Acute Appendicitis




Obstruction of lumen -->   lumen wall dilates and thickens --> bacterial overgrowth and breakdown of mucosal barrier --> inflammation of wall causes peritonitis --> perforation releases bacteria into peritoneal cavity



1-8% of children in urgent care setting for abdominal pain, lower incidence but higher rate of perforation in children 0-4 years of age

Factors associated with increased risk of perforation (Hung et al 2012):

  • Age <4yo
  • Pain >24 hrs at presentation
  • Fever
  • Muscle guarding
  • Elevated CRP (not WBC!)

Clinical Signs/Symptoms

Fever + Anorexia (absent in 40%) + migration to RLQ (absent in 50%)

History and PE:

  • Neonates: abdominal distension, palpable mass, hypothermia, hypoTN, irritability
  • Infants: vomiting, fever, R hip complaints, diarrhea, diffuse tenderness
  • Preschool: vomiting b/f pain, anorexia
  • School age: abdominal pain and vomiting uniformly present, anorexia

Location of McBurney's point (1), located two thirds the distance from the umbilicus (2) to the right anterior superior iliac spine (3)

General Exam tips:

children prefer to lie still with hips flexed, splinting, rovsing’s sign (pain in RLQ w/ palpation on L), obturator sign (pain on internal rotation of hip à appendix in pelvis), iliopsoas sign (pain on extension of R hip à retrocecal appendix)

Details of the HPI( a. duration of pain, b. hx of emesis, c. presence of abdominal tenderness and d. pain with activity)  more reliably elicited from patients than physical exam findings (Kharbanda et al 2012)

Lab Findings

Elevations in WBC and CRP, UA to r/o other causes (although 7-25% of kids with appendicitis have pyruia), b-HCG in young girls

Serial lab findings more sensitive (84%) for diagnosis than initial clinical presentation alone (63%)—specifically changes in CRP, neutrophil count, and bands (Li et al 2011)

Evaluation and Diagnosis

Remember analgesia! (doesn’t mask findings or delay diagnosis)

clinical picture + lab findings +/-imaging

There are several clinical predictor algorithms available (see below), for score <2 can send patient home, scores >7 require surgical consult, intermediate scores may benefit from imaging


Note: neonatal appendicitis, while rare, should be on the differential in a toxic-appearing neonate with abdominal distension. If initial radiographs/US don’t show signs of NEC, have a low-threshold for laparoscopy/laparotomy to asses for appendicitis (Schwartz et al 2011)


Equivocal clinical picture:  graded compression US --> negative/equivocal findings -->  focused CT with IV contrast  (may go straight to CT in obese children)




-74-100% sensitivity, 88-99% specificity

-0.5% false negative, 33% false positive

-inaccurate exam a/w higher BMI and low pretest clinical suspicion

-fat absorbs and diffuses US beam

-findings: free fluid, diameter >6mm, wall thickness >2mm, calcified appendicolith, thickening of mesentery

-visualization of appendix rate 22-98%


-95-100% sensitivity, 93-100% specificity

-less operator dependent, establishes alternative diagnoses for abdominal pain

-radiation exposure to a growing childà3-10mSv (Ref: 2.4mSv/year is background radiation)


No changes in perforation rates since introduction of imaging, but a decrease in negative appendectomy rates as been noted (Bachur et al 2012)

Imaging and lab work increases the rate of definitive diagnosis significantly—when clinical picture, labwork, and imaging agree the false positive rate is just 1% (Gendel et al 2011)

There is a lower rate of CT-alone in children’s hospitals  suggesting education is needed at other centers on the proper imaging choices for kids (Raval et al 2012), similarly pediatric ultrasonographers better at identifying the appendix on US (Trout et al 2012)

Differential Diagnosis

  • Surgical emergencies: bowel obstruction, malrotation, intussusceptions, ovarian/testicular torsion, ectopic, torsion of omenutm
  • Nonsurgical emergencies: HUS, DKA, primary peritonitis
  • Nonsurgical: nephrolithiasis, SCD, HSP, PID, PNA, UTI, gastroenteritis


  • Early: analgesia, hydration, single prophylactic dose of broad spectrum antibiotics
  • Perforation/Gangrene: can do early vs. interval appendectomy!, minimum 5 days post-op abx
    • ​Patient who received interval appendectomy (abx course and then appy 6-8 wks after diagnosis) had inc time away from normal activity and increased rates of adverse events when compared with early appendectomy for perforated appendicitis (Blakely et al 2011)
  • Appendiceal Abscess/Phlegmon: pt present >5-7 days from onset, can initially be treated non-operatively if no s/s peritonitis (requires CT scan on admission to identify candidates for percutaneous drainage)


  • Early:  post-op infection and abscess formation, intestinal dysfunction
  • Late: SBO from adhesions, stump appendicitis


  1. Bachur RG, Hennelly K, Callahan MJ, Chen C, Monuteaux MC. Diagnostic Imaging and Negative Appendectomy Rates in Children: Effects on Age and Gender. Pediatrics 2012; 129 (5): 877-884.
  2. Blakely ML, Williams R, Dassinger MS, et al. Early vs. Interval Appendectomy for Children with Perforated Appendicitis. Archives of Surgery. 2011; 146(6): 660-665.
  3. Gendel I, Gutermacher M, Buklan G, et al. Relative value of clinical, laboratory and imaging tools in diagnosing pediatric acute appendicitis. Eur J Pediatr Surg 2011; 21(4): 229-22.
  4. Hung MH, Lin LH, Chen DF. Clinical manifestations in children with rupture appendicitis. Pedatr Emerg Care 2012; 28 (5): 433-5.
  5. Kharbanda AB, et al. Interrater Reliability of Clinical Findings in Children with Possible Appendicitis. Pediatrics 2012; 129 (4): 695-700.
  6. Li YC, Chen CY, Huang MY, Wu KH, Yang WC, Wu HP. Significant change between primary and peated serum laboratory tests at different time points in pediatric appendicitis. Eur J Emerg Med 2011; Epub ahead of print.
  7. Raval MV, Deans KJ, Rangel SJ, Kelleher KJ, Moss RL. Factors associated with imaging modality choice in children with appendicitis. J Surg Res 2012; Epub
  8. Schwartz KL, Gilad E, Sigalet D, et al. Neonatal acute apendicitis: a proposed algorithm for timely diagnosis. J Pediatr Surg 2011; 46(11): 2060-4.
  9. Trout AT, Sanchez R, Ladino-Torres MF, et al. A critical evaluation of US for the diagnosis of pediatric acute appendicitis in real-life setting: how can we improve the diagnostic value of sonography?. Pediatr Radiol 2012; Epub