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AN48.1-8 | Pelvic wall and viscera — Part 3
SELF-CHECK
A. As the ureter crosses the pelvic brim at the bifurcation of the common iliac artery
B. As the ureter passes through the broad ligament 2 cm lateral to the cervix, where the uterine artery crosses above it
C. As the ureter enters the bladder trigone
D. As the ureter passes posterior to the ovary
Reveal Answer
Answer: .
"Water under the bridge" — the uterine artery crosses over the ureter 2 cm lateral to the cervix (at the base of the broad ligament). When the surgeon ligates the uterine artery, the ureter is immediately below. Inadvertent clamping, ligation, or thermal injury to the ureter at this point is the most common cause of ureteric injury in gynaecological surgery.
CLINICAL PEARL
Obstructed labour and the obstetric conjugate: The critical diameter for vaginal delivery is the obstetric conjugate (shortest anteroposterior diameter of the pelvic inlet, from the posterior surface of the pubic symphysis to the sacral promontory — normally >11 cm). A contracted pelvis (obstetric conjugate <10 cm) leads to cephalopelvic disproportion and obstructed labour — the most common cause of uterovesical fistula in India. The ischial spines can be palpated vaginally to estimate mid-pelvic dimensions (interspinous diameter normally 10.5 cm). Prominent ischial spines and a convergent pelvic sidewall suggest android pelvis — poor prognosis for vaginal delivery.