Hello and welcome to the Stone News, a newsletter where we discuss every three months the most recent and relevant studies in stone disease.

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Kidney stone disease continues to challenge us not only in the operating room but also in how we define success, adopt new technologies, and keep our patients engaged long term. 

In this edition of Stone News, we take a closer look at three areas where our field is moving forward. A systematic review reminds us that “stone-free” is not always as clear-cut as we think. Artificial intelligence is starting to lend us a digital hand in ureteroscopy, showing real potential to improve intraoperative vision. And outside the hospital, a study on the first 699 users of a kidney stone app gives us insight into how digital health can support — and sometimes struggle — to keep patients motivated.

Together, these studies reflect an exciting mix of standardization, innovation, and patient involvement. 
 

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We all know the feeling of seeing a CT showing a tiny fragment left behind after surgery. What size is acceptable? Two millimeters? Four? Five? This systematic review shows that the answer depends on which paper you read.

What is clear, however, is that fragments larger than 4 mm—especially in the lower pole—can cause stone-related events. They are more likely to grow, cause infection, or send your patient back to the OR. CT remains the most reliable imaging method, although it comes at the cost of radiation. 

Until we have international consensus, the safest approach is to treat any fragment over 4 mm as clinically relevant and keep a close eye on it.

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Imagine having an extra pair of eyes during ureteroscopy that can instantly highlight the stone margins. That is exactly what the “Segment Anything Model” (SAM) promises. This AI tool outperformed older algorithms at recognizing and segmenting stones in ureteroscopic videos and, importantly, worked well across different datasets and hospitals. 

The future? Automated stone sizing, improved documentation, and maybe even real-time alerts during surgery. While we are not yet ready to let a robot do the lasering, SAM shows that artificial intelligence is no longer a distant dream in endourology.

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This study tracked the first 699 users of the myLit-Control^® App, a digital health tool designed for kidney stone management to facilitate self-care and prevent recurrence in patients with urolithiasis. 

The users of the app can view historical data and set clinical goals and reminders to help maintain adequate water intake, take their medication, and monitor urinary pH by synchronizing the data via Bluetooth with the Lit-Control^® pH Meter 2.0.

Most of the users in the study were middle-aged, and men slightly outnumbered women. The app’s most popular features were fluid intake logging (66%), monitoring of the urinary pH (53%) and treatment follow-up for lithiasis (31%), showing a treatment adherence of almost 60%.. Engagement was high, with 75% of users employing at least one feature to monitor their health. Another key finding was the negative correlation between age and both pH values and adherence. This suggests that older patients tend to show lower treatment compliance and lower urinary pH levels, which may increase the risk of uric acid stone formation.

The message is clear: digital tools work, but patients need nudges to keep going. Integrating apps with clinic visits and adding personalized feedback could make them part of everyday stone prevention. Think of it as having a stone-coach in your patient’s pocket.