Impact of overweight/obesity on the development of hematoma following tissue expander-based breast reconstruction

Background: Overweight and obesity are well-known risk factors for postoperative complications; however, their impacts on hematoma formation have not been clarified. Several studies have suggested that overweight/obesity could have procoagulative effects, potentially reducing a risk for developing postoperative bleeding complications. This study aimed to investigate the effects of overweight/obesity on hematoma formation following tissue expander-based breast reconstruction. Method: Patients who underwent immediate tissue expander-based unilateral breast reconstruction between January 2010 and November 2018 were reviewed. They were categorized into four groups according to body mass index (BMI): underweight (<18.5 kg/m(2)), normal weight (18.5-25.0 kg/m(2)), overweight (25.0-30.0 kg/m(2)), and obesity (>30.0 kg/m(2)). The outcome was major postoperative hematoma, defined as one requiring emergent surgical intervention. Independent impacts of variables on hematoma development were evaluated via uni- and multivariable analyses. Results: A total of 1,431 patients were analyzed, including 133 cases (9.3%) with underweight, 952 (66.5%) with normal weight, 302 (21.1%) with overweight, and 44 (3.1%) with obesity. Postoperative major hematoma developed in 29 cases (2.0%). The rate of hematoma formation was 2.3%, 2.6%, 0.3%, and 0% in the underweight, normal weight, overweight, and obesity groups, respectively, showing a significantly decreasing trend (p = 0.009), while those of other complications including seroma and mastectomy flap necrosis revealed the opposite trends, being significantly elevated as patient BMI increased. Multivariate analyses found overweight to be an independent protector against major hematoma compared with normal weight (p = 0.014; odds ratio=0.071). Conclusion: Overweight/obesity might have a protective effect on development of major bleeding complications following tissue expander-based breast reconstruction. (C) 2020 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.