Surgical anatomy of the female pelvis — structured SAQ (15 marks)

(a) Three named relations of the ureter along its pelvic course, and the structure crossing it at the lateral cervical step (3 marks)

One mark for each named relation, one mark for the crossing structure.

• Relation 1: crosses the pelvic brim over the bifurcation of the common iliac artery.
• Relation 2: runs along the medial leaf of the broad ligament peritoneum and passes under the uterine artery at the level of the internal os, 1.5–2 cm lateral to the cervix (the 'water under the bridge').
• Relation 3: traverses the cardinal ligament to enter the bladder.
• Crossing structure at the lateral cervical step: the lateral cervical branch of the uterine artery crosses over the ureter — the named source of bleeding at this step.[1][6]

(b) Pararectal space: Latzko vs Okabayashi, by boundaries and surgical use (4 marks)

One mark for the pararectal space definition, one for each compartment's boundaries, one for the surgical use of each.

• Pararectal space definition: the avascular retroperitoneal space developed by incising the medial leaf of the broad ligament peritoneum lateral to the infundibulopelvic ligament, bounded medially by the ureter, laterally by the internal iliac artery, posteriorly by the sacrum, and floored by the levator ani and the sacrogenital fold.
• Latzko pararectal space (lateral): between the internal iliac artery (laterally) and the ureter (medially); opened first to expose the internal iliac artery and used for internal iliac artery ligation and the lateral parametrial step of radical hysterectomy.
• Okabayashi pararectal space (medial): between the ureter (laterally) and the rectum (medially); opened deeper in the same incision; used to skeletonise the ureter down to the ureterovesical junction while preserving it during parametrial dissection.
• Surgical use: the Okabayashi space is the corridor for nerve-sparing radical hysterectomy, allowing skeletonisation of the ureter and preservation of the pelvic splanchnic nerves in the lateral parametrium.[1][4]

(c) Three named zones of pelvic autonomic nerve injury at hysterectomy, and the nerves at risk at each (4 marks)

One mark for each zone, one for the nerve at risk at each, with the named mechanism of injury.

• Zone 1 — presacral: the hypogastric nerves (sympathetic, from the superior hypogastric plexus) descend over the sacral promontory; injury during presacral dissection or sacrocolpopexy mesh placement.
• Zone 2 — lateral parametrial: the pelvic splanchnic nerves (parasympathetic, from S2–S4) cross the cardinal ligament; injury during division of the cardinal ligament in non-nerve-sparing radical hysterectomy.
• Zone 3 — uterosacral: the inferior hypogastric (pelvic) plexus runs in the uterosacral ligament to the uterus and vagina; injury during division of the uterosacral ligaments or bladder dissection.
• Mechanism: bilateral injury produces bladder dysfunction (loss of detrusor contractility and impaired sensation); unilateral injury produces partial loss. Nerve-sparing radical hysterectomy (Querleu–Morrow C1) preserves these nerves.[4]

(d) Immediate response and principle of haemostasis at the lateral cervical step (4 marks)

One mark for stopping, one for identification, one for the principle, one for the named action.

• Stop and apply pressure: do not blind-diathermy near the ureter; apply pressure with a swab or suction to allow visualisation.
• Identify the bleeding vessel: the lateral cervical branch of the uterine artery crossing over the ureter; trace the ureter above and below the bleeding point; identify the vessel exactly.
• Principle of haemostasis: named-vessel control — suture-ligate with fine absorbable suture (4-0 or 5-0 PDS or Vicryl) or apply a clip; bipolar diathermy is acceptable if the ureter is identified and away from the field; never use unipolar diathermy near the ureter.
• Action if haemostasis not secured: call for help, consider conversion to laparotomy, ensure intra-operative cystoscopy with indigo carmine to confirm bilateral ureteric efflux at the end of the procedure, and check the postoperative creatinine on day 2.[1][6]