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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
Key points
- Classic pain migrates from periumbilical region to RLQ
- Anorexia, nausea, low-grade fever, leukocytosis support diagnosis
- CT abdomen/pelvis with IV contrast is preferred in nonpregnant adults when imaging is needed
- Ultrasound first in children and pregnancy; MRI if pregnancy ultrasound nondiagnostic
- Treatment is appendectomy or selected antibiotic-first strategy; perforation/abscess needs source control
Overview
Appendicitis usually begins with luminal obstruction by fecalith, lymphoid hyperplasia, tumor, or parasite, leading to distension, bacterial overgrowth, ischemia, and perforation. Visceral pain begins periumbilically and localizes to the RLQ as the parietal peritoneum becomes inflamed.
Epidemiology
Appendicitis is a common surgical emergency, peaking in adolescents and young adults. Perforation risk rises with delayed diagnosis, extremes of age, pregnancy, immunosuppression, and atypical anatomy.
Clinical Features
Symptoms
Periumbilical pain migrating to RLQ
Anorexia, nausea, vomiting after pain onset
Low-grade fever
Diffuse pain, high fever, or sepsis suggests perforation
Pregnancy may shift pain upward
Signs
McBurney point tenderness
Rebound, guarding, Rovsing, psoas, or obturator signs
Tachycardia/fever
Generalized peritonitis
Investigations
First-line
CBC and CRPLeukocytosis supports but does not confirm diagnosis
Pregnancy testEssential in reproductive-age patients
UrinalysisCan show sterile pyuria; helps evaluate urinary mimics
Second-line
CT abdomen/pelvis with IV contrastPreferred in nonpregnant adults
UltrasoundFirst-line in children and pregnancy
MRIPregnancy when ultrasound nondiagnostic
Specialist
Surgical consultationWhen diagnosis likely or imaging confirms
Diagnostic laparoscopyHigh suspicion with equivocal imaging in selected cases
1
Uncomplicated appendicitis
- NPO, IV fluids, analgesia, antiemetics
- Antibiotics covering gram-negatives and anaerobes
- Laparoscopic appendectomy standard definitive treatment
2
Complicated appendicitis
- Perforation/peritonitis: urgent surgery plus antibiotics
- Abscess/phlegmon: antibiotics with percutaneous drainage when feasible
- Sepsis: aggressive resuscitation and source control
3
Special populations
- Pregnancy: do not delay confirmed appendicitis
- Older adult: consider appendiceal/cecal malignancy if atypical
Complications
- Perforation: Abscess, generalized peritonitis, sepsis.
- Appendiceal abscess: May need drainage.
- Pylephlebitis: Rare septic portal thrombophlebitis.
USMLE Step 2 CK Exam Tips
- 1Pain before vomiting favors appendicitis
- 2Migration from periumbilical to RLQ is classic
- 3Pregnancy test is mandatory
- 4Ultrasound first in pregnancy/children; CT in nonpregnant adults
- 5Perforation can temporarily reduce pain before diffuse peritonitis
- 6Appendicolith predicts higher antibiotic-failure risk
- 7RLQ pain + chronic diarrhea/weight loss may be Crohn
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