Amniotic Fluid Embolism

Question 1

Definition of amniotic fluid embolism

Answer 1

Cardiorespiratory collapse caused by anaphylaxis or complement activation in response to foetal cells or amniotic fluid (liquor) entering the maternal circulation.
A rare cause of maternal collapse, typically diagnosed at post-mortem with the presence of foetal cells in maternal pulmonary capillaries.

Question 2

Causes of amniotic fluid embolism

Answer 2

• Aetiology can possibly be attributed to strong uterine contractions, excessive amniotic fluid and disruption of vessels supplying the uterus

Question 3

Incidence of amnitoic fluid embolism

Answer 3

1.7 per 100,000 maternities. Survival is now around 81%, though neurological morbidity in survivors is well recognised

Question 4

Risk factors for amniotic fluid embolism

Answer 4

Increased maternal age, IOL, C-section, multiple pregnancy

Question 5

Presentation of amniotic fluid embolism

Answer 5

Amniotic fluid embolisation usually presents around the time of labour and delivery. It can present similarly to sepsis, PE or anaphylaxis, with acute onset:
* Collapse during labour or birth, or within (usually) 30 minutes of birth
* Hypotension, respiratory distress, and hypoxia
* Possibly seizures and cardiac arrest
* Pulmonary hypotension may develop secondary to vascular occlusion either by debris or vasoconstriction. This may resolve and result in development of ventricular dysfunction or failure
* Coagulopathy may follow with PPH
* Profound foetal distress

Question 6

Investigations for amnitoic fluid embolism

Answer 6

• Clinical diagnosis requiring immediate management- diagnosis can only accurately be made in post-mortem
• Bloods: ABG, FBC, UE, X-match. BP, CXR, ECG

Question 7

Management of amnitoic fluid embolism

Answer 7

• ABCDE approach
• IMPORTANT: aortocaval compression significantly reduces cardiac output from 20 weeks of gestation onward and the efficacy of chest compressions during resuscitation
• Manual displacement of the uterus to the left is effective in relieving aortocaval compression
• Could alternatively use a left lateral tilt of the woman from head to toe at an angle of 15–30 on a firm surface (protect spine in case of trauma)
• Intubation in an unconscious woman with a cuffed endotracheal tube should be performed immediately by an experienced anaesthetist (may be more difficult in pregnancy)
• Two wide bore cannulas inserted with aggressive volume replacement
• In women over 20 weeks of gestation, if there is no response to correctly performed CPR within 4 minutes of maternal collapse or if resuscitation is continued beyond this, then PMCS (perimortem caesarean section) should be undertaken to assist maternal resuscitation. Ideally, this should be achieved within 5 minutes of the collapse-> should not be delayed by moving the woman
• The management of AFE is supportive rather than specific, as there is no proven effective therapy
• Early involvement of senior experienced staff, including obstetricians, anaesthetists, haematologists and intensivists, is essential to optimise outcome
• Coagulopathy needs early, aggressive treatment, including the use of fresh frozen plasma
• In maternal collapse, survival rates of over 50% have been reported