USMLE Step 1 Question 323

Question:

A 33-year-old woman undergoes abdominal surgery to correct a ureteral stricture of unknown origin. Anterior to the psoas at the level of the aortic bifurcation, the surgeon observes three tubular structures: gonadal artery, gonadal vein, and ureter. In the absence of anatomic variations, which description best identifies the ureter?

Correct Answer: C.  Most posterior structure at the level described; inferiorly it courses anterior to the iliac bifurcation.

At the level of the aortic bifurcation, the ureter typically runs posterior to the gonadal artery and vein. When crossing the pelvic brim at the level of the iliac bifurcation, the ureter courses anteriorly. On its way to the urinary bladder, the ureter is typically then posterior to the uterine artery (or vas deferens in men); this final relationship gives rise to the “water [urine] under the bridge” mnemonic.