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Topic

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Meatus of the urethra

The meatus of the urethra, also known as the external urethral orifice, is the terminal opening of the urethra through which urine is excreted from the urinary tract to the external environment. Its anatomy differs between males and females: in males, it is located at the tip of the glans penis, while in females, it is located in the vulvar vestibule between the clitoris and vaginal opening. This structure has important clinical relevance in urology, gynecology, and imaging.

Synonyms

  • External urethral orifice

  • Urethral opening

  • Urinary meatus

Location and Structure

  • In males:

    • Located at the tip of the glans penis

    • Appears as a vertical slit, often slightly ventrally displaced

    • Marks the termination of the penile urethra

  • In females:

    • Located in the vulvar vestibule

    • Lies between the clitoris (superiorly) and vaginal orifice (inferiorly)

    • Marks the termination of the short female urethra

Relations

  • Male: Surrounded by glans penis, distal to corpus spongiosum

  • Female: Related anteriorly to the clitoris, posteriorly to the vaginal orifice, and laterally to labia minora

  • Both sexes: Opens to the external environment and directly relates to periurethral tissues

Function

  • Terminal outlet for urine excretion from the bladder

  • Provides passage for semen in males (dual function)

  • Contributes to continence by working with urethral sphincters

  • Serves as an anatomical landmark in urological procedures

Clinical Significance

  • Meatal stenosis: Narrowing of the orifice, more common in males, causes weak urinary stream

  • Infections: Site of urethritis or periurethral inflammation

  • Congenital anomalies: Hypospadias (ventral displacement) and epispadias (dorsal displacement)

  • Trauma: Catheter-related injuries or external trauma may cause scarring and narrowing

  • Surgical relevance: Landmark in catheterization, cystoscopy, and reconstructive urology

MRI Appearance

T1-weighted images:

  • Appears as a small low-signal intensity opening at the distal urethra

  • Surrounded by bright fat signal in both male and female perineum

T2-weighted images:

  • Meatus itself appears low signal, but lumen or any fluid may appear bright

  • Periurethral tissues show intermediate signal

T1 Fat-Sat Post-Contrast:

  • Meatus does not enhance

  • Pathological periurethral tissue (infection, tumor) may enhance around the opening

3D T2 SPACE / CISS:

  • Urethral meatus appears as a small low-signal opening with surrounding bright fluid or fat

  • Provides high-resolution visualization of distal urethra and its relation to external structures

CT Appearance

Non-Contrast CT:

  • Meatus itself is not directly seen

  • Urethral lumen may appear faintly if distended with urine

  • Perimeatal tissues appear as soft tissue density

Post-Contrast CT:

  • Meatus itself does not enhance

  • Surrounding tissues may enhance mildly

  • Pathology (inflammation, abscess, tumor) may appear as enhancing soft tissue around the external opening

MRI image

Meatus of the urethra mri axial anatomy image-img-00000-00000

MRI image

Meatus of the urethra mri coronal image