Obstetric Anaesthesia Emergencies: Collapse on the Labour Ward

Collapse on the labour ward is managed as an adult cardiac arrest with pregnancy-specific changes: call it out as an obstetric cardiac arrest, relieve aortocaval compression by displacing the uterus to the left from 20 weeks, look for the obstetric causes alongside the 4Hs and 4Ts, and prepare for resuscitative hysterotomy from the first minute. At the CT1 anaesthetics interview you are the first anaesthetist there, and the marks are for what you do before the consultant arrives.

Key takeaways

• According to MBRRACE-UK's September 2025 report, 257 women died during or up to six weeks after pregnancy in the UK in 2021 to 2023, a rate of 12.82 per 100,000 women giving birth.
• Thrombosis and thromboembolism was the leading cause of maternal death in that triennium; cardiac disease and COVID-19 were joint second.
• The Resuscitation Council UK's 2025 guidelines say to relieve aortocaval compression above 20 weeks and prefer manual left uterine displacement to lateral tilt, because it lets you compress the chest.
• The same guidance adds the 4Ps to the 4Hs and 4Ts: pre-eclampsia and eclampsia, puerperal sepsis, placental and uterine complications, and peripartum cardiomyopathy.
• The OAA Quick Reference Handbook card says to perform resuscitative hysterotomy by five minutes if there is no return of spontaneous circulation and the pregnancy is 20 weeks or more.
• Intubation may be difficult and airway pressures higher, so the airway plan is announced early and a supraglottic device with a drainage port is acceptable.

Why do women die in pregnancy in the UK now?

Women die of clots, heart disease, infection, mental illness and bleeding, in roughly that order of frequency. MBRRACE-UK's Saving Lives, Improving Mothers' Care report published in September 2025 covers deaths from 2021 to 2023 and lists thrombosis and thromboembolism first, cardiac disease and COVID-19 joint second, then mental health conditions and epilepsy and stroke.

The same report says maternal suicide was the leading cause of death between six weeks and one year after pregnancy, and psychiatric causes accounted for 34% of deaths in that later period. Inequalities persisted: Black women had a two-fold higher mortality rate than White women, and women aged 35 or older were nearly twice as likely to die as those aged 25 to 29.

For the interview, one sentence of this shows you know why the labour ward emergency looks the way it does: haemorrhage is dramatic but a pulmonary embolus or a cardiac event is more often what kills.

What do you do in the first minute of a maternal collapse?

Confirm cardiac arrest, call for help, and declare 'obstetric cardiac arrest' so the right teams come. The OAA Quick Reference Handbook card 1-1 puts the declaration first, with a team for the mother at any gestation and a neonatal team if the pregnancy is 22 weeks or more.

• Lie flat and apply manual uterine displacement to the left if 20 weeks or more, or if the uterus is palpable at or above the umbilicus.
• Start CPR and call for the cardiac arrest trolley; identify a team leader, allocate roles including a scribe, and note the time.
• Apply defibrillation pads and check the rhythm. Defibrillation is safe in pregnancy.
• Give 100% oxygen by bag-valve-mask, then a supraglottic airway with a drainage port or a tracheal tube if trained, with waveform capnography.
• Obtain IV access above the diaphragm; if that fails, use upper-limb intraosseous access.

In practice, the two points assessors listen for are the uterine displacement and the early call for the obstetric and neonatal teams. Both are pregnancy-specific, and both are what a foundation doctor without labour ward experience omits.

Why does the uterus need displacing, and how?

From 20 weeks the gravid uterus compresses the aorta and inferior vena cava when the woman is supine, which reduces venous return and makes chest compressions less effective. The Resuscitation Council UK's 2025 special circumstances guideline says to relieve aortocaval compression as early as possible above 20 weeks and to maintain it throughout resuscitation.

The 2025 guidance prefers manual left uterine displacement to lateral tilt in cardiac arrest, because of the practicalities of delivering compressions. The OAA card gives the alternative as a left lateral tilt of 15 to 30 degrees from head to toe on a firm surface. Either way, the person doing it stands on the patient's left and pulls the uterus towards themselves.

Which causes do you look for beyond the 4Hs and 4Ts?

You look for the 4Hs and 4Ts systematically and then the pregnancy-specific causes. The Resuscitation Council UK's 2025 guideline names these the 4Ps: pre-eclampsia and eclampsia, puerperal sepsis, placental and uterine complications, and peripartum cardiomyopathy.

• Hypovolaemia: obstetric haemorrhage, including concealed bleeding, abnormal placentation, uterine rupture and atony.
• Hypoxia: pulmonary embolism, failed intubation, aspiration, pulmonary oedema in pre-eclampsia, and anaphylaxis.
• Distributive causes: sepsis, a high regional block and anaphylaxis.
• Thrombosis: amniotic fluid embolism, pulmonary embolism, myocardial infarction and air embolism.
• Toxins: local anaesthetic, magnesium and illicit drugs.
• Tamponade and cardiac causes: aortic dissection and peripartum cardiomyopathy.

According to the OAA card, tranexamic acid 1 g is given if haemorrhage is suspected, calcium chloride is used for magnesium overdose, and lipid emulsion is the treatment for local anaesthetic toxicity. As a CT1 candidate you are expected to name these causes and know the antidotes exist, not to run the infusion from memory.

When do you perform a resuscitative hysterotomy?

The OAA Quick Reference Handbook says to perform emergency hysterotomy by five minutes if there is no return of spontaneous circulation and the pregnancy is 20 weeks or more, and immediately where there are fatal maternal injuries or a prolonged pre-hospital arrest. The stated purpose is to improve the mother's outcome.

The Resuscitation Council UK's 2025 guideline frames it as time-sensitive: preparation should begin early, and the procedure should be done as soon as possible, at the site of the arrest, by a skilled team. That said, the labour ward is not the operating theatre, and moving the patient is what costs the minutes. Say that the equipment comes to the patient.

What changes about the airway in a pregnant patient?

The airway is harder and the margin is smaller. The OAA card notes intubation may be difficult and airway pressures may be higher, and it presumes oesophageal intubation if there is no expired carbon dioxide. Oxygen consumption is higher and functional residual capacity lower, so desaturation is quicker.

For a CT1 answer, the safe statement is that you would ventilate with 100% oxygen by bag-valve-mask, insert a second-generation supraglottic device if you are trained, and hand the airway to the most experienced person arriving, with capnography on from the first breath.

How do you recognise the woman who is about to collapse?

You recognise her with a validated obstetric early warning score and an ABCDE assessment, which is why the Resuscitation Council UK's 2025 guidance opens its pregnancy section with prevention. Obstetric-specific early warning systems exist because normal pregnancy shifts heart rate, blood pressure and respiratory rate, and a general score misses the trend.

If the scenario starts before the arrest, say so: position her left lateral, give oxygen, get IV access, call the obstetric registrar and the anaesthetic consultant, and treat the likely cause while the team assembles. Preventing the arrest scores the same judgement marks as running one.

How this comes up at the CT1 anaesthetics interview

Maternal collapse is a clinical judgement station favourite because it tests a structured approach under pressure with two pregnancy-specific decisions the candidate either knows or does not. The assessors score clinical judgement and decision making, reflective practice and working under pressure, five marks each per assessor, and give a global rating out of 10.

A strong spoken answer declares the arrest, displaces the uterus, calls the obstetric and neonatal teams, runs the standard algorithm, names the 4Ps, and says the hysterotomy decision is being prepared for from the first minute. anaestheticinterview's bank of 340 questions includes labour ward scenarios with AI-marked spoken practice, which is the format this station uses.