Risk factor scoring for predicting venous thromboembolism in obstetric patients

Objective: The aim of this study was to develop a risk factor scoring system for the prediction of venous thromboembolism in obstetric patients. Study Design: We conducted a retrospective case-control study of all pregnant or postpartum women admitted to the Jack D. Weiler Hospital from 1987 through 1998 with a discharge diagnosis indicating thromboembolism. For each study subject the three women who were delivered immediately before that index patient were selected for the control group. Data collected included the following: history of thrombosis, age, body mass index, previous abdominal surgical procedures, presence of systemic diseases, and blood type. Each patient was assigned a score that was based on the risk factors identified. Results: We identified 21 patients who had sustained thromboembolic events during pregnancy or 6 weeks post partum. Nineteen of the thromboembolic events (90%) were diagnosed during pregnancy, and these cases were distributed throughout gestation—8 (42%) in the first trimester, 2 (10%) in the second trimester, and 9 (48%) in the third trimester. Six (28%) of these patients had pulmonary embolisms. Two cases of postpartum thromboembolic events were documented. Both were cases of pulmonary embolism. There was 1 maternal death. Patients with a score >2 were at significantly increased risk for having a thromboembolism, with an odds ratio of 4.8 (P< .05). The sensitivity, specificity, positive predictive value, and negative predictive value of this cutoff point were 21%, 95%, 57%, and 78%, respectively. Conclusion: Obstetric patients with high risk factor scores were at increased risk for thromboembolism. (Am J Obstet Gynecol 2000;182:1073-5.)