Impact of Combining Ultrasound Parameter and the Caprini Score on Predicting Lower Extremity Deep Venous Thrombosis After Orthopedic Surgery.

Aims: This study combined a new ultrasound venous filling degree (VFD) parameter with the Caprini score to assess the clinical value of the Caprini score in predicting deep venous thrombosis (DVT) of the lower extremities.

Methods: This retrospective study included 150 inpatients undergoing orthopedic lower extremity surgery at the First Affiliated Hospital of the Air Force Medical University between June 2023 and June 2024. They included 41 (27.3%) cases of knee arthroplasty, 32 (21.3%) hip arthroplasty, 30 (20%) knee arthroscopy, 28 (18.7%) lower limb fractures, 12 (8%) bone tumor, and 7 (4.7%) cases of other surgery types. The data collected involved preoperative vein diameter, flow velocity, blood flow, venous lumen cross-sectional perimeter (C), lumen cross-sectional area (A), C2/A ratio (VFD) of the common femoral vein (CFV), femoral vein (FV), and popliteal vein (POV). The postoperative sonographic parameters and clinical data were compared between the DVT and non-DVT groups. Receiver operating characteristic (ROC) curve of parameters was evaluated as predictive values for DVT. Additionally, the C2/A ratio was combined with the Caprini score to assess their combined impact on DVT prediction.

Results: There were significant differences in ultrasound parameters of CFV inner diameter, CFV blood flow, CFV-C, CFV-A, CFV-C2/A, FV blood flow, FV-C, FV-C2/A, POV blood flow, POV-C, POV-A, and POV-C2/A between the DVT group (24.7%, 37/150) and the non-DVT group (75.3%, 113/150) (all p < 0 .05). Area under curve (AUC) for the C2/A (CFV, FV, and POV) were 0.939 (95% confidence interval (CI): 0.888-0.972, p < 0.001), 0.937 (95% CI: 0.886-0.970, p < 0.001), and 0.917 (95% CI: 0.861-0.956, p < 0.001), respectively. When the Caprini score >2, an AUC for predicting DVT was 0.844 (95% CI: 0.776-0.899, p < 0.001). The AUC of the Caprini score >2 combined with C2/A (CFV, FV, and POV) were 0.953 (95% CI: 0.905-0.981, p < 0.001), 0.965 (95% CI: 0.922-0.988, p < 0.001), and 0.948 (95% CI: 0.900-0.978, p < 0.001), respectively.

Conclusions: The ultrasound parameter of VFD-C2/A shows a high predictive value for DVT in patients undergoing orthopedic surgery. Combined with the Caprini score, the predictive value of DVT may be further enhanced compared to using the Caprini score alone.