Amniotic fluid embolism is a rare, unpreventable and often fatal complication of pregnancy.
It occurs when amniotic fluid enters a mother’s bloodstream and triggers an allergic-like reaction.
Normally during pregnancy, amniotic fluid (which includes fetal cells and hair, intestinal cells and other debris) stays within the uterus, sealed inside the amniotic sac.
Amniotic fluid embolism (AFE) can only occur when the barrier between the amniotic fluid and maternal blood circulation is compromised. This allows the amniotic fluid to enter the mother’s bloodstream and the lungs.
An amniotic embolism can also trigger an allergic reaction, much like anaphylaxis seen with insect or food allergies where breathing can be restricted.
AFE can happen in healthy women during labour or shortly after giving birth in both vaginal and c-section births. It can also occur during a pregnancy termination or when an amniocentisis is performed.
What Happens With An Amniotic Fluid Embolism?
There are two phases of AFE.
During the first phase, the mother may begin to experience shortness of breath and have a sudden drop in blood pressure (hypotension).
Cardiac arrest may follow quickly and many women will fall into a coma within minutes. Around 60-80% of women don’t survive the first stage of AFE.
Women who do survive the first phase will enter the second phase of AFE, the haemorrhagic phase.
Symptoms include severe shortness of breath, shivering, coughing, vomiting, fetal distress and excessive bleeding due to a condition called disseminated intravascular coagulation (DIC). DIC prevents blood from clotting.
What Are The Risk Factors?
A review of evidence based research has shown there are a number of factors linked to an increased risk of AFE, including:
- Being 35 years of age or older at the time of your child’s birth
- Having preeclampsia (high blood pressure with excess protein in the urine after 20 weeks of pregnancy)
- Placenta previa (covering the cervix) or placenta abruption (coming away from the uterus wall before birth).
- Being medically induced before labour begins spontaneously.
- Having an operative birth, including c-section, forceps or vacuum birth
- Having polyhydramnios (too much amniotic fluid)
- Cervical lacerations (tearing of the cervix)
- Uterine rupture (tear in the uterus wall).
While an amniotic fluid embolism can’t be prevented, it’s important to remember it is extremely rare.
The incidence of AFE is reported to range from 1 in 8,000 to 1 in 80,000 pregnancies.
How Is AFE Diagnosed?
The truly frightening aspect of AFE is there are no warning signs and no known prevention or treatment.
There are no tests to diagnose AFE when it does occur so care providers must rely on the following symptoms to make a diagnosis:
- Extreme shortness of breath
- Low blood oxygen
- Choking, coughing
- Turning blue
- Sudden onset of severe chest pain
- Sudden drop in blood pressure or cardiac arrest
- Severe haemorrhage from various body sites
If all of the above symptoms occur during labour, c-section, dilation and evacuation, or within 30 minutes of birth without any other explanation a diagnosis of AFE will be made.
How Is AFE Treated?
If AFE is diagnosed, treatment must begin immediately.
- The mother will have oxygen therapy usually via a ventilator
- She will be given large volumes of intravenous fluids
- CPR will be performed if a cardiac arrest occurs
- If the baby hasn’t been born, a c-section will be performed within five minutes or as soon as possible after cardiac arrest
- Medications may needed to control blood pressure
- Blood transfusions to replace the blood lost during the haemorrhagic phase.
The baby will be monitored for signs of distress and be born as soon as possible once the mother’s condition is stable. This increases the baby’s chances of survival.
What Is The Outcome?
Over 30 years ago, the maternal mortality rate for AFE was almost 90%. Better resuscitation techniques, intensive care facilities, and early recognition of AFE
has increased survival rates for women and babies.
AFE accounts for 4.7% of direct maternal deaths in the UK, 13% in France, 30% in Singapore, and around 10% in the USA and Australia. Babies who are alive at the time of AFE occurring have a 70% chance of survival.
The majority of women survive but around 80% will go on to have long-term brain and organ damage. Around 50% of babies who survive will experience some form of nervous system damage or cerebal palsy.
AFE is thankfully a rare complication of pregnancy and birth. It can’t be prevented and it is difficult to predict if and when AFE will occur. If you have experienced AFE and plan on future pregnancies, discuss your options with an obstetrician beforehand.
Recommended Reading: The Cascade Of Intervention – What You Need To Know.