A 12-year-old boy visited a regional tertiary cancer center. He underwent chemotherapy for his brain medulloblastoma. However, he complained of flank pain and CT scans detected multiple small stones in the bilateral kidneys and ureters (RT. mid-ureteral two stone of 4mm and LT. distal ureteral three stones of 4mm). Mild degree of hydroureteronephrosis was identified in the bilateral sides. Hounsfield-unit was 1,200.

<Bilateral kidney and ureteral stones and hydronephroureterosis>

<Discussion Topics: Why should we treat this patient? Surgery vs medication?>

The urologist performed medical expulsive therapy for 2 weeks. Chemotherapy was postponed due to the risk of infection. The follow-up images showed no change. The patient was finally referred to my hospital to undergo ureteroscopic removal of urinary calculi.

<Discussion Topics: (1) RIRS vs PCNL. What is your first option? The flexible ureteroscopy is usually available for a 12-year-old boy.>

I tried to perform flexible ureteroscopic removal first. The renal and ureteral stones were safely removed in the left side without difficulty. However, the right-sided ureteral hydronephroureterosis seemed to be more severe than that shown in the CT scans and a short-segment ureteral narrowing was identified in the far distal part of the right ureter. The flexible ureteroscopic approach was impossible.

<A kinked and narrowed ureter>

<Discussion Topics: (1) What is your next option? Antegrade approach vs PCN (2) Should we consider DJ stenting? If yes, what size would be appropriate? >

The terumo guidewire was not introduced through the kinked ureteral segment. I tried antegrade approach first through the percutaneous puncture. However, the ureter kinking was not straightened and the ureteral stones could not be removed.

<Antegrade approach to the kinked ureter>

<Discussion Topics: (1) What is your next option? Antegrade approach is not really available? (2) Now, should we consider DJ stenting? If yes, what size would be appropriate? >

I was determined to wait for several days after I placed a PCN tube. I expected that the hydroureteronephrosis could be straightened after decompression of the renal hydronephrosis.

Then I performed percutaneous antegrade ureteral stone surgery by using a ureteral access sheath and a flexible ureterorenoscope. The stones were completely removed. The stone consisted of calcium oxalate dihydrate (60%) and calcium oxalate monohydrate (40%).

< Stones in the ureter>

<Discussion Topics: (1) What is your next option? Now, should we consider DJ stenting? If yes, what size would be appropriate? (2) What is your next plan? >

Conclusion

Urologists can consider and perform flexible ureteroscopic stone surgery first for children with renal and ureteral stones. However, we should actively consider the status of the renal collecting system, i.e. presence of hydronephrosis, ureteral kinking, or ureteral stricture. This consideration is important, especially for children with urinary stones.