Clinical overview
Maternal collapse is the acute, life-threatening event in which a pregnant or recently delivered woman loses, or is at imminent risk of losing, an effective circulation or airway. It spans the spectrum from the faint that recovers spontaneously to full cardiac arrest, and it is one of the rare moments in obstetrics where the registrar must act inside seconds, not minutes. In South Africa this is not a theoretical concern. The Saving Mothers reports of the National Committee on Confidential Enquiries into Maternal Deaths (NCCEMD) repeatedly identify obstetric haemorrhage, hypertensive disease of pregnancy, and non-pregnancy-related infection (predominantly HIV-associated, in a country with a very high antenatal HIV prevalence) as the leading direct and indirect causes of maternal death — and many of these deaths are preceded by a period of physiological deterioration that was either not recognised or not resuscitated competently. A registrar who can run a structured resuscitation, modified correctly for the pregnant physiology, and who reaches for a scalpel at the right moment, saves lives.
The principle that organises everything in this chapter is simple and must be internalised: resuscitating the mother is the best way to resuscitate the fetus, and after roughly 20 weeks' gestation emptying the uterus is part of resuscitating the mother. The pregnant patient is not a smaller-margin version of a non-pregnant adult; she has a second patient inside her and an anatomy and physiology that actively sabotage standard resuscitation unless you compensate. The two modifications you will be examined on relentlessly are relief of aortocaval compression and timely perimortem caesarean section. Everything else is good ALS practice applied to a high-risk patient.
Core knowledge
Physiological changes that make pregnancy resuscitation different
Figure M1.1 — Pregnancy physiology changes that shorten resuscitation time and mandate obstetric modifications.
The gravid physiology alters airway, breathing, and circulation simultaneously, and each change shortens the time you have.
- Airway and breathing. Capillary engorgement of the upper airway mucosa, weight gain, and breast enlargement make the pregnant airway oedematous, friable, and harder to intubate (a smaller endotracheal tube is often needed). Functional residual capacity falls while oxygen consumption rises, so the apnoeic reserve is small — desaturation is rapid, and pre-oxygenation is essential. Progesterone-driven minute ventilation produces a compensated respiratory alkalosis at baseline, so a "normal" PaCO₂ in a sick pregnant woman may signal impending failure.
- Aspiration risk. Lower oesophageal sphincter tone falls and intra-gastric pressure rises, so the pregnant patient is at high risk of regurgitation and aspiration. Early airway protection and cricoid pressure are part of the modified approach.
- Circulation. Plasma volume and cardiac output rise substantially through pregnancy, and the dilutional ("physiological") anaemia plus increased blood volume mean a woman can lose a large volume before classic signs of shock appear — then decompensate abruptly. Heart rate and cardiac output are higher; systemic vascular resistance is lower.
- Aortocaval compression. From about 20 weeks the gravid uterus compresses the inferior vena cava and aorta when the woman is supine. This reduces venous return, and during chest compressions it can cut the achievable cardiac output dramatically. Closed-chest compressions in a supine term patient may generate as little as a fraction of an effective output unless the uterus is displaced. This single fact drives the manual left uterine displacement and the perimortem caesarean teaching.
Causes of maternal collapse
A useful, exam-ready framework groups the reversible causes. The generic ALS "4 Hs and 4 Ts" (Hypoxia, Hypovolaemia, Hypo/hyperkalaemia and metabolic, Hypothermia; Thrombosis, Tamponade, Toxins, Tension pneumothorax) still applies, but obstetrics adds its own. A pregnancy-specific aide-mémoire is the "BEAU-CHOPS" type list — Bleeding/DIC, Embolism (pulmonary or amniotic fluid), Anaesthetic complications, Uterine atony, Cardiac disease, Hypertension/pre-eclampsia/eclampsia, Other (the 4 Hs/4 Ts), Placental causes (abruption/praevia), and Sepsis.
In the South African context the practical priorities map onto the Saving Mothers causes: massive obstetric haemorrhage (atony, abruption, praevia, ruptured uterus, ruptured ectopic — see postpartum-haemorrhage and antepartum-haemorrhage), eclampsia and complications of severe pre-eclampsia/HELLP (see pre-eclampsia-and-hellp and hypertension-in-pregnancy), sepsis (including pregnancy-related and HIV-associated infection), venous thromboembolism, amniotic fluid embolism, high/total spinal and local-anaesthetic toxicity, and cardiac disease (rheumatic and cardiomyopathy are disproportionately represented locally). Hypoglycaemia, hyperkalaemia, and magnesium toxicity (in a woman on magnesium sulphate for eclampsia) are reversible metabolic causes that must be actively excluded.
Assessment
Recognising the deteriorating patient before arrest
Most arrests are heralded. The discipline that prevents collapse is structured early-warning observation: respiratory rate, oxygen saturation, heart rate, blood pressure, temperature, and conscious level, tracked on an obstetric early-warning chart and acted on. A rising respiratory rate is the most sensitive early sign and the most often ignored. Escalate on trend, not only on a single threshold breach.
