Incidence and propagation of infrageniculate deep venous thrombosis in trauma patients

Background: The incidence and propagation of thrombosis involving vessels distal to the popliteal vein has not been clearly defined in trauma patients. Our aim was to determine the incidence and rate of propagation of infrageniculate deep venous thrombosis (DVT) in a trauma population and identify potential risk factors specific to propagation. Methods: Retrospective review of all trauma admissions between the years 2001 and 2003 was conducted. Only those 18 years or older with an isolated infrageniculate DVT who underwent a lower extremity venous duplex scan during admission were included in the study. Nature of injury, injury severity score (ISS), method of DVT prophylaxis, thrombus location, and risk factors for hypercoagulable states were recorded. Results: During the study period, 698 trauma admissions were included, and 109 (15.7%) with infrageniculate DVT were identified. Thirty-nine (35.7%) had thrombus propagation (14 suprageniculate and 25 infrageniculate) with a mean ISS of 27.6. Seventy (64.3%) had infrageniculate DVT without propagation and a mean ISS of 19.6. Thirty-eight (97%) patients with propagating infrageniculate DVT had received mechanical prophylaxis, and 33 (84%) also received chemical prophylaxis. The 14 patients with suprageniculate thrombus propagation were the most severely injured (mean ISS = 35.1). Elevated ISS, operation, age <= 62 years, and intensive care unit admission were positively correlated with propagation of infrageniculate DVT. Conclusion: The incidence and propagation of infrageniculate DVT in an aggressively prophylaxed trauma population are greater than previously reported. The clinical significance of isolated infrageniculate DVT remains to be determined, but when associated with a multiple injury trauma, the patient may be at risk for future suprageniculate DVT formation and may benefit from therapeutic anticoagulation.