Pilot study of ureteral movement in stented patients: First step in understanding dynamic ureteral anatomy to improve stent comfort

Background and Purpose: Ureteral stents may cause significant morbidity, including pain, dysuria, hematuria, and infection. New biomaterials, coatings, and designs have been studied in an attempt to reduce stent-related symptoms, but to date, the ideal comfortable stent has not been developed. In order to facilitate development of a stent that will mold and change with patient movement, we examined stent and ureteral movement with changes in patient body position. Patients and Methods: Four women and two men with a median age of 60.5 +/- 7.7 years who underwent shockwave lithotripsy and insertion of a ureteral stent were enrolled. Static radiographs were performed with the patients in four positions: supine, standing, sitting, and bending forward. Differences in stent position were analyzed digitally relative to fixed bony reference points to determine ureteral movement. Results: The renal stent curl was most cephalad when the patient was supine and moved caudally an average of 2.5 +/- 1.5 cm when the patient stood up. The absolute vertical length of the stent was greatest when the patient was supine (31.1 +/- 1.2 cm) and shortened with standing (28.3 +/- 2.3 cm) and sitting (26.6 +/- 1.5 cm). The bladder curl moved an average of 2.3 +/- 1.2 cm vertically with patient movement. Conclusions: By measuring stent position, we were able to quantify the range of motion of the ureter during changes in body position. Stent movement appears to be a combination of bowing in the proximal ureter and moving within the bladder. Future stent designs may take this into account to decrease stent-related symptoms.