The collapsed patient — the structured primary survey
When you reach a collapsed woman, the assessment is the resuscitation: call for help immediately and assess Airway, Breathing, Circulation, Disability, Exposure in parallel.
- Confirm cardiac arrest by checking responsiveness and breathing and feeling for a central (carotid) pulse for no more than 10 seconds. Do not delay compressions for prolonged pulse-seeking.
- Airway / Breathing: look, listen and feel; give high-flow oxygen; anticipate the difficult airway and aspiration.
- Circulation: large-bore intravenous access (two cannulae), send bloods including full blood count, urea and electrolytes, calcium and magnesium, glucose, coagulation studies and crossmatch; assess for haemorrhage (revealed and concealed — think intra-abdominal and intrauterine).
- Disability: conscious level (AVPU/GCS), pupils, and capillary glucose; in the pre-eclamptic, consider eclamptic seizure and intracranial event.
- Exposure: examine for bleeding, rash (anaphylaxis), and the abdomen/uterus; estimate gestation (a fundus at or above the umbilicus implies ≥20 weeks and mandates the pregnancy modifications).
Targeted investigations
Bedside tests guide the reversible-cause hunt: capillary glucose, arterial blood gas (see arterial-blood-gas), 12-lead ECG, and point-of-care ultrasound where available (free fluid, cardiac activity, gross volume status). Send a magnesium level if the patient was on magnesium sulphate and toxicity is suspected. Crossmatch early and activate the massive transfusion protocol if haemorrhage is the likely mechanism.
Management
The modified ALS algorithm for pregnancy
Figure M1.2 — Modified ALS in pregnancy from recognition to the four-minute decision and five-minute delivery target.
Run standard adult Advanced Life Support, with pregnancy modifications layered on. The headline numbers (rate, depth, ratios, drug doses, defibrillation energies) are unchanged from non-pregnant ALS — do not under-treat the pregnant patient.
Drill — Cardiac arrest in pregnancy (≥20 weeks):
- Recognise and call. Confirm arrest. Shout for help and activate the full multidisciplinary team at once: senior obstetrician, anaesthetist, neonatal/paediatric team, theatre, blood bank, and porters. State clearly "maternal cardiac arrest" so everyone understands a perimortem caesarean may be needed.
- Start high-quality CPR immediately. Chest compressions at the standard rate and depth, hand position on the lower half of the sternum, minimise interruptions, allow full recoil. Ratio of compressions to ventilations and use of the defibrillator follow standard ALS.
- Relieve aortocaval compression. Apply manual left uterine displacement — stand at the patient's side and push the gravid uterus up and to the left, off the great vessels — and keep doing it throughout the resuscitation. Manual displacement is preferred to a left-lateral tilt because effective compressions are hard to deliver on a tilted patient; if a tilt is used, keep the torso as flat as possible.
- Airway early. Anticipate a difficult, oedematous airway and high aspiration risk; pre-oxygenate, intubate early with a smaller tube, apply cricoid pressure, and confirm placement.
- Defibrillate for shockable rhythms with standard energy levels. Adhesive pads are preferred; remove fetal/uterine monitors before shock delivery.
- Give standard ALS drugs at standard doses (adrenaline, amiodarone as per rhythm). Do not withhold or reduce drug doses because the patient is pregnant.
- Hunt and treat reversible causes using the 4 Hs / 4 Ts plus the obstetric causes (BEAU-CHOPS). In particular: stop magnesium and give intravenous calcium (calcium gluconate or chloride) if magnesium toxicity is the suspected cause; give intralipid for local-anaesthetic systemic toxicity; treat anaphylaxis with adrenaline; decompress a tension pneumothorax; and control haemorrhage aggressively with uterotonics, mechanical measures and massive transfusion (see shock-management and fluids-in-og).
Perimortem (resuscitative) caesarean section — the defining obstetric modification
Figure M1.3 — Perimortem caesarean as a maternal resuscitation manoeuvre when there is no ROSC by about four minutes.
This is the principle the FCOG examiner most wants you to own. In a pregnant woman of ≥20 weeks' gestation (uterus at or above the umbilicus) who has arrested, if there is no return of spontaneous circulation after about 4 minutes of correctly performed CPR, deliver the fetus by caesarean — aiming to achieve delivery by about 5 minutes from the onset of arrest.
The rationale is maternal first: emptying the uterus abolishes aortocaval compression, returns a large volume of blood to the central circulation, improves the efficacy of chest compressions and ventilation, and gives the best chance of return of spontaneous circulation. Neonatal survival is a secondary, and not the primary, indication.
Operational points that the drill demands:
- Do not move the patient to theatre and do not wait for the fetal heart, for consent, for an anaesthetist, or for a full sterile field. The procedure is done where the arrest is, with continuing CPR.
- The only equipment that is essential is a scalpel. A midline vertical skin incision and a vertical (classical) uterine incision give the fastest access and are acceptable in this setting.
