Venous thromboembolism is a disease characterized by the formation of a thrombus in the venous bloodstream. It affects most often the veins of the lower limbs – deep venous thrombosis, and lungs – pulmonary thromboembolism.
Pregnancy is a condition of the female organism that predisposes to thrombotic events. The incidence of venous thromboembolism in pregnant women is 4-5 times higher than that of non-pregnant women. The reason for this is the presence in the future mother of the three leading factors called Virhov Triad for thrombosis: venous stenosis, vascular wall damage and hypercoagulation. Hypercoagulation is a physiological change, normal for pregnancy. In the puerperium, the time from birth to the eighth week after, the blood clotting parameters gradually become normal.
What are the risk factors for a thrombotic event during pregnancy?
Many risk factors – inherited or acquired – have been proven to develop thromboembolism during pregnancy. The most common are hereditary factors – gene mutations associated with the coding of proteins involved in blood clotting (hereditary thrombophilias) – Factor V Leiden mutation, prothrombin gene mutation G20210A, antithrombin III deficiency, plasminogen activation disorders, and etc.
Acquired risk factors include obesity, immobilization of the pregnant woman for more than 4 days, traumas, estrogen therapy, varicose veins, airplanes lasting over 5 hours. It was found that in pregnant women over the age of 35, the incidence of thrombotic events was significantly higher in pregnant women under this age. Also, patients undergoing assisted reproductive technologies are at an increased risk of deep venous thrombosis of the upper limbs due to activation of the coagulation system by high serum estrogen levels.
The highest risk of a thrombotic event occurs during the third trimester of pregnancy and during the first week after birth. Venous slack – one of the conditions for forming a thrombus, may occur in the first trimester, but its peak is in 36 g. It is due to the hormone-induced progesterone vasodilatation and the compression of pelvic venous vessels from the pregnant uterus.
What are the clinical symptoms of venous thromboembolism?
Symptoms of venous thromboembolism during pregnancy are similar to those of non-pregnant women. Deep venous thrombosis is manifested with pain and discomfort, swelling and increased circumference of the affected limb. Sometimes there is pain in the abdomen. It should be borne in mind that swelling and discomfort in the lower limbs are symptoms that occur in a normal pregnancy.
Pulmonary embolism is clinically manifested by dyspnoea (difficulty in breathing), tachycardia (increase in heart rate), chest pain and haemoptysis (sputum of blood).
What’s the Proper Treatment?
Any woman with a thrombotic event and / or hereditary thrombophilia who is planning a pregnancy should always consult a specialist for appointment to thromboprophylaxis.
The most commonly used anticoagulant is heparin. It is not toxic to the fetus as it does not cross the placenta. Disadvantages of treatment with this drug are its parenteral administration and the induced thrombocytopenia over time (platelet count reduction). For these reasons, during the pregnancy, treatment is performed with low molecular weight heparins dosed subcutaneously at twice daily intake. They have good thrombophilic efficacy, are safe, and have been shown to have less rare bleeding episodes.
Oral anticoagulants taken by the woman before pregnancy must necessarily be replaced up to 7 weeks. with low molecular weight heparins due to their teratogenic effects on the fetus.
In women with recurrent thrombotic events and contraindications for anticoagulation therapy, it is appropriate to place a lower empty vein filter.