• Inflammation of the appendix 2/2 outlet obstruction (w/ fecalith, 2/2 lymphoid hyperplasia, etc.), fills w/ mucus under pressure w/ vascular/lymphatic stasis of appendiceal wall. This can result in inflammation of surrounding structures and/or rupture
Epidemiology (BMJ 2006;333:530; N Engl J Med 2003;348:236)
• Most common surgical abd emergency in peds; most common in teen yr, slightly M > F
• ∼20% of pts undergoing ex lap for appendectomy have normal appendix
Differential Diagnosis
• Same as for acute abdomen; specifically consider other RLQ structures (nephrolithiasis, testicular or ovarian torsion, ovarian cyst, ectopic pregnancy, PID, intussusception, IBD, UTI, or pyelonephritis)
Clinical Manifestations (JAMA 2007;298:438)
• Only 50% patients have classic symptoms described by Murphy w/ colicky periumbilical abdominal pain, followed by N/V, anorexia, and subsequent migration of pain to RLQ
• Can also (but may not) see diarrhea, constipation, fever, bilious emesis, etc.
• Generally w/ pain progressing from central to RLQ w/i 24 hr
• More difficult to ascertain Hx in younger pts; w/ increased time to diagnosis and higher risk of perforation (delay in rx of >36 hr results in perforation rate of ∼65%)
• Abdominal exam for guarding and rebound (evidence of peritonitis), localization of pain (usually RLQ but can vary in small children w/ retrocecal or pelvic appendix)
• McBurney point: ⅔ down along line from umbilicus to anterior superior iliac spine; classically point of maximal tenderness in simple appendicitis (BMJ 2006;333:530)
• Rovsing sign: Palpation of LLQ w/ pain in RLQ; sens 30%, spec 84%
• Psoas sign: Pain w/ straight leg extension at R leg while lying on R side; inflamed appendix lying on R psoas muscle. Sens 26–36%, spec 86–87%
• Obturator sign: Pain w/ flexion and internal rotation at R hip; inflamed appendix in contact w/ obturator internus muscle. Sens 28%, spec 87%
• Complete PE (including pelvic or testicular exam) as lobar PNA, testicular or ovarian torsion or ectopic pregnancy can all mimic appendicitis
• W/ perforation, pain initially crescendos then improves w/ subsequent worsening clinical status, progression to frank peritonitis and shock
• PAS & Alvarado scoring systems do not have adequate predictive values. (Am J Emerg Med 2011;29:972); though modified Alvarado may ↓ CT use (Arch Surg 2011;146:64)
Diagnostic Studies (JAMA 2007;298:438; Pediatr Ann 2008;37:433; Radiology 2006;241:83)
• Evaluate w/ CBC diff. Based on history and PE, consider electrolytes w/ LFTs (esp sexually active female), amy, lipase, type & screen, U/A, Bcx and Ucx, CRP/ESR
• Inc WBC w/ sens 67% and spec 80%. Low/nml WBC NPV 92%. Left shift sens 59%, spec 90%. High WBC & left shift combined sens 79%, spec 80% (Pediatr Emerg Care 2007;23:69)
• Abd U/S – no radiation; assess for noncompressible, fluid-filled, blind tube >6 mm in diameter in RLQ. Limited by body habitus and inter-operator variability. In pediatric patients, sens 88% (95% CI: 86%, 90%) and spec 94% (95% CI: 92%, 95%)
• Abd imaging is often obtained; studies are equivocal w/ regard to ↓ time to OR and ↓ false + rate abd CT in pediatric patients (I+/O+, often w/ rectal contrast) – very sensitive 94% (95% CI: 92%, 97%), spec 95% (95% CI: 94%, 97%) and high PPV; w/ dilated (>7 mm) fluid-filled appendix w/ thickened walls, failure of contrast to fill appendix and fat stranding or can show other etiologies for pain
• Young children <10 yo tend to have limited fat which decreases visualization rate of appendix and can lead to equivocal studies (AJR Am J Roentgenol 2001;176:497)
Management and Complications (BMJ 2006;333:530)
• Managed w/ surgical removal of appendix, very low rates of surgical complications
• The most common complication is appendiceal rupture prior to OR w/ subsequent peritonitis
• Risk of perforation w/ >36 hr from sx onset 16–36%, inc 5% every 12 hr thereafter
• Lower SES confers ↑ risk for rupture to school-aged children (JAMA 2004;292:1977)
• Mgmt w/ triple Abx (amp/gent/Flagyl) and surgical clean out once inflammation quiets; now single-agent rx w/ pip/tazo shown to be equivalent (Pediatrics 2007;119:905)