PAEA Surgery End Of Rotation (EOR) Practice Exam

Kidney stones measuring less than what size may pass spontaneously?

1. 3 mm

2. 4 mm

3. 5 mm

4. 6 mm

The correct answer is: 5 mm

Kidney stones that are 5 mm or smaller have a good chance of passing spontaneously through the urinary tract. This is important because the likelihood of spontaneous passage decreases as the stone size increases. Stones smaller than 5 mm are more likely to get pushed along by the urine flow due to less resistance in the ureter, while larger stones can cause obstruction and may require medical intervention. Typically, stones that measure 4 mm or less have a very high probability of passing spontaneously, often cited as around 80% or higher. Stones that measure precisely 5 mm are at a critical size where the passage probability drops but is still considered feasible. Stones larger than this size often necessitate treatments such as extracorporeal shock wave lithotripsy (ESWL) or ureteroscopy, especially as they approach sizes of 6 mm and above, which significantly increases the risk of complications. Understanding these size parameters helps guide management and counseling for patients presenting with kidney stones, emphasizing the importance of monitoring and the potential for spontaneous resolution based on stone size.