Abdominal Ureter

The abdominal ureter is the portion of the ureter extending from the renal pelvis to the pelvic brim. It is a retroperitoneal muscular tube that descends along the posterior abdominal wall before crossing the iliac vessels and entering the pelvis. The right and left abdominal ureters follow similar general courses, although their anterior relations differ because of the asymmetrical arrangement of the abdominal viscera.

The abdominal ureter is clinically important because it includes the ureteropelvic junction and terminates near another region of relative narrowing at the pelvic brim. Its close relationships with the psoas major, gonadal vessels, genitofemoral nerve, mesenteric structures, and iliac vessels provide important landmarks during abdominal and retroperitoneal surgery.

Extent

The abdominal ureter begins where the renal pelvis narrows to become the ureter at the ureteropelvic junction.

It extends inferiorly through the retroperitoneum until it crosses the pelvic brim, after which it continues as the pelvic ureter.

Ureteropelvic Junction

The ureteropelvic junction, also called the pelviureteric junction, is the transition between the funnel-shaped renal pelvis and the narrower ureter.

It represents the proximal end of the abdominal ureter and is traditionally recognized as one of the major sites of relative ureteric narrowing.

General Course

From the renal pelvis, the abdominal ureter descends almost vertically along the posterior abdominal wall.

It travels anterior to the psoas major muscle, remains behind the parietal peritoneum, and proceeds toward the bifurcation of the common iliac artery or the proximal external iliac artery at the pelvic brim.

Retroperitoneal Position

The abdominal ureter is a retroperitoneal structure.

It lies posterior to the parietal peritoneum and anterior to the posterior abdominal wall musculature and associated nerves.

Relationship to Psoas Major

The psoas major muscle forms the principal muscular bed of the abdominal ureter.

The ureter descends on the anterior surface of psoas major from the renal region toward the pelvic brim.

Genitofemoral Nerve

The genitofemoral nerve emerges through the anterior surface of psoas major and descends on the muscle.

Because the ureter also lies on the anterior surface of psoas major, the genitofemoral nerve is an important posterior relation of the abdominal ureter.

Gonadal Vessels

The gonadal vessels, consisting of the testicular vessels in males and ovarian vessels in females, descend through the retroperitoneum and cross anterior to the ureter.

This crossing is a useful anatomical landmark during retroperitoneal surgery.

Relationship to the Renal Vessels

The proximal ureter begins inferior to the renal hilum as a continuation of the renal pelvis.

Its upper course is therefore closely related to the structures of the renal hilum and renal vascular pedicle.

Right Abdominal Ureter

The right abdominal ureter descends retroperitoneally on the right psoas major muscle.

Its anterior relations differ from those of the left ureter because of the presence of the duodenum, right-sided mesentery, and adjacent intestinal structures.

Anterior Relations of the Right Ureter

Structures that may lie anterior to or cross the right abdominal ureter include:

• The descending part of the duodenum proximally
• The gonadal vessels
• Branches of vessels supplying the right colon
• The root of the small intestinal mesentery
• Loops of small intestine

The precise relationships vary with the level of the ureter and the position of mobile abdominal viscera.

Duodenal Relationship

The proximal right ureter lies posterior to the second part of the duodenum.

This relationship is relevant during mobilization of the duodenum and surgical exposure of the right retroperitoneum.

Root of the Mesentery

The root of the small intestinal mesentery crosses structures of the posterior abdominal wall and lies anterior to part of the right ureter.

The ureter therefore remains protected within the retroperitoneum while mesenteric structures occupy a more anterior plane.

Left Abdominal Ureter

The left abdominal ureter descends on the anterior surface of the left psoas major muscle.

Its anterior relationships are influenced by the descending and sigmoid colon, their mesenteric attachments, gonadal vessels, and associated vascular structures.

Anterior Relations of the Left Ureter

Structures related anteriorly to the left abdominal ureter may include:

• The gonadal vessels
• Branches of the left colic vessels
• The descending colon and its mesocolic tissues
• The sigmoid mesocolon near the lower abdominal course
• Loops of small intestine where they overlie the retroperitoneum

Sigmoid Mesocolon

Near the lower portion of the left abdominal ureter, the sigmoid mesocolon and its associated vessels may cross anterior to the ureter.

This relationship is particularly important during colorectal and sigmoid surgery.

Posterior Relations

The most consistent posterior relation of the abdominal ureter is the psoas major muscle.

The genitofemoral nerve is also related posteriorly as it descends on the anterior surface of psoas major.

Medial and Lateral Relationships

The abdominal ureter lies near the major vessels of the posterior abdominal wall but remains lateral to the great vessels during much of its course.

Its exact medial and lateral relationships differ on the right and left because of the positions of the inferior vena cava, abdominal aorta, kidneys, and colonic structures.

Relationship to the Inferior Vena Cava

The right ureter descends lateral to the inferior vena cava through much of its abdominal course.

