Maternal cardiac arrest and perimortem caesarean (resuscitative hysterotomy)
Overview
Cardiac arrest during pregnancy is uncommon but time‑critical. Management follows standard adult ALS principles with specific, early modifications to account for the gravid uterus and altered maternal physiology. The principal objective is maternal resuscitation.
Perimortem caesarean (resuscitative hysterotomy) is performed primarily to improve maternal circulation and ventilation; neonatal benefit is an important secondary consideration when the pregnancy is sufficiently advanced.
UK resuscitation guidance (Resuscitation Council UK) provides the definitive ALS modifications and time targets for perimortem delivery (Resuscitation Council UK, 2025).
Epidemiology and common causes
- About half of maternal cardiac arrests are due to embolic events (pulmonary embolism, including amniotic fluid embolism) or major antepartum haemorrhage. Published estimates suggest approximately 30% embolic and approximately 20% haemorrhagic causes.
- Other causes include sepsis, peripartum cardiomyopathy, anaesthetic complications (including aspiration), anaphylaxis, severe pre‑eclampsia/eclampsia, arrhythmia and myocardial infarction.
Key physiology relevant to resuscitation
- From about 20 weeks’ gestation (uterus palpable at or above the umbilicus) the gravid uterus can compress the inferior vena cava (IVC) and aorta when the woman is supine, reducing venous return and cardiac output.
- The elevated diaphragm reduces functional residual capacity and increases the risk of rapid desaturation and aspiration.
- Chest anatomy changes and increased blood volume alter the mechanics and metabolic demands during resuscitation.