Amniotic fluid embolism (AFE) although rare carries a high risk of severe morbidity and death, a study from Australia has confirmed.

Maternity data were assessed over seven years in a cohort of 606,393 deliveries in New South Wales. Twenty cases of AFE were identified giving an incidence of 3.3 per 100,000 deliveries. All were in singleton pregnancies, 79% were in multiparous women.

Seven women died; a case fatality rate of 35%. In the six women who died in hospital the perinatal death rate (stillbirths + neonatal deaths) was 50%. Perinatal mortality where the mother survived was 23%.

Of the seven maternal deaths one occurred outside hospital, five on the day of delivery and one more than three weeks after delivery following cerebral infarction, pulmonary embolism and MI after a lengthy stay in ITU.

The majority of the survivors required, sometimes protracted, ITU treatment and transfusion of packed cells, fresh frozen plasma, platelets or cryoprecipitates. Three of the survivors sustained cerebral infarction. All the women delivered in tertiary care centres survived.

Induction of labour with vaginal prostaglandin (but not oxytocin) and manual removal of the placenta were newly identified risk factors for AFE in this study. Placenta praevia and abruption, instrumental and Caesarean deliveries, were all associated with an increased risk of AFE. Compared with the whole cohort, women sustaining AFE were significantly older and more likely to be multiparous.

Leakage of amniotic fluid with its fetal squames and vernix into the maternal circulation (AFE) is an uncommon but often rapidly fatal complication of pregnancy.

Embolised material can obstruct arteries leading to tissue necrosis, MI and stroke, and its vasoactive nature can result in disseminated intravascular coagulation and haemorrhagic complications.

Known modes of presentation include coma, hypotension, seizure, bleeding disorder and cardiac arrest.

Although a frequently catastrophic complication of childbirth AFE is thankfully rare.

I found this study of interest not just because it served as a useful reminder of the condition but also its demographic and delivery associations. Survival appeared strongly linked to rapid high-tech intensivist intervention.

Dr Chris Barclay