Abnormal developmental relationships between the ureter and inferior vena cava can produce clinically important variations such as a retrocaval ureter.

Relationship to the Abdominal Aorta

The left ureter lies lateral to the abdominal aorta as it descends toward the pelvic brim.

Major aortic branches and their associated tissues may contribute to the medial relationships of the left ureter.

Pelvic Brim

The abdominal ureter terminates at the pelvic brim, where it crosses the iliac vascular region and enters the pelvis.

This transition marks the beginning of the pelvic ureter.

Relationship to the Common Iliac Artery

The ureter commonly crosses anterior to the common iliac artery near its bifurcation.

Depending on individual anatomy, the ureter may instead cross the proximal external iliac artery.

Relationship to the External Iliac Artery

When the common iliac artery bifurcates at a higher level, the ureter may cross anterior to the external iliac artery as it enters the pelvis.

The iliac vessels therefore provide an important landmark for identifying the abdominal-to-pelvic transition of the ureter.

Constriction at the Pelvic Brim

The region where the ureter crosses the iliac vessels at the pelvic brim is traditionally described as a site of relative narrowing.

Ureteric calculi may encounter resistance in this region during passage toward the urinary bladder.

Major Ureteric Constrictions

Three regions are classically emphasized as sites of physiological narrowing along the ureter:

1. The ureteropelvic junction
2. The region where the ureter crosses the pelvic brim and iliac vessels
3. The ureterovesical junction, including the intramural portion of the ureter

Abdominal Ureter and the Constrictions

The abdominal portion is directly associated with the first two of these clinically important regions.

It begins at the ureteropelvic junction and ends as the ureter crosses the iliac vascular region at the pelvic brim.

Ureteric Wall

The wall of the abdominal ureter has the same basic organization as the remainder of the ureter.

It consists of a mucosa lined by urothelium, a muscular wall, and an external adventitial connective tissue layer.

Urothelium

The ureteric lumen is lined by urothelium, also called transitional epithelium.

This specialized epithelium accommodates changes in luminal diameter while maintaining a barrier between urine and the underlying tissues.

Lamina Propria

A connective tissue lamina propria lies beneath the urothelium.

Together, the urothelium and underlying connective tissue form the ureteric mucosa.

Muscular Wall

Smooth muscle within the ureteric wall produces coordinated contractions that propel urine toward the bladder.

In the upper ureter, the muscular coat is commonly described as having inner longitudinal and outer circular smooth muscle layers, with additional muscular organization developing distally.

Adventitia

The outer adventitia consists of connective tissue containing blood vessels, lymphatics, and autonomic nerve fibers.

It also helps anchor the ureter within the surrounding retroperitoneal connective tissue.

Peristalsis

Urine is transported through the abdominal ureter by peristaltic contractions of its smooth muscle wall.

These contractions allow urine to move toward the bladder even when body position does not favor gravity-dependent flow.

Blood Supply

The abdominal ureter receives a segmental arterial supply from nearby vessels rather than from a single continuous artery.

Contributing branches may arise from the renal, gonadal, aortic, and common iliac arteries, with additional sources supplying the pelvic ureter.

Longitudinal Vascular Network

Small arterial branches form a longitudinal vascular network within the ureteric adventitia.

This network permits anastomosis between segmental arterial contributions along the length of the ureter.

Surgical Importance of the Blood Supply

Excessive stripping of the ureter from its surrounding adventitial tissue can damage its segmental blood supply.

Preservation of periureteric connective tissue is therefore important when the ureter is mobilized surgically.

Venous Drainage

Venous drainage generally accompanies the arterial supply.

Blood from the abdominal ureter drains through veins associated with the renal, gonadal, and iliac vascular systems.

Lymphatic Drainage

Lymphatic drainage of the ureter follows its regional vascular relationships.

The upper abdominal ureter drains toward lumbar lymph nodes, while lower portions communicate with lymphatic pathways associated with the iliac vessels.

Innervation

The ureter receives autonomic fibers through plexuses associated with the renal, aortic, and hypogastric regions.

These fibers accompany vessels and connective tissue along the ureteric course.

Visceral Afferent Fibers

Visceral afferent fibers from the ureter travel centrally with sympathetic pathways, particularly to lower thoracic and upper lumbar spinal cord levels.

Distension or vigorous contraction of the ureter can therefore produce characteristic referred pain patterns.

Ureteric Pain

Pain arising from the abdominal ureter is commonly perceived in the flank and may radiate inferiorly as a calculus travels toward the pelvis.

The changing distribution of referred pain reflects the segmental innervation and progressive movement of the obstructing material.

Ureteric Calculi

Ureteric calculi may descend from the renal pelvis into the abdominal ureter.

Stones can produce obstruction, ureteric distension, muscular spasm, and severe colicky pain, particularly when they encounter relatively narrow portions of the ureter.

Ureteric Colic

Ureteric colic results from obstruction and powerful smooth muscle contractions attempting to propel urine and an obstructing calculus distally.

