Hydroureter is the dilation of the ureter, the muscular tube that carries urine from the kidney to the bladder. On ultrasound, a dilated ureter appears as a tubular, anechoic structure extending from the renal pelvis toward the bladder. The normal ureter is usually not visible on ultrasound because it is small and surrounded by bowel gas, so visualization of the ureter generally indicates dilation. Hydroureter commonly occurs alongside hydronephrosis and can be caused by ureteral stones, strictures, external compression from tumors, pregnancy, or vesicoureteral reflux. Tracing the dilated ureter to the point where it returns to normal size can help locate the site of obstruction.
Sonography Term