Superficial outside-flap shunt (SOS) is associated with a low incidence of postoperative DIEP flap venous congestion: A single-institution retrospective cross-sectional study

Introduction: Venous congestion burdens up to 15% of deep inferior epigastric artery perforator (DIEP) flap breast reconstructions. For these cases, venous augmentation by superficial outside shunt (SOS) is associated with 100% success in secondary salvage surgeries. Intraoperative venous augmentation using other techniques yields a 0.3% rate of return to theater due to venous congestion, but there is no evidence assessing the effectiveness of the SOS technique applied preventively. Comparing this preventive approach to data prior to its implementation, we expect to find a reduced number of venous congested flaps with reduced flap losses and revision surgeries. Patients and methods: This retrospective cross-sectional study involved DIEP flap breast reconstructions performed between 2011 and 2020. The control group included patients receiving additional venous anastomosis as a secondary salvage procedure. The "preventive SOS group" included patients who received preventive SOS during the main surgery. Age, body mass index (BMI), pregnancies, perioperative treatments (neoadjuvant or adjuvant chemo or radiotherapy), follow-up complications (arterial ischemia, venous congestion, hematomas, partial/total flap loss), and revision surgeries (breast debridement, flap remodeling) were recorded and compared. Results: Within 695 flaps performed, 397 flaps were included in the control group, and 298 flaps were included in the preventive SOS group. The groups were homogeneous for age (p = 0.418), BMI (p = 0.747), and flap weight (p = 0.064). Fifty-one flaps (12.8%) in the control group compared to zero (0.0%) in the preventive SOS group required return to theater (p < 0.001). Conclusions: We reported encouraging preliminary results for SOS to prevent DIEP flap venous congestion. These results must be validated prospectively.