04 URETERS
# 04 URETERS
The ureters are long, retroperitoneal, cross multiple structures and are easy to injure in pelvic surgery — which is why their course, relations and surgical landmarks appear in almost every Part A paper.
Overview
Each ureter is a muscular tube 25–30 cm long conveying urine from renal pelvis to bladder by active peristalsis. It is retroperitoneal throughout, divided into two roughly equal parts:
➡ Abdominal ureter — PUJ to pelvic brim
➡ Pelvic ureter — pelvic brim to VUJ
The wall has an inner urothelium, a smooth muscle coat (inner longitudinal, outer circular — the reverse of the gut), and an outer adventitia.
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Course of the ureter
Abdominal course
The ureter begins at the pelviureteric junction (PUJ) at roughly L2. It descends anterior to psoas major — a classic trap is to call it lateral to psoas; it lies on psoas. It then crosses the tips of the L2–L5 transverse processes before reaching the pelvic brim.
Crossing into the pelvis
The ureter enters the pelvis by crossing anterior to the bifurcation of the common iliac artery at the pelvic brim, just in front of the sacroiliac joint. This is the most commonly tested single fact about the ureter and is how surgeons locate it during colorectal or gynaecological resection.
Pelvic course
The ureter then runs along the lateral pelvic side wall, anterior to the internal iliac artery, before turning medially near the ischial spine toward the bladder. The relationship near the bladder differs by sex:
➡ Male: the vas deferens crosses anterior to the ureter.
➡ Female: the uterine artery crosses anterior to the ureter ~1–2 cm lateral to the cervix, at the level of the lateral vaginal fornix.
This uterine artery–ureter crossing is the single most surgically important relationship in this lesson and the reason ureteric injury complicates hysterectomy.
> "Water under the bridge" — gonadal vessels (abdomen) and uterine artery / vas deferens (pelvis) all cross anterior to the ureter. Ureter = water; vessels = bridge.
The ureter pierces the bladder wall obliquely at the trigone (VUJ). The oblique tunnel acts as a one-way flap valve; loss of this geometry causes vesicoureteric reflux in children.
The three constrictions
The ureter narrows at three predictable points. These are the three sites where renal stones impact — examinable every cycle.
| Constriction | Location | Approximate diameter |
|---|---|---|
| 1. Pelviureteric junction (PUJ) | L2 — where renal pelvis meets ureter | ~2 mm |
| 2. Pelvic brim | Where ureter crosses common iliac bifurcation | ~4 mm |
| 3. Vesicoureteric junction (VUJ) | Where ureter enters bladder wall obliquely | ~1–2 mm (narrowest) |
👩⚕️ The VUJ is the narrowest point and the most common site of stone impaction. Patients with a VUJ stone often complain of irritative bladder symptoms (frequency, urgency, suprapubic discomfort) because the stone irritates the trigone — a classic SBA scenario.
Anatomical relations
Abdominal ureter
➡ Posterior: psoas major, tips of L2–L5 transverse processes, genitofemoral nerve (a stone here irritates the nerve, referring pain to scrotum/labium and medial thigh)
➡ Anterior (right): 2nd part of duodenum, right colic and ileocolic vessels, root of mesentery, gonadal vessels, terminal ileum
➡ Anterior (left): left colic vessels, gonadal vessels, sigmoid mesocolon
Pelvic ureter
➡ Lateral: internal iliac artery
➡ Anterior — male: vas deferens
➡ Anterior — female: uterine artery (~1 cm lateral to cervix), broad ligament
➡ Near bladder: seminal vesicles (M), lateral vaginal fornix (F)
Blood supply
The blood supply is segmental and runs longitudinally in the adventitia — stripping the adventitia devascularises the ureter. Vessels approach from the medial side in the abdomen and the lateral side in the pelvis, so mobilise from the opposite side surgically.
| Segment | Arterial supply |
|---|---|
| Upper (abdominal) | Renal, gonadal, aortic branches |
| Middle | Common and internal iliac |
| Lower (pelvic) | Vesical, uterine, middle rectal, vaginal |
Innervation
Visceral afferents travel with sympathetics to T11–L2 — this is why ureteric colic refers in a loin-to-groin pattern.
