静脉血栓的形成主要由血液缓慢、静脉壁损伤和高凝状态三大因素。在妊娠期、盆腔及下肢血管高度扩张，血流缓慢，以及术后病人半卧位，影响下肢静脉回流，同时由于疼源、阴道流血，持续导尿和输液等，影响病人早期活动之故；另外，由于子宫收缩将许多凝血因素排入全身血液循环 The formation of venous thrombosis mainly by the slow blood, venous wall injury and hypercoagulable state of the three factors. In pregnancy, pelvic and lower extremity vascular height expansion, slow blood flow, and postoperative patients in the semi-recumbent position, affecting the lower extremity venous return, at the same time due to pain, vaginal bleeding, persistent catheterization and infusion, affecting the patient’s early activities; In addition, many clotting factors are released into the systemic circulation due to uterine contractions