Case Report: Venous crossover bypass to the contralateral internal mammary vein to restore venous outflow in revision surgery in autologous free flap breast reconstruction.

Breast reconstruction using free flaps is a standardized procedure in specialized centers. Despite a very low flap failure rate, total flap loss has devastating consequences for affected patients. Venous congestion remains one of the most common causes of flap compromise, requiring revision surgery. Herein, we present a salvage technique for revision surgery to restore venous outflow using a crossover bypass to the contralateral internal mammary vein (IMV). Our patient had undergone multiple previous oncological surgeries, including a partial sternum resection. As the ipsilateral IMV proved insufficient, the ipsilateral cephalic vein was initially used as a recipient vein. Because of subsequent venous congestion, the cephalic vein was repurposed as a crossover bypass to the contralateral IMV. Following this procedure, the flap healed without further complications. A venous crossover bypass to the contralateral internal mammary vessels represents a reliable salvage option, even in complex revision surgery.