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Wednesday, August 31, 2011

Venous Thromboembolism (VTE) Management with Special Reference to Cesarean Section

Posted by Dr Prahallad Panda on 9:37 PM Comments

Women undergoing cesarean section delivery may need thromboembolism prophylaxis, according to an American College of Obstetricians and Gynecologists (ACOG) Practice Bulletin published in the September 2011 issue of Obstetrics & Gynecology.
Venous thromboembolism (VTE) is a major contributor to maternal mortality. The risk of VTE is increased during pregnancy especially during cesarean section delivery and the consequences can be severe if the clot finds its way to heart and lungs.
 A deep vein thrombosis of the right leg. Note ...Image of DVT Right Leg
Deep vein thrombosis (DVT) is a kind VTE phenomenon, where clot usually starts in the deep veins of leg or pelvis. These clots may dislodge and get lodged in the lungs, which may prove to be fatal. As many as two of every 1,000 pregnant women are likely to experience a DVT.
Compared with nonpregnant women, pregnant women have a 4-fold to 5-fold increased risk for thromboembolism. About 80% of thromboembolic events during pregnancy are venous, with pulmonary embolism and other VTE responsible for 1.1 deaths per 100,000 deliveries, or 9% of all maternal deaths in the United States.
Virchow's triad explains venous thrombosis that can occur in three ways: decreased flow rate of the blood, damage to the blood vessel wall and an increased tendency of the blood to clot (hypercoagulability).
Several medical conditions can lead to DVT, important amongst those can be; physical trauma, infections, heart failure, surgery, prolonged immobilization (such as when orthopedic casts are used, or during long-haul flights, leading to traveller's thrombosis), obesity, smoking and certain drugs (such as oral contraceptives, or erythropoietin).
A woman's risk of a DVT rises during pregnancy and the six weeks afterward; and one to two weeks after child birth. That can be due to slowing of blood flow from the weight gain or compression of abdominal/pelvic veins by the pressure of womb containing the fetus; less active mother in the last trimester and during those first few weeks of recovery from childbirth. It's also because pregnancy temporarily changes blood to make it clot more easily; a nature's protection to minimize blood loss during child birth.
A Cesarean section, like any major surgery, further increases that risk.
There can be painful swelling of legs, bluish-red or pale colorization of legs; shortness of breath, cough, pain in chest, bluish colorization of limbs and distress if clot has reached the lungs. Pain can be elicited, even on gentle pressing the calf muscles.
  1. Tests those are more frequently used in diagnosing DVT can be D-dimer blood test (Estimation of fibrin degradation products) and Doppler ultrasound exam of the legs.
  2. Other tests can be: Plethysmography (measurement of blood flow) of the legs and X-rays to show veins in the affected area (venography).
  3. Blood tests may be done to check if there is increased chance of blood clotting (hypercoagulability). Such tests include:
The only specific Level A ACOG recommendation (based on good and consistent scientific evidence) is that compression ultrasonography of the proximal veins is the recommended initial diagnostic test when signs or symptoms suggest new onset deep vein thrombosis.
ACOG Recommendations
Level B ACOG recommendations and conclusions (based on limited or inconsistent scientific evidence) include the following:
Heparin compounds are the preferred anticoagulants in pregnancy.
To minimize postpartum bleeding complications, a reasonable strategy is to resume anticoagulation therapy no sooner than 4 to 6 hours after vaginal delivery, or 6 to 12 hours after cesarean delivery.
Warfarin, low molecular weight heparin (LMWH), and unfractionated heparin are compatible with breast-feeding because they do not accumulate in breast milk and do not lead to anticoagulation in the infant.
Level C ACOG recommendations (based primarily on consensus and expert opinion) include the following:
Women with a history of thrombosis who have not been thoroughly evaluated for possible underlying causes should receive testing for antiphospholipid antibodies, as well as for inherited thrombophilias.
For women with acute thromboembolism during the current pregnancy, or for those at high risk for VTE, including women with mechanical heart valves, therapeutic anticoagulation is recommended.
For women in whom restarting anticoagulation is planned after delivery, pneumatic compression devices should be left in place until the woman is ambulatory and anticoagulation therapy is resumed.
In the last month of pregnancy, or sooner if delivery appears imminent, women receiving either therapeutic or prophylactic anticoagulation may be converted from LMWH to unfractionated heparin, which has a shorter half-life.
Neuraxial blockade should be withheld for 10 to 12 hours after the last prophylactic dose of LMWH, or 24 hours after the last therapeutic dose of LMWH.
For all women not already receiving thromboprophylaxis, placement of pneumatic compression devices before cesarean delivery is recommended. However, an emergency cesarean delivery should not be delayed for the placement of compression devices.
"Fitting inflatable compression devices on a woman's legs before cesarean delivery is a safe, potentially cost-effective preventive intervention. Inflatable compression sleeves should be left in place until a woman is able to walk after delivery or — in women who had been on blood thinners during pregnancy — until anticoagulation medication is resumed."
As a performance measure, ACOG proposes using the percentage of patients evaluated for risk factors for thrombosis at the beginning of pregnancy, during pregnancy, and at the time of delivery.
Ongoing patient assessment is imperative because half of VTE-related maternal deaths occur during pregnancy and the rest during the postpartum period, Warning signs in some women may be evident early in pregnancy, others will develop symptoms that manifest later in pregnancy or after the baby is born.
Recommendations published in MedScape
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