Ureter

At a glance

English

Ureter

Latin (TA2)

Ureter

System

Urinary

Region

Abdomen

Side

Paired, left and right

About the ureter

Each ureter is a thick-walled tube about twenty-five to thirty centimetres long and a few millimetres wide. It starts at the pelviureteric junction, where the renal pelvis narrows near the hilum of the kidney, and ends by opening into the urinary bladder. Its course is divided into an abdominal part, a pelvic part and a short intramural part that passes through the bladder wall. Throughout, it lies behind the peritoneum and is closely stuck to it, so it moves with the peritoneum when that is lifted at surgery.

In the abdomen the ureter runs down on the front of psoas major, roughly in line with the tips of the lumbar transverse processes on an X-ray, and is crossed in front by vessels and by the roots of the mesenteries. On the right it lies behind the duodenum and the ileocolic and right colic vessels; on the left, behind the sigmoid mesocolon. At the pelvic brim it crosses either the end of the common iliac artery or the start of the external iliac artery. It then follows the side wall of the pelvis anterior to the internal iliac vessels, before turning forwards and medially at the level of the ischial spine to reach the back of the bladder.

It enters the bladder obliquely, tunnelling through its wall for about two centimetres before opening at a slit-like ureteric orifice at a lateral corner of the trigone. As the bladder fills, its pressure squeezes this tunnel shut, which stops urine flowing back up. The wall has a lining of transitional epithelium (urothelium), a middle coat of smooth muscle and an outer adventitia carrying a rich network of vessels and nerves. Urine is moved by waves of peristalsis, not by gravity.

Three natural narrowings are where stones tend to lodge: the pelviureteric junction, the crossing of the pelvic brim and the entry into the bladder. A stone causes severe colicky pain spreading from the loin to the groin. Failure of the oblique entry lets urine reflux towards the kidney, a common problem in children, and duplicated or ectopic ureters are frequent congenital variants. The ureter is also at risk of injury during pelvic and abdominal operations. It is examined by CT, ultrasound or a flexible scope passed up from the bladder.

Function and supply

Begins at

Begins at the pelviureteric junction as the continuation of the renal pelvis, near the hilum of the kidney.

Ends at

Ends at the ureteric orifice in the trigone of the urinary bladder after an oblique course through the bladder wall.

Function

Propels urine from the kidney to the bladder by peristalsis; its oblique passage through the bladder wall prevents backflow.

Nerve supply

A ureteric plexus fed by the renal, aortic, superior and inferior hypogastric plexuses; pain fibres reach spinal segments T11 to L2, so ureteric pain is felt from the loin round to the groin and upper front of the thigh.

Blood supply

A chain of small branches: the renal artery above, the abdominal aorta and common iliac artery in the middle, and vesical branches of the internal iliac artery below, joined by anastomoses in the adventitia; veins follow the arteries.