Female urethra

The female urethra is a simple short tube, that transports the urine out of the body, extending from the internal urethral orifice of the bladder to the external urethral orifice in the vestibule of the vagina. 

Gross anatomy

The female urethra measures approximately 4 cm in length. It is embedded in the anterior vaginal wall and runs with the vagina through the urogenital hiatus. 

The female urethra begins at the internal urethral meatus at the bladder neck and opens in the vestibule of the vagina, 2.5 cm below the clitoris. Paraurethral (Skene) glands line the urethra at the external urethral meatus. 

Relations

• anteriorly: pubic symphysis
• posteriorly: vagina
• laterally: puborectalis muscle

Blood supply

• arterial supply: internal pudendal and vaginal arteries
• venous drainage: similarly named veins

Lymphatic drainage

• internal iliac nodes

Innervation

• pudendal nerve

Variant anatomy

• urethral agenesis

Radiographic features

Fluoroscopy

• micturating cystourethrogram (MCU): will reveal a "spinning-top" appearance with normal 'wavy' walls caused by the pelvic floor muscles
• retrograde urethrogram: proves troublesome because the balloon will almost completely fill the urethra but special equipment can be used

Ultrasound

• transvaginal, transperineal or transurethral approach can all be used
• imaged as as tubular structure anterior to the vagina, coursing between the bladder and the vestibule of the vagina ⁵ 

CT

• the urethra can be assessed in axial plane to assess for diverticula, stones and tumour but MRI is considered the best modality ^4-5

MRI

The use of an endovaginal coil has been shown to significantly improve SNR and image quality. On T1C+ or T2 axial images the female urethra appears "target-like" with four layers ³:

• lower signal outer ring
• higher intensity outer zone
• low signal inner ring
• high signal inner zone

Related pathology

The female urethra has a much shorter course and a simpler structure than the male urethra and it is less prone to disease.

• urethral diverticulum
  • female prostate sign
• urethral diverticulum adenocarcinoma
• urethral stricture