Instrumental vaginal birth — structured oral station (12 minutes)

Opening prompt — "Tell me what you do from the doorway."

Model response — run it in this order and say it out loud: ^[1][2]

• "This is delay in the second stage with a suspicious trace at a low station. I would explain to her that I think the baby needs help to be born, and take her consent."
• "Before touching an instrument I confirm the prerequisites: full dilatation, membranes ruptured, cephalic, direct occipitoanterior position confirmed on examination, station plus 2, nothing palpable abdominally, bladder emptied, epidural topped up and effective, consent taken, paediatrician called, and an agreed plan if it fails."
• "This is a low, non-rotational birth in a good position with no moulding, so I would do it in the birth room and I would tell the team my abandonment point before I start."^[1][2]

Examiner listens for: the checklist recited without prompting, the classification stated (low, non-rotational), and the abandonment point named before the first pull. ^[1]

Probe 1 — "Which instrument, and why?"

• "Either is reasonable here. Forceps are less likely to fail — risk ratio 0.58 in the Cochrane review of 31 trials and 5754 women — but carry more third- and fourth-degree tears, risk ratio 1.83, and more maternal pain. Vacuum causes more scalp trauma: cephalhaematoma, retinal haemorrhage and jaundice."^[3]
• "If I choose a vacuum I would use a rigid cup, because soft cups fail more often, risk ratio 1.62. I would site it at the flexion point, 3 cm anterior to the posterior fontanelle in the midline, sweep the rim for maternal tissue, and raise the vacuum in a single step."^[1][3]
• "If I choose forceps I would assemble and check them outside, insert the left blade first, wander into a cephalic application, and verify before traction — sagittal suture midline and perpendicular to the shanks, posterior fontanelle one finger-breadth above the shanks, fenestrations barely palpable."^[1][2]

Probe 2 — "You have pulled twice and the head has not descended. What now?"

• "The stop rules are: no descent with the first correctly applied pull, no birth after three pulls, two cup detachments, or about 20 minutes. Two pulls without descent means I stop and reassess rather than pull harder."^[1]
• "I would not swap to a second instrument. Sequential vacuum then forceps carried intracranial haemorrhage risk ratio 3.9, facial nerve injury 13.3 and seizures 13.7 compared with spontaneous birth, and for several outcomes the combined risk exceeded the sum of each instrument alone."^[4]
• "I would move to theatre for caesarean, warn the team that the head may be impacted after the attempt, ensure a second pair of hands for disimpaction, and call the consultant."^[1][8]

Examiner is testing whether you can stop. A candidate who escalates force or reaches for forceps has failed the safety domain regardless of the rest. ^[4]

Probe 3 — "Compare instrumental birth with a second-stage caesarean for this woman."

• "In a prospective cohort of 393 women needing operative birth in theatre at full dilatation, caesarean was associated with more major haemorrhage over one litre, adjusted odds ratio 2.8, and longer hospital stay, 3.5. Babies born by caesarean were more likely to need intensive care, 2.6, but less likely to have trauma than those born by forceps, 0.4."^[8]
• "Major haemorrhage was halved when a skilled obstetrician performed the operation, adjusted odds ratio 0.5 — which is the argument for calling for senior help rather than for choosing one route over the other."^[8]

Probe 4 — "The birth is achieved with a mediolateral episiotomy. What are you worried about, for her and for the baby?"

• Maternal: obstetric anal sphincter injury, extension of the episiotomy, vaginal and cervical laceration, postpartum haemorrhage, urinary retention, haematoma and infection. Sphincter injury complicates about 3.0% of vacuum and 4.7% of forceps births in national data; mediolateral episiotomy is protective with odds ratio 0.11 at vacuum and 0.08 at forceps.^[7]
• Neonatal: chignon, cephalhaematoma, subgaleal haemorrhage, intracranial haemorrhage, skull fracture, retinal haemorrhage and facial nerve palsy. "Subgaleal blood collects beneath the epicranial aponeurosis, crosses suture lines and can hold a large fraction of the baby's blood volume — a cephalhaematoma cannot cross a suture."^[6]
• What I would do: rectal examination in every case, correct classification and repair, paired cord gases, a documented neonatal scalp examination with a subgaleal surveillance plan, and a single dose of intravenous co-amoxiclav — ANODE reduced infection from 19% to 11%, risk ratio 0.58.^[5][7]

Probe 5 — "She is frightened and asks why you need to use forceps. Talk to her."

This is a scored domain. Demonstrate it out loud, at her eye level, using her name: ^[1]

• "Your baby is telling us it is getting tired, and you have been pushing hard for an hour. I can help the baby out now with an instrument, and that is quicker and safer than waiting."
• "I will place a small instrument around the baby's head and pull gently with your contractions. I will need you to keep pushing with me. I will make a small cut to protect you from a bigger tear."
• "If the baby does not come after three pulls, I will stop and we will move next door for a caesarean instead. I will tell you before that happens, not afterwards."
• Check understanding, invite questions, keep the partner informed, and commit to a debrief before she goes home.^[1][2]

Probe 6 — "What goes in the notes?"

• Indication, prerequisites confirmed, station, position, instrument and cup type, number of pulls, times of application and birth, episiotomy, cord gases, tears and repair, blood loss, antibiotic given, and everyone present.^[1]
• "The note matters because if the baby needs cooling, the neonatal team will read it, and because whoever counsels her next pregnancy will read nothing else."^[1]