USMLE Step 1 Question 299

Question:

A 56-year-old woman complains of colicky right flank pain of several hours duration. She has a history of renal calculi, and denies dysuria. Urinalysis shows microscopic hematuria but no leukocyte esterase. Abdominal x-ray demonstrates a calculus at vertebral level L2.

Where is the renal calculus most likely located?

Correct Answer: C.  Intersection of renal pelvis and ureter

This patient has a recurrence of kidney stones. Although calculi are often lodged at the junction of the ureter and bladder, in the ureter as it crosses the pelvic brim, or the intersection of the renal pelvis and ureter, the last option correlates with the radiographic finding.

The corticomedullary junction is the site of ascending and descending loops of Henle, as well as collecting ducts. Calculi are unlikely to impact here.

The minor calices of the kidney open into the major calices, and are an unlikely site of impaction.