Abstract:Objective To analyze the concentration of galactomannan (GM) in bronchoalveolar lavage fluid (BALF) and its value in the diagnosis of COVID-19 related invasive pulmonary fungal infection(IPFI). Methods From 2022 to 2023, 41 patients with COVID-19 related IPFI confirmed, clinically diagnosed or to be diagnosed in the First Affiliated Hospital of Anhui Medical University were taken as the experimental group, and 42 patients with simple pneumonia were taken as the control group. Bronchoscopic alveolar lavage was performed in both groups, and the contents of GM in both BALF and serum were detected at the same time. The concentration difference and clinical diagnostic value of GM between the two groups of different specimens were analyzed, and ROC was used to evaluate the diagnostic efficacy. Results Compared with the control group, the experimental group had higher BALF GM concentrations [（2.27±1.78） ng/L vs (0.51±0.28) ng/L, t =6.329, P＜0.01) and serum GM concentrations [(1.57±0.56) ng/L vs (0.32±0.11) ng/L, t =14.190, P＜0.01＝. The optimal cut-off value for diagnosing IPFI with BALF was 1.82 ng/L, with sensitivity and specificity of 77.9% and 89.2%, respectively, and AUC of 0.92 (95%CI: 0.871-0.955). The optimal cut-off value for serum was 0.67 ng/L, with sensitivity and specificity of 64.9% and 92.2%, respectively, and AUC of 0.89 (95%CI: 0.854-0.925). However, the false positive rate of BALF was slightly higher than that of serum (10.8% vs 7.8%). Conclusion GM can be serve of as a good indicator for evaluating IPFI related to COVID-19. The GM detection in BALF has more clinical value in the diagnosis of IPFI than serum.