MRCOG Part 1 · Anatomy · Urinary System

Ureters: MRCOG Part 1 questions and key facts

Understanding the anatomy of the ureter is essential for the MRCOG Part 1 candidate, as iatrogenic ureteric injury represents a significant surgical hazard in gynaecology. The ureter descends through the abdomen and pelvis, crossing anterior to the genitofemoral nerve on the psoas major and posterior to the ovarian vessels. Deep in the pelvis, it runs within the cardinal ligament at the base of the broad ligament, crossing directly beneath the uterine artery approximately 1.5 to 2 centimetres lateral to the internal cervical os. Structurally, the ureter is lined by transitional epithelium, a specialised stratified layer capable of distension. Mastery of these precise relationships and histological features is frequently tested to assess anatomical safety during procedures such as hysterectomy and oophorectomy.

The Uterio bank has 7 questions on this topic. 2 are below in full; the syllabus detail is in the Anatomy study guide.

How the exam tests ureters

  • Spatial relationships of the abdominal ureter to the genitofemoral nerve and crossing ovarian vessels.
  • Proximity of the ureter to the uterine artery within the cardinal ligament during total hysterectomy.
  • Histological classification and functional properties of the transitional epithelium lining the inner mucous coat.
  • Mechanisms of iatrogenic ureteric obstruction arising from deep or lateral placement of surgical ligatures.

High-yield facts

  1. The ureter descends anterior to the genitofemoral nerve as the nerve lies on the psoas major muscle.
  2. Ovarian vessels descending from the abdomen cross anteriorly over the ureters.
  3. The ureter passes directly beneath the uterine artery approximately 1.5 to 2 centimetres lateral to the cervix.
  4. The crossing of the uterine artery over the ureter occurs at the level of the internal cervical os.
  5. In the pelvis, the ureter traverses the base of the broad ligament within the cardinal ligament.
  6. Ligation of the uterine artery during hysterectomy is the surgical step that most commonly injures the ureter.
  7. Placing surgical clamps too laterally, too deep, or in bleeding fields can incorporate the ureter into ligatures.
  8. The inner mucous coat of the ureter is lined by transitional epithelium, also termed urothelium.
  9. Transitional epithelium is a specialised stratified epithelium that stretches and recoils to accommodate changing urine volumes.
  10. When empty, the ureteric epithelium has rounded cell layers, but stretches thinner when filled with urine.

Common pitfalls

  • Confusing the crossing order of pelvic vessels: the ureter runs deep to both the ovarian vessels and the uterine artery.
  • Misidentifying the ureteric lining as simple or stratified squamous epithelium rather than specialised transitional epithelium.
  • Forgetting that the ureter passes anterior to the genitofemoral nerve on the surface of psoas major.

Practice questions: ureters

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Question 1

Anatomy

What is the relationship of the ureters to the genitofemoral nerve and the ovarian vessels?

  1. AThe ureters cross in front of the genitofemoral nerve and behind the ovarian vessels.
  2. BThe ureters cross behind the genitofemoral nerve and in front of the ovarian vessels.
  3. CThe ureters run parallel to the genitofemoral nerve and ovarian vessels.
  4. DThe ureters are not related to either the genitofemoral nerve or the ovarian vessels.
  5. EThe ureters cross in front of both the genitofemoral nerve and the ovarian vessels.
Show answer and explanation

Correct answer: A. The ureters cross in front of the genitofemoral nerve and behind the ovarian vessels.

Key takeaway

The ureters cross in front of the genitofemoral nerve and behind the ovarian vessels. This anatomical relationship is important during pelvic surgery to avoid iatrogenic injury.

Understanding the spatial relationships of the ureters is crucial for gynaecological and urological procedures.

The ureters cross in front of the genitofemoral nerve and behind the ovarian vessels. Specifically, as the ureters descend into the pelvis, they pass anterior to the genitofemoral nerve, which lies on the psoas major muscle. The ovarian vessels, which descend from the abdomen, cross over the ureters.

This relationship is particularly relevant during procedures like oophorectomy or hysterectomy, where careful dissection is required to avoid injuring the ureters. Knowing that the ureters lie behind the ovarian vessels helps surgeons navigate this region safely.

Question 2

Anatomy

After a total hysterectomy and bilateral salpingo-oophorectomy, a patient develops left ureteral obstruction. Ligation of which artery most commonly endangers the ureter in this procedure?

  1. AIliolumbar artery
  2. BInternal iliac artery
  3. COvarian artery
  4. DUterine artery
  5. EVaginal artery
Show answer and explanation

Correct answer: D. Uterine artery

Key takeaway

The ureter passes directly beneath the uterine artery approximately 1.5–2 cm lateral to the cervix at the level of the internal os — the classic "water under the bridge" relationship. Because of this crossing, ligation of the uterine artery during hysterectomy is the surgical step that most commonly injures the ureter.

The ureter and the uterine artery cross each other at a clinically critical point in the pelvis. As the ureter descends into the pelvis, it runs in the base of the broad ligament within the cardinal ligament and passes directly beneath the uterine artery approximately 1.5–2 cm lateral to the cervix at the level of the internal cervical os. This crossing is the basis of the classic surgical mnemonic "water under the bridge" — water is the ureter, the bridge is the uterine artery overhead.

During total hysterectomy, the uterine artery is ligated and divided as it passes over the ureter. If the clamp or suture is placed too laterally, too deep, or in a field obscured by bleeding, the ureter can be incorporated into the ligature — producing the ligated or kinked ureter and the post-operative ureteric obstruction described in the stem. This is the single most common mechanism of iatrogenic ureteric injury in hysterectomy, which is why the uterine artery is the answer.

The ovarian artery travels in the infundibulopelvic (suspensory) ligament and crosses the ureter near the pelvic brim during salpingo-oophorectomy; the ureter can be injured in that region too, but it is not the most common mechanism of ureteric obstruction after hysterectomy. The internal iliac artery and its proximal branches run medial/posterior to the ureter as it crosses the pelvic brim and are not the usual culprits in hysterectomy-related ureteric injury. The iliolumbar and vaginal arteries do not cross the ureter at a point where standard hysterectomy technique endangers it.

5 more ureters questions in the bank

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What the syllabus covers under ureters

  • Course
  • Structure

Read the full section in the Anatomy guide, or check the next exam dates.