Improving Documentation in Plastic Surgery: Sister Bra Size Group and BMI Are More Indicative of Breast Weight Than Cup Size.

Abstract

Accurate documentation of breast size is critical for surgical planning, insurance authorization, and research in breast reconstruction. However, breast size is inconsistently recorded, often limited to brassiere cup size, which may not reliably predict breast tissue weight. The authors of this study aim to evaluate whether "sister bra size group"-a previously unverified classification incorporating both bra cup and band sizes-better correlates with breast weight than cup size alone. A retrospective review was conducted of 209 patients (395 breasts) who underwent mastectomy between 2017 and 2023 at a single institution. Preoperative bra cup and band sizes, mastectomy specimen weights, BMI, and demographic characteristics were recorded. Patients were categorized into sister bra size groups. Spearman's correlation coefficients and multivariate linear regression were used to evaluate associations with breast weight. Sister bra size group showed the strongest Spearman's correlation with breast weight (ρ = 0.76), followed by cup size (ρ = 0.67), BMI (ρ = 0.61), and band size (ρ = 0.48). Age did not have a significant correlation with mastectomy specimen weight (ρ = 0.02). In multivariate analysis, sister size (P = .016) and BMI (P < .001) remained statistically significant predictors of breast weight, whereas cup and band sizes did not. Cup size alone is not a reliable predictor of breast tissue weight. Sister bra size groups provide a stronger correlation and a more accurate alternative. Incorporating this variable into clinical documentation may improve preoperative planning and create a more standardized framework for research.