Ureteric stent

A ureteral stent (pronounced you-REE-ter-ul), or ureteric stent, is a thin tube inserted into the ureter to prevent or treat obstruction of the urine flow from the kidney. The length of the stents used in adult patients varies between 24 and 30 cm. Additionally, stents come in differing diameters or gauges, to fit different size ureters. The stent is usually inserted with the aid of a cystoscope. One or both ends of the stent may be coiled to prevent it from moving out of place; this is called a JJ stent, double J stent or pig-tail stent. Ureteral stents are used to ensure the openness of a ureter, which may be compromised, for example, by a kidney stone or a procedure. This method is sometimes used as a temporary measure, to prevent damage to a blocked kidney, until a procedure to remove the stone can be performed. Indwelling times of 12 months or longer are indicated to hold ureters open, which are compressed by tumors in the neighbourhood of the ureter or by tumors of the ureter itself. In many cases these tumors are inoperable and the stents are used to ensure drainage of urine through the ureter. If drainage is compromised for longer periods, the kidney can be damaged. Stents may also be placed in a ureter that has been irritated or scratched during a ureteroscopy procedure that involves the removal of a stone, sometimes referred to as a 'basket grab procedure'. Stents placed for this reason are normally left in place for about a week. These stents ensure that the ureter does not spasm and collapse after the trauma of the procedure. A technical drawback of ureteric stents is that they by-pass the 1-way valve at the entrance of the ureter into the bladder, the normal vesicoureteral (ureteral-bladder) junction. The function of this valve is to prevent backflow of urine from the bladder to the kidney (vesicoureteral reflux). A ureteric stent thus leads to the loss of the valve function thereby opening up the ureter to backflow.