Cervical cerclage — structured oral station (12 minutes)

Opening prompt — "What is your assessment, and do you think she needs a cerclage?"

Model response — say it in this order: ^[1][2]

• "She fits the responder phenotype for cerclage: a singleton gestation, a previous spontaneous preterm birth, and a cervix under 25 mm before 24 weeks — here 15 mm at 20 weeks."
• "I would confirm gestational age and viability, exclude ruptured membranes and chorioamnionitis, and screen for vaginal and urinary infection before offering an ultrasound-indicated cerclage."
• "I would counsel her on the benefit in her phenotype and the risks of the procedure, and offer the stitch."^[1]

Examiner is listening for: the phenotype, the threshold, and the exclusions before theatre.

Probe 1 — "What evidence supports offering her a cerclage?"

• "The Berghella individual-patient-data meta-analysis of women with a singleton, a previous spontaneous preterm birth and a cervix under 25 mm before 24 weeks. Cerclage reduced preterm birth before 35 weeks from 41.3 per cent to 28.4 per cent (RR 0.70) and composite perinatal mortality and morbidity (RR 0.64)."^[2]
• "This contrasts with the To trial, which found no benefit of cerclage for a short cervix in unselected women — benefit is concentrated in the responder phenotype."^[3]

Probe 2 — "Which technique would you use, and how do they differ?"

• "I would use a McDonald cerclage — a purse-string suture at the cervicovaginal junction, tied to reduce the internal os, with the knot left accessible for removal at 36 to 37 weeks."^[1]
• "The Shirodkar alternative dissects the bladder and rectal reflections to place a submucosal band higher on the cervix, nearer the internal os; it is used when a higher, more durable stitch is wanted but is harder to remove."^[1]
• "Before the stitch I would confirm the anomaly screen is satisfactory, exclude contraindications, and discuss suture material with the C-STICH evidence in mind."^[4]

Probe 3 — "She asks whether the type of suture matters."

• "C-STICH randomised over 2000 women to monofilament or braided suture. Pregnancy loss was 8.0 per cent with monofilament versus 7.6 per cent with braided (adjusted RR 1.05), so monofilament did not reduce pregnancy loss. I would explain that the trial informs the choice but does not mandate one over the other."^[4]

Probe 4 — "At 26 weeks she ruptures her membranes with the stitch in situ. What now?"

• "I would assess her for chorioamnionitis — temperature, pulse, uterine tenderness, fetal heart, inflammatory markers — and confirm the gestation and the absence of labour."
• "The decision is removal versus retention. The systematic review found retention prolonged pregnancy but with more chorioamnionitis; removal was associated with less infection and better 5-minute Apgar scores in the pooled observational data."^[5]
• "I would individualise to gestation and infection risk, involve the neonatal team for counselling on viability, and make the decision with my consultant — balancing latency against infection."^[5]

Probe 5 — "She is anxious about losing another baby. How do you respond?"

This is a scored domain — demonstrate it out loud: ^[1]

• Sit at her eye level, acknowledge her fear from her previous loss, and explain the plan plainly and without false promises.
• Outline what the cerclage can and cannot do, the surveillance in place, and the plan for complications.
• Offer written information, a follow-up contact, and continuity of carer.