Background The performance of conventional cryoprobe in difficult-to-reach areas of the lung such as apical upper lobe was frequently limited due to its larger caliber and stiffness. The flexible 1.1mm ultrathin cryoprobe may address this clinical dilemma. 
 
Methods Retrospective review of rEBUS guided transbronchial cryobiopsy (TBLC) of lung nodules from April 2017 to December 2022. Data of ultrathin cryoprobe (Group A) was compared to historical 1.9mm cryoprobe (Group B).
 
Results 130 TBLC were performed during the study period using the ultrathin (Group A, n=47) and conventional cryoprobe (Group B, n=83). Large caliber bronchoscopes were used in all Group B cases while thin bronchoscopes were used in 66% of Group A cases.  The target lesion was significantly smaller in the ultrathin group [2.10 (IQR 1.53-2.32) vs. 2.65 (IQR 2.20-3.67) cm, p<0.001] and was more peripherally situated (5th vs. 3rd median airway generation, p<0.001) with target to pleural distance of 1.85 (IQR 0.97-2.33) vs. 2.30 (IQR 1.81-3.14) cm, p<0.001. More target nodules were localized in the apical upper lobe in Group A (29.8% vs. 13.3%, p<0.05). The overall diagnostic yield was 81.5% with no difference between two groups (Group A 83.0% vs. Group B 80.7%, p>0.05). There was no severe bleeding encountered but mild to moderate bleeding was recorded in 41.6% which was no difference between two groups (Group A 51.1% vs. Group B 36.1%, p>0.05). One pneumothorax (0.8%) was encountered in our study.

Conclusion rEBUS guided TBLC with 1.1mm cryoprobe potentially allow access into smaller lung nodules in difficult-to-reach areas in the lung with non-inferior diagnostic yield and similar complication profile.