Influencing factors on seroma formation following mastectomy: a retrospective cohort study

Seroma is the most common postoperative complication following mastectomy and may result in additional postoperative interventions and increased treatment burden. However, its etiology and predictive factors remain insufficiently understood. This study aimed to identify predictors of postoperative seroma formation.

We conducted a retrospective analysis of 245 patients (301 breasts) who underwent conventional mastectomy or skin-/nipple-sparing mastectomy, with or without immediate implant reconstruction and axillary surgery, at the University Hospital Leipzig between 2019 and 2023. Variables analyzed included epidemiological characteristics, neoadjuvant chemotherapy, tumor status, perioperative factors, and wound drainage output. Seroma formation was assessed via drains placed in the breast and axilla. Statistical analyses included univariable and multivariable regression and random forest modeling.

In univariable analyses, higher body mass index (BMI), longer surgical duration, diabetes mellitus, hypertension, advanced tumor stage, and elevated C-reactive protein levels were associated with increased breast seroma formation. Random forest analysis identified BMI, number of resected lymph nodes, surgical duration, hypertension, and diabetes as key predictors, all of which remained significant in multivariable models. For axillary seroma, BMI, number of resected lymph nodes, and tumor stage were significant in univariable analyses, while BMI and number of resected lymph nodes remained significant in multivariable models.

Seroma formation is primarily influenced by BMI, extent of lymph node removal, and surgical duration, with hypertension and diabetes as additional risk factors for breast seroma.