Dual Venous Drainage for the Free Latissimus Dorsi Muscle Flap-Using the Serratus Vein Tributary-Making Virtue of a Necessity.

 Most flap failures in the lower limb are on account of venous congestion. Literature shows a decrease in the incidence of venous failure when two veins are anastomosed. The thoracodorsal pedicle of the latissimus dorsi free flap affords the possibility of a single venous anastomosis. The lack of a second venous outflow could result in venous congestion in the distal limits of the flap, particularly when long flaps are required for large defects or when the recipient veins are smaller in diameter.  We describe a consecutive series of 11 cases of latissimus dorsi flaps for leg and foot defects with a mean defect size of 310 cm , where the serratus anterior vein was used as a second venous outflow channel to ensure maximal venous drainage.  There were no re-explorations for anastomotic causes. Only one case had partial distal muscle necrosis. There was a delayed anastomotic blowout due to infection resulting in amputation in one case. There was no partial distal muscle necrosis in nine of the ten cases.  Using the serratus vein as a second venous outflow is of use in reducing incidence of venous occlusion and distal muscle necrosis and can be specially indicated for large flaps and venous diameter discrepancy.