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Left ureter

The left ureter is a muscular tubular structure approximately 25–30 cm long, extending from the renal pelvis of the left kidney to the urinary bladder. It transports urine through peristaltic contractions. The ureter has three anatomical constrictions where obstruction is most common:

  1. Ureteropelvic junction (UPJ) – where the renal pelvis narrows into the ureter

  2. Pelvic brim (crossing iliac vessels) – where the ureter crosses the common iliac artery

  3. Ureterovesical junction (UVJ) – where the ureter enters the bladder wall

The left ureter courses downward and medially along the psoas muscle, crosses the common iliac artery and vein, and enters the pelvis. In males, it passes posterior to the vas deferens; in females, it passes posterior to the ovarian vessels and lateral to the cervix before entering the bladder.

The wall of the ureter is composed of transitional epithelium (urothelium), a muscular layer responsible for peristalsis, and an outer adventitia that anchors it in place.

Clinically, the left ureter is important in renal colic, ureterolithiasis, strictures, tumors, trauma, and surgical procedures (e.g., hysterectomy, colectomy, kidney transplantation), as iatrogenic injury is a risk.

Synonyms

  • Left urinary duct

Function

  • Transports urine from the renal pelvis to the urinary bladder

  • Maintains unidirectional flow via peristalsis and intramural ureteral valves

  • Prevents vesicoureteral reflux at the UVJ

  • Plays a role in hydration, electrolyte balance, and excretion

MRI Appearance

T1-weighted images:

  • Normal lumen is usually collapsed and appears as a thin linear low-signal structure

  • Dilated ureter with urine shows low-to-intermediate signal intensity

T2-weighted images:

  • Urine-filled ureter appears bright (hyperintense)

  • Ureteral wall appears hypointense, providing excellent contrast

  • Useful for evaluating hydronephrosis, strictures, or masses

STIR:

  • Suppresses fat signal, improving visualization of the ureter within retroperitoneal fat

  • Highlights perivascular or peritoneal edema, fibrosis, or inflammation

T1 Fat-Saturated (Pre-contrast):

  • Ureter lumen may show intermediate signal intensity, contrasting with suppressed fat planes

  • Allows differentiation of ureter from surrounding tissues

T1 Fat-Saturated Post-Contrast (Gadolinium):

  • Enhances ureteral wall mildly and homogeneously

  • Pathologies (tumors, infection, inflammation) show heterogeneous or asymmetric enhancement

  • Detects ureteral tumors, strictures, or periureteral disease

MRI Non-Contrast 3D Imaging (MR Urography):

  • Provides 3D reconstruction of ureter course and caliber

  • Demonstrates sites of obstruction, kinking, or extrinsic compression

  • Preferred in hydronephrosis and stone evaluation when contrast is contraindicated

CT Appearance

CT Pre-Contrast:

  • Detects calcified ureteral stones as hyperdense foci

  • Ureter appears as a soft-tissue density; better seen if dilated

  • Gold standard for stone detection (non-contrast CT KUB)

CT Post-Contrast (Excretory Phase):

  • Ureter opacifies with contrast, clearly delineating lumen and course

  • Demonstrates strictures, filling defects (stones, tumors, clots), and extravasation

  • Useful for staging of urothelial carcinoma

CT Urography (CTU):

  • Best non-invasive modality for complete evaluation of ureter

  • Multiphase scans (non-contrast, nephrographic, and excretory phases) allow assessment of stones, tumors, and obstruction

  • 3D reconstructions provide anatomic mapping for surgery and interventional planning

MRI images

Left ureter MRI coronal image anatomy image -img-00000-00000

MRI images

Left ureter MRI sagittal image anatomy image -img-00000-00000

CT image

Left ureter coronal image