Topics

Topic

design image
Ampulla of vas deferens

The ampulla of the vas deferens is the terminal, dilated segment of the vas deferens located posterior and inferior to the base of the bladder. It represents the segment where sperm is temporarily stored and concentrated before combining with seminal vesicle secretions to form the ejaculatory duct.

This enlargement is characterized by a thicker wall, expanded lumen, and increased mucosal folding compared to the proximal vas deferens. Its close relationship to the seminal vesicles, prostate, and ejaculatory ducts makes it a key structure in male reproductive anatomy, infertility assessments, and evaluation of pelvic pathologies.

Synonyms

  • Ampullary portion of the vas deferens

  • Dilated terminal vas

  • Ampulla ductus deferentis

Location and Structure

  • Lies posterior to the bladder, medial to each seminal vesicle

  • Expands from the straight vas deferens to form a fusiform dilation

  • Joins the duct of the seminal vesicle to form the ejaculatory duct

  • Lined by highly folded pseudostratified columnar epithelium

  • Has a thick muscular wall for propulsion during ejaculation

Relations

  • Anteriorly: Posterior bladder wall

  • Posteriorly: Rectum and rectovesical pouch

  • Superiorly: Peritoneum of the rectovesical fold

  • Inferiorly: Base of the prostate gland

  • Laterally: Seminal vesicles

  • Medially: Contralateral ampulla of vas deferens

Function

  • Stores and concentrates sperm before ejaculation

  • Contributes to the formation of seminal fluid by secreting minor components

  • Contracts vigorously during ejaculation, propelling sperm into the ejaculatory duct

  • Plays a role in sperm viability and transit

Clinical Significance

  • Dilatation may occur in obstruction, infection, or post-vasectomy changes

  • May be involved in ejaculatory duct obstruction, causing infertility

  • Target structure in surgeries such as vasectomy reversal

  • Evaluated during assessment for masses, cysts, or inflammatory conditions

  • Relevant landmark in pelvic oncologic imaging (e.g., prostate cancer spread)

MRI Appearance

T1-weighted images:

  • Ampulla wall: intermediate signal intensity

  • Lumen: may show variable intermediate signal depending on protein content of stored fluid

  • Perivesical fat: bright, outlining the structure clearly

  • Smooth fusiform dilation at the posterolateral bladder base

T2-weighted images:

  • Ampullary lumen: bright fluid signal, appearing hyperintense

  • Wall: low-to-intermediate signal

  • Useful for distinguishing ampulla from seminal vesicles (which appear more lobulated)

  • Sharp contrast against darker muscular structures

STIR:

  • Ampullary fluid: bright signal

  • Wall: intermediate-to-dark

  • Fat suppression improves visualization against pelvic fat planes

T1 Fat-Saturated Post-Contrast:

  • Wall shows mild, thin, uniform enhancement

  • Lumen does not enhance

  • Enhancement helps differentiate ampullary wall from adjacent seminal vesicle septations

  • Surrounding fascia enhances slightly, maintaining clear tissue planes

DWI (Diffusion-Weighted Imaging):

  • Lumen: variable signal depending on protein concentration; mild diffusion restriction possible due to viscous content

  • Wall: intermediate signal, no true restricted diffusion in normal tissue

  • Useful for evaluating obstruction or inflammatory thickening

CT Appearance

Non-Contrast CT:

  • Ampulla appears as soft-tissue density medial to seminal vesicles

  • Lumen may appear slightly lower in attenuation than surrounding muscle

  • Fusiform enlargement visible at posterolateral bladder aspect

  • Clear differentiation from seminal vesicles based on shape (ampulla smoother, less lobulated)

Post-Contrast CT (standard):

  • Ampulla wall enhances moderately

  • Lumen remains low-attenuation

  • Adjacent bladder wall, seminal vesicles, and prostate boundaries visible

  • Useful for assessing mass effect, calcifications, or postoperative changes

MRI image

Ampulla of vas deferens MRI axial image-img-00000-00000