Uterine rupture and scar dehiscence — structured SAQ (15 marks)

(a) Differential and most likely diagnosis (4 marks)

One mark for naming uterine rupture as most likely with justification; up to three for a structured differential with discriminating features. ^[1][2]

• Most likely: complete uterine rupture. Four features support it — a uterine scar, oxytocin augmentation, new pain breaking through a working epidural, and a sustained fetal bradycardia. Maternal tachycardia of 118 bpm with a preserved blood pressure fits early concealed intraperitoneal haemorrhage.^[1][3]
• Placental abruption — a tense, tender, hypertonic uterus, revealed or concealed bleeding and early coagulopathy; no loss of station.
• Cord prolapse or cord compression — bradycardia following membrane rupture with a cord palpable on examination; the abdominal pain is unexplained.
• Amniotic fluid embolism — respiratory collapse and hypoxia first, then coagulopathy; the uterus is intact.
• Non-obstetric acute abdomen (appendicitis, torsion, perforated viscus) — usually no fetal bradycardia and no scar tenderness.^[1][2]

A mark is available for stating the operational rule: in a labouring woman with a uterine scar, a sustained bradycardia is a rupture until laparotomy proves otherwise, and fetal bradycardia was the only fetal heart rate finding that differentiated rupture from successful VBAC in the matched case-control data. ^[2]

(b) Immediate management, first five minutes (5 marks)

One mark per point with its reasoning, maximum five. ^[1][5]

• Stop the oxytocin infusion immediately — it is driving the contraction pressure that is tearing the scar, and sequential prostaglandin then oxytocin exposure is the strongest identified risk factor for complete rupture.^[8]
• Declare a suspected uterine rupture, call for help by name and role and activate the massive obstetric haemorrhage protocol — consultant obstetrician, anaesthetist, theatre, neonatal team, blood bank. Start the clock and appoint a scribe.^[5]
• Transfer to theatre for immediate laparotomy. Do not top up the epidural for the pain, do not wait for an ultrasound, and do not perform fetal blood sampling. Time to delivery over 30 minutes versus under 20 minutes carried an odds ratio of 16.7 for intrapartum or infant death.^[1][4]
• Resuscitate on the way: high-flow oxygen, two large-bore cannulae, full blood count, coagulation with fibrinogen, crossmatch four to six units, urea and electrolytes, calcium and lactate; tranexamic acid 1 g intravenously over 10 minutes.^[1][5]
• Anaesthesia: general anaesthesia given the bleeding and the need for speed; state that this is a joint decision made out loud with the anaesthetist, and that resuscitation continues in theatre rather than delaying it.^[1][5]

(c) The surgical decision (3 marks)

One mark for the decision, one for the criteria, one for the adjuncts and the honesty about the evidence. ^[5][6]

• Proceed to hysterectomy. The combination of a full-thickness defect extending laterally toward the uterine vessels, 2500 mL of loss, and a fibrinogen of 1.0 g/L in an unstable woman means further reconstruction will not outrun the coagulopathy.^[5][6]
• State the criteria you are applying: haemodynamic instability, an unreconstructable or laterally extending defect, established coagulopathy, and the absence of a safe window to repair. Repair is reserved for the stable woman with clean approximable lower-segment edges and no lateral, cervical or bladder extension.^[1][6]
• Adjuncts while preparing: deliver the fetus first, clamp or compress the bleeding edges, bilateral uterine artery ligation and internal iliac ligation if skilled help is present, pelvic packing, cell salvage, and transfusion to fibrinogen at or above 2 g/L, platelets above 50 x 10 to the 9 per litre, normal calcium and active warming. Check the bladder and ureters before and after.^[5][6]

Credit for acknowledging confounding by indication in the comparative data: in a nationwide study of 644 ruptures, 44.6% had repair and 55.4% hysterectomy, and the hysterectomy group was older, more comorbid and more often had impaired consciousness on arrival. ^[6]

(d) Counselling for a future pregnancy (3 marks)

One mark for the recurrence data with the site caveat, one for the birth plan, one for the honest discussion of timing. ^[7]

• Recurrence depends on where the rupture was. In the largest published series of pregnancies after a previous complete rupture (72 maternities), there were 3 new complete ruptures (4.2%) and 6 uneventful partial ruptures (8.3%). All three complete ruptures occurred preterm and in scars outside the lower segment — the recurrence rate was 0% where the previous rupture was in the lower segment and 8.6% where it was outside it. Her rupture was in the lower segment, which is the more favourable group.^[7]
• Birth plan: elective caesarean before the onset of labour, in a unit with immediate theatre and blood access, with an obstetric consultant present and a documented plan for early presentation with any pain or bleeding. No trial of labour.^[1][7]
• Be honest about timing. Corrected perinatal mortality in that series was 1.3%, but prematurity below 37 weeks occurred in 36.1% and was largely iatrogenic — driven by clinician and maternal anxiety. Deciding when to deliver is the hardest part, and delivering too early causes its own harm.^[7]

Also credit: contraception and inter-pregnancy interval advice, a debrief about this birth with open disclosure, and a written summary of the operative findings for her next team. ^[3][7]