During a type III (Wertheim) radical hysterectomy for Stage IB1 cervical cancer, the surgeon isolates the ureter within the parametrium. At which anatomical relationship is the ureter most vulnerable to injury during dissection of the cardinal ligament?

• A Where it crosses the external iliac artery at the pelvic brim
• B Where it enters the bladder at the trigone
• C Where it lies lateral to the infundibulopelvic ligament
• D Where it passes beneath the uterine artery near the level of the internal os ✓

Explanation

The classic teaching is 'water under the bridge': the ureter passes beneath the uterine artery approximately 1.5 to 2 cm lateral to the cervix, within the cardinal ligament. Dissecting the ureteral tunnel through the parametrium to divide the cardinal ligament at the pelvic sidewall places it at maximal risk here. Crossing the common iliac vessel at the brim and the trigonal entry are also recognised injury sites but lie outside the parametrial dissection field.

Reference: Williams Gynecology, 4th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.