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BMI is an independent predictor of urologic and major surgical complications in gender-affirming phalloplasty
Sahil Sharma
*1, Martha MacDonald
1, Alyxandra Rhamsay
2, Sheuli Chowdhury
1, Patricia Fuentes
1, Emma Lascar
1, Peter W. Henderson
1, Peter J. Taub
1, Elan Horesh
3, Joshua Safer
21Division of Plastic and Maxillofacial Surgery, Icahn School of Medicine, New York, NY; 2Center for Transgender Medicine and Surgery, Icahn School of Medicine at Mount Sinai, New York, NY; 3Center for Transgender Medicine and Surgery, Division of Plastic and Maxillofacial Surgery, Icahn School of Medicine at Mount Sinai, New York, NY
Background: Body mass index (BMI) has been identified as a risk factor for complications across various procedures, yet its impact on outcomes following gender-affirming phalloplasty (GAP) remains unclear. Thus, this study evaluated whether BMI predicts complications following GAP.
Methods: All patients who underwent GAP between June 2017 and January 2025 at a single institution were retrospectively reviewed. Patients were classified by BMI into non-overweight (<25), overweight (25-29.9), and obese (≥30) groups. Outcomes included any major complication (defined as requiring urgent return to the operating room), urologic complications (urinary tract infection (UTI), urinary retention (UR), stricture, and fistula) and non-urologic outcomes (dehiscence, delayed wound healing, surgical site infection, partial/complete necrosis, and hematoma). Multivariable logistic regression was performed for each outcome, adjusting for age, hypertension, diabetes, smoking, urethral lengthening, and flap type. Adjusted odds ratios (aOR) were calculated using the non-overweight group as the reference. Tests for linear trend evaluated dose-response across BMI categories, and BMI was also modeled continuously to estimate per-unit change in odds.
Results: Among 67 patients, 20 (29.9%) were non-overweight, 26 (38.8%) overweight, and 21 (31.3%) were obese. The obese group had significantly higher odds of UTI (aOR 19.71; p=0.007) and UR (aOR 36.92; p=0.043); differences were not significant for the overweight group. Across BMI groups, linear trends were observed for UTI (trend aOR 4.43, p=0.008) and UR (trend aOR 5.71, p=0.038). Each 1 kg/m
2 increase in BMI was associated with higher odds of UTI (aOR 1.21), UR (aOR 1.29), and any major complication (aOR 1.23) (all p<0.05).
Conclusion: BMI independently predicted UTI and UR following GAP, with urologic risk increasing in a stepwise fashion across BMI categories. Modeled continuously, BMI also predicted major complications, underscoring the importance of preoperative BMI optimization and counseling regarding urologic and major complication risk.
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