Should 1 or 2 venous anastomoses be done in microsurgical flap transfer?

Background: Venous compromise is still the most common cause of free flap failure. The need of a second venous anastomosis to prevent free flap failure is controversial. It is proposed that the use of dual venous anastomoses reduces venous compromise. However, some surgeons suggest that dual venous drainage reduces venous blood flow causing a potential risk of thrombosis. Objective: This study aimed to compare the frequency of reexploration secondary to venous thrombosis in free flap surgeries in reconstruction of soft tissue defects with 1-vein versus 2-vein anastomosis. Materials and Methods: We performed a retrospective cohort study including 298 flaps. In 180 of these patients, 2-vein anastomosis was done, and in 118, 1-vein anastomosis was done. The study was conducted at Aga Khan University Hospital from January 2017 to December 2018. Results: The number of venous anastomosis was not associated with flap survival. The group with dual anastomosis required more frequent reexploration as compared with 1 venous anastomosis group (8% vs 1.7%). Outcome and salvage rate were better in the 2-vein group as compared with the 1-vein group (64% vs 50%). Conclusion: There is no difference in flap survival in single or dual venous anastomosis, but we have noticed higher reexploration rates in the 2-vein group. However, outcome is better in the 2-vein group.