An in vivo endoluminal ultrasonographic study of peristaltic activity in the distal porcine ureter

Purpose: Experiments were performed to quantify the duration and frequency of ureteric peristaltic activity in the laparotomized and non-laparotomized pig in its virgin and post-instrumented states. Materials and Methods: Pigs (n = 10) in a steady state of hydration were st udied under halothane anesthesia in two groups. The study was undertaken in two separate sessions at a week's interval. In group I laparotomy and vesi cotomy were undertaken to obtain ELUS images. In group II, peristalsis was studied using an ELUS probe introduced through the working channel of a 22F rigid cystoscope. Peristalsis was visualized as a periodic diameter-change of ureter and recorded (for approx. 30 minutes) on videotape after an init ial period of adaptation of approx. 30 minutes. Results: The ureter acts Like a pump discharging urine into the bladder thr ough peristaltic activity. ELUS imaging of ureteric peristalsis correlated well with "eyeballing" of the passage of peristalsis through a ureter (grou p I). The shortest peristaltic activity in group I was 6.0 +/- 2.0 seconds in the non-instrumented- and 5.1 +/- 1.4 seconds in the instrumented ureter . In group II it was 6.8 +/- 1.5 seconds in the non-instrumented- and 6.4 /- 1.5 seconds in the instrumented ureter. Chronic dilatation of ureter led to decrease in peristalsis frequency. Interestingly, acute dilatation caus ed an increase in ureteric peristalsis frequency. Conclusions: Ureteric peristalsis acts as a pump discharging urinary boluse s (intraluminal fluid load) unidirectionally into the bladder. ELUS provide s us an opportunity to quantify and study ureteric peristalsis.