bronchoalveolar

Bronchoalveolar is an anatomical and medical term describing the region of the lower respiratory tract that comprises the bronchioles and the alveolar spaces. The bronchioles are small airways that lead to alveolar ducts and sacs, whose lining includes alveolar epithelium. The bronchoalveolar unit is the functional region where air exchange occurs and where immune defenses operate.

Bronchoalveolar lavage, or BAL, is a diagnostic procedure performed during bronchoscopy. Sterile saline is instilled into a segment of the lung and subsequently aspirated to collect material from the alveolar and bronchial spaces. The retrieved fluid is analyzed microbiologically and cytologically and can be used to measure chemical mediators. BAL helps diagnose infections (including atypical, fungal, and mycobacterial forms), inflammatory or interstitial lung diseases, alveolar hemorrhage, and certain malignancies. Cellular differential counts (e.g., macrophage, lymphocyte, eosinophil levels) can aid interpretation and guide management.

Clinical use of BAL is generally well tolerated, but risks exist and may include transient hypoxemia, cough, minor bleeding, and, rarely, pneumothorax. The procedure provides a minimally invasive means to sample lower respiratory tract material when noninvasive tests are inconclusive.

Historically, the term bronchoalveolar carcinoma appeared in older literature to describe certain pulmonary cancers; modern classifications have shifted away from this term toward more precise categories such as adenocarcinoma and adenocarcinoma in situ.