Topics

Topic

design image
Vas deferens

The vas deferens, also called the ductus deferens, is a thick-walled, muscular tube in the male reproductive system. It carries sperm from the epididymis to the ejaculatory duct and plays a crucial role in fertility. The duct is palpable within the spermatic cord and is an important surgical landmark in vasectomy. Radiologically, it is relevant in evaluation of male infertility, congenital anomalies, trauma, and pelvic pathology.

Synonyms

  • Ductus deferens

  • Deferent duct

  • Vas

Location and Course

  • Origin: Begins as the continuation of the tail of the epididymis in the scrotum

  • Course:

    • Ascends within the spermatic cord through the inguinal canal

    • Passes over the external iliac vessels and into the pelvis

    • Runs medially and inferiorly along the lateral pelvic wall, crossing superior to the ureter (“water under the bridge”)

    • Expands into an ampulla posterior to the bladder before joining the duct of the seminal vesicle to form the ejaculatory duct

  • Termination: Opens into the prostatic urethra via the ejaculatory duct

Relations

  • In the scrotum: Lies within spermatic cord with arteries, veins, lymphatics, and nerves

  • At pelvic brim: Crosses superior to external iliac vessels

  • In pelvis: Related anteriorly to the bladder, posteriorly to the rectum, and medially to the seminal vesicles

  • At termination: Joins seminal vesicle to form ejaculatory duct

Function

  • Transport of sperm from epididymis to ejaculatory duct

  • Muscular peristalsis during ejaculation propels sperm into prostatic urethra

  • Serves as a site for male sterilization in vasectomy

Clinical Significance

  • Vasectomy: Common male sterilization procedure by transecting vas deferens

  • Congenital absence: Associated with cystic fibrosis and infertility

  • Obstruction: May result from infection, trauma, or scarring, leading to azoospermia

  • Palpation: Thick cord-like structure, often identifiable on clinical exam

  • Tumors/Inflammation: Rare but may involve vas deferens (e.g., tuberculosis, carcinoma spread)

MRI Appearance

T1-weighted images:

  • Vas deferens appears as a tubular, low-to-intermediate signal intensity structure

  • Lumen is typically collapsed unless fluid-filled

  • Fat around cord appears bright, aiding identification

T2-weighted images:

  • Tubular wall shows low signal intensity

  • If lumen contains fluid, it appears bright; normally collapsed lumen may appear dark

  • Surrounding fat appears bright, enhancing contrast

STIR (Short Tau Inversion Recovery):

  • Vas deferens remains low signal

  • Fluid or inflammatory changes appear bright

  • Surrounding fat suppressed to dark signal, highlighting duct

T1 Fat-Sat Post-Contrast:

  • Normal vas deferens enhances mildly and uniformly

  • Inflammatory or neoplastic changes may show focal or irregular enhancement

  • Abscess or obstructed duct shows rim enhancement with non-enhancing lumen

CT Appearance

Non-Contrast CT:

  • Vas deferens seen as a thin, tubular soft tissue structure within spermatic cord and pelvis

  • Difficult to identify without dilatation or calcification

  • Calcifications (e.g., chronic infection, schistosomiasis, TB) may be present along course

Post-Contrast CT:

  • Shows mild enhancement of duct wall

  • Dilated or thickened vas deferens is more conspicuous in infection or obstruction

  • Tumor or infiltrative disease may appear as enhancing nodular thickening

  • Perivasal fat stranding indicates inflammation (e.g., vasitis)

MRI image

Vas deferens MRI axial anatomy image-img-00000-00000

MRI image

Vas deferens MRI axial anatomy image-img-00000-00000_00001

MRI image

Vas deferens MRI axial sagittal image-img-00000-00000

CT image

Vas deferens CT axial anatomy image-img-00000-00000

CT image

Vas deferens CT axial anatomy image-img-00000-00000_00001