Assessment and Management of Suspected Appendicitis

Initial Clinical Risk Stratification

The American College of Emergency Physicians recommends a risk-stratified clinical approach combining symptoms, physical examination, and laboratory findings to guide imaging decisions, with CT abdomen/pelvis with IV contrast as the primary diagnostic tool in non-pregnant adults, followed by prompt surgical consultation and broad-spectrum antibiotics once appendicitis is confirmed 1, 2, 3
Initial clinical risk stratification should begin by systematically assessing specific clinical predictors to categorize patients into low, intermediate, or high probability groups 1, 4
Fever >38°C combined with focal right lower quadrant tenderness is a high-risk clinical feature that warrants direct surgical consultation 4
Right lower quadrant pain without clear peritoneal signs is an intermediate-risk feature that requires obtaining imaging 1
Nausea with focal abdominal tenderness is an intermediate-risk feature that requires obtaining imaging 4
Equivocal physical examination findings are an intermediate-risk feature that requires obtaining imaging 1
Vomiting before pain onset makes appendicitis less likely and is a low-risk feature 2
Absence of right lower quadrant tenderness is a low-risk feature that may consider discharge with 24-hour follow-up 1
Normal vital signs with minimal laboratory abnormalities are low-risk features that may consider discharge with 24-hour follow-up 1

The American College of Emergency Physicians recommends obtaining WBC with differential and C-reactive protein in all patients with suspected appendicitis 2
WBC >10,000/mm³ AND CRP ≥8 mg/L combined has the strongest predictive value (positive likelihood ratio 23.32, negative likelihood ratio 0.03) 4
WBC >15,000/mm³ alone has a positive likelihood ratio of 3.47 4
Isolated WBC elevation has limited value (positive likelihood ratio only 1.59-2.7) 4
CRP ≥10 mg/L alone has a positive likelihood ratio of 4.24 4

The Alvarado score (adults) or Pediatric Appendicitis Score (children) should be applied to systematically integrate clinical findings, but never used alone to confirm appendicitis 2, 4
A score ≤3 on the Alvarado score indicates very low probability and considers discharge with 24-hour follow-up 4
A score of 4-6 on the Alvarado score indicates intermediate probability and requires obtaining imaging before any surgical decision 4
A score ≥7 on the Alvarado score indicates high probability and warrants surgical consultation with or without imaging 4

The American College of Emergency Physicians recommends CT abdomen and pelvis with IV contrast as the primary imaging modality in non-pregnant adults 1, 5
CT abdomen and pelvis with IV contrast has a sensitivity of 96-100% and specificity of 93-95% 5, 2
IV contrast is essential and increases sensitivity to 96% compared to unenhanced CT 5
Oral contrast is not necessary and delays diagnosis 5, 2
Ultrasound is the first-line imaging modality in children and adolescents to avoid radiation exposure, with a sensitivity of 76% (formal ultrasound) to 91% (point-of-care ultrasound by emergency physicians) and specificity of 95-97% 2, 3
Ultrasound findings indicating appendicitis include appendiceal diameter ≥7 mm, non-compressibility, and focal tenderness 2
MRI without IV contrast is recommended in pregnant patients if ultrasound is inconclusive, with a sensitivity of 94% and specificity of 96% 2, 3

The American College of Emergency Physicians recommends administering broad-spectrum antibiotics immediately covering aerobic gram-negatives and anaerobes (e.g., piperacillin-tazobactam, or cephalosporin/fluoroquinolone plus metronidazole) if CT shows uncomplicated appendicitis 3
Surgical consultation for appendectomy as soon as reasonably feasible (within 24 hours for uncomplicated cases) is recommended if CT shows uncomplicated appendicitis 3
Urgent surgical intervention for source control is recommended if CT shows complicated appendicitis (perforation, abscess, phlegmon) 3
Large periappendiceal abscess (>3 cm) may warrant percutaneous drainage rather than immediate appendectomy 3

The American College of Emergency Physicians recommends discussing an antibiotics-first strategy as an alternative to surgery in highly selected patients with uncomplicated appendicitis and NO appendicolith on CT 3
The overall success rate of antibiotics-first strategy is 63-73% at one year, with high-risk CT findings predicting antibiotic failure (≈40% failure rate) including appendicolith present, appendiceal diameter >13 mm, and mass effect 3

The American College of Emergency Physicians recommends not administering analgesics before completing diagnostic evaluation, as premature analgesia can mask evolving peritoneal signs 6
Not proceeding directly to surgery based on incomplete clinical findings without imaging is recommended, as this risks unnecessary surgery and missing alternative diagnoses 2
Delaying antibiotics once appendicitis is confirmed or strongly suspected increases complication risk and is not recommended 3
Relying solely on clinical examination in elderly patients is not recommended, as atypical presentations are common and CT is essential 2
Ultrasound accuracy is highly operator-dependent, and both ultrasound and MRI may incorrectly classify up to half of perforated appendicitis cases as simple appendicitis 2
Assuming absence of peritoneal signs excludes appendicitis, especially in early presentations, children, elderly, and pregnant patients, is not recommended 3, 6