Breast Augmentation in Transwomen: Can We have a Formula?

 Breast augmentation in transwomen is a surgical challenge as there is no available guideline for preoperative assessment of breast implant size, which caters to them specifically. The aim of our study is to derive a formula for preoperative breast implant size estimation, which would remove the personal bias, help in one-to-one discussion, and better understanding, reducing operative time, cost, and revision surgery rate.  This is a retrospective study conducted from October 2018 to December 2020. We maintained a routine protocol for measurements in our patients, which has been previously published. Linear multivariate regression equation was applied to derive a formula using minimum of parameters, namely, CC (chest circumference at the inframammary fold [IMF]), POMP (circumference at the point of maximum projection of breast mound), and LOWERDIFF (lower value of difference in each breast between the stretched nipple [IMF] and the nonstretched nipple [IMF distance]).  A total of 51 transwomen underwent surgery in this period. The mean volume of implant used was 354.51 mL. Complications consisted of pain and discomfort in six patients, delayed healing in two patients, and wound dehiscence in one. A formula for preoperative calculation of breast implant was obtained with these data. A mathematical correlation was found between complications encountered and the percentage by which the inserted implants exceeded the calculated size.  We could estimate the breast implant size preoperatively through a simple formula that require only four anthropometric measurements. This equation is a significant advantage for the surgeon and a useful tool for patient education. Its usefulness will be established if applied in prospective studies. From our study, it appears 9% above the calculated size is better avoided.