BackgroundSeroma formation is the most common complication after mastectomy and places patients at risk of associated morbidities. Microporous polysaccharide hemospheres (MPH) consists of hydrophilic, plant based, polysaccharide particles and is currently used as an absorbable hemostatic agent. An animal model evaluating MPH and seroma formation after mastectomy with axillary lymph node dissection showed a significant decrease in seroma volume. Study aim was to evaluate topical MPH on the risk of post-mastectomy seroma formation as measured by total drain output and total drain days.MethodsProspective randomized single-blinded clinical trial of patients undergoing mastectomy for the treatment of breast cancer. MPH was applied to the surgical site in the study group and no application in the control group.ResultsFifty patients were enrolled; eight were excluded due to missing data. Forty-two patients were evaluated, control (n = 21) vs. MPH (n = 21). No difference was identified between the two groups regarding demographics, tumor stage, total drain days, total drain output, number of clinic visits, or complication rates. On a subset analysis, body mass index (BMI) greater than 30 was identified as an independent risk factor for high drain output. Post hoc analyses of MPH controlling for BMI also revealed no statistical difference.ConclusionsUnlike the data presented in an animal model, no difference was demonstrated in the duration and quantity of serosanguinous drainage related to the use of MPH in patients undergoing mastectomy for the treatment of breast cancer. BMI greater than 30 was identified as an independent risk factor for high drain output and this risk was not affected by MPH use. NCT03647930, retrospectively registered 08/2018.