Background: The vascular thrombosis rate of free tissue transfers has been reported to be 2 - 5%. Most thromboses occur within the first 48 hours postoperatively. On rare occasions we have experienced late (postoperative day 5 or later) free flap vascular thromboses. To our knowledge there have been no published reports which evaluate the potential etiologic or predictive factors associated with these cases. In an effort to identify potential factors associated with late free flap thrombosis, we retrospectively reviewed all free tissue transfers performed at a single institution over a 16-year period.

Purpose: To quantify the incidence of late microvascular thromboses in a large number of elective free flaps, used for oncologic reconstruction, and identify specific factors that may be causative, predictive or associated with late thrombosis.

Methods: All patients who underwent free tissue transfer, performed between 4/1/1986 and 4/1/2002 at the University of Texas, MD Anderson Cancer Center were reviewed. A comprehensive database was used to identify patients who developed a vascular thrombosis on postoperative day 5 or later. A retrospective chart review was conducted to analyze multiple factors potentially associated with these late thromboses.

Results: A total of 9 patients who developed a late free flap thrombosis were identified. Only one (11%) of the nine flaps could be salvaged at re-exploration. No identified pre- or postoperative factors were associated with late flap thrombosis. Adverse intraoperative events including sever vasospasm, poor arterial inflow requiring anastamotic revision and requirement of a vein graft were noted in 6 of the 9 cases. Five of the 9 cases also required at least one anastamotic revision at the time of the initial surgery. Smoking, atherosclerosis and diabetes do not appear to affect late free flap thrombosis.

Conclusions: Late free flap vascular thrombosis is rare and the salvage rate is low. Certain adverse intraoperative events and the need for anastamotic revision are factors that may correlate with or predict late vascular thromboses.