Amniotic fluid embolism is considered as an obstetric emergency condition characterized by accidental entry of amniotic fluid, fetal cells including fetal hair in to the mother’s blood stream through the placenta and eventual triggering of life threatening allergic response in the mother. This condition usually occurs immediately following child birth or within short period after delivery of the baby. Common outcome of amniotic fluid embolism is complete shut down of cardiac and lung functions and inference with the normal blood coagulation mechanism.This is one of the most common causes of maternal mortality; actually it is the fifth cause. Immediate medical attention is required to save the woman.
Usually the symptoms of amniotic fluid embolism develop rapidly and worsen within a short span of time. Common presenting symptoms include difficulty in breathing, excessive fluid accumulation in the lung causing pulmonary edema, sudden fall in blood pressure, sudden collapse of cardiovascular system, abnormal triggering of the blood coagulation system resulting into formation of blood clots throughout the small blood vessels of the body followed by (due to depletion of all the platelets and the other coagulation factors) severe bleeding, alteration of the mental status (depression, anxiety etc), nausea, vomiting, severe degree of shivering and chill, increased heart rate which may often due to disturbance in the rhythm generation by the heart, episodes of convulsion and finally coma followed by death.
The above mentioned symptoms usually appear in two phases; during the first phase shortness of breathing, fall in blood pressure rapidly progresses to circulatory collapse followed by loss of consciousness. In the next phase, the second phase severe degree of internal bleeding occurs followed by death of the patient. Usually about 27% women suffering from amniotic fluid embolism die in the first phase and about 40% of the survivors enter the second phase.Other than all the above mentioned maternal symptoms life of the baby inside the uterus is also jeopardized due to severe degree of oxygen deprivation (fetal distress) which may lead to permanent brain damage in the baby.
Certain severe complications may arise due to amniotic fluid embolism; these include
1) Permanent damage to the brain tissue due to poor oxygen supply to the brain. Patient may permanently become vegetative due to brain death
2) Prolonged stay in the hospital” amniotic fluid embolism require prolonged stay in the hospital especially in the in the intensive acre units.
3) Death: death occurs in about 10% of the cases of amniotic fluid embolism patients even in developed countries. In most of the cases death occurs within an hour of starting of the symptom.
The exact underlying causes of amniotic fluid embolism is not clearly understood however the basic thing is the symptoms of the disease appears once the fetal tissue and the amniotic fluid enters the maternal circulation usually through tear in the placental bed. The unborn baby is covered in a sac like structure inside the maternal uterus known as amniotic membrane and this sac contains amniotic fluid which protects the baby. Usually there are three prerequisites for entry of amniotic fluid into the maternal circulation; these are rupture or tear in the amniotic membrane, rupture of the uterine or cervical veins and positive pressure gradient from uterus to vein.It is thought that the amniotic fluid contains various substances which are capable of inducing inflammatory reaction in the mother’s body as well as can stimulate the clotting system.Paradoxically entry of amniotic fluid in the maternal circulation during delivery is not uncommon. However it is not known why some of the women suffer from this disease and some not while in most of the women amniotic fluid enters the maternal circulation during delivery.
This condition is quite rare; it is estimated that about 1 to 12 women suffer from amniotic fluid embolism per 100,000 deliveries.
Factors associated with amniotic fluid embolism include
1) increased maternal age, usually above 35 years of age
2) Abnormality in the placenta: placenta is the structure which facilitates transfer of nutrients and oxygen to the growing fetus from the mother. Certain structural abnormalities of placenta may occur; these are placenta previa, when the placenta is covering the opening of the cervix either partially or fully, abnormal and premature separation of placenta from the uterine wall (placental abruption) compromising the physical barrier between the mother and the baby.
3) Preeclampsia: condition in which the mother suffers from high blood pressure and increase urinary excretion of protein usually after 20 weeks of pregnancy.
4) Induction of labor
5) Surgical delivery of baby like caesarean section, forceps delivery or vacuum extraction may increase the chance of amniotic fluid embolism
6) According to some genetic make up may play some role in causing amniotic fluid embolism.
Amniotic fluid embolism requires prompt treatment. The main aim is to maintain adequate oxygen in the circulation and maintenance of normal blood pressure.
The measures taken are
1) Placement of catheter to measure exact arterial blood pressure
2) Oxygenation of the patient suing breathing tube
3) Drugs to support the cardiac function, to reduce pressure fluid in the lungs (pulmonary edema)
4) Transfusion of blood or blood products in patients having severe blood loss
5) Emergency caesarean section is to deliver the baby in mothers yet to deliver.