What is an amniotic fluid embolism?

An amniotic fluid embolism, or AFE, is thankfully an extremely rare complication of birth. It only occurs in about 1 in 40,000 deliveries, but it can be deadly, with a 20 to 60 percent mortality rate. Here we will break down what it is and how it can be treated.

An AFE is when a woman has some sort of overactive inflammatory response to her baby’s cells. At every delivery there is some mixing of mom and baby’s blood, but most women will not react at all to her baby’s cells being introduced into her blood stream.

In AFE, however, the body goes into overdrive. In the most simplistic way, you can think of it as the mom having an anaphylactic reaction to her baby’s cells, just as someone who is allergic to peanuts would if they ate a peanut butter sandwich.

An AFE can look very different in each woman, but the classic picture is a mom who has just given birth (either vaginally or by C-section). She then develops a sudden onset of shortness of breath. If oxygen levels are being monitored, doctors will see her oxygen levels rapidly drop to a dangerous level. Her blood pressure will also drop dangerously low. This is often followed by complete cardiovascular collapse, where her heart will often stop beating or beat abnormally. Hemorrhage is often seen at this time, since the parts of the blood responsible for clotting can no longer do their job.

The treatment for AFE lies in the ability for the obstetric team to first realize what is going on and correctly diagnose it. Minutes matter, so quick thinking and calling in additional help is the most important step.

The next step in treatment is to quickly start cardiac life support management, which means helping the woman get the oxygen she needs and helping her heart pump blood, usually through chest compressions and sometimes with a defibrillator. Managing bleeding with medicines and transfusion is critical as well. Transferring the woman to the ICU so she can be closely monitored and treated is critical once she is stabilized.

For women who survive to this point, they still may go on to have injuries to their lungs and have trouble breathing. Injury to the brain (like that seen in stroke patients) can also occur.

It can be hard to predict who will go on to develop an AFE since they are so rare. However, we do know that older women, women who’ve had more babies, have a male fetus, undergo induction of labor, deliver by forceps or vacuum or via C-section, have a placenta previa or abruption, or are a racial minority all increase the risk. Unfortunately these are all very broad, so it is almost impossible to know who will be affected by an AFE.

We still have much to learn and understand about AFE. Hopefully as we continue to do more research, we will be better able to understand why AFE happens in some women and not others, and how to more effectively treat it so those women who do experience one have a better chance at a full recovery.