Amniotic fluid embolism — structured oral station (12 minutes)

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

Model response — the order matters more than the content: ^[4][6]

• "This is a maternal collapse. I would pull the emergency buzzer, put out the maternal cardiac arrest call, and say out loud that I am the team leader. I want an anaesthetist, my consultant, the neonatal team, a scribe and the massive haemorrhage protocol activated now."
• "While that is happening: 100% oxygen with a bag-valve-mask and early intubation by the anaesthetist; check for a pulse for no more than ten seconds; if pulseless, compressions flat on a firm surface, hands on the centre of the sternum, with continuous manual left uterine displacement."^[6]
• "I would start the clock aloud. She is at term and undelivered, so if there is no output at four minutes I am performing a perimortem caesarean in this room, for her."^[6][1]
• "Two large-bore cannulae above the diaphragm, bloods including fibrinogen, and I would stop the syntocinon."^[4][5]

Examiner is listening for: leadership declared, parallel action, uterine displacement, the four-minute commitment, and pre-emptive activation of transfusion before there is any visible blood. ^[4]

Probe 1 — "What is your differential, and what makes you favour one?"

• "Amniotic fluid embolism is top of my list: sudden hypoxia and hypotension in established labour with immediate fetal compromise. What will confirm my suspicion clinically is coagulopathy appearing out of proportion to any blood loss."^[2][5]
• "I am actively excluding: pulmonary embolism — hypoxia and right heart strain but no early disseminated intravascular coagulation; anaphylaxis — a trigger, urticaria, bronchospasm, response to adrenaline; high or total spinal — she has no block in situ, so that is out; local anaesthetic toxicity — again no recent block; eclampsia — no hypertension or proteinuria; and concealed haemorrhage or uterine rupture, which I can partly assess by palpating the abdomen."^[1][2]
• "Sepsis is on the list, and the absence of fever is one of the four research criteria that supports amniotic fluid embolism over infection."^[2]

Probe 2 — "How would you confirm the diagnosis?"

• "I would not, because I cannot. Amniotic fluid embolism is a clinical diagnosis of exclusion. No laboratory test confirms or excludes it."^[1][2]
• "Fetal squames in maternal pulmonary blood are neither sensitive nor specific and are no longer required. Tryptase, complement and zinc coproporphyrin are research assays, not decision tools."^[1]
• "The Clark and Society for Maternal-Fetal Medicine criteria from 2016 exist to define uniform research cohorts: sudden cardiorespiratory arrest or hypotension with respiratory compromise; overt disseminated intravascular coagulation after the collapse; onset in labour or within 30 minutes of delivery of the placenta; and no fever of 38.0 degrees Celsius or above. All four are required, which deliberately excludes some real clinical cases."^[2]

Examiner is listening for the phrase "diagnosis of exclusion" delivered without hedging, then the criteria quoted accurately with their purpose named. ^[2]

Probe 3 — "She has return of spontaneous circulation after the caesarean. Echocardiography shows a dilated, hypokinetic right ventricle and a small left ventricle. What now?"

• "This is phase one physiology: acute pulmonary vasoconstriction with right ventricular failure and an underfilled left ventricle. I would deliberately not volume-load her — a fluid bolus distends the right ventricle, bows the septum leftward and drops output further."^[3]
• "I would correct hypoxia, hypercarbia and acidosis, all of which raise pulmonary vascular resistance; start noradrenaline or vasopressin to maintain right coronary perfusion pressure, with vasopressin preferred because it does not raise pulmonary vascular resistance; add an inodilator such as milrinone or dobutamine; and ask for inhaled nitric oxide or prostacyclin."^[3]
• "I would involve intensive care and cardiology immediately and ask early about extracorporeal membrane oxygenation, because the referral and cannulation take time I will not have later."^[3][1]

Probe 4 — "She is now bleeding heavily and her clotting has collapsed. Talk me through your transfusion."

Assessor feeds these results: fibrinogen 0.6 g/L, platelets 58 × 10⁹/L, INR 2.4. ^[5]

• "Fibrinogen first: cryoprecipitate or fibrinogen concentrate, targeting a fibrinogen at or above 2 g/L. Fibrinogen falls first and fastest in obstetric consumptive coagulopathy."^[5]
• "Platelets to keep above 50 × 10⁹/L; red cells and fresh frozen plasma in a ratio-based pack until viscoelastic or laboratory guidance is available; calcium replacement for the citrate load; and active warming."^[5][1]
• "Tranexamic acid 1 g intravenously over 10 minutes for the haemorrhage component, recognising that the evidence base for that is the WOMAN trial in postpartum haemorrhage rather than amniotic fluid embolism specifically."^[1]
• "I would repeat fibrinogen and viscoelastic testing every 30 to 60 minutes while she is bleeding, and I would treat the uterus surgically in parallel — but I would not expect surgery to work on an uncorrected coagulopathy."^[5][1]

Probe 5 — "Your consultant suggests recombinant activated factor VII. What do you say?"

This probe tests whether you will disagree respectfully with a senior — a scored behaviour, not just a knowledge point. ^[7]

• "I would say: I have a concern about that. The systematic review of published amniotic fluid embolism cases found substantially worse outcomes in women who received recombinant factor VIIa, plausibly because it drives thrombosis in a pulmonary microvasculature already loaded with platelet-rich thrombus."^[7]
• "I would suggest we maximise conventional replacement first — fibrinogen to 2 g/L, platelets above 50 × 10⁹/L, plasma, calcium and warming — and reserve factor VIIa for haemorrhage that remains genuinely uncontrollable after that. If we do use it, I would want it documented as a considered last resort."^[7][5]

Probe 6 — "What about A-OK?"

• "A-OK is atropine 1 mg intravenously, ondansetron 8 mg intravenously and ketorolac 15 to 30 mg intravenously, aimed at the vagal, serotonergic and thromboxane components of the response."^[8]
• "The evidence is case reports and small series, and it appears in the Society for Maternal-Fetal Medicine checklist as an option rather than a standard. I would give it once the core resuscitation is running, I would not delay CPR, delivery, vasopressors or blood products for it, and I would say clearly that the evidence is weak."^[8][4]

Probe 7 — "Her husband is outside. He has just been told to wait. What do you do?"

Rapport, respect and communication are three of the eight scored domains. Say the words aloud in the station. ^[4]

• Delegate a named senior midwife to stay with him continuously, then go yourself as soon as you can safely hand over leadership.
• Sit down, at his level, use her name and his name. "I am the obstetric registrar looking after Sarah. I need to tell you that she has become very unwell very suddenly during labour. Her heart stopped and our team is resuscitating her now. We have delivered your baby to help her."
• Warn, then inform, then pause. Avoid jargon. Do not say "amniotic fluid embolism" without immediately explaining it in plain words: "a rare and severe reaction to pregnancy that affects the lungs, heart and blood clotting."
• Be honest about uncertainty: "I cannot tell you yet whether she will survive. I will come back and tell you everything I know as soon as I know it."
• Ask what he needs, offer to call family, and commit to a formal debrief later.^[4][9]

Probe 8 — "What will you tell her afterwards about a future pregnancy?"

• "Successful subsequent pregnancies after amniotic fluid embolism are reported, and there is no established recurrence risk that I could quote to her — but the evidence is thin, so I would be honest about that uncertainty."^[1]
• "I would recommend birth in a tertiary unit with immediate blood availability, a documented plan, and early anaesthetic and intensive care involvement, and I would offer pre-pregnancy counselling with my consultant."^[1][9]
• "I would also make sure she has had a proper debrief about what happened this time, because the psychological morbidity is substantial and often untreated."^[9]