Next Step: CT Abdomen and Pelvis with IV Contrast
For a 21-year-old female presenting with 12 hours of right lower quadrant pain, tenderness, and rebound tenderness, the next step is CT abdomen and pelvis with IV contrast (Option B). This clinical presentation is highly suspicious for acute appendicitis, and imaging is essential before proceeding to surgery. 1
Why CT is the Correct Next Step
Clinical examination alone is notoriously unreliable for diagnosing appendicitis, with negative appendectomy rates as high as 25% when relying solely on physical findings. 1, 2 While this patient has classic peritoneal signs (rebound tenderness), CT imaging is necessary to:
- Confirm the diagnosis of appendicitis with sensitivity of 95% (95% CI: 0.93-0.96) and specificity of 94% (95% CI: 0.92-0.95) 3
- Identify alternative diagnoses that occur in 23-45% of patients presenting with right lower quadrant pain, including ovarian pathology (torsion, ruptured cyst), ectopic pregnancy, pelvic inflammatory disease, diverticulitis, inflammatory bowel disease, and urologic conditions 4, 1
- Detect complications such as perforation, abscess formation, or peritonitis that would alter surgical approach 5
Why Other Options Are Incorrect
Open Appendectomy Without Imaging (Option A)
Proceeding directly to surgery without imaging risks unnecessary operations and missed alternative diagnoses. 1 Preoperative CT reduces negative appendectomy rates from 16.7% to 8.7%, and in a young female, gynecologic pathology must be excluded before surgery. 6
Plain Abdominal X-ray (Option C)
Plain radiography has no role in diagnosing acute appendicitis and provides minimal useful information compared to CT. 1 This would delay definitive diagnosis without adding diagnostic value.
IV Fluids and 24-Hour Observation (Option D)
This patient has peritoneal signs (rebound tenderness), which indicates she is NOT low-risk and requires immediate imaging, not observation. 1 The presence of rebound tenderness suggests possible peritonitis and warrants urgent diagnostic evaluation. Observation is only appropriate for low-risk patients without peritoneal signs who can be safely discharged with 24-hour follow-up. 1
Optimal CT Protocol
CT abdomen and pelvis with IV contrast is the preferred protocol, providing superior sensitivity (0.96,95% CI: 0.92-0.98) compared to unenhanced CT (0.91,95% CI: 0.87-0.93). 3 The addition of intravenous contrast improves visualization of appendiceal inflammation and helps identify alternative diagnoses. 3
Critical Management Points
- Do not delay CT beyond 12 hours in patients with peritoneal signs, as progression to perforation increases morbidity 6
- Maintain NPO status and provide IV hydration while awaiting imaging 1
- Avoid excessive opioid analgesia that could mask evolving symptoms, though mild pain control is appropriate 1
- If CT confirms appendicitis, proceed immediately to surgical consultation for appendectomy with appropriate preoperative antibiotics 1
- If CT is negative or shows alternative pathology, manage accordingly with gynecologic consultation if needed 1, 7