Prolonged activated partial thromboplastin time in thromboprophylaxis with unfractionated heparin in patients undergoing cesarean section

Aim: Hemorrhage is an important complication of heparin‐thromboprophylaxis after surgery. We attempted to clarify the incidence rate of prolonged activated partial thromboplastin time (APTT), representative of hemorrhagic tendency, in Japanese women who received thromboprophylaxis with unfractionated subcutaneous heparin administration after cesarean section (CS). We also determined factors which affected postoperative APTT. Methods: We studied 280 women who were administered thromboprophylaxis with unfractionated subcutaneous heparin 5000 IU two times per day after CS. Postoperative APTT under heparin was measured and the incidence of its prolongation was determined. Preoperative APTT, blood loss during surgery, postoperative hematocrit, postoperative serum total protein level, and postpartum body weight were measured, and their correlation with postoperative APTT was determined. Results: Preoperative and postoperative APTT values were 28.3 (26.7–30.3) and 33.8 (31.0–37.5) seconds for median (interquartile range), respectively. Overall, 7.1% of patients showed ≥45 s postoperative APTT. Two patients (0.7%) showed ≥60 s APTT, one of whom suffered subcutaneous hemorrhage around the abdominal incision with complete healing. There were no other hemorrhagic complications. Preoperative APTT positively, and postpartum body weight inversely, correlated with postoperative APTT. The amount of blood loss, postoperative hematocrit, and postoperative serum total protein level did not correlate with postoperative APTT. No discernible deep vein thrombosis or pulmonary embolism occurred. Conclusion: Although 7.1% of women under heparin‐thromboprophylaxis showed a prolonged APTT that was 150% of the preoperative APTT, serious side effects were not observed. Subcutaneous administration of unfractionated heparin, if checking APTT prolongation 1 day after surgery, may be safe method of thromboprophylaxis after CS.