What is the most appropriate next step in managing a hemodynamically stable 28-year-old woman with 12 hours of right lower‑quadrant pain, leukocytosis, and an inconclusive transabdominal ultrasound?

CT Abdomen and Pelvis with IV Contrast

In a hemodynamically stable 28-year-old woman with 12 hours of right lower quadrant pain, mild leukocytosis (WBC 12.5-14), and an inconclusive transabdominal ultrasound, the most appropriate next step is CT abdomen and pelvis with IV contrast (Option A). 1, 2

Rationale for CT as the Definitive Next Step

The American College of Radiology explicitly recommends proceeding directly to CT abdomen and pelvis with IV contrast when ultrasound is nondiagnostic or equivocal in adults with suspected appendicitis 2, 3. This approach is supported by several key factors:

• Superior diagnostic accuracy: CT demonstrates 85.7-100% sensitivity and 94.8-100% specificity for acute appendicitis, far exceeding the performance of repeat ultrasound 1, 2, 3
• High alternative diagnosis detection: CT identifies alternative diagnoses in 23-45% of patients presenting with right lower quadrant pain, fundamentally changing management in a substantial proportion of cases 1, 3
• Avoids diagnostic delay: Equivocal ultrasound results require CT anyway, so proceeding directly prevents unnecessary delays that could allow disease progression 1

Why Not Transvaginal Ultrasound (Option B)?

While transvaginal ultrasound can be considered first-line in reproductive-age women to evaluate gynecologic causes, it is not the appropriate next step after an already inconclusive transabdominal ultrasound 1. The key considerations are:

• The initial ultrasound was already inconclusive, indicating technical or anatomical limitations that additional ultrasound is unlikely to overcome 1
• Combined transabdominal and transvaginal ultrasound achieves 97.3% sensitivity and 91% specificity only when performed by experienced operators, but performance varies dramatically with patient factors 1
• Non-visualization rates remain high (20-81% of cases), creating persistent diagnostic uncertainty 1
• The staged algorithm of ultrasound followed by CT when ultrasound is inconclusive is the evidence-based approach, not repeating ultrasound with a different technique 2, 3

Why Not Diagnostic Laparoscopy (Option C)?

Diagnostic laparoscopy is reserved for situations where imaging remains inconclusive but clinical suspicion remains high 2. In this case:

• CT has not yet been performed, and it provides 85.7-100% sensitivity for appendicitis while also detecting alternative diagnoses 1, 2
• The patient is hemodynamically stable without peritoneal signs (no rebound tenderness), making invasive diagnostic procedures premature 2
• Diagnostic laparoscopy should only be considered after CT if imaging remains inconclusive and clinical suspicion persists 2

Why Not Open Appendectomy (Option D)?

Proceeding directly to open appendectomy without confirmatory imaging would be inappropriate because:

• The negative appendectomy rate without preoperative imaging is 14.7-25%, compared to only 1.7-7.7% with CT confirmation 3
• Clinical determination of appendicitis is notoriously poor, with misdiagnosis rates of 34-68% based on clinical assessment alone 4, 3
• The absence of rebound tenderness and relatively mild leukocytosis (12.5-14) do not meet criteria for immediate surgical intervention without imaging confirmation 2, 3

Optimal CT Protocol

The American College of Radiology recommends CT abdomen and pelvis with IV contrast without enteral contrast for this clinical scenario 3. This protocol provides:

• Rapid acquisition without delays associated with oral contrast administration 5
• Excellent sensitivity (90-100%) and specificity (94.8-100%) 2, 3
• Detection of alternative diagnoses including gynecologic pathology (21.6% of alternative diagnoses), right colonic diverticulitis (8%), and other gastrointestinal conditions (46% of alternative diagnoses) 3

Critical Clinical Pitfalls to Avoid

• Do not assume the absence of fever excludes appendicitis—fever is absent in approximately 50% of appendicitis cases 3
• Do not rely on WBC count alone—normal or mildly elevated WBC has limited diagnostic power with a positive likelihood ratio of only 2.47 3
• Do not discharge without definitive imaging in a patient with 12 hours of persistent right lower quadrant pain and an inconclusive initial study 2, 3