Objectives Patients with gynecologic malignancies have high rates of postoperative venous thromboembolism. Currently, there is no consensus for perioperative thromboprophylaxis. The Gynecologic Oncology division at Sunnybrook Health Sciences Centre in Toronto, Canada, implemented a dual thromboprophylaxis strategy for laparotomies in 12/2017. We aimed to compare rates of pulmonary embolus(PE) within 30 days postoperatively, and to identify risk factors for PE.

Methods Prospective study of laparotomies for gynecologic malignancies from 12/2017–10/2018, with comparison to historical cohort from 01/2016–11/2017 using the institutional National Surgical Quality Improvement Program database(NSQIP).

Preintervention, patients received low molecular weight heparin(LMWH) during admission and those deemed high-risk continued 30-day prophylaxis. Postintervention, all patients received both mechanical thromboprophylaxis with sequential compression devices during admission and 30-day prophylaxis with LMWH.

Results There were 371 and 163 laparotomies pre-and post-intervention.

After implementation, PE rates decreased from 5.1% to 0% (p=0.001). PEs were diagnosed by CT scan prompted by symptoms, at a median of 2 days postoperatively.

Patient characteristics (age, BMI, diabetes, smoking, tumor stage), rate of malignant cases, operative blood loss and duration, and length of stay(LOS) were similar between groups. There were more cytoreductive procedures preintervention (p ≤0.0001).

Univariate analysis revealed that surgery preintervention (OR:4.25, 95%CI 1.04–17.43, p=0.04), LOS≥5 days (OR:11.94, 95%CI 2.65–53.92, p=0.002), and operative blood loss ≥500mL (OR:2.85, 95%CI 1.05–7.8, p=0.04) increased risk of PE. On multivariable analysis, surgery preintervention remained associated with more PEs(OR:4.16, 95%CI 1.03–16.79, p=0.05), when adjusting for operative blood loss.

Conclusions Aggressive dual thromboprophylaxis after laparotomy appears to significantly reduce PE in this high-risk patient population.