What is the most appropriate next step for a patient presenting to the emergency department with right lower quadrant pain, tenderness, leukocytosis (elevated white blood cell count), and an inconclusive abdominal ultrasound?

CT Abdomen and Pelvis with IV Contrast is the Most Appropriate Next Step

For a patient with right lower quadrant pain, suprapubic tenderness, mild leukocytosis (WBC 12.5-14), and an inconclusive ultrasound, proceed immediately to CT abdomen and pelvis with IV contrast—this is the definitive next imaging study recommended by the American College of Radiology. 1

Why CT is the Correct Choice

Diagnostic Performance After Inconclusive Ultrasound

• CT abdomen and pelvis with IV contrast demonstrates 95% sensitivity and 94% specificity for appendicitis, making it the gold standard when ultrasound fails to provide a diagnosis 1
• The American College of Radiology explicitly recommends CT when ultrasound is nondiagnostic or equivocal, as it identifies alternative diagnoses in 23-45% of cases presenting with right lower quadrant pain 1
• A staged algorithm of ultrasound followed by CT achieves 99% sensitivity and 91% specificity 2

Why the Other Options Are Incorrect

Option B (Transvaginal Ultrasound) is Wrong:

• Transvaginal ultrasound should be considered as initial imaging when there is specific clinical concern for acute gynecologic pathology, not after an already inconclusive transabdominal ultrasound 1
• You've already performed ultrasound—adding transvaginal imaging at this point delays definitive diagnosis without addressing the broader differential 1

Option C (Diagnostic Laparoscopy) is Premature:

• Diagnostic laparoscopy is premature without definitive imaging confirmation 1
• CT must be obtained first to guide surgical decision-making and avoid unnecessary operative intervention 1
• Operating without imaging risks both a negative appendectomy (historically 14.7-25% without preoperative imaging) and missing the actual pathology 2

Option D (Open Appendectomy) is Dangerous:

• The American College of Radiology recommends against open appendectomy without imaging confirmation, as it risks both a negative appendectomy and missing the actual pathology 1
• Preoperative CT reduces negative appendectomy rates from 14.7% to 1.7-7.7% 2

Critical Clinical Context

Don't Be Fooled by "Mild" Leukocytosis

• Normal or mildly elevated WBC does not exclude appendicitis—the "classic" presentation occurs in only approximately 50% of patients 3
• Never rely on WBC count alone to exclude appendicitis or other surgical pathology—imaging is mandatory 3
• Laboratory findings have limited diagnostic power, with a positive likelihood ratio of only 2.47 2

The Broad Differential Requires CT

• CT identifies the cause of right lower quadrant pain in the majority of cases, with 41% of patients with non-appendiceal diagnoses requiring hospitalization and 22% requiring surgical or image-guided intervention 3
• Alternative diagnoses frequently detected include gynecologic conditions (21.6%), gastrointestinal etiologies (46.0%), right colonic diverticulitis (8%), ureteral stones, and intestinal obstruction (3%) 2, 4

Timing is Critical

Delaying CT imaging in favor of serial examinations or additional ultrasound modalities is not recommended, as it risks progression to perforation if appendicitis is present 1

Practical Implementation

• Order CT abdomen and pelvis with IV contrast without enteral contrast for rapid acquisition 2
• The use of oral or rectal contrast may not be needed depending on institutional preference 1
• CT without enteral contrast achieves sensitivity of 90-100% and specificity of 94.8-100%, allowing for rapid diagnosis without delays 2

Common Pitfall to Avoid

The absence of fever and rebound tenderness does not exclude serious pathology—fever is absent in approximately 50% of appendicitis cases 2. Your patient has suprapubic and lower quadrant tenderness with leukocytosis, which warrants definitive imaging regardless of the absence of classic peritoneal signs 1, 3.