The Optimal Number of Transbronchial Biopsies Needed to Evaluate Rejection in the Lung Allograft

Transbronchial biopsy (TBB) is the procedure of choice used for the diagnosis of acute rejection in the lung allograft. At least 5 pieces of alveolated lung tissue are required for assessment of acute rejection, as recommended by the Lung Rejection Study Group (LRSG). Sampling practices vary between centers with no consensus on the number of biopsies needed to meet this requirement. Herein, we present the Cleveland Clinic experience. 500 flexible bronchoscopies with TBB in post lung transplant patients are retrospectively reviewed. The number of TBB and pieces of lung parenchyma collected are recorded. An adequate sample is defined by the presence of at least 5 pieces of lung tissue, each with bronchioles and a minimum of 100 alveoli, allowing for pathologic grading of perivascular/interstitial cellular infiltrates and airway inflammation .The procedural complications are noted. TBB are performed under conscious sedation using a flexible adult forceps under fluoroscopic guidance, and are usually taken from two lobes. Mean duration of the procedure is 23 min +/- 7 min. The average number of transbronchial biopsy passes per procedure is 8 (range of 3-14, SD 1.5). Mean number of pieces of tissue collected is 7.6 (range of 3-11, SD 1.08). The average number of evaluable fragments of lung parenchyma per procedure is 6.6. Adequate pathologic sample is achieved in only 30 to 50% of the time when 3-5 TBB are performed. Adequacy rates increase and range between79% to 95% when 6 to 11 biopsy passes are done; reaching up to 100% with 12 to 14 passes (Figure). The overall adequacy rate is 87%. Complications such as bleeding (n=3, 0.6%); pneumothorax (n=6, 1.2%), excessive sedation (n=1, 0.2%), and respiratory failure (n=7, 1.4%) are observed in only 3.4% of procedures with no death recorded. A total of 6 to 11 TBB provides adequate lung tissue samples for assessment of acute rejection and is associated with minimal risks for complications.