Amniotic Fluid Embolism
Amniotic Fluid Embolism
Amniotic fluid embolism is a rare condition that may occur during delivery or in the immediate postpartum period. It is essentially unpredictable and unpreventable, and its outcome is often devastating. The complication develops when amniotic fluid breaches the physical barrier between the maternal and fetal environments as a result of uterine trauma, such as through a tear in the cervix or lower uterus. Amniotic fluid that enters the mother’s blood stream can cause obstruction (or embolism) of circulation in a blood vessel in the body or lung.
The incidence of this rare event has been difficult to measure but is estimated to be between 1 in 4,500 and 1 in 80,000 pregnancies. Certain factors may increase the risk of a woman having amniotic fluid embolism. The condition is a medical emergency requiring rapid treatment to manage low blood oxygen and low blood pressure in the mother and to safely deliver the baby, if he or she hasn’t been born yet.
Signs and Symptoms of Amniotic Fluid Embolism
Unfortunately, there are no warnings signs for amniotic fluid embolism. Its clinical manifestations may be similar to that of anaphylactic or septic shock. Symptoms develop suddenly and progress rapidly. The condition has been described as having an acute phase and a late phase. Symptoms that may occur early in the acute phase, within 30 minutes of the amniotic fluid entering the blood stream, are:
- Sudden anxiety
- Shortness of breath
- Low blood pressure (hypotension)
- Bluish or purplish discoloration of the skin and mucous membranes (cyanosis)
- Cardiopulmonary arrest
- Problems with blood clotting (coagulopathy)
In the late phase of amniotic fluid embolism, symptoms, such as feeling cold, restlessness, and respiratory distress, in the mother may precede catastrophic injury or death caused by the following:
- Life-threatening coagulopathy (disseminated intravascular coagulation)
- Tissue injury
- Multi-organ failure
- Cardiac arrest
Risk Factors for Amniotic Fluid Embolism
Amniotic fluid embolism is unique to pregnancy and thus only affects pregnant women. The following risk factors have been identified, but the condition cannot be attributed to any one of these factors. Women who have amniotic fluid embolism probably have multiple contributing factors, one of which could be genetic.
- Maternal age of 35 years or older
- Medically induced labor
- Caesarean section
- Placenta problems, including placenta previa and placental abruption
- Multiple pregnancies
Amniotic Fluid Embolism Causes
Autopsy studies of fatal cases of amniotic fluid embolism suggest that three pathophysiologic mechanisms may contribute to the development of the condition. These include the mechanical obstruction of vessels, a subsequent inflammatory effect on the maternal circulatory system, and an as of yet poorly understood immunologic mechanism. The condition begins with the entry of amniotic fluid into the maternal blood stream. The amniotic fluid, which may contain epithelial squamous cells, lanugo hair, and fat from the fetus, can easily lead to obstruction of blood vessels. The mother’s body also seems to react to the invasion of the amniotic fluid as it would to trauma, infection, or allergy and sets off an inflammatory process. Because amniotic fluid embolism can progress very similarly to anaphylactic shock, it is thought that the immune system may also play a role in its development.
Diagnosis of Amniotic Fluid Embolism
A diagnosis of amniotic fluid embolism is typically made after other conditions have been ruled out. This is in large part because the symptoms are vague and can mimic those of many other diseases. In some cases, a diagnosis is only made after maternal death.
No specific test can be used to diagnose amniotic fluid embolism. The diagnosis usually relies on the presence of one or more of four otherwise unexplained events occurring during childbirth (or during labor, caesarean delivery, and dilation and evacuation) or within 30 minutes postpartum:
- Acute hypotension
- Cardiac arrest
- Acute hypoxia (the body as a whole or a region of the body is deprived of adequate oxygen)
- Coagulopathy or severe hemorrhage
Several tests may be helpful in the diagnosis and treatment of amniotic fluid embolism. These include certain blood tests (arterial blood gas analysis, a comprehensive blood cell count and platelet count, and a coagulation profile), and electrocardiogram, chest x-ray, and transesophageal echocardiography. A diagnosis is typically made after other conditions have been ruled out. In some cases, a diagnosis is only made after maternal death.
Amniotic Fluid Embolism Treatment
If your doctor recognizes amniotic fluid embolism early, treatment can be life-saving but most survivors display some sort of organ dysfunction or neurologic impairment. Treatment of amniotic fluid embolism is supportive. Life-threatening symptoms are managed first and aggressively. This includes rapid control of the airway and therapy to prevent or correct hypoxemia. Resuscitative efforts may be needed to maintain breathing. The focus is then on treatment of hypotension and restoration of maternal circulation. If a severe hemorrhage is present, coagulopathies must be treated. A multitude of medications and treatments may be used in the treatment of amniotic fluid embolism. Almost all women with amniotic fluid embolism require transfer to the intensive care unit for further treatment and monitoring.
The fetus is continuously monitored closely for any signs of a problem and delivered when considered safe or to decrease fetal toxicity and improve resuscitation efforts.
Prognosis of Amniotic Fluid Embolism
According to a review published in the International Journal of Critical Illness & Injury Science, the prognosis of women with amniotic fluid embolism has improved but continues to be relatively poor. The rate of death has been reported to range from 20 to 40 percent. Complications, including organ dysfunction and neurologic impairment, in survivors can be significant. The death rate for the fetus is also high (between 20 to 25 percent), and only 50 percent of surviving babies are neurologically intact. It is not known whether amniotic fluid embolism will recur in future pregnancies.