Incidence and risk factors of immediate postoperative deep vein thrombosis in patients undergoing spinal surgery: a retrospective cohort study.

Abstract

While most studies focus on postoperative deep vein thrombosis (DVT) identified several days after surgery, DVT detected immediately after spinal surgery, which may reflect thrombus formation during surgery or the early postoperative period, remains insufficiently investigated. This study aimed to investigate the incidence and identify factors associated with immediate postoperative DVT in patients undergoing spinal surgery. This retrospective cohort study included 541 consecutive patients who underwent spinal surgery between January and May 2025. Immediate postoperative DVT was defined as DVT absent on ultrasonography performed within 24 hours before surgery but detected immediately after surgery in the Post-Anesthesia Care Unit (PACU). Variables with P < 0.20 in univariate analysis were entered backward multivariable logistic regression. Model discrimination and calibration were assessed, and internal validation was performed using 1,000 bootstrap resamples. Among 541 patients, immediate postoperative DVT was detected in 103 (19%). All DVTs were distal DVTs; 99 of 103 patients (96%) had intermuscular calf vein thrombosis. Older age, lower-extremity arterial disease, elevated D-dimer, preoperative walking disability, hypertension, longer operative time, and hyperlipidemia remained independently associated with immediate postoperative DVT. The apparent AUC was 0.815 (95% CI, 0.769-0.860), and the optimism-corrected AUC was 0.789 (95% bootstrap interval, 0.745-0.830), with a calibration slope of 0.865. Immediate postoperative DVT was common among patients undergoing spinal surgery and consisted exclusively of distal DVTs, predominantly intermuscular calf vein thromboses. In this cohort, patients with specific baseline characteristics and perioperative factors had a higher likelihood of immediate postoperative distal DVT following spinal surgery.