Female Urethra

The female urethra is a short, straight fibromuscular tube that conveys urine from the urinary bladder to the external urethral orifice. Unlike the male urethra, which is long and serves dual excretory and reproductive functions, the female urethra is exclusively urinary and much shorter, measuring approximately 4 cm in length. Its short length and proximity to the vagina and anus make it clinically significant, especially in the context of urinary tract infections and continence mechanisms. It is embedded within the anterior vaginal wall and passes through the urogenital diaphragm before opening into the vestibule of the vulva.

Length and Diameter

• Length: Approximately 3.5–4.5 cm in adults
• Diameter: 6–8 mm

The short length of the female urethra contributes to easier catheterization but also increases susceptibility to ascending infections.

Course and