At which week intravenous heparin is introduced in a primigravida with mechanical hea valves?
As soon as pregnancy is diagnosed, oral anticoagulants should be discontinued and subcutaneous heparin should be initiated. In the second trimester, warfarin is the treatment of choice, with INR monitoring. Warfarin should be given only after the 12th gestational week and should be stopped before delivery around 35th week. At the 36th week of gestation, intravenous heparin should be initiated. To avoid the risk of bleeding during labor and delivery, heparin should be discontinued 24 hours prior. Anticoagulation should then be resumed 4 hours after delivery. Must know: Warfarin has been associated with fetal wastage due to spontaneous aboion and stillbihs, optic nerve atrophy and blindness, microcephaly, mental retardation, and even death due to intracranial hemorrhage. Its use in the first trimester is associated with warfarin embryopathy in 4-10% of newborns, a syndrome comprising nasal bone hypoplasia and epiphyseal stippling. Breast-feeding women can be prescribed warfarin because it is not secreted in the breast milk. Complications of heparin administration include abdominal wall hematoma or abscess, thrombocytopenia, alopecia, and osteoporosis. Low-dose aspirin has been safely used in pregnancy. Dipyridamole should not be used in a pregnant patient. Ref: Tolstrup K. (2009). Chapter 31. Cardiovascular Disease in Pregnancy. In M.H. Crawford (Ed), CURRENT Diagnosis & Treatment: Cardiology, 3e.
32
36
40
At the time of labour