Prognostic factors for successful outcome in sialendoscopy for sialolithiasis

Background The success of sialendoscopy depends on several factors. The 2008 introduced lithiasis-stenosis-dilatation (LSD) classification intended to describe more precise the stone-duct system. We investigated whether the LSD classification and additional pre- and intraoperative parameters could be used as prognostic factors for success. Methods We retrospectively assessed patients with primary sialendoscopy for sialolithiasis between September 2018 und March 2020. Among others, the outcome variables were the stone size, location and LSD classification. Results We included 37 patients. The success group included 12/37 (32 %) patients. The median stone size was 3.7 millimeters (mm) in the success group and 10.0 mm in the failure group (Mann-Whitney test; p < 0.0001). In the success group, 11/12 stones were distal in contrast to the failure group (13/25 stones proximal; Pearson's chi-square test; p = 0.010). We noted 10 L1S0D0 stones in the success group in contrast to the failure group (15 L3aS0D0 stones; Pearson chi-square test; p = 0.001). For distal stones smaller than 5 mm, the success rate was 100 % and for proximal stones larger than 4 mm, it was 0 %. For stones free in the duct lumen (L1S0D0), the success rate was 60-100 %. Conclusion The distal stone location and the smaller stone size in a normal duct should be beneficial prognostic factors for success. Future studies should focus on the LSD classification, stone volume, stone duct orientation and stone distance from the papilla.