<P> A ureteral stent, sometimes as well called 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 . </P> <P> Ureteral stents are used to ensure the patency 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 . </P>

Where is a stent inserted for kidney stones