Amniotic fluid embolism (AFE) is a pathology, the development of which is associated with the ingress of amniotic fluid into the mother’s circulatory system, followed by an anaphylactoid reaction to the components of this fluid. Clinical manifestations are mainly due to cardiopulmonary shock and a violation of the coagulation system. Diagnosis is carried out by a comprehensive assessment of physical, laboratory and instrumental data. Treatment of AFE consists in the elimination of anaphylactoid reaction, normalization of the cardiovascular and respiratory systems, restoration of CBV and hemostasis system.
O88.1 Amniotic fluid embolism
Amniotic fluid embolism, or anaphylactoid pregnancy syndrome, is a pathological condition in obstetrics, which is characterized by the ingress of amniotic fluid into the systemic bloodstream of the mother. For the first time, the clinical picture of AFE was described in 1926 by the Brazilian physician J. By Meyer. In 1941, the totality of signs of this condition was combined by the Americans P. Steiner and K. Lashbow into a special obstetric syndrome.
The overall prevalence of amniotic fluid embolism ranges from 1 to 8 cases per 10,000 births. At the same time, the maternal and perinatal mortality rate for this complication ranges from 84-87%. In the general structure of maternal mortality, disease accounts for about 15-17% of all cases.
There are several mechanisms for the development of amniotic fluid embolism: an increase in intrauterine pressure, a drop in blood pressure in the veins of the uterus, direct contact between the amniotic sac and damaged blood vessels. The first group includes all factors that can excessively increase the pressure in the amniotic sac, which normally amounts to 20 mm of water during labor. The cause of amniotic fluid embolism in such cases may be:
- multiple pregnancy
- the child’s body weight is over 4500 g (“large fruit”)
- pelvic presentation
- loss of cervical elasticity
- improper stimulation of contractile activity of the uterus
- the birth of a child is too fast
- the presence of meconial masses in the amniotic fluid
- anatomical and physiological features of the fetus and /or the birth canal of the mother.
The development of amniotic fluid embolism against the background of a drop in venous pressure is usually due to absolute or relative hypovolemia and a decrease in pressure in the veins of the uterus during childbirth below 40 mm of water. art. This condition may occur against the background of:
- diabetes mellitus
- various heart defects
- loss of vascular tone in high-cost women
- taking diuretics
- irrational use of antihypertensive or vasodilating agents.
A high risk of amniotic fluid embolism is always associated with direct injury to the amniotic sac and violation of the integrity of the uterine blood vessels. In most cases, this mechanism of AFE development is due to:
- premature detachment of the normally located placenta or its presentation
- by rupture of the uterus
- performing cesarean section or fruit-destroying operations
- manual examination of the uterine cavity
- the pathological preliminary period.
The pathogenesis of clinical symptoms in amniotic fluid embolism is based on the ingestion of prostaglandins, cytokines, histamine and other eicosanoids into the mother’s circulatory system together with amniotic fluid. They cause an anaphylactoid reaction with the development of pulmonary vascular spasm, a violation of the blood clotting system and a mechanical block in the microcirculatory bed of the lungs.
Depending on the prevalence of certain symptoms of this pathology, the following forms of pathology are distinguished:
- Collaptoid. It is characterized by pronounced cardiac shock. Leading symptoms: “collapse” of blood pressure, threadlike accelerated pulse, pallor of the skin of the hands and feet, accompanied by their cooling, loss of consciousness.
- Convulsive. The main manifestation of this form of this disease is generalized convulsive syndrome.
- Hemorrhagic. It is caused by the displacement of the hemostasis system towards hypocoagulation. Main signs: profuse bleeding from the nose, mouth, vagina, puncture sites and catheter placement.
- Edematous. A clinical variant of amniotic fluid embolism, manifested by pulmonary edema, which, in turn, causes acute respiratory failure.
- Lightning fast. The most dangerous form of amniotic fluid embolism, characterized by rapid development and multiple organ failure.
