Ureteric drainage and peristalsis after stenting studied using colour Doppler ultrasound

To study peristalsis and drainage of the stented ureter under normal physiological conditions.

Fifteen non-obstructed patients with ureteric stents and 15 control subjects (i.e. 45 unstented ureters and 15 stented ureters) had ureteric jets and flow analysed using colour Doppler ultrasound (CDU). Cross-sectional and longitudinal studies were performed.

Unstented ureters had forceful ureteric jets at a frequency of 0.5-4 jets/min per ureter. Asymmetry of frequency within subjects was common (1-3 jets/min). Some patent stented ureters had no recordable flow on CDU (four cases, three within the first week of stenting). In the remainder, three types of flow pattern were recorded; weak peristaltic jets were seen in a minority (four of 15), flow around the stent (periprosthetic flow) in 11 of 15 and flow through the lumen (luminal flow) in eight of 15. Jets were only seen late after stenting (> 2 months). The periprosthetic flow was mildly peristaltic in some patients and periprosthetic and jet flow increased relative to luminal flow during peak diuresis.

Passive drainage (periprosthetic and luminal flow) is the principal mode of urine transport in the stented ureter throughout the diuretic response and particularly within a week of stenting. With longer duration of stenting (> 2 months) weak peristaltic activity and active ureteric transport became more evident, notably during peak diuresis. CDU is not reliable for diagnosing obstruction of the stented ureter.