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.