To investigate the changes in the stone composition between 2 stages of stone surgery.

We prospectively enrolled 600 patients from a single medical center between October 2015 and June 2021. The stones were analyzed using Fourier transformation infrared spectrometer (Bruker, Karlsruhe, Germany). Calculi were classified based on their primary component. Ultimately, a total of 520 patients met the criteria and entered the final analyses. The stone composition between the 2 stages of surgery was compared.

Of the 520 patients, 277 were male and the mean age was 52.9±12.8 years. The average time delay between 2 stone analyses was approximately 33.2 days. One hundred and eighty-six cases (35.8%) had different compositions on the second-stage analyses, with a total of 67 (36.0%) cases transitioning to a totally different type of stones. Forty-one (16.5%) cases initially identified as infection stones changed to non-infection stones and 35 (12.9%) cases transformed from non-infection stones to infected stones.

Up to 35.8% of stones underwent changes during the second stone composition analysis, and up to 36.0% of these altered stones had transformed to a totally different type. Conducting stone composition analysis between 2 stages of surgery is essential for the development of follow-up treatment and drug prevention plans.