👩⚕️ The site of pain hints at the level of the stone:
- Upper ureter → loin/flank
- Mid ureter → iliac fossa (mimics appendicitis)
- VUJ → scrotum/labium, tip of penis, suprapubic frequency/urgency
Peristalsis is myogenic, driven by pacemaker cells in the renal pelvis — not abolished by sympathetic blockade.
Lymphatic drainage
➡ Upper → para-aortic (with kidney)
➡ Middle → common iliac
➡ Lower → internal and external iliac
Surgical landmarks and iatrogenic injury
The ureter is the most commonly injured structure in pelvic surgery.
| Site | Operation | Mechanism |
|---|---|---|
| Pelvic brim | Sigmoid / AP resection | Mistaken for gonadal vessels or ligated with IMA pedicle |
| Lateral to cervix | Hysterectomy | Clamped with the uterine artery ("water under the bridge" failure) |
| VUJ | Bladder / lower ureteric surgery | Direct injury during reimplantation |
| Ovarian fossa | Oophorectomy | Adherent to infundibulopelvic ligament |
👩⚕️ Highest-yield surgical fact: during hysterectomy, the uterine artery passes anterior to the ureter ~1 cm lateral to the cervix. Identify the ureter before clamping the uterine pedicle.
Intraoperatively the ureter is pale, pinkish-white, runs in the retroperitoneum, and shows visible peristalsis ("vermiculation") when pinched gently.
Clinical correlations
Ureteric colic — severe colicky loin-to-groin pain; patients are restless (unlike peritonitis). Microscopic haematuria is common. Non-contrast CT KUB is the investigation of choice. Obstruction with infection ("obstructed infected system") is an emergency requiring stent or nephrostomy.
PUJ obstruction — congenital narrowing or aberrant lower-pole renal artery; causes hydronephrosis with a non-dilated ureter — distinguishes it from more distal obstruction.
Vesicoureteric reflux — loss of the oblique VUJ tunnel; causes recurrent pyelonephritis and renal scarring in children.
[Image: MCQs banner]
Test yourself
A 53-year-old man undergoing right nephrectomy is approached posteriorly. Which structure is encountered first at the hilum?
- ((Right renal artery::Middle structure at the hilum; sits between vein and ureter.))
- ((Ureter::☑️ Hilum from posterior to anterior: Ureter → Artery → Vein.))
- ((Right renal vein::Most anterior hilar structure; encountered last from behind.))
- ((Right testicular vein::Drains to IVC on the right; not a hilar structure.))
👩⚕️ Anterior → posterior at the renal hilum: Vein → Artery → Ureter.
The point of entry of the ureter from the abdomen into the pelvis occurs at the:
- ((Ischio-iliac joint::Not a real anatomical joint.))
- ((Bifurcation of common iliac arteries::☑️ Ureter crosses anterior to the bifurcation at the pelvic brim, in front of the SI joint.))
- ((Sacroiliac joint::The crossing is in front of the SI joint, but the landmark examiners want is the iliac bifurcation.))
- ((Ischial spine::Marks the level of the ischial spine for pudendal nerve block, not ureteric entry.))
What is the correct relationship of the internal iliac artery and the ureter at the pelvic brim?
- ((Vein is anterior to the iliac artery::Veins generally lie posterior to their arteries in the pelvis.))
- ((Ureter is anterior to the iliac artery::☑️ Ureter crosses anterior to the internal iliac artery as it descends the pelvic side wall.))
- ((Artery is anterior to the iliac vein::True for some segments but not the relationship being tested.))
- ((Artery is posterior to the iliac vein::Reversed — artery is anterior to vein in the pelvis.))
