Ureters

About the Ureters

The ureters are two muscular tubes, each roughly 25 to 30 centimeters long in adults, that carry urine from the renal pelvis of each kidney down to the urinary bladder. Rather than relying on gravity, they move urine by peristalsis, waves of smooth muscle contraction. They enter the bladder obliquely, passing through its wall in a way that acts as a valve, so that when the bladder fills and contracts urine is prevented from flowing back up toward the kidneys. Failure of this mechanism, vesicoureteral reflux, is common in children with urinary infections. Each ureter has natural narrow points, at the junction with the kidney, where it crosses the iliac vessels at the pelvic brim, and where it enters the bladder, which are typical sites for kidney stones to lodge, causing severe colicky pain known as renal colic. Because the ureters run close to the uterine arteries, they are at risk of injury during pelvic surgery such as hysterectomy.