# Spontaneous knot formation complication of double J: two case reports

## TL;DR

This paper reports two cases where ureteral stents spontaneously formed knots, possibly due to ureteral peristalsis or anatomical anomalies, and highlights the importance of radiographs before stent removal.

## Contribution

The paper presents the first evidence that spontaneous stent knotting can occur due to ureteral peristalsis or anomalies, not just traction.

## Key findings

- Spontaneous knot formation in double J stents was observed in two patients without prior urological surgery.
- Stents were successfully removed using gentle traction under general anesthesia.
- Radiographs before stent removal are emphasized to detect knots and prevent complications.

## Abstract

Use of ureteral stents has become an integral part of urological practice. However, it also brought with it many complications. Double J (DJ) stent knotting is a rare stent complication, and only a few cases have been reported in the literature. Although the exact cause is unknown and, in the literature, it is generally thought that knots occur due to traction. In this case report we present for the first time that spontaneous knots can occur due to ureteral peristalsis or ureteral anomalies.

Two patients (67 and 35 aged-Caucasian person) with ureteral stones who presented to the emergency department with colicky pain and had no previous history of urological surgery. We observed knot formation in the routine urinary system radiographs taken before stent removal in two patients whose ureters were observed to be narrow during endoscopic ureteral stone treatment. The stents were successfully removed using gentle traction under general anesthesia.

We discussed the cause and solution of spontaneous knot formation. We emphasized the importance of the direct urinary system radiograph taken before DJ stent removal.