The chicken or the egg? Relationship between venous congestion and hematoma in free flaps.

[BACKGROUND] Postoperative hematoma and venous congestion after free tissue transfer may occur independently or concurrently. We aimed to explore the association between these two events.

[METHODS] All free flap reconstructions for head and neck (HN) and breast from a single institution between 2004 and 2014 were retrospectively reviewed for reoperation for venous congestion and/or hematoma.

[RESULTS] There were 2985 free flap cases for HN reconstruction and 2345 cases for breast reconstruction. In HN, 100 patients developed a hematoma (3.4%) and 84 patients developed venous congestion (2.8%). The prevalence of hematoma was 17.8% and 2.9% in the presence and absence of congestion, respectively (p<0.001). Among the 15 patients who had both hematoma and venous congestion were separate events that occurred from 1 to 9 days apart in 8 patients. Hematoma caused the compression of the pedicle vein in 4 patients, while venous congestion possibly caused hematoma in 3 patients. In breast, 56 patients developed a hematoma (2.4%) and 64 patients developed venous congestion (2.7%). The prevalence of hematoma was 12.5% and 2.1% in the presence and absence of congestion, respectively (p<0.001). In the 8 patients who developed both, hematoma and congestion were separate events in 4 patients. Venous congestion caused hematoma in 3 patients, and hematoma caused venous congestion in 1 patient.

[CONCLUSIONS] Although postoperative hematoma and venous congestion often present concurrently, most events are not causally associated. When related, however, venous congestion leading to hematoma is more common in breast reconstruction, while hematoma preceding venous congestion is more common in HN reconstruction.