Ureter

Ureter

Also known as: ureters

A muscular, retroperitoneal tube ≈25–30 cm long that carries urine from the renal pelvis to the urinary bladder by peristalsis, with three physiological narrowings where stones lodge.

Show on body map Kidney — Coronal Section Male Reproductive Organs

Overview

Length≈25–30 cm

Diameter≈3–5 mm

Peristalsis≈1–5 waves/min

Narrowest pointUreterovesical junction

Each ureter begins at the ureteropelvic junction (≈L2) and has an abdominal part and a pelvic part, of roughly equal length. The abdominal ureter descends retroperitoneally on the anterior surface of psoas major, roughly along the tips of the lumbar transverse processes, and is crossed anteriorly by the gonadal vessels. It enters the pelvis by crossing the pelvic brim anterior to the bifurcation of the common iliac artery (in front of the sacroiliac joint). The pelvic ureter runs down the lateral pelvic wall anterior to the internal iliac artery, turns anteromedially at the level of the ischial spine, and passes under the uterine artery (female, ≈1–2 cm lateral to the cervix) or the ductus deferens (male) — "water under the bridge" — before piercing the bladder wall obliquely.

The intramural (intravesical) part runs obliquely through the detrusor for ≈1.5–2 cm; bladder filling compresses it, forming a flap valve that prevents vesicoureteric reflux. The ureters open at the lateral angles of the trigone.

Three physiological constrictions — the ureteropelvic junction, the pelvic brim (crossing of the iliac vessels) and the ureterovesical junction (the narrowest) — are the typical sites where calculi impact. Urine is propelled by peristaltic waves (≈1–5 per minute) originating from pacemaker cells in the renal pelvis/calyces, not by gravity.

Location: Retroperitoneal, from the renal pelvis (≈L2) along psoas major, across the pelvic brim, to the posterolateral bladder base.

Parts & subdivisions

Abdominal part
On psoas major, behind the parietal peritoneum; crossed anteriorly by gonadal vessels. Right: behind the duodenum, right colic and ileocolic vessels, root of the mesentery. Left: behind the left colic vessels and sigmoid mesocolon.
Pelvic part
Crosses the common iliac bifurcation, descends on the lateral pelvic wall to the ischial spine, then turns medially under the uterine artery or ductus deferens.
Intramural part
Oblique course through the bladder wall (≈1.5–2 cm) acting as a valve against reflux.

Anatomy

Innervation: Renal, aortic, superior and inferior hypogastric plexuses. Visceral pain afferents enter the cord at T11–L2, so ureteric colic is referred from the loin to the groin (inguinal region, scrotum/labium majus, anterior thigh — genitofemoral L1–L2 distribution).
Arterial supply: Segmental, longitudinally anastomosing branches from the renal artery (upper), gonadal artery, abdominal aorta, common iliac and internal iliac arteries (superior/inferior vesical; uterine in females) for the lower part. Abdominal branches approach from the medial side, pelvic branches from the lateral side — important when mobilising the ureter surgically.
Venous drainage: Corresponding veins to the renal, gonadal and internal iliac veins.
Lymphatic drainage: Lateral aortic (lumbar), common iliac, external and internal iliac nodes, following the arterial supply.
Relations: Posterior: psoas major, genitofemoral nerve, common iliac bifurcation, internal iliac vessels. Anterior: gonadal vessels; on the right the duodenum, ileocolic vessels and terminal ileum (appendix nearby); on the left the left colic vessels and sigmoid colon. In the pelvis: uterine artery (female) or ductus deferens (male) crosses superior/anterior to it.
Histology: Star-shaped lumen lined by urothelium (transitional epithelium) on a lamina propria; muscularis of inner longitudinal and outer circular smooth muscle (the reverse of the gut), with an additional outer longitudinal layer in the lower third; adventitia.
Development: Stalk of the ureteric bud. A bifid bud gives a duplex system; in complete duplication the ureter from the upper pole inserts lower and more medially (Weigert–Meyer rule) and may be ectopic or obstructed (ureterocele), while the lower-pole ureter tends to reflux.

Function

Transport urine from kidney to bladder by peristalsis
Prevent reflux of urine into the kidney (ureterovesical valve)

Clinical significance

Ureteric calculi

Stones lodge at the three narrowings (UPJ, pelvic brim, VUJ). On a plain film the ureter's course is projected along the tips of the lumbar transverse processes, across the sacroiliac joint and toward the ischial spine — calcifications along this line suggest ureteric stones (phleboliths are a common mimic).

Iatrogenic injury

The ureter is at risk during hysterectomy (uterine artery ligation, clamping the ovarian vessels near the infundibulopelvic ligament), colorectal surgery and aortic surgery.

Vesicoureteric reflux

A short or laterally placed intramural segment allows urine to reflux into the ureter during voiding, predisposing children to recurrent pyelonephritis and renal scarring; diagnosed by micturating cystourethrogram and graded I–V.

Mnemonics

Water under the bridge

The ureter (water) passes beneath the uterine artery or ductus deferens (the bridge).

Test yourself

During hysterectomy, ligation of the uterine artery near the lateral vaginal fornix risks injury to which structure that passes immediately beneath it?

Obturator nerve
Internal iliac vein
Ureter
Round ligament of the uterus

Answer: Ureter

"Water under the bridge": the ureter passes under the uterine artery about 1–2 cm lateral to the cervix. In males it passes under the ductus deferens.

A 40-year-old man has colicky loin-to-groin pain. At which site does a ureteric stone most commonly impact because the lumen is narrowest there?

Ureteropelvic junction
Where the ureter crosses the pelvic brim
Where the gonadal vessels cross the ureter
Ureterovesical junction

Answer: Ureterovesical junction

The three physiological narrowings are the ureteropelvic junction, the pelvic brim (crossing of the iliac vessels) and the ureterovesical junction; the intramural ureterovesical junction is the narrowest and the commonest site of impaction.