Application of bronchoalveolar lavage fluid in patients with pulmonary complications after allogeneic hematopoietic stem cell transplantation

Objective: To evaluate the diagnostic value of bronchoalveolar lavage (BAL) for pulmonary complications in patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and its safety. Methods: Patients with pulmonary complications after allo-HSCT underwent BAL. Microbiological smears, culture, PCR of CMV-DNA, EBV-DNA and TB-DNA, macro genomes new generation sequencing (mNGS) techniques were performed to detect pathogens in BAL fluid (BALF) . Results: A total of 73 allo-HSCT patients with 86 times of pulmonary complications enrolled this prospective study. They underwent 132 times of BAL procedures. The clinical diagnoses of 88.4% cases were made based on BALF analysis. Of them, 67 cases (77.9%) had infectious pulmonary complications, including 29 cases (33.7%) of fungal infection, 18 cases (20.9%) of mixed infection, 11 cases (12.8%) of viral infection and 9 cases (10.5%) of bacterial infection. The other 9 cases (10.5%) of non-infectious pulmonary complications included 8 cases (9.3%) of idiopathic pneumonia syndrome (IPS) and 1 case (1.2%) of pulmonary infiltration of lymphoma. The diagnoses of the remaining 10 cases (11.6%) were not determined. The platelet counts of 33 patients were less than 50×10(9)/L before BAL. None of them developed severe bleeding complications during or after BAL. Transient fever occurred in 10 patients after BAL. Blood cultures showed staphylococcal bacteremia in them and anti-infection therapies were effective. No life-threatening complications occurred in all of the patients during or after BAL. Conclusion: BALF analysis was informative for the diagnosis of pulmonary complication and safe for patients with pulmonary complications after allo-HSCT.