The effect of axillary lavage with a gentamicin solution before wound closure will reduce the drainage volume and subsequently day of drainage removal.

Inclusion criteria will be a diagnosis of mammary neoplasms and plans to undergo an elective ALND of Berg´s levels I and II due to axillary metastasis determined preoperatively by core biopsy or evidence of metastasis in the SLNB in the intraoperative or in the differed analysis. Exclusion criteria will be chronic renal failure due to possible toxicity of gentamicin and patients undergoing a modified radical mastectomy.

The patients will be randomized by means of an Internet randomization module into 2 groups: those patients undergoing 2 lavages of the axillary surgical bed with normal saline (Group 1) and those ones first undergoing lavage with normal saline followed by a second lavage with a gentamicin solution (Group 2).

Surgical dissection will be performed using harmonic scalpel (Ultracision, Ethicon Endosurgery, Johnson and Johnson, Cincinnati, OH, USA). Once finished the ALND, a Jackson-Pratt drain will be left in place and connected to a low pressure vacuum device.

Methodology: Irrigation technique and extraction of microbiological samples:

The lavage will be performed immediately prior to closure of the wound, once placed the drainage into the cavity. In both groups, prior to the lavage, a microbiological sample from the surgical bed will be obtained with a swab (sample 1), followed by a lavage with 500 ml normal saline. After aspiration of the saline, a new microbiological sample will be obtained (sample 2). In Group 1 a second lavage with 500 ml normal saline will be performed, while in Group 2 the second lavage will be performed with an antibiotic solution, including gentamicin (240 mg) dissolved in 500 ml normal saline. After aspirating this second lavage, a third microbiological sample will be obtained in the same way as the two previous ones, in both groups (sample 3).

Indication of drain removal and obtention of sample 4:

After discharge, the patient will be asked to quantify the drainage volume daily. Drain will be removed when drainage volume was <30 ml/day. The drainage volume of the last day was collected in a syringe for microbiological study (sample 4).

Inclusion Criteria:

• diagnosis of mammary neoplasms and plans to undergo an elective ALND of Berg´s levels I and II due to axillary metastasis determined preoperatively by core biopsy or evidence of metastasis in the SLNB in the intraoperative or in the differed analysis.

Exclusion Criteria:

• chronic renal failure due to possible toxicity of gentamicin
• patients undergoing a modified radical mastectomy.