Amniotic fluid embolism symptoms
The scenario of the development of anaphylactoid syndrome of pregnant women is determined by the severity of the embolism and the leading syndrome (collapse, convulsions, bleeding, pulmonary edema). Both relatively mild course and lightning-fast forms, which quickly end in cardiac arrest, are possible.
These reactions with this disease are manifested by the sudden appearance of general excitement and fear, chills and an increase in body temperature, pronounced dyspnea of an inspiratory or mixed nature, cough, “collapse” of blood pressure, increased heart rate and BH. There are also pains in the heart, nausea, vomiting, tonic-clonic convulsions, swelling and pulsation of the cervical veins, generalized cyanosis and paleness (“marbling of the skin”), profuse bleeding of various localization. Depending on the clinical form of amniotic fluid embolism, one or another of its manifestations may prevail.
Diagnosis of amniotic fluid embolism includes the collection of anamnestic data and complaints during childbirth, physical examination, laboratory and instrumental studies. A higher risk of developing AFE is observed in women with a history of genital surgery, frequent gynecological pathologies, a large number of births, especially with complications.
- Objective status assessment. The complaints made by a pregnant woman largely depend on the clinical form of amniotic fluid embolism. Physical examination includes an assessment of heart rate, BH and blood pressure, as well as the identification of symptoms of AFE, after which, if necessary, an examination of the cervix and its palpation can be performed.
- Analyses. The program of laboratory tests in women with signs of amniotic fluid embolism includes blood tests (platelet, erythrocyte, hemoglobin and hematocrit), coagulogram (D-dimer, fibrinogen level, blood clotting and APTT), biochemical examination (blood pH, electrolytes).
- Instrumental diagnostics. Of the instrumental methods of investigation for amniotic fluid embolism, an ECG is used, which reveals signs of myocardial ischemia and sinus tachycardia, as well as an chest radiography, which allows to determine the presence of interstitial pulmonary edema of a draining nature in the form of a “butterfly” and an increase in the right parts of the heart. In the presence of central venous access, the CVP is monitored.
Amniotic fluid embolism treatment
Therapeutic measures are aimed at relieving anaphylactoid reaction, cardiopulmonary shock and preventing the development of critical disorders of the hemostasis system.
- Oxygenation. First of all, the woman is provided with the supply of moistened oxygen or is transferred to a ventilator.
- Pharmacological correction. Next, high doses of glucocorticosteroids (prednisone or hydrocortisone) are administered, the CBV is replenished with a large volume of blood-substituting fluids (balanced colloids and crystalloids). Sodium bicarbonate is used to correct acidosis. With severe hypotension on the background of amniotic fluid embolism, the drugs of choice are sympathomimetics (ephedrine), if necessary, dopamine or dobutamine can be used. To eliminate hemorrhagic syndrome, fibrinolysis inhibitors (tranexamic acid), antithrombin concentrates, prothrombin and blood preparations are administered.
- Delivery. The tactics of obstetric care for amniotic fluid embolism depends on the results of treatment. If the therapeutic measures were effective and the woman’s condition was stabilized, delivery is carried out through the birth canal. With the development of complications of amniotic fluid embolism or the absence of the effect of conservative treatment, an immediate caesarean section is indicated. With massive uterine bleeding that cannot be stopped, the uterus is extirpated.
Prognosis and prevention
The outcome depends on the overall severity of the woman’s condition, the rate of development of symptoms and the effectiveness of therapeutic measures. In most cases, the prognosis is unfavorable for both mother and child. Prevention of amniotic fluid embolism involves early diagnosis and treatment of conditions that can potentially lead to AFE: preeclampsia and eclampsia, fetoplacental insufficiency.
It is necessary to stop uterine hypertonicity during pregnancy, compliance with the doses prescribed by the attending obstetrician-gynecologist of drugs, rational choice of the method of delivery. Also, preventive measures include pregnancy planning, timely registration in the women’s clinic and its regular visits with the passage of all diagnostic tests, the performance of special physical therapy for pregnant women, the exclusion of intense psycho-emotional stress.