What is Amniotic Fluid Embolism?

Amniotic fluid embolism (AFE) is a life-threatening condition that affects pregnant women shortly before, during, or immediately after labor and delivery. It is a syndrome marked by the start of hypoxia, hypotension, seizures, or disseminated intravascular coagulopathy (DIC), which is caused by the inflow of amniotic components (fetal cells, hair, or other debris) into the maternal circulation.

Meyer was the first to report it in 1926, and Steiner and Lushbaugh were the first to characterize the illness in 1941. AFE is a very uncommon obstetrical complication that has a significant death risk among pregnant women.

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Causes and symptoms

Amniotic fluid embolism is a condition that happens when the expectant mother experiences a systemic reaction comparable to an allergic reaction to amniotic fluid, fetal cells, or fetal tissue debris. Because of small tears in the bottom region of the uterus, the part of the cervix that forms a channel connecting the vagina to the uterus (endocervix), or damage or abnormality affecting the placenta, amniotic fluid, and other material enters the mother's circulation.

Researchers currently believe that the symptoms are produced by the mother's immune system reacting to the amniotic fluid or fetal cells as foreign agents and that it is an immune-mediated complication.

Identified risk factors include - older maternal age, multiparity, multiple pregnancies, intense contractions during labor, abdominal trauma, cesarean section, placenta previa, eclampsia, tears in the uterus or cervix, and early separation of the placenta from the uterus wall. Potential fetal risk factors include male babies, fetal distress, and death.

Amniotic fluid embolism indications and symptoms generally occur rapidly. Headaches, chest pain, coughing, sweating, nausea, and vomiting are early warning signs. Other early symptoms include difficulty breathing or shortness of breath (dyspnea), an abnormally rapid heartbeat (tachycardia), tachypnea, hypotension, bluish discoloration of the skin and mucous membranes due to a lack of oxygen in the blood (cyanosis), and a deficiency in the amount of oxygen reaching the body's tissues (oxygen deficiency) (hypoxia).

There may be a quick increase in blood pressure in the lungs' blood vessels (pulmonary hypertension) as well as a sudden narrowing of blood vessels (vasospasm). Sudden chills, shivering, and anxiety are common premonitory symptoms.

Epidemiology

Amniotic fluid embolism is a rare condition that can happen soon before, during, or after birth. The exact number of women who have had this problem is unknown. Amniotic fluid embolism is a very uncommon condition. Rare illnesses are frequently misdiagnosed or overlooked, making it difficult to estimate their true prevalence in the general population. Pregnancies have been estimated to be 1 in 8,000 to 1 in 80,000.

Diagnosis and treatment

Amniotic fluid embolism is diagnosed solely based on the presence of specific clinical signs. There are currently no proven diagnostic assays, imaging studies, or pathologic indicators for the diagnosis of AFE. To aid in the management of amniotic fluid embolism, a range of tests can be performed.

A whole blood count is one of these procedures, and it can identify low hemoglobin levels or excessive amounts of specific cardiac enzymes. Low platelet and fibrinogen levels, increased prothrombin time, and activated partial thromboplastin time (APTT), can be detected using blood coagulation tests.

Low oxygen levels can be detected using two separate tests: continuous pulse oximetry and arterial blood gas analysis (ARG). An x-ray of the chest may reveal fluid in the lungs, a prominent pulmonary artery, or heart enlargement (cardiomegaly). An electrocardiogram can detect right-heart strain, irregular cardiac rhythms, and ventricular dysfunction (dysfunction of the right or left upper chamber of the heart). Right heart strain, followed by higher pulmonary pressures and consequent left-sided failure, is a finding on echocardiography specific to AFE.

AFE is a medical emergency with aggressive and supportive treatment. Individuals who are impacted will need to be treated by a team of specialists including anesthesiologists, obstetricians, maternal-fetal medicine specialists, hematologists, and intensivists. Specific therapeutic procedures and interventions may differ depending on a variety of factors, including the severity of the disorder, the presence or absence of certain symptoms, whether the patient is conscious, breathing, etc., the patient's age and general health, the health and status of the fetus, and/or other factors.

Physicians will first try to restore a woman's breathing and heart function. If a woman is unconscious, cardiopulmonary resuscitation (CPR) may be performed. Some women may be prescribed medications (vasopressors and inotropic) to improve heart function or prevent fluid build-up in the lungs or around the heart. Some women will need blood transfusions to replenish lost blood and clotting factors, which are necessary for blood coagulation.

Future perspective

AFE is a potentially fatal condition, however, with proper early pericardiac arrest care, results can be improved. When possible, obstetric institutions should have clinicians on hand who have received official training and certification in advanced cardiac life support and are capable of performing bedside transesophageal echocardiography. Education and team training may also be beneficial in these efforts to prepare for such rare but serious incidents.

Researchers are looking towards identifying and using particular biomarkers for amniotic fluid embolism to aid in diagnosis. Because of the disease's rarity, no therapy studies have been conducted on a significant group of individuals. To assess the long-term safety and effectiveness of various treatments for amniotic fluid embolism proposed in the medical literature, more research is needed.

References:

• Pacheco, L. D., Clark, S. L., Klassen, M., & Hankins, G. (2020). Amniotic fluid embolism: principles of early clinical management. American journal of obstetrics and gynecology, 222(1), 48–52. https://doi.org/10.1016/j.ajog.2019.07.036
• (2019). Amniotic Fluid Embolism. [online] National Organization for Rare Disorders. Available at: https://rarediseases.org/rare-diseases/amniotic-fluid-embolism/
• Tamura, N., Farhana, M., Oda, T., Itoh, H., & Kanayama, N. (2017). Amniotic fluid embolism: Pathophysiology from the perspective of pathology. The journal of obstetrics and gynaecology research, 43(4), 627–632. https://doi.org/10.1111/jog.13284
• Kaur, K., Bhardwaj, M., Kumar, P., Singhal, S., Singh, T., & Hooda, S. (2016). Amniotic fluid embolism. Journal of anaesthesiology, clinical pharmacology, 32(2), 153–159. https://doi.org/10.4103/0970-9185.173356

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