Objective: This study prospectively compared lymphedema rates with perometer, tape measure, and bioimpedance spectroscopy (L-Dex) in patients with breast cancer undergoing axillary lymph node dissection (ALND). Background: Perometer, tape measure, and L-Dex are all used for diagnosing lymphedema, although lymphedema rates may vary between these techniques. Methods: From November 2016 to March 2020, patients who underwent ALND had arm measurements performed preoperatively and biannually with pero