本文报道1例急性粒-单核细胞白血病(急性髓系白血病M₄型)（CBFB基因阳性）患者，经亲缘半相合造血干细胞移植后并发下肢微血栓形成，并总结其诊治经验。该患者经常规化疗后获完全缓解，但又于2年后复发，遂予行亲缘半相合造血干细胞移植。在患者接受移植后的常规治疗期间，动态观察其凝血相关指标[包括D-二聚体（D-dimer, D-D）、抗凝血酶Ⅲ（antithrombin Ⅲ， AT-Ⅲ）、血管性血友病因子（von Willebrand factor， vWF）、纤维蛋白原降解产物（fibrinogen degradation products， FDP）、纤维蛋白单体（fibrin monomer， FM）]。在移植后100 d左右，患者出现黄疸及转氨酶升高，采用经右下肢股静脉置管行血浆置换治疗3次。在去除静脉置管1周后，患者出现左踝部指凹性水肿，血管B超检查提示其左下肢腓肠肌浅静脉丛有微血栓形成；凝血指标检测显示，D-D、vWF、FDP、FM等指标升高，AT-Ⅲ水平降低。予口服拜瑞妥5 mg/d抗栓治疗2周后，患者上述凝血指标渐趋正常，左下肢肌间静脉丛血栓和肢肿消失。在造血干细胞移植后，除密切检查血管B超，动态监测D-D、AT-Ⅲ、vWF、FDP、FM等凝血指标可预测移植相关微血栓和高凝状态，并为临床开展有效抗的凝治疗提供实验依据。

This article reports a case of acute myelomonocytic leukemia (AML-M₄, CBFB gene positive) with lower limb microthrombus formation after haploidentical hematopoietic stem cell transplantation, and summarizes the experience of diagnosis and treatment. The patient received achieved complete remission (CR) after routine chemotherapy, but relapsed 2 years later and underwent a haploidentical hematopoietic stem cell transplantation. During routine treatment after transplantation, the patient’s coagulation related indicators, including D-dimer (D-D), antithrombin Ⅲ (AT-Ⅲ), von Willebrand factor (vWF), fibrinogen degradation products (FDP) and fibrin monomer (FM), were dynamically observed. The patient experienced jaundice and elevated transaminases around 100 days after transplantation, and underwent plasma exchange treatment three times through the right lower limb femoral vein catheterization. After removing the venous catheter for one week, there was left ankle concavea pitting edema of the left ankle. Vascular ultrasound examination indicated the formation of microthrombus in the superficial venous plexus of the gastrocnemius muscle in the left lower limb. D-D, vWF, FDP, FM and other indicators were increased, while AT-Ⅲ levels was decreased. After 2 weeks of oral administration of 5 mg/d berritol for antithrombotic treatment, the above coagulation indicators gradually returned to normal, and the left lower limb intermuscular venous plexus thrombosis and limb swelling disappeared. Therefore, dynamic monitoring of coagulation indicators, such as D-D, AT-Ⅲ, vWF, FDP, and FM may serve as diagnostic indicators for predict transplant related microthrombus and hypercoagulable status, providing an experimental basis for effective anticoagulant treatment in clinical practice.