Right Lower Quadrant Pain with Urination
The most likely diagnosis is nephrolithiasis with ureteral obstruction, and you should immediately order a non-contrast CT abdomen and pelvis as the first-line diagnostic test. 1
Primary Differential Diagnosis
The leading diagnosis when right lower quadrant pain correlates specifically with urination is nephrolithiasis with ureteral obstruction, as ureteral stones cause colicky pain radiating from flank to groin that intensifies with ureteral peristalsis during voiding. 1
Secondary considerations include:
- Complicated urinary tract infection (pyelonephritis or cystitis with upper tract involvement), though this is less likely than nephrolithiasis when pain is specifically triggered by urination. 1
- Appendicitis remains in the differential for any right lower quadrant pain, but the temporal relationship with urination makes this less likely. 1, 2
Immediate Diagnostic Approach
Order CT abdomen and pelvis WITHOUT contrast as your first-line imaging study. 1
- Unenhanced CT is the gold standard for stone detection with sensitivity and specificity near 100% for urinary tract calculi. 1
- This imaging modality will definitively diagnose or exclude nephrolithiasis while also identifying alternative pathology if stones are not present. 1
Alternative Imaging Considerations
Consider ultrasonography only in specific circumstances:
- Pregnancy confirmed or suspected - ultrasound avoids radiation exposure. 1
- Young patients where radiation is a concern - though ultrasound has only 96% sensitivity for detecting stones compared to CT's near 100%. 1
Clinical Pitfalls to Avoid
- Do not assume urinary symptoms always mean simple cystitis - the right lower quadrant location with pain during urination strongly suggests ureteral pathology rather than bladder infection. 1, 3
- Do not delay imaging in favor of empiric treatment - obstructing ureteral calculi can progress to hydronephrosis and kidney failure if not identified and managed appropriately. 3
- Do not order contrast-enhanced CT initially - contrast is unnecessary for stone detection and may obscure small calculi. 1
Post-Imaging Management Algorithm
If CT confirms nephrolithiasis:
- Initiate pain management and antiemetics. 3
- Determine stone size and location to guide conservative versus interventional management. 3
- Urology consultation if stone >5mm, signs of obstruction with hydronephrosis, or severe uncontrolled pain. 3
If CT shows appendicitis instead:
- Initiate broad-spectrum IV antibiotics immediately. 4
- Obtain immediate surgical consultation for appendectomy (CT with contrast has 95% sensitivity and 94% specificity for appendicitis). 1, 4
If CT shows alternative pathology: