This includes people with active bleeding conditions (such as gastrointestinal ulcers), or disease states with increased risk of bleeding (e.g., low platelets, severe liver disease, uncontrolled hypertension). For patients undergoing surgery, treatment with anticoagulants is generally suspended. Similarly, spinal and lumbar puncture (e.g., spinal injections, epidurals, etc.) carry increased risk, so treatment is suspended prior to these procedures.Warfarin should not be given to people with heparin-induced thrombocytopenia until platelet count has improved or normalised. Warfarin is usually best avoided in people with protein C or protein S deficiency, as these thrombophilic conditions increase the risk of skin necrosis, which is a rare but serious side effect associated with warfarin. Pregnancy
Warfarin is contraindicated in pregnancy, as it passes through the placental barrier and may cause bleeding in the fetus; warfarin use during pregnancy is commonly associated with spontaneous abortion, stillbirth, neonatal death, and preterm birth. Coumarins (such as warfarin) are also teratogens, that is, they cause birth defects; the incidence of birth defects in infants exposed to warfarin in utero appears to be around 5%, although higher figures (up to 30%) have been reported in some studies. Depending on when exposure occurs during pregnancy, two distinct combinations of congenital abnormalities can arise. First trimester of pregnancy
Usually, warfarin is avoided in the first trimester, and a low-molecular-weight heparin such as enoxaparin is substituted. With heparin, risks of maternal haemorrhage and other complications are still increased, but heparins do not cross the placental barrier, so do not cause birth defects. Various solutions exist for the time around delivery.
During the initial stage of treatment, INR is checked daily; intervals between tests can be lengthened if the patient manages stable therapeutic INR levels on an unchanged warfarin dose. Newer point-of-care testing is available and has increased the ease of INR testing in the outpatient setting. Instead of a blood draw, the point-of-care test involves a simple finger prick. Maintenance dose
Recommendations by many national bodies, including the American College of Chest Physicians, have been distilled to help manage dose adjustments.The maintenance dose of warfarin can fluctuate significantly depending on the amount of vitamin K1 in the diet. Keeping vitamin K1 intake at a stable level can prevent these fluctuations. Leafy green vegetables tend to contain higher amounts of vitamin K1. Green parts of members of the family Apiaceae, such as parsley, cilantro, and dill are extremely rich sources of vitamin K; cruciferous vegetables such as cabbage and broccoli, as well as the darker varieties of lettuces and other leafy greens, are also relatively high in vitamin K1. Green vegetables such as peas and green beans do not have such high amounts of vitamin K1 as leafy greens. Certain vegetable oils have high amounts of vitamin K1. Foods low in vitamin K1 include roots, bulbs, tubers, and most fruits and fruit juices. Cereals, grains, and other milled products are also low in vitamin K1. Self-testing
Anticoagulation with warfarin can also be monitored by patients at home. International guidelines on home testing were published in 2005.