Timing of pedicle thrombosis and flap loss after free-tissue transfer.

A series of 990 consecutive free flaps was reviewed to determine how often pedicle thrombosis occurred, when it occurred, and if the timing of thrombosis detection had any relationship to the probability of flap salvage. The overall thrombosis rate was 5.1 percent, and the flap loss rate was 3.2 percent. The majority (80 percent) of thrombi occurred within the first 2 postoperative days. Only 5 thrombi (10 percent) were known to have occurred after the third postoperative day. No flaps that developed thrombosis after the third postoperative day were salvaged successfully. Had flap monitoring been discontinued after the first 3 postoperative days, our results in this series would have been unchanged. Thrombosis of the vein (54 percent) was more common than arterial thrombosis (20 percent) or thrombosis of both artery and vein (12 percent). Almost all purely arterial thrombi (90 percent) occurred before the end of the first postoperative day, whereas 41 percent of all venous thrombi occurred later. We conclude that arterial monitoring is most critical immediately after surgery. Beginning on the second postoperative day, venous monitoring becomes progressively more important to flap success. The cost-effectiveness of postoperative monitoring of free flaps is greatest during the first 2 days, after which it decreases significantly.