Twin birth — structured oral station (12 minutes)

Opening prompt — "She is 7 cm. Set the room up for me."

Model response — the checklist, out loud: ^[1][8]

• "Confirm the presentation of both twins by ultrasound on admission, not by palpation, and confirm the chorionicity from the first-trimester record."
• "Dual continuous electronic fetal monitoring, ideally with a fetal scalp electrode on twin 1 so I can prove I am watching two different hearts rather than one heart twice."
• "Intravenous access, group and hold, and an oxytocin infusion drawn up but not running."
• "The epidural is already in, which is a real advantage — I may need to put a hand inside the uterus for twin 2 and I do not want to be arranging anaesthesia at that moment."
• "In the room: the ultrasound machine, two resuscitaires and two neonatal teams, an anaesthetist aware, a theatre free, and an experienced obstetrician present for the second stage. I would ask the coordinator to let my consultant know now, not later."^[1]

Examiner is listening for: ultrasound on admission, two-heart monitoring, epidural rationale, and pre-emptive escalation. ^[1]

Probe 1 — "Is vaginal birth reasonable here at all? Justify it."

• "Yes. The rule is that the presentation of twin 1 decides the mode. Twin 1 is cephalic, so planned vaginal birth is a legitimate option; the presentation of twin 2 does not by itself require caesarean."^[1][8]
• "The evidence is the Twin Birth Study: 2804 women, twin 1 cephalic, 32+0 to 38+6 weeks. The composite of fetal or neonatal death or serious neonatal morbidity was 2.2% with planned caesarean and 1.9% with planned vaginal birth — odds ratio 1.16, 95% confidence interval 0.77 to 1.74, no significant difference."^[1]
• "And at two years there was still no difference: 5.99% versus 5.83% for death or neurodevelopmental delay."^[2]
• "The caveat I would state is that every centre in that trial had emergency caesarean facilities and staff in the hospital at the time of planned vaginal birth. The trial licenses offering vaginal birth in a unit like this one; it does not license it anywhere."^[1]

Probe 2 — "Why is she being delivered at 37 weeks and not 39?"

• "Because in twins the prospective risk of stillbirth from continuing and the risk of neonatal death from delivering cross earlier than in singletons. In dichorionic twins beyond 34 weeks those risks balanced at 37 weeks, and delaying a further week to 38 weeks added 8.8 perinatal deaths per 1000 pregnancies."^[4]
• "For monochorionic diamniotic twins the trend towards excess stillbirth appeared after 36 weeks, and RANZCOG C-Obs 42 recommends birth by 37+0 weeks. Monoamniotic twins are delivered preterm by caesarean because of cord entanglement."^[3][4]

Probe 3 — "Twin 1 is born. Talk me through the next five minutes."

This is the heart of the station. ^[1][5]

• "No bolus uterotonic. The uterus has to keep working for twin 2."
• "Ultrasound immediately for the lie and presentation of twin 2, and reassess the CTG."
• "Stabilise the lie with an abdominal hand into a longitudinal axis while I decide."
• "Restart or increase the oxytocin infusion if contractions have faded."
• "Amniotomy only when the presenting part is fixed in the pelvis — never over a high head, because that invites cord prolapse."
• "And I would say out loud that a transverse twin 2 after birth of twin 1 is the single strongest predictor of a combined delivery: in the Twin Birth Study subanalysis, adjusted odds ratio 47.7, confidence interval 15.4 to 124.5. So I act now rather than waiting for it to settle."^[5]

Probe 4 — "It stays transverse. Do the internal podalic version for me."

• "Adequate anaesthesia — the epidural topped up. Cervix fully dilated. Membranes intact if at all possible, because they give me a cushion of liquor and room to work; a dry uterus clamped round a transverse fetus is a much harder operation."^[8]
• "Ultrasound first to locate the head, spine and feet."
• "An assistant's hand, or my own free hand, holds the fetal head at the fundus abdominally throughout — without that the fetus simply rotates back."
• "My vaginal hand follows the trunk to the lower limbs and grasps both feet together. I identify a foot by the heel and the short straight line of the toes; a hand has a mobile thumb and long fingers, and pulling on a hand is the classic error."
• "Bring the feet down through the cervix with steady continuous traction, rupture the membranes once the feet are through — not before — and then extract as a breech: trunk to the scapulae, arms with Lövset if extended or nuchal, head by Mauriceau-Smellie-Veit or forceps."^[8]

Probe 5 — "How long have you got? What does the inter-twin interval evidence actually say?"

A trap probe. The wrong answer is a stopwatch. ^[6][7]

• "In a series of 118 twin pairs, umbilical arterial pH below 7.00 occurred in none of the second twins born within 15 minutes, 5.9% of those born at 16 to 30 minutes, and 27% of those born beyond 30 minutes."^[7]
• "But I would interpret that carefully. The long interval is largely a marker of a difficult second twin rather than the cause of the acidosis. So I would not rush an uncomplicated second twin with a reassuring CTG purely to beat a clock."
• "What the data do justify is acting decisively when the CTG is abnormal or the lie will not stabilise — which is this case."
• "And the outcome that motivates all of it: second twins born at term have an increased risk of death compared with first twins, odds ratio 2.3, driven by intrapartum anoxia and trauma."^[6]

Probe 6 — "She is exhausted and asking whether the second baby is all right."

Scored domain. Say the words. ^[1]

• Move to her head, use her name: "Your first baby is out and doing well. The second one is lying sideways, which is common, and I am going to turn it and help it out feet-first. You will feel pressure. Your epidural is topped up so you should not be in pain."
• Keep the partner informed and give them a job — "stay by her head and talk to her."
• Narrate the good news as it happens, and commit to explaining everything properly afterwards.^[1][8]

Probe 7 — "Both babies are out. Anything else?"

• "The third stage is where twin births catch people out. The uterus that held two babies is the one that will not contract — active management with an oxytocin infusion, and I treat this as a high-risk third stage every time."^[8]
• "Inspect both placentas and the dividing membrane, and document which placenta belonged to which baby."
• "Cord gases from both twins after a complicated second birth."
• "Then debrief her, and offer twin feeding and lactation support."