A ureteral stent of the correct length will ensure patient comfort, trouble-free drainage and prevent irritative voiding symptoms. Ureteral stents are available in lengths ranging from 20 to 28 cm (a further range of shorter stents are also available for renal transplant patients); a specific length has to be chosen for each patient.
Multilength or flexible-length ureteral stents are also available. They are made of a softer polymer that allows the pigtail to unfurl to the proper length, but these stents are less stable in position, and the proper positioning of the pigtails can be difficult (99). In a correctly positioned stent, the proximal pigtail should be formed within the renal pelvis, and the distal pigtail should project beyond the vesicoureteral junction (VUJ). Stents that are too short will retract into the ureter when the proximal pigtail forms in the renal pelvis, complicating stent retrieval. An overly long stent will be redundant within the bladder and may cause irritative voiding symptoms (Fig. 5B).
Accurately estimating stent length (85,99) can be difficult. In the technique called the kinked/bent wire technique, an attempt is made to directly measure uret-eral length by kinking a wire when it is just beyond the VUJ in the urinary bladder and then kinking it again after withdrawing it into the renal pelvis. Patel and Abubacker found that this technique overestimated the ureteral length in 83% of patients (90). These authors also found that the patient height was the most reliable method to estimate stent length, with patients less than 5 ft 10 inch. in height receiving 22 cm-long stents, patients 5 ft 10 inch. to 6 ft 4 inch. in height 24 cm-long stents, and patients greater than 6 ft 4 inch. in height 26 cm-long stents. Other authors have also reported on using patient height as a guide for stent length (99,100).
Other methods to estimate ureteral length are using an endocatheter ruler, or calculating ureteral length from a previous imaging study, such as an intravenous urogram (101,102).
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