What is the next step in managing a 21-year-old female with 12 hours of right lower abdominal pain, tenderness, and rebound tenderness, suggestive of acute appendicitis?

Next Step in Management

The next step is CT abdomen and pelvis with IV contrast, not observation, as this patient presents with classic signs of acute appendicitis requiring imaging confirmation before proceeding to surgery. 1, 2

Why Imaging is Essential Before Surgery

Clinical diagnosis alone is insufficient and leads to unacceptably high negative appendectomy rates of 14.7-25% without preoperative imaging. 1, 2 Even with classic presentation (right lower quadrant pain, tenderness, and rebound), imaging is critical because:

• CT reduces the negative appendectomy rate to 1.7-7.7%, significantly improving patient outcomes 2
• Classic presentation occurs in only approximately 50% of appendicitis cases, making clinical diagnosis unreliable 1, 2
• CT identifies alternative diagnoses in 23-45% of patients presenting with right lower quadrant pain and classic symptoms, fundamentally changing management 1, 2

Diagnostic Performance of CT

CT abdomen and pelvis with IV contrast demonstrates 85.7-100% sensitivity and 94.8-100% specificity for acute appendicitis. 1, 2, 3 The optimal protocol uses:

• IV contrast without enteral contrast for rapid acquisition without delays 2
• Appendiceal diameter >8.2 mm as the diagnostic threshold 2, 3
• Assessment for periappendiceal fat stranding, appendicoliths, and perforation 2, 3

Why Observation is Inappropriate

24-hour observation (Option D) is not indicated for this patient with clear peritoneal signs. 2 Observation is only appropriate for:

• Low-risk patients without rebound tenderness who can be safely discharged with return precautions 2
• Borderline cases with equivocal imaging findings (appendix 7-8mm) without clear periappendiceal infiltration 2

This patient has rebound tenderness, indicating peritoneal irritation, which places her in the intermediate-to-high risk category requiring definitive imaging. 1 Delays in diagnosis increase the risk of perforation, gangrene, and peritonitis, which prolong hospital stay and increase morbidity. 1

Alternative Diagnoses Detected by CT

CT frequently identifies other surgical and non-surgical conditions that mimic appendicitis: 1, 2

• Right colonic diverticulitis (8% of cases) 2
• Gynecologic pathology (21.6% of alternative diagnoses) including ovarian torsion, ectopic pregnancy, and pelvic inflammatory disease 2, 4
• Ureteral stones and intestinal obstruction (3% of cases) 2
• Gastrointestinal conditions (46% of alternative diagnoses) 2

Management Algorithm After CT

If CT confirms appendicitis (appendix >8.2mm with periappendiceal infiltration): 2, 3

• Immediate surgical consultation for appendectomy 1, 2
• Both open and laparoscopic approaches are viable, with laparoscopy preferred in high-resource settings 1

If CT shows borderline findings (appendix 7-8mm without clear infiltration): 2

• Hospital observation for 24 hours with serial abdominal exams 2
• Repeat imaging if symptoms progress 2

If CT is negative for appendicitis: 2

• Pursue alternative diagnoses identified on imaging 2
• Discharge with strict return precautions and mandatory 24-hour follow-up 2

Critical Pitfalls to Avoid

Do not rely on absence of fever to exclude appendicitis—fever is absent in approximately 50% of cases. 1, 2

Do not proceed directly to appendectomy without imaging confirmation, as this leads to unnecessary surgery in 14.7-25% of cases. 1, 2

Do not discharge or observe patients with rebound tenderness without imaging, as this represents peritoneal irritation requiring definitive diagnosis. 1, 2