Introduction
There is variation in the literature and between breast units in the diffuse cortical thickening (DCT) threshold used for preoperative lymph node needle sampling. In our centre, needle sampling is performed in patients with DCT of 2 mm and above (LN3 of an LN1 to LN5 ultrasound classification). Results triage patients to appropriate axillary surgery: sentinel node biopsy or axillary clearance. This study investigates our 2 mm needle sampling threshold, to determine whether we can safely increase to 2.3 or 3 mm as used in some centres.