[BIRADS 0 patient reclassification in a first-level of care unit].

Background: In Mexico and the world, breast cancer is the cancer type with the highest incidence and mortality for women. Its incidence has increased due to a higher life expectancy and a higher exposure to risk factors. Screening is done by mammography using the BIRADS (Breast Imaging Reporting and Data System) system, the standard for mammography screening report which classifies lesions assigning recommendations for patient follow-up. The system goes from 0 (not conclusive) to 6 (demonstrated malignancy), being of interest for this study the BIRADS 0 category.

Objective: To describe patients classified as BIRADS 0 by mammography and their reclassification in a first-level hospital during 2021.

Material and methods: Retrospective, descriptive, cross-sectional, observational study. Women over 40 years with a BIRADS 0 result were studied. The following databases were used: Institutional Cancer Registry, Family Medicine Information System, Electronic Clinical File, and the mammography and patient list from preventive medicine.

Results: Reclassification by ultrasound (US) was achieved in 100% of patients, in all of the BIRADS US categories. In 3.8% of BIRADS 0 patients, ductal adenocarcinoma was found and confirmed by histological testing.

Conclusion: All of the reassessed lesions with US were adequately reclassified.