Low bleeding rates following transbronchial lung cryobiopsy in unclassifiable interstitial lung disease

<bold>Background:</bold> Bronchoscopic transbronchial lung cryobiopsy (TBLC) is a guideline-endorsed alternative to surgical lung biopsy for tissue diagnosis in unclassifiable ILD. We aimed to characterise the incidence, severity and risk factors for clinically significant bleeding following TBLC using an expert-consensus airway bleeding scale, in addition to other complications and diagnostic yield. <bold>Methods:</bold> A retrospective cohort study of consecutive adult outpatients with unclassifiable ILD who underwent TBLC following multidisciplinary discussion at a single centre in the UK between July 2016 and December 2021. TBLC was performed under general anaesthesia with fluoroscopic guidance and a prophylactic endobronchial balloon. <bold>Results:</bold> 126 patients underwent TBLC (68.3% male; mean age 62.7 years; FVC 86.2%; DLCO 54.5%). Significant bleeding requiring balloon blocker reinflation for >20 minutes, admission to ICU, packed red blood cell transfusion, bronchial artery embolization, resuscitation or procedural abandonment, occurred in 10 cases (7.9%). Significant bleeding was associated with traction bronchiectasis (OR 7.1, CI 1.1-59.1, p=0.042), histological UIP pattern (OR 4.0, CI 1.1-14, p=0.046) and medium-large vessels present on histology (OR 37.3, CI 6.5-212, p<0.001). BMI ≥ 30 (P=0.017) and traction bronchiectasis (P=0.025) were significant multivariate predictors of longer total bleeding time. Pneumothorax occurred in 9 cases (7.1%) and the 30-day mortality was 0%. Diagnostic yield was 80.6%. <bold>Conclusion:</bold> TBLC has an acceptable safety profile in experienced hands. Radiological traction bronchiectasis and obesity increase the risk of significant bleeding following TBLC.