The Registry Partners January 2020 CTR Coding Break discusses abstracting when the sentinel lymph nodes fail to map and examples of different wording in the medical record. A sentinel lymph node biopsy is a surgical procedure that removes one or more nearby or regional lymph nodes to test for cancer cells to which cancer cells will likely spread to first. The procedure includes an injection of dye, radio label, or combination to identify a lymph node(s) for removal and examination. Sentinel node procedures are collected for breast and cutaneous melanoma sites. The presentation reviews scenarios when a sentinel lymph node was planned (intended or attempted) but failed to map. This affects the coding of certain data fields; Date Sentinel LN, Date Sentinel LN Biopsy Flag, Sentinel LN Examined, and Sentinel LN Positive. In summary, a patient undergoing sentinel lymph node biopsy who fails to map will often undergo an axillary lymph node dissection.