American Board of Internal Medicine (ABIM) Certification Practice Exam

For stones larger than 15 mm, what procedure is indicated?

1. Lithotripsy

2. Endoscopic stone fragmentation

3. Ureteroscopy

4. Conservative management

The correct answer is: Endoscopic stone fragmentation

For stones larger than 15 mm, endoscopic stone fragmentation is indicated because larger stones often require more invasive techniques due to the difficulty of passing them naturally. Endoscopic procedures, like those employed in percutaneous nephrolithotomy (PCNL), allow direct access to the kidney and urinary tract, enabling effective removal or fragmentation of large stones. This approach minimizes complications and maximizes stone clearance compared to non-invasive methods or conservative management. While lithotripsy is used for smaller stones and can be effective, it may not fracture larger stones adequately, which is why invasive techniques are preferred. Ureteroscopy is typically suited for stones that are smaller and located in the ureter. Conservative management is usually not effective for larger stones, as they are less likely to pass spontaneously without intervention. Thus, endoscopic stone fragmentation is the most appropriate procedure for stones exceeding 15 mm.