Which statement correctly describes the anatomical relations of the ureter?
- ((Crossed posteriorly by the gonadal veins::Gonadal vessels cross anterior — "water under the bridge".))
- ((Passes posterior to the common iliac bifurcation::Reversed — it crosses anterior to the bifurcation.))
- ((Crossed anteriorly by the gonadal veins::☑️ Gonadal vessels, vas deferens and uterine artery all pass anterior to the ureter.))
- ((Common iliac arteries divide posterior to the ureter::Reversed — ureter lies anterior to the bifurcation.))
- ((Lies lateral to psoas major::Ureter descends on (anterior to) psoas, not lateral to it.))
👩⚕️ "Water under the bridge" covers gonadal vessels, vas deferens and uterine artery in one mnemonic.
A 34-year-old woman has a urinary leak 5 days after total abdominal hysterectomy. Most likely site of injury?
- ((Lateral to the cervix at the uterine artery::☑️ Uterine artery crosses anterior to the ureter ~1 cm lateral to cervix — classic hysterectomy injury.))
- ((Pelviureteric junction::PUJ is not in the hysterectomy field.))
- ((Where ureter crosses psoas::Abdominal course; well above the operative field.))
- ((Vesicoureteric junction::Possible during cystotomy, but not the classic hysterectomy site.))
A 45-year-old man has severe loin-to-groin pain radiating to the scrotum with urinary frequency. Where is the stone?
- ((PUJ::Loin/flank pain without bladder symptoms.))
- ((Pelvic brim::Iliac fossa pain, mimics appendicitis.))
- ((Vesicoureteric junction::☑️ Narrowest point; trigonal irritation explains frequency/urgency.))
- ((Mid-ureter at L4::Not a recognised constriction.))
👩⚕️ Three constrictions — PUJ, pelvic brim, VUJ — with VUJ narrowest.
Which is true of the ureteric blood supply?
- ((Supplied by a single ureteric artery::Supply is segmental, not single-vessel.))
- ((Abdominal ureter receives branches from renal, gonadal and aortic arteries::☑️ Segmental; vessels run longitudinally in adventitia.))
- ((Pelvic ureter is supplied solely by the internal iliac::Vesical, uterine, middle rectal and vaginal arteries all contribute.))
- ((Vessels approach the abdominal ureter laterally::Medial in abdomen, lateral in pelvis.))
Ureteric pain is referred to which dermatomes?
- ((T6–T10::Foregut/mid-abdominal viscera.))
- ((T11–L2::☑️ Visceral afferents travel with sympathetics — explains loin-to-groin radiation.))
- ((L2–L4::Lumbar plexus; anterior thigh.))
- ((S2–S4::Pelvic parasympathetic / perineum.))
Revision summary
- 25–30 cm, retroperitoneal; inner longitudinal + outer circular muscle (reverse of gut).
- Course: PUJ (L2) → on psoas → over tips of L2–L5 TPs → anterior to common iliac bifurcation at pelvic brim → lateral pelvic wall → oblique VUJ.
- Three constrictions (= stone sites): PUJ, pelvic brim, VUJ. VUJ narrowest.
- Water under the bridge: gonadal vessels, vas deferens, uterine artery all cross anterior to ureter.
- Hilum anterior → posterior: Vein → Artery → Ureter.
- Blood supply: segmental, longitudinal in adventitia; medial in abdomen, lateral in pelvis.
- Pain: T11–L2 loin-to-groin. Upper = flank; mid = iliac fossa (mimics appendicitis); VUJ = scrotum/labium + frequency/urgency.
- Lymph: para-aortic → common iliac → internal/external iliac.
- Iatrogenic injury: hysterectomy at uterine artery (1 cm lateral to cervix); colorectal surgery at pelvic brim.
- Stones: non-contrast CT KUB; obstructed infected system = emergency stent/nephrostomy.