16.1 AFE

Question 1

a) Amniotic fluid embolism (AFE) is one of four major direct causes of maternal mortality in the 2006–2008
report from Centre for Maternal and Child Enquiries (CMACE).
State the other three major causes. (15%)

Answer 1

1. Genital tract sepsis.
2. Pre-eclampsia and eclampsia.
3. Thromboembolism

Question 2

b) How does AFE present clinically? (25%)

Answer 2

Sudden, profound, catastrophic
maternal collapse usually

during labour but also during*
caesarean section or
after delivery
(also, rarely, occurs with
amniocentesis, abdominal injury
in pregnancy or in early pregnancy).

> > Cardiovascular and respiratory collapse:

raised pulmonary vascular resistance,
acute right heart failure,
hypoxaemia.

Direct myocardial depression from *
humoral factors and also from hypoxaemia.

Left heart failure,
pulmonary oedema,
hypotension.

ARDS may result in survivors.

> > Disseminated intravascular coagulation. *
Massive haemorrhage may
contribute to cardiovascular collapse.

> > Neurological:
seizures and loss of consciousness

Question 3

c) What are the differential diagnoses of AFE? (40%)

Answer 3

Depends on the stage in the time course of the process and the current
features seen, but includes the following:
» Pulmonary embolism.
» Eclampsia.
» Sepsis.
» Anaphylaxis.
» Local anaesthetic toxicity.
» Myocardial infarction.

Question 4

d) Describe two possible theories on the pathophysiology of AFE. (20%)

Answer 4

Entry of amniotic fluid containing
fetal material into maternal circulation

via small tears in lower uterine segment,
endocervix or site of placental implantation.

1. > > Embolic theory:
   fetal tissue or/and amniotic fluid
   forcibly entering maternal circulation

causes transient pulmonary vasospasm,
cardiac failure, hypoxaemia.*

2. > > Immune theory:*

biochemical mediators in
solution in amniotic fluid trigger
anaphylactoid reaction.
Likely to be a combination of both