Patients who are randomized for the Pintution Clip will receive a preoperative ultrasound-guided marking in the axillary lymph nodes that indicate for surgical removal. Surgical procedure is standardized with a handheld probe leading intraoperatively to the marked lymph node and its excision. Successful detection, time of the procedure (beginning of localization intervention to completed lymph node excision), and intra- and postoperative complication rate will be measured. Intra- and postoperative complications are adverse events during the surgery or within 48 hours after the surgery.

Patients who are randomized for the standard clip will receive a preoperative ultrasound-guided marking with HydroMark® Clip in the axillary lymph node that indicate for surgical removal. Surgical procedure is standardized with intraoperative ultrasound-guided wire-localization of the clip and lymph node excision. Successful detection, time of the procedure (beginning of localization intervention to completed lymph node excision), and intra- and postoperative complication rate will be measured. Intra- and postoperative complications are adverse events during the surgery or within 48 hours after the surgery.

The intervention studies a metal Clip (Sirius Pintution) to localize axillary lymph nodes during TAD. Intraoperative localization of the lymph node will be conducted using a hand-held probe identifying the clip.

The primary outcome is the efficacy of both methods for lymph node marking. Efficacy is defined as performance time during the surgery from skin incision (either with hooked wire or scalpel) until the complete excision of the marked lymph node. Time is measured in minutes. Manageability includes process performance of the marker insertion (questionnaire for the study physician: "did you experience problems or barriers in inserting the marker?"; "if yes, what kind of?"). Safety is also observed via the questionnaire ("did your patient experience adverse events? bleeding, seroma, (...), other?"). This is also true for sufficiency ("Did you acieve a successful lymph node marking?"; "Have you been able to localize the marker during the surgery or has it been dislocated?"; "Did you manage to remove the marked lymph node including the marker").

As a secondary outcome, the failure rate (unsuccessful localisation of the marked lymph node) will be measured. As the failure rate is supposed to be low in general, this topic is not the focus of our study.

The safety outcome variables include allergic reactions, bleeding, bruising, dislocation, pain, scar, and very rare events such as lymphedema or neurologic damages.