What is the preferred initial imaging study for an adolescent female presenting with right upper quadrant (RUQ) abdominal pain?

Preferred Imaging for RUQ Pain in Adolescent Females

Abdominal ultrasonography is the definitive first-line imaging study for an adolescent female presenting with right upper quadrant abdominal pain, with the highest appropriateness rating (9/9) from the American College of Radiology. 1, 2

Why Ultrasound is the Clear Choice

Ultrasound should be performed as the initial imaging modality because it offers multiple critical advantages in this specific population 3, 1:

• No radiation exposure, which is particularly important in adolescent females of reproductive age 1, 2
• Excellent sensitivity and specificity for gallbladder pathology, the most common cause of acute RUQ pain 3, 4
• Rapid availability and shorter study time compared to other modalities 3
• Comprehensive evaluation that can identify gallstones, biliary dilatation, liver abnormalities, and alternative diagnoses beyond just gallbladder disease 3, 4, 5

Essential Pre-Imaging Step

Obtain a pregnancy test before any imaging studies in all adolescent females of reproductive age to rule out pregnancy-related conditions, particularly ectopic pregnancy 1, 2, 6. This is mandatory and prevents unnecessary radiation exposure if additional imaging becomes necessary.

When to Consider Second-Line Imaging

If ultrasound findings are equivocal or negative but clinical suspicion remains high, consider these options in order 3, 1, 2:

• Cholescintigraphy (HIDA scan) has higher sensitivity and specificity for acute cholecystitis than ultrasound, with appropriateness rating 6/9 3, 1
• MRI with MRCP is superior to CT for biliary sources of pain, with 85-100% sensitivity for cholelithiasis/choledocholithiasis, and avoids radiation 2
• CT abdomen with IV contrast can confirm or refute cholecystitis in equivocal cases with ~90% negative predictive value, but should not be first-line due to radiation exposure in young patients 3, 2

Critical Pitfalls to Avoid

• Never use CT as first-line imaging in adolescent patients when ultrasound is highly effective and avoids radiation exposure 1, 2
• Never skip pregnancy testing before proceeding with any imaging, as this can lead to unnecessary radiation and missed ectopic pregnancy 1, 2, 6
• Do not order plain radiographs as they have minimal diagnostic value for RUQ pain evaluation 2, 6
• Do not assume normal ultrasound excludes all pathology - a normal gallbladder appearance makes acute gallbladder pathology very unlikely, but alternative diagnoses should still be considered 3

Additional Laboratory Testing

Concurrent with ultrasound ordering, obtain 2, 6:

• Complete blood count to assess for leukocytosis indicating infection or inflammation 2, 6
• Liver function tests (ALT, AST, alkaline phosphatase, bilirubin) to evaluate hepatobiliary disease 2, 6
• Urinalysis to evaluate for renal stones or urinary tract infection 1, 2, 6