Optimizing Outcomes in Nipple-sparing Mastectomy: Mastectomy Flap Thickness Is Not One Size Fits All

Nipple-sparing mastectomy (NSM) places greater stress on the breast-skin envelope compared with traditional mastectomy techniques. Precise mastectomy flap dissection is critical to optimize breast skin flap thickness and minimize complication risk. This study evaluated patient-specific factors associated with mastectomy flap quality to improve technical success in NSM. Ideal NSM flap thickness was determined for all NSMs from 2006 to 2016 with available preoperative breast magnetic resonance imaging (MRIs). Demographic, operative variables, and flap thickness were compared for NSMs as stratified by body mass index (BMI) and mastectomy weight. Of the 1,037 NSMs, 420 cases (40.5%; 243 patients) had MRI data available, which included 379 (36.5%) preoperative breast MRIs. Average BMI was 24.08 kg/m(2), whereas average mastectomy weight was 442.28 g. NSMs were classified according to BMI <25 kg/m(2), 25-30 kg/m(2), and >30 kg/m(2). Average ideal overall NSM flap thicknesses in these groups were 10.43, 12.54, and 14.91 mm, respectively. Each incremental increase in average overall NSM flap thickness per BMI category was statistically significant (P < 0.0001; P < 0.0001; P = 0.0002). NSMs were also classified into mastectomy weight categories: <400 g, 400-799 g, and >= 800 g. Average overall NSM flap thicknesses in these groups were 9.97, 12.21, and 14.50 mm, respectively. Each incremental increase in average overall NSM flap thickness per mastectomy weight category was similarly statistically significant (P < 0.0001; P < 0.0001; P < 0.0001). NSM flap thickness and quality is related to BMI and breast size. Characterizing these anatomic variations preoperatively will help surgeons optimize mastectomy flap dissections and minimize ischemic complications in breast reconstruction after NSM.