Characteristics of normal and refluxing ureterovesical junctions.

In order to quantitatively define the mechanism of urereterovesical junction (UVJ) competence and vesicoureteral reflux, we measured ureteral pressures using a continuously perfused catheter with a single side opening. Studies were performed under general anesthesia on 11 competent and 9 refluxing UVJs. The amplitude of ureteral contractions was essentially the same in refluxing and non-refluxing systems, but peristaltic frequency was significantly lower in the presence of even the milder forms of reflux. With the bladder empty, a high pressure zone was observed at the UVJ in both refluxing and non-refluxing systems, with no significant pressure difference between the 2 groups. No relaxation was observed during urine transport across the UVJ. With bladder filling, a greater increase in profile pressure occurred at the UVJ of non-refluxing than refluxing systems. The UVJ-bladder pressure gradient of non-refluxing systems increased with bladder filling, whereas the gradient in the refluxing systems decreased. It appears that refluxing ureters have a decreased peristaltic frequency and fail to maintain a pressure gradient at the UVJ with bladder filling.