The pain often occurs in waves corresponding to periods of increased ureteric peristaltic activity.

Ureteropelvic Junction Obstruction

Obstruction at the ureteropelvic junction interferes with drainage from the renal pelvis into the ureter.

Persistent obstruction can produce dilation of the renal collecting system and hydronephrosis.

Hydroureter

Obstruction distal to a portion of the ureter may cause dilation of the ureter proximal to the blockage, producing hydroureter.

If obstruction also affects the renal collecting system, hydroureter may occur together with hydronephrosis.

Retrocaval Ureter

A retrocaval ureter, also called a circumcaval ureter, is a developmental vascular anomaly in which the right ureter passes posterior to the inferior vena cava before curving around it.

The abnormal relationship results primarily from development of the inferior vena cava rather than from abnormal development of the ureter itself.

Retroperitoneal Fibrosis

Retroperitoneal fibrosis can encase the abdominal ureters within fibrotic tissue.

Compression and medial displacement of the ureters may interfere with urinary drainage and produce obstructive uropathy.

Abdominal and Colorectal Surgery

The abdominal ureters are important structures to identify during operations involving the colon, mesentery, retroperitoneum, abdominal aorta, and iliac vessels.

Knowledge of their predictable relationship to psoas major and the gonadal vessels helps reduce the risk of inadvertent injury.

Ureteric Injury

The ureter can be injured by transection, ligation, crushing, thermal damage, ischemia, or incorporation into sutures.

Injury may be more difficult to recognize when normal anatomy has been distorted by previous surgery, inflammation, malignancy, fibrosis, or congenital variation.

Identification During Surgery

The abdominal ureter can often be identified as a pale tubular structure descending vertically on the anterior surface of psoas major.

Its relationship to the gonadal vessels, genitofemoral nerve, and iliac vessels provides additional anatomical orientation.

Peristalsis as an Identifying Feature

Visible peristaltic movement can sometimes assist in distinguishing the ureter from nearby vascular or connective tissue structures.

However, surgical identification should rely on anatomical relationships and direct visualization rather than peristalsis alone.

Abdominal Ureter Course

1. The renal pelvis narrows at the ureteropelvic junction.
2. The ureter descends retroperitoneally along the posterior abdominal wall.
3. It lies on the anterior surface of psoas major.
4. The genitofemoral nerve lies posterior to it on psoas major.
5. The gonadal vessels cross anterior to the ureter.
6. Additional abdominal viscera and mesenteric structures lie anterior to it.
7. The ureter continues inferiorly toward the pelvic brim.
8. It crosses anterior to the common iliac bifurcation or proximal external iliac artery.
9. After crossing the pelvic brim, it continues as the pelvic ureter.

Right and Left Ureter Comparison

Feature	Right Abdominal Ureter	Left Abdominal Ureter
Muscular bed	Psoas major	Psoas major
Gonadal vessels	Cross anteriorly	Cross anteriorly
Major medial vessel	Inferior vena cava	Abdominal aorta
Important anterior visceral relations	Duodenum, mesenteric root, intestinal structures	Descending and sigmoid colonic or mesocolic structures
Inferior termination	Pelvic brim	Pelvic brim

Key Anatomical Features

• The abdominal ureter extends from the renal pelvis to the pelvic brim.
• It begins at the ureteropelvic junction.
• It is retroperitoneal.
• It descends on the anterior surface of psoas major.
• The genitofemoral nerve is an important posterior relation.
• The gonadal vessels cross anterior to the ureter.
• The right and left ureters have different anterior visceral relations.
• The right ureter is related medially to the inferior vena cava.
• The left ureter lies lateral to the abdominal aorta.
• The ureter crosses the iliac vascular region at the pelvic brim.
• The ureteropelvic junction and pelvic brim are important regions of relative narrowing.
• The ureter has a segmental arterial supply with longitudinal anastomoses in its adventitia.
• Its muscular wall produces peristaltic contractions that propel urine toward the bladder.
• After crossing the pelvic brim, the abdominal ureter becomes the pelvic ureter.

Clinical Importance

The abdominal ureter is clinically important because it connects the renal collecting system with the pelvic ureter while passing through a surgically significant region of the retroperitoneum. Its predictable course on psoas major and relationships with the gonadal vessels and iliac vessels provide useful landmarks for identifying it during abdominal and retroperitoneal procedures.

Two clinically important regions of relative ureteric narrowing are associated with this portion of the ureter: the ureteropelvic junction at its origin and the region of the pelvic brim at its distal end. Obstruction at these or other levels can cause ureteric colic, hydroureter, hydronephrosis, and impairment of renal drainage.

Understanding abdominal ureter anatomy provides the foundation for studying retroperitoneal anatomy, ureteric constrictions, ureteric calculi, ureteropelvic junction obstruction, hydronephrosis, ureteric blood supply, abdominal surgery, colorectal surgery, and the transition between the abdominal and pelvic portions of the urinary tract.