Fetal surveillance modalities in labour — structured oral station (12 minutes)

Opening prompt — "She is 5 cm, low risk, and wants to stay mobile. What is your plan?"

Model response: ^[1][2]

• "On admission she meets the criteria for intermittent auscultation: no antenatal or intrapartum risk factors, cephalic with normal growth and liquor, normal uterine activity and resting tone, and a fetal heart rate of 110 to 160 with a regular rhythm and no decelerations heard."
• "Auscultation every 15 to 30 minutes in the active first stage, and after every contraction or at least every 5 minutes in the second stage. Counted for a full minute, immediately after a contraction, with a hand on her radial pulse each time."
• "Her body mass index of 42 is not by itself a reason for continuous monitoring under 40, but it does tell me that if we ever need a CTG, the signal will be difficult — so I would plan that escalation now rather than at 3 am."^[1][2]

Examiner is listening for: the criteria as a list, the intervals as numbers, and anticipatory planning. ^[1]

Probe 1 — "Why not just put a CTG on everyone? It is safer."

• "The Cochrane review is the honest answer. Continuous CTG halves neonatal seizures — risk ratio 0.50, 95 per cent confidence interval 0.31 to 0.80 — but makes no difference to perinatal death or cerebral palsy, and increases caesarean birth by a risk ratio of 1.63 and instrumental birth by 1.15."^[3]
• "So in a low-risk woman it converts a small reduction in seizures into a real increase in operative birth. Admission CTG is the same story: five randomised trials and 16 341 women showed more continuous monitoring with no improvement in any maternal or neonatal outcome."^[7][3]
• "That is why the ANZ guideline recommends auscultation for low-risk women and reserves CTG for risk factors."^[1]

Probe 2 — "She now needs oxytocin. What changes?"

• "Oxytocin is an intrapartum risk factor, so I recommend continuous CTG and I explain why, rather than announcing it."^[1]
• "I would start the CTG before the augmentation begins so I have a baseline, and I would go and find a wireless monitor first, because the reason women end up in bed is the cables, not the monitoring."^[6][1]
• "I would also plan the escalation: with a body mass index of 42, I expect contact loss, so I would establish early whether she has any contraindication to a scalp electrode."^[1]

Probe 3 — "The trace is losing contact every few minutes. Talk me through it."

Systematic, in order: ^[4][1]

• "First, check the maternal pulse against the trace. An inadequate trace and maternal heart rate contamination travel together, and the second is far more dangerous than the first."^[4]
• "Re-palpate the abdomen and reposition the ultrasound transducer over the fetal back; reposition the toco. Check the straps, the gel and the battery."
• "Consider wireless or beltless abdominal fetal ECG if we have one."
• "If I still cannot get a continuous, interpretable trace in a woman on oxytocin, I escalate to a fetal scalp electrode."
• "What I will not do is write 'CTG normal' across twenty-five minutes of contact loss. An uninterpretable trace is an abnormal finding."^[1][4]

Probe 4 — "Take me through the scalp electrode."

• Prerequisites: ruptured membranes, adequate cervical dilatation, and relative certainty about the position of the presenting part.^[1]
• Contraindications — the same list as fetal blood sampling: maternal HIV, hepatitis B or hepatitis C; active genital herpes lesions; suspected intrauterine sepsis; known or suspected fetal bleeding disorder or thrombocytopenia. "Group B streptococcus colonisation is not a contraindication."^[1]
• Technique: aseptic, identify the presenting part, avoid fontanelles, sutures, the eyes, the face and the genitalia, rotate the spiral to engage, confirm the trace, and account for the electrode at birth.^[1][5]
• Consent with real numbers: "In a cohort of over 170 000 births, scalp injury occurred in 1.2 per cent with the electrode versus 0.9 per cent without, and cephalohaematoma in 1.0 versus 0.9 per cent. Absolute risk is very low, and the authors supported use when clinically indicated."^[5]

Probe 5 — "Why is an internal electrode better than a good external trace?"

• "It records a true fetal electrocardiogram, R-wave to R-wave, rather than an autocorrelated ultrasound estimate, so variability is more faithful and signal loss is lower."^[8]
• "In a second-stage study with simultaneous recording, external monitoring had more than double the signal loss — 10 per cent versus 4 per cent — and, importantly, showed more accelerations and fewer decelerations than the internal trace, with more of those accelerations coinciding with contractions."^[8]
• "That artefact profile is exactly what maternal contamination looks like. An inadequate external trace in an at-risk second stage is a reason to go internal, not a reason to relax."^[8][4]

Probe 6 — communication. "She is upset. She wanted to stay mobile and now she is wired to a machine."

Respect and rapport are two of the eight domains. Show them. ^[1][6]

• Sit at her level, acknowledge the loss: "I know this is not the labour you planned, and I am sorry we have had to change it."
• Explain the reason in her words: "The drip makes contractions stronger and closer together, and that can be harder for the baby, so we watch the heartbeat all the time while it runs."
• Be honest about the trade-off: "Continuous monitoring roughly halves the risk of newborn seizures, but it does increase the chance of a caesarean. It is a trade-off, and with the drip running I think it is the right one."
• Give back what you can: "The cables are the problem, not the monitoring. I am going to find the wireless monitor so you can stand and move. If we cannot get one, I will help you change position often."
• Keep the decision hers: "If you would prefer not to have continuous monitoring, tell me and we will talk it through with my consultant and find the safest plan we can both live with."^[1][6][3]

Probe 7 — "She declines the scalp electrode. Now what?"

• "I would document the discussion, involve my consultant, and be explicit that I now have an at-risk labour I cannot monitor reliably."^[1]
• "Practically: keep trying external and wireless routes, keep the maternal pulse displayed, use structured auscultation as a backup with a documented interval, review her progress more frequently, and lower my threshold to recommend birth if labour is not progressing."^[1][2]
• "I would revisit the conversation rather than treat the refusal as final, and I would make sure she knows the door stays open."^[1]