The ureter is a muscular tube, approximately 25 to 30 centimeters long, that connects each kidney to the urinary bladder. Urine produced by the kidney drains into the renal pelvis and flows down the ureter to the bladder through waves of muscular contraction called peristalsis. Under normal conditions, the ureter is too small to be seen on ultrasound. However, when the ureter is dilated (hydroureter) — typically due to obstruction from stones, strictures, or tumors — it becomes visible as a fluid-filled tubular structure. The distal ureter near the bladder is most commonly visualized. Ureteral jets, the rhythmic spurts of urine entering the bladder from the ureteral orifices, can be seen on color Doppler and confirm ureteral patency.
Sonography Term