A Comparison of Relative Parameters in Male and Female Nipple-Areola Complexes: An Observational Study Using a Novel Online Search Technique and Implications for Transgender Top Surgery

Background: Chest masculinization and breast augmentation, often collectively referred to as “top surgery” in the transgender community, are frequently performed procedures for female-to-male (FTM) and male-to-female (MTF) individuals, respectively. Numerous studies have investigated the optimal placement of the nipple-areola complex (NAC) in chest masculinization and male gynecomastia surgeries through the selection of healthy male-identifying volunteers, but few have recruited female-identifying volunteers. The aim of this study was to use images collected from various online databases as a novel method to identify surgically relevant ratios for transgender top surgery and differences between the male and female NAC.

Methods: Two hundred images (50% female, 50% male) were compiled from online database searches. Inclusion criteria for the images were as follows: 1) upright position; 2) subjects’ arms hanging to their sides in a relaxed position. Multiple parameters, including areola width (AW), areola height (AH), nipple width (NW), nipple height (NH), clavicle to inframammary fold (IMF), NAC to IMF, internipple distance (IND), and chest width (CW), were measured using GNU Image Manipulation Program (GIMP). The following ratios between male and female groups were compared using unpaired t-tests (alpha error set to 0.05): 1) AW to AH; 2) NW to NH; 3) NAC to IMF to clavicle to IMF; 4) sternal notch to CW; and 5) IND to CW.

Results: There was a statistically significant difference for male versus female groups in AW to AH (1.284 vs 1.019, p<0.0001), NAC to IMF to clavicle to IMF (0.1306 vs 0.2661, p<0.0001), and IND to CW (0.7529 vs 0.7292, p<0.0073). There was no significant difference for male versus female groups in sternal notch to CW (0.6438 vs 0.6304, p=0.3674), or NW to NH (1.181 vs 1.124, p=0.3850).

Conclusions: Our results highlight many important differences between the placement of the male NAC versus the female NAC that must be considered during chest masculinization and breast augmentation surgeries. The results from our study suggest that the male NAC is more oval in shape, more laterally placed, and located more superiorly than the female NAC. These results corroborate previously established data from other research groups and anecdotal observations from various surgeons who perform gender-affirmation procedures. The results from our study provide a unique method for female and male NAC comparison and demonstrate that there are objective differences between the male and female NAC that can be utilized in clinical practice to improve upon current “top surgery” standards of care.