Specimen size evaluated using the direct retrieval technique of cryobiopsy through the working channel of a therapeutic bronchoscope

A 1.1-mm ultrathin cryoprobe may be small enough to retrieve relatively large specimens through a therapeutic bronchoscope’s wide working channel, potentially simplifying and enhancing cryobiopsy procedures. The aim of this study was to evaluate the size of specimens obtained by cryobiopsy using an ultrathin cryoprobe, directly retrieved through the 3.0-mm working channel of a therapeutic bronchoscope. This prospective study enrolled patients with undiagnosed endobronchial lesions scheduled for biopsy during rigid bronchoscopic intervention under general anesthesia. Forceps biopsies using standard-size biopsy forceps were followed by cryobiopsies using a 1.1-mm ultrathin cryoprobe. All specimens were retrieved directly through the 3.0-mm working channel of a therapeutic bronchoscope. Thirty patients were analyzed, with a total of 244 biopsy samples (124 from forceps biopsy and 120 from cryobiopsy). The size of cryobiopsy specimens retrieved directly through the working channel was significantly larger than that of forceps biopsy specimens (median: 6.8 mm 2 vs. 2.5 mm 2 ; p < 0.001). During cryobiopsy, tissue adhering to the probe became stuck at the distal end of the working channel in 15 instances (freezing times: 5 s [ n = 1], 7 s [ n = 2], and 8 s [ n = 12]). Moderate bleeding occurred in 6 patients (20%), and all cases were effectively managed using bronchoscopy. The direct specimen retrieval technique using a 1.1-mm cryoprobe through the 3.0-mm working channel of a therapeutic bronchoscope yields significantly larger specimens than forceps biopsy. In most cases, specimens can be successfully retrieved with freezing times of up to 7 s. Date of registration 15/03/2023. UMIN-Clinical Trials Registry; Identifier: UMIN000050607 https://www.umin.ac.jp/ctr/index.htm