appendicitis

Etiology

• appendiceal lumenal obstruction resulting in vascular congestion, edema & inflammation
  • appendicolith
    • consists of fecal material
    • most common etiology (40%)
    • appendicoliths are associated with more inflammation & higher risk for abscess &/or perforation
  • calculi
  • inspissated barium from previous contrast study
  • Helminths
    • pinworms, tapeworms, roundworms
  • carcinoma
  • carcinoid
  • submucosal lymphoid hyperplasia secondary to viral infection
• immunocompromised patients
  • tuberculosis
  • cytomegalovirus
  • Cryptosporidium
  • Kaposi's sarcoma

Epidemiology

• incidence of appendicitis increases with increasing temperature, independent of season

Clinical manifestations

• classic symptoms are infrequent
• abdominal pain
  • initially, poorly localized periumbilical pain (4-6 hr)
  • right lower quadrant pain with rebound tenderness
    • McBurney's point is the point of maximal tenderness in the classic presentation
    • if pain subsides temporarily, suspect perforation
• nausea/vomiting
• anorexia
• low-grade fever, consider perforation if T > 101 F
• hyperesthesia may be present
• a mass in the right lower quadrant suggests a periappendiceal abscess
• right-sided tenderness on rectal examination

Laboratory

• complete blood count (CBC)
  • leukocytosis generally 10,00-20,000/mm3 with band forms
  • WBC > 20,000/mm3 should raise suspicion of perforation
  • WBC may be normal in immunocompromised hosts
• peripheral blood smear for toxic granulation
• urinalysis: microscopic hematuria or pyuria may occur if inflamed appendix abuts bladder
• urine pregnancy test in women of child-bearing age
• stool guaiac

Radiology

• multidetector computed tomography* (CT)
  • sensitivity, 98.5%
  • specificity, 98.0%;
  • negative predictive value, 99.5%
  • positive predictive value, 93.9%.
• computed tomography (CT) with rectal contrast
  • presence of inflammatory mass
  • abscess
  • appendicolith
  • thickened appendiceal wall may enhance with contrast
  • sensitivity 99%, specificity 95%, positive-predictive value 93%, negative-predicitive value 99%
  • low-dose CT as good as standard CT
  • addition of oral contrast to IV contrast does not improve accuracy
• plain abdominal film
  • appendicolith
  • blurring of right psoas margin
  • lumbar scoliosis with convexity to the right
  • sentinel loop of bowel in right-lower quadrant
  • gas-containing abscess or pneumoperitoneum with perforation
• graded-compression ultrasound
  • appendix appears fluid-filled, non-compressible & > 6 mm in diameter
  • radiographic exam of choice in women of child-bearing age
  • first examination in children
  • sensitivity of ultrasound increases with symptom duration
    • 81% for < 12 hours versus 96% for 49-71 hours
  • specificity of ultrasound: 80%-86%
• cross-sectional magnetic resonance imaging if ultrasound inconclusive & radiation exposure from CT to be avoided i.e. pregnancy
  • MRI for appendicitis s 92%, specificity was 98%
  • heterogeneity among studies is high for sensitivity
• 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

Complications

• perforation
• periappendiceal abscess
• 4-fold increase in colorectal cancer with 1 year

Differential diagnosis

• cholecystitis
• diverticulitis - including Meckel's diverticulitis
• gastroenteritis
• ectopic pregnancy
• acute salpingitis
• tubo-ovarian abscess
• mittelschmerz
• ovarian torsion
• ruptured ovarian cyst
• ureteral calculus
• pyelonephritis
• perinephric abscess
• Crohn's disease
• Yersinia enterocolitis
• mesenteric adenitis
• psoas abscess
• torsion of an undescended testicle
• perforated duodenal ulcer
• omental torsion
• mucocele
• strangulated inguinal hernia
• Mycobacterium avium intracellulare in patients with AIDS
• intussusception
• volvulus

Management

• pelvic examination on all women
• hospitalization
• antibiotics coverage for gram-negative aerobic bacilli (E. coli), obligate anaerobes (Bacteroides sp.), & enteric Streptococci (S. milleri)
  • antibiotic treatment as an alternative to surgery is controversial
    • may be a reasonable alternative
      • feasible for the initial treatment of uncomplicated appendicitis in adults
      • fever of > 38 C, diameter of appendix > 14 mm or presence of an appendicolith predict failure of antibiotic therapy
      • amoxicillin-clavulanate alone may prevent need for surgery in 68% of patients
    • 10 days of antibiotics
    • recurrence rate is 27%
    • slightly higher appendectomy rate with oral antibiotic monotherapy
  • appendectomy remains standard of care
  • at 7 years, quality of life similar with antibiotics vs appendectomy, but satisfaction higher with appendectomy
  • nonoperative treatment fails during the index hospital admission in 15%
    • 25% undergo later appendectomy, generally within 1 year
    • 60% without appendectomy after 25 years
• mild to moderate infections:
  • cefoxitin, moxifloxacin, or ticarcillin-clavulanic acid, or
  • metronidazole plus cefazolin, cefuroxime, ceftriaxone, cefotaxime, ciprofloxacin, or levofloxacin
  • anti-pseudomonal or anti-enterococcal activity not needed
• high risk (elderly, immunocompromised) or severe infection:
  • imipenem-cilastatin, meropenem, doripenem, or piperacillin-tazobactam, or
  • combination of metronidazole plus cefepime, ceftazidime, ciprofloxacin, or levofloxacin
  • Enterococcal coverage recommended
• pregnancy
  • see appendicitis in pregnant patients
  • surgery should not be delayed because of pregnancy (imaging first)
• pediatrics:
  • ertapenem, meropenem, imipenem-cilastatin, ticarcillin-clavulanate, or piperacillin-tazobactam, or
  • combination of metronidazole plus ceftriaxone, cefotaxime, cefepime, or ceftazidime, or
  • combination of gentamicin or tobramycin plus metronidazole or clindamycin, with or without ampicillin
  • cefoxitin may be as effective as piperacillin-tazobactam
  • selected uncomplicated cases may be treated successfully with antibiotics alone (without surgery)
  • failure rate for surgery less than antibiotics alone especially if appendicolith (1% vs 10%)
• surgical consultation:
  • immediate surgery (appendectomy) unless patient is poor surgical risk or diagnosis is uncertain
  • if patient is poor surgical risk
    • treat with intravenous (IV) antibiotics as long as symptoms are subsiding
    • percutaneous drainage for perforation with peri- appendiceal abscess
  • s
  • delay of surgery for 12-24 hours in clinically stable patients does not affect outcomes
  • appendectomy performed within 24 hours of presentation is not associated with perforation or other complications
  • laparoscopic surgery recommended
  • operative management associated with reduced mortality, length of hospital stay, & overall costs than medical manangement (all ages)
    • complications fewer in older patients with medical management
• prognosis
  • 0.7% mortality in young healthy adults
  • 31% mortality in the elderly with abscess or perforation

More general terms

• intestinal disease
• acute inflammation

More specific terms

• appendicitis in pregnant patients

Additional terms

• appendectomy
• appendix; vermiform appendix

Patient information

appendicitis patient information

Database

• OMIM: https://mirror.omim.org/entry/107700