ObjectiveTo investigate the factors for PE development and the necessity of IVC filter placement. Specifically, propose a scoring system to identify patient populations who benefit from IVC filter placement. MethodsSingle-institution retrospective cohort study between 2010-2022. Inclusion criteria were open posterior thoracolumbar fusion, ≥ 7 segments, and adult patients ≥ 18 years old. Patients undergoing any surgical approach other than posterior were excluded. Risk factors such as smoking status, illicit drug use/type, body mass index (BMI), gender, age, anticoagulation history and status on presence of PE were reviewed. Results365 patients were identified; 170 (46.6%) patients were male, and 195 (53.4%) were female. 24 (6.6%) had IVC filters placed before the surgery. The overall rate of PE was 8 (2.2%), all in patients without IVC filter. Analysis showed that gender, age, and BMI did not affect incidence of PE. Smoking status, history of illicit drug use (cocaine/cannabis), and history of deep vein thrombosis/PE significantly increased the incidence of PE. Based on multivariate logistic regression, we developed a scoring system composed of aforementioned significant risk factors to determine risk of developing PE. Our scoring system stratified risk to low-risk (0-3 points), medium-risk (4-6 points), and high-risk (7-8 points). ConclusionRisk of PE is relatively low after long-segment posterior thoracolumbar fusion. Smoking (former and current), history of cocaine/cannabis use, and history of venous thromboembolism are risk factors in such patients. We recommend prophylactic IVC filter use only in high-risk subgroups and under discretion between physician and patient in medium-risk subgroups.