In a 28-year-old woman with 12 hours of right lower quadrant pain, leukocytosis and an inconclusive transabdominal ultrasound, what is the most appropriate next step in management?

Most Appropriate Next Step: Transvaginal Ultrasound (TVUS)

In a 28-year-old woman with right lower quadrant pain, mild leukocytosis, and an inconclusive transabdominal ultrasound, the most appropriate next step is transvaginal ultrasound (TVUS) before proceeding to CT imaging. 1

Rationale for TVUS as Next Step

• The American College of Radiology appropriateness criteria specifically rate pelvic ultrasound (transvaginal) as "appropriate" (rating 5) for women with pelvic pain presenting with right lower quadrant symptoms. 1

• In young women of reproductive age, gynecologic pathology accounts for approximately 21.6% of alternative diagnoses when appendicitis is suspected, including ovarian torsion, ectopic pregnancy, ruptured ovarian cysts, and pelvic inflammatory disease. 2

• TVUS provides superior visualization of pelvic structures compared to transabdominal ultrasound and can definitively identify or exclude gynecologic emergencies without radiation exposure. 2

• The staged ultrasound approach (transabdominal followed by transvaginal when needed, then CT if both inconclusive) achieves 99% sensitivity and 91% specificity for appendicitis while minimizing radiation exposure in young women. 2

When to Proceed Directly to CT

If TVUS remains inconclusive or negative but clinical suspicion for appendicitis persists, immediate CT abdomen and pelvis with IV contrast (without oral contrast) is the definitive next step. 1, 2

• CT with IV contrast demonstrates 85.7-100% sensitivity and 94.8-100% specificity for acute appendicitis. 2, 3

• CT without enteral contrast achieves diagnostic accuracy of 90-100% sensitivity and 94.8-100% specificity while avoiding the 1-hour delay associated with oral contrast administration. 2, 3

• CT identifies alternative diagnoses in 23-45% of patients presenting with right lower quadrant pain, fundamentally changing management. 2

Critical Clinical Considerations

• The absence of rebound tenderness in this patient is significant—it indicates absence of peritoneal irritation, which is a key finding in established appendicitis. 2

• Fever is absent in approximately 50% of appendicitis cases, so its absence does not exclude the diagnosis. 2

• The WBC of 12.5 represents mild leukocytosis; while elevated, this level has limited diagnostic power with a positive likelihood ratio of only 2.47 for appendicitis. 2

• Suprapubic tenderness in a young woman raises concern for gynecologic pathology (bladder/uterine/adnexal) more than isolated appendicitis. 2

Algorithm Summary

1. Perform TVUS immediately to evaluate for gynecologic emergencies and better visualize the appendix from a pelvic approach. 1, 2

2. If TVUS is diagnostic (confirms gynecologic pathology or clearly visualizes normal appendix with no inflammatory findings), manage accordingly. 2

3. If TVUS is nondiagnostic or equivocal, proceed immediately to CT abdomen/pelvis with IV contrast without oral contrast. 1, 2

4. If CT confirms appendicitis, proceed to surgical consultation for appendectomy. 2

5. If imaging remains negative but symptoms persist or worsen, consider diagnostic laparoscopy, which provides both diagnostic and therapeutic value. 2

Why Not the Other Options

• Diagnostic laparoscopy (Option C) is premature without completing the non-invasive imaging algorithm first, as it carries surgical risks and anesthesia exposure. 2

• Open appendectomy (Option D) without imaging confirmation results in negative appendectomy rates of 14.7-25%, which is unacceptably high when imaging can reduce this to 1.7-7.7%. 2

• CT first (Option A) exposes a young woman to unnecessary radiation when TVUS can potentially provide the diagnosis without radiation and is specifically recommended by ACR guidelines for women with pelvic pain. 1, 2