Amniotic Fluid Embolism
Amniotic fluid embolism (AFE) is extremely rare obstetric complication. This illness occurs when amniotic fluid, fetal cells, fetal hair, or other debris from the fetus enters the mother’s blood stream. The interaction of these particles with the mother’s blood triggers an allergic reaction. This reaction results in cardiorespiratory collapse and coagulopathy. AFE is one of the most common causes of maternal mortality in the world.
There are two phases of progression. During the first phase the individual will experience acute shortness of breath and hypotension. Quickly the heart begins to fail and it dilates and there is a reduction in oxygen to the heart and lungs. Patients will eventually go into a coma, and most do not survive past this first stage.
Some patients will make it beyond the first stage into the second phase, also known as the hemorrhagic phase. This phase is characterized by shivering, coughing, vomiting, and a bad taste in the mouth. As the name suggests the most important characteristic of this phase is the excessive bleeding due to an inability of blood to clot. As the cardiovascular system function deteriorates the fetus will go into distress; death will be imminent unless the child is delivered.
AFE is highly unpredictable and often occurs during delivery and labor or in the immediate post-partum period. It is difficult to control if it occurs during labor and delivery as the physician’s main goal in to safely deliver the baby. There are four main criteria that help identify this catastrophic complication: acute hypotension, acute hypoxia, coagulopathy or severe hemorrhage, having these complications occur during labor/delivery or within 30 minutes post-partum.
While there is no perfect certainty as to why this illness occurs, there are a few events that need to occur to allow amniotic fluid to enter the uterine veins. These include membranes rupture, ruptured uterine/cervical veins, and a pressure gradient from the uterus to the vein.
Fetal tissue present in the maternal bloodstream is not uncommon. Typically, tests will reveal that at least some small amount is always present in the maternal blood flow. However, for a few individuals this might cause a complex chain reaction in which the mother becomes allergic to the particles and soon dies.
There are several risk factors associated with AFE. These include:
- multiparity-having the development of two or more child in one gestational term, or having given birth to more than two children,
- maternal age-increased age is associated with increased risk,
- male fetus,
- intrauterine fetal demise-medical term for the condition of a baby that has died in the womb,
- amniotomy-artificially breaking the fetal membranes prior to childbirth to induce delivery,
- placental abruption-when the placenta separates from the mother’s uterus,
- chorioamnionitis-an inflammation of the fetal membranes caused by bacterial infection,
Signs & Symptoms
Some symptoms that might lead a health care professional to be suspicious of AFE include:
- acute-onset respiratory distress,
- hypoxemia or cyanosis-low oxygen levels or the presence of bluish skin due to low oxygen,
- seizures or coma.
Unfortunately, there is no medical test that can positively confirm the presence of amniotic fluid embolism. However, as is the case with innovative medical techniques, health care professionals are often able to make a diagnosis of exclusion. This means that they rule out other possibilities via testing. One example of very prominent exclusion criteria is the presentation of acute cardiorespiratory collapse or hemorrhase in the last period of gestation. Possible issues include septic shock, myocardial infarction, aspiration, or placental abruption.
Certain laboratory tests may help in providing physicians with the idea that complications a mother-to-be is experiencing are a result of AFE. Some of these tests include blood count, arterial blood gases, chest x-ray, VQ scan, EKG and echocardiogram. Also, doctors may be able to perform an examination of the cervix looking for the presence of amniotic fluid debris by taking hysterectomy specimens.
Ventilation/perfusion (V/Q) lung scans, also known as a V/Q scan, is used to examine the circulation of air and blood within a patient’s lungs. The scan requires the use of two nuclear tests. This means that two medical isotopes are used to detect the flow of breathing (ventilation) and blood circulation (perfusion) in the lungs. Having these scans performed will require that a patient either inhale or have injected radioactive material (isotopes) so that ventilation and perfusion can be detected and analyzed on the scans. In patients with AFE, VQ scans are typically revealed as decreased perfusion.
There is no treatment that can reverse AFE. However, physicians are able to help manage the condition by providing those women afflicted with transfusion of red blood cells (RBCs), fresh frozen plasma and clotting factors, and ventilation and circulatory support. These treatments given will help to replace blood lost and reverse the coagulopathy. This complication is responsible for approximately 10% of maternal mortality in the US. However, with early diagnosis it is often manageable.