- Continue chest compressions and uterine displacement during the delivery, and continue full resuscitation after delivery — the procedure is to help the mother, so resuscitation does not stop because the baby is out.
- Have the neonatal team ready to receive and resuscitate the newborn (see neonatal-resuscitation).
- The decision and the incision are the obstetrician's responsibility. This is why, structurally, an obstetric registrar must be able to perform it without hesitation.
Post-resuscitation care
If return of spontaneous circulation is achieved, the patient needs intensive-care-level support: targeted oxygenation and ventilation, haemodynamic stabilisation, identification and definitive treatment of the underlying cause, and careful electrolyte and glucose management (see fluids-electrolytes-og). In the South African system this usually means stabilisation at the level where collapse occurred and urgent referral to a regional or tertiary unit with high-care or ICU capacity, following the National Integrated Maternal and Perinatal Care Guideline referral pathways, with the highest available level of clinical escort.
South African resource and system context
The principles above are universal, but their delivery is shaped by where you are. At district level the obstetric team may be the resuscitation team — there may be no on-site intensivist and limited blood. This makes three things non-negotiable locally: drills and skills-drills so that every member of a small team knows the perimortem caesarean trigger; a functioning emergency trolley, oxygen, suction and a massive transfusion / blood-ordering pathway; and early communication with the referral hospital so that a stabilised survivor can be transferred without delay. The NDoH guideline and the Saving Mothers recommendations consistently emphasise that recognition, basic resuscitation competence, and timely referral — not exotic equipment — are what close the gap.
Red flags / pitfalls
- Forgetting aortocaval compression. Running a textbook arrest on a supine term patient without left uterine displacement is the commonest, most lethal error — your compressions may be near-useless. Displace the uterus from the first minute.
- Hesitating over the perimortem caesarean. Waiting for theatre, consent, the anaesthetist, a sterile field, or a fetal heart beat squanders the maternal benefit. The trigger is no ROSC by ~4 minutes at ≥20 weeks — decide early, deliver by ~5 minutes.
- Under-dosing the pregnant patient. ALS drug doses, compression depth/rate and defibrillation energies are not reduced in pregnancy. Treating her as fragile kills her.
- Missing magnesium toxicity. A woman on magnesium sulphate for eclampsia who collapses with loss of reflexes and respiratory depression needs calcium — stop the magnesium, do not just keep giving ALS drugs.
- Under-estimating concealed haemorrhage. Because of pregnancy's expanded volume, vital signs can stay deceptively normal until sudden decompensation. Anticipate, crossmatch and transfuse early; think abruption and ruptured uterus when the abdomen is the source.
- Airway complacency. The pregnant airway is oedematous, desaturates fast and aspirates easily — anticipate difficulty, pre-oxygenate, and protect the airway early.
- Stopping resuscitation when the baby is delivered. Delivery is a step in maternal resuscitation, not its endpoint. Continue CPR and post-arrest care.
- No team activation. A single clinician cannot run a maternal arrest. Call the whole team — obstetrics, anaesthetics, neonatology, theatre, blood bank — with the first breath.
Evidence anchors
- RCOG Green-top Guideline No. 56 — Maternal Collapse in Pregnancy and the Puerperium. The primary structured reference for the causes, the modified ALS algorithm, manual uterine displacement, and the perimortem (resuscitative) caesarean trigger (no ROSC by ~4 minutes from ~20 weeks, aiming for delivery by ~5 minutes).
- South African National Integrated Maternal and Perinatal Care Guideline (NDoH, 2024), NDoH. The SA obstetric source of truth for emergency management, level-of-care and referral pathways.
- Saving Mothers / NCCEMD (South African Confidential Enquiry into Maternal Deaths), latest triennium. Defines the leading SA maternal-death causes (obstetric haemorrhage, hypertensive disease, non-pregnancy-related/HIV-associated infection) and repeatedly highlights failures of recognition, basic resuscitation, and timely referral.
- ILCOR 2025 CoSTR and ERC 2025 guidelines (adult Advanced Life Support, with pregnancy considerations). The basis for unchanged compression rate/depth, ventilation ratios, drug doses and defibrillation energies, layered with the pregnancy modifications.
- RCOG GTG 52 — Prevention and Management of Postpartum Haemorrhage and GTG 63 — Antepartum Haemorrhage, with the WOMAN trial (Lancet 2017) supporting early tranexamic acid in obstetric haemorrhage, for the haemorrhage-driven collapse pathway.
- NICE NG133 — Hypertension in Pregnancy (2019), for magnesium sulphate use in eclampsia/severe pre-eclampsia (and thus the calcium antidote in magnesium toxicity).
Standard ALS thresholds and timings stated here (the ~4-minute decision / ~5-minute delivery target, manual left uterine displacement, the ≥20-week / fundus-at-umbilicus trigger, and the "scalpel is the only essential equipment" teaching) reflect RCOG GTG 56 and resuscitation-council teaching; confirm exact figures against the current guideline editions before quoting them as fixed.