Obstetric venous thromboembolism: Evaluation of prophylactic approach based on risk scores, D-dimer levels, and ultrasonography findings in a tertiary hospital in Japan

Pulmonary embolism remains a leading cause of maternal mortality in developed countries despite developments in venous thromboembolism prophylaxis strategies. This study aimed to evaluate the effectiveness of our approach involving risk-scoring, D-dimer level assessment, and ultrasonography for obstetric venous thromboembolism.This retrospective cohort study included women who delivered at 22-41 weeks of gestation in The University of Tsukuba Hospital, Japan between January and December 2020. Venous thromboembolism risk (determined according to Japanese guidelines) and D-dimer levels were evaluated within 20 weeks of gestation, 30-34 weeks of gestation, and during the pre-delivery period (36 weeks of gestation or any time before preterm delivery). Compression and color Doppler ultrasonography for lower extremity deep vein thrombosis were performed if D-dimer levels were ≥3.2 μg/mL (for those undergoing cesarean delivery, 1.0 μg/mL).Of 1026 women, 6 women had deep vein thrombosis during pregnancy and 1 during the puerperium period. Pulmonary embolism was not observed. The D-dimer screening result was positive for 8 women (2%) within 20 weeks of gestation (deep vein thrombosis was confirmed in 3 of them), 87 women (10%) (no deep vein thrombosis) at 30-34 weeks of gestation, and 367 women (36%) during the pre-delivery period (asymptomatic deep vein thrombosis in one). Based on the Japanese guidelines, 1%, 11%, 33%, and 55% of women had high, intermediate, low, and no postpartum risk factors, respectively.Our approach appears useful for antenatal venous thromboembolism screening in the first trimester. For postpartum prophylaxis, more cost-effective strategies are needed.