Comparing outcomes between stacked/conjoined and non-stacked/conjoined abdominal microvascular unilateral breast reconstruction.

BACKGROUND Stacked and conjoined free flaps are increasingly utilized in autologous breast reconstruction to augment tissue transfer volume. However, there is a paucity of comparative data on abdominally-based stacked/conjoined versus non-stacked/conjoined flaps. The purpose of this study was to compare ability to match native breast size, complications, recovery, and symmetrizing procedures between these two cohorts in unilateral breast reconstruction. METHODS A retrospective review of all stacked (two separate hemiabdominal)/conjoined (bipedicled full abdominal) flaps and non-stacked/conjoined (unipedicled hemiabdominal) flaps in unilateral abdominally-based autologous breast reconstructions was performed from 2011 to 2018. Variables including demographics, operative characteristics, complications, and revisions were compared in 36 stacked/conjoined patients versus 146 non-stacked/conjoined patients. RESULTS The stacked/conjoined cohort had more DIEP flaps (91.7 vs. 65.1%) and the non-stacked/conjoined group more MS-TRAMs (34.2 vs. 6.9%, p = .000). Additionally, non-stacked/conjoined flaps had greater utilization of combined medial and lateral row perforators (p = .000). Mean flap weight was significantly higher than mastectomy weight in stacked/conjoined flaps (+110.7 g) when compared to non-stacked/conjoined flaps (-40.2) (p = .023). Average follow-up was 54.7 ± 27.5 and 54.6 ± 29.3 months, respectively. Stacked/conjoined flaps had lower fat necrosis rates (8.3 vs. 25.4%, p = .039) and had a decreased risk of fat necrosis on multivariable regression analysis (OR 0.278, p = 0.045). There were otherwise no differences in flap, breast, or donor-site complications. Stacked/conjoined flaps also had a lower rate of contralateral breast reduction (p = .041). CONCLUSION Stacked/conjoined flaps were associated with a lower risk of fat necrosis compared with non-stacked/conjoined flaps and had a lower rate of contralateral symmetrizing reductions in patients undergoing unilateral abdominally-based breast reconstruction.