) surgical consultation: a) immediate surgery (appendectomy) unless patient is poor surgical risk or diagnosis is uncertain [3] b) if patient is poor surgical risk 1] treat with intravenous (IV) antibiotics as long as symptoms are subsiding 2] percutaneous drainage for perforation with peri- appendiceal abscess c) s d) delay of surgery for 12-24 hours in clinically stable patients does not affect outcomes [5] e) appendectomy performed within 24 hours of presentation is not associated with perforation or other complications [22] f) laparoscopic surgery recommended [29] g) operative management associated with reduced mortality, length of hospital stay, & overall costs than medical manangement (all ages) [36] - complications fewer in older patients with medical management [36] 9) prognosis a) 0.7% mortality in young healthy adults b) 31% mortality in the elderly with abscess or perforation

Interactions

disease interactions

Related

appendectomy appendix; vermiform appendix

Specific

appendicitis in pregnant patients

General

acute inflammation intestinal disease

Database Correlations

OMIM 107700

References

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