The overall incidence of venous thromboembolism is about 0.7 per thousand maternities, but pulmonary embolus is currently the single most common cause of maternal mortality. Major risk factors are operative delivery, age, multiparity and previous thromboembolism. Because of the risks in anticoagulant therapy and the difficulties of clinical diagnosis, it is essential to use objective tests, usually venography for deep-vein thrombosis and lung scan for pulmonary embolus. The acute phase will normally be treated with a continuous infusion of heparin, followed by subcutaneous heparin, given until at least six weeks post-delivery. Warfarin may be substituted after the first week post-delivery. In contrast to the treatment of other forms of thromboembolism, patients with artificial heart valves should be managed with warfarin until 36 weeks of pregnancy. Although the fetal risks in warfarin therapy are greater than those of subcutaneous heparin, the obvious alternative, subcutaneous heparin, does not provide adequate prophylaxis against thromboembolism. In patients who have had venous thromboembolism in the past, the maternal risks do not justify prolonged prophylaxis with subcutaneous heparin as usually given (20 000 units per day) throughout pregnancy. Further clinical trials are necessary to select the best alternatives. Antithrombin III deficiency should be managed with subcutaneous heparin taken from before conception until at least one week post-delivery, when warfarin therapy can be recommended. In addition, the labour should be covered with antithrombin III concentrate.
静脉血栓栓塞的总体发病率约为每千例分娩0.7例，但肺栓塞目前是孕产妇死亡的单一最常见原因。主要危险因素包括手术分娩、年龄、多胎妊娠和既往血栓栓塞史。由于抗凝治疗存在风险且临床诊断困难，使用客观检查至关重要，通常采用静脉造影诊断深静脉血栓形成，采用肺部扫描诊断肺栓塞。急性期通常采用肝素持续静脉输注治疗，随后皮下注射肝素，持续至产后至少六周。产后第一周后可改用华法林。与其他形式的血栓栓塞治疗不同，有人工心脏瓣膜的患者在妊娠36周前应使用华法林治疗。尽管华法林治疗对胎儿的风险大于皮下注射肝素，但明显的替代方法皮下注射肝素并不能提供足够的血栓栓塞预防作用。对于既往有静脉血栓栓塞史的患者，整个孕期按通常剂量（每天20000单位）皮下注射肝素进行长期预防，对母亲的风险并不合理。需要进一步的临床试验来选择最佳替代方案。抗凝血酶III缺乏症患者应在受孕前开始皮下注射肝素，持续至产后至少一周，之后可推荐使用华法林治疗。此外，分娩时应使用抗凝血酶III浓缩物。
