Water Under the Bridge

Mnemonic

“Water under the bridge”:

• The ureter is the water
• The bridge is the uterine artery in women, and the vas deferens in men

The ureter passes beneath both, at the level of the ischial spine, about 2 cm lateral to the cervix.

This is the single most important relation in pelvic surgery: the ureter is at greatest risk during hysterectomy when the uterine artery is clamped, and the classic surgical instruction is to identify the ureter before dividing the artery.

The ureter’s other danger points are the three constrictions where stones lodge: the pelviureteric junction, the crossing of the common iliac vessels at the pelvic brim, and the vesicoureteric junction, which is the narrowest.

Expansion

• Female - the uterine artery crosses anterior and superior to the ureter, about 2 cm lateral to the cervix at the level of the internal os
• Male - the vas deferens crosses anterior to the ureter

Water (the ureter) passes under the bridge (the artery or vas).

This is the single most important relation in pelvic surgery. Clamping the uterine artery during hysterectomy without first identifying the ureter is the classic mechanism of ureteric injury, and the risk is greatest when anatomy is distorted by fibroids, endometriosis or malignancy.

Other points where the ureter is vulnerable: at the pelvic brim during colorectal surgery, and near the infundibulopelvic ligament during oophorectomy, where the gonadal vessels cross it.