Oil red O stain of alveolar macrophages is an effective screening test for gastroesophageal reflux disease in lung transplant recipients.

Background: Gastroesophageal reflux disease (GORD) and microaspiration may be associated with acute graft dysfunction and development of obliterative bronchiolitis (OB) after lung transplantation. The "gold standard" for diagnosis of GORD is the 24-hour esophageal pH-monitoring study, although no simple, non-invasive screening test is routinely employed. Oil red O staining of alveolar macrophages in bronchoalveolar lavage (BAL) fluid identifies exogenous lipid and may be a surrogate marker for microaspiration.