Amniotic fluid embolism is a rare but serious condition that occurs when amniotic fluid — the fluid that surrounds a baby in the uterus during pregnancy — or fetal material, such as fetal cells, enters the mother's bloodstream. Amniotic fluid embolism is most likely to occur during delivery or immediately afterward.
Amniotic fluid embolism is difficult to diagnose. If your doctor suspects you might have amniotic fluid embolism, you'll need immediate treatment to prevent potentially life-threatening complications.
Amniotic fluid embolism develops suddenly and rapidly.
Signs and symptoms of amniotic fluid embolism might include:
- Sudden shortness of breath
- Excess fluid in the lungs (pulmonary edema)
- Sudden low blood pressure
- Sudden failure of the heart to effectively pump blood (cardiovascular collapse)
- Life-threatening problems with blood clotting (disseminated intravascular coagulopathy)
- Altered mental status, such as anxiety
- Rapid heart rate or disturbances in the rhythm of the heart rate
- Fetal distress, such as a slow heart rate
- Sudden fetal heart rate abnormalities
- Bleeding from the uterus, incision or intravenous (IV) sites
Amniotic fluid embolism occurs when amniotic fluid or fetal material enters the mother's bloodstream. Why this happens isn't well understood. A likely cause is a breakdown in the placental barrier, such as from trauma.
When this breakdown happens, the immune system responds by releasing products that cause an inflammatory reaction, activating abnormal clotting in the mother's lungs and blood vessels that can result in a serious blood-clotting disorder known as disseminated intravascular coagulation.
However, amniotic fluid embolisms are rare — and it's likely that some amniotic fluid commonly enters the mother's bloodstream during delivery without causing problems. It's not clear why in some cases this leads to amniotic fluid embolism.
Further research on what causes amniotic fluid embolisms is needed.
Amniotic fluid embolisms are rare, which makes it difficult to identify risk factors. It's estimated that there are between 1 and 12 cases of amniotic fluid embolism for every 100,000 deliveries.
Research suggests that several factors might be linked to an increased risk of amniotic fluid embolism, however, including:
- Advanced maternal age. If you're 35 or older at the time of your child's birth, you might be at increased risk of amniotic fluid embolism.
- Placenta problems. If there are abnormalities in your placenta — the structure that develops in your uterus during pregnancy — you might be at increased risk of amniotic fluid embolism. Abnormalities might include the placenta partially or totally covering the cervix (placenta previa) or the placenta peeling away from the inner wall of the uterus before delivery (placental abruption). These conditions can disrupt the physical barriers between you and your baby.
- Preeclampsia. If you have preeclampsia — high blood pressure and excess protein in the urine after 20 weeks of pregnancy — you might be at increased risk of developing amniotic fluid embolism.
- Medically induced labor. Limited research suggests that certain labor induction methods are associated with an increased risk of amniotic fluid embolism. Research on this link, however, is conflicting.
- Operative delivery. Having a C-section, a forceps delivery or a vacuum extraction might increase your risk of amniotic fluid embolism. These procedures can disrupt the physical barriers between you and your baby. It's not clear, however, whether operative deliveries are true risk factors for amniotic fluid embolisms or are used after the condition develops to ensure a rapid delivery.
- Polyhydramnios. Having too much amniotic fluid around your baby may put you at risk of amniotic fluid embolism.
Amniotic fluid embolism can cause serious complications for you and your baby.
If you have amniotic fluid embolism, you're at increased risk of:
- Brain injury. Low blood oxygen can cause permanent, severe neurological damage or brain death.
- Lengthy hospital stay. Women who survive an amniotic fluid embolism often require treatment in the intensive care unit and — depending on the extent of their complications — might spend weeks or months in the hospital.
- Maternal death. The number of women who die of amniotic fluid embolism (mortality rate) is very high. The numbers vary, but as many as 20 percent of maternal deaths in developed countries may be due to amniotic fluid embolisms. However, prompt evaluation and treatment may save your life.
- Infant death. Your baby is at risk of brain injury or death. Prompt evaluation and delivery of your baby improves survival.
The diagnosis of amniotic fluid embolism is based on a doctor's evaluation. A diagnosis is typically made after other conditions have been ruled out. In some cases, a diagnosis is only made after maternal death. Your health care provider might order the following lab tests during your evaluation:
- Blood tests, including those that evaluate clotting, heart enzymes, electrolytes and blood type, as well as a complete blood count (CBC)
- Electrocardiogram (ECG or EKG) to evaluate your heart's rhythm
- Pulse oximetry to check the amount of oxygen in your blood
- Chest X-ray to look for fluid around your heart
- Echocardiography to evaluate your heart's function
Amniotic fluid embolism requires rapid treatment to address low blood oxygen and low blood pressure.
Emergency treatments might include:
- Catheter placement. Your health care team places a thin, hollow tube into one of your arteries (arterial catheter) to monitor your blood pressure. You'll also have another tube placed into a vein in your chest (central venous catheter), which can be used to give fluids, medications or transfusions, as well as draw blood.
- Oxygen. You might need to have a breathing tube inserted into your airway to help you breathe.
- Medications. Your doctor might give you medications to improve and support your heart function. Other medications might be used to decrease the pressure caused by fluid going into your heart and lungs.
- Transfusions. If you have uncontrollable bleeding, you'll need transfusions of blood, blood products and replacement fluids.
If you have amniotic fluid embolism before delivering your baby, your doctor will treat you with the goal of safely delivering your baby as soon as possible. An emergency C-section might be needed.
Experiencing a life-threatening pregnancy condition can be frightening and stressful for you and your family. You and your baby might experience serious complications and require lengthy hospital stays.
Amniotic fluid embolism is a medical emergency, leaving you no time to prepare. If you're concerned about your risk of amniotic fluid embolism, talk with your doctor. Keep in mind, however, that amniotic fluid embolisms are rare, unpredictable and unpreventable.
During this challenging time, lean on loved ones for support. Consider joining a survivors' network. Also, work with your health care provider to determine how you can safely manage your recovery and your role as the mother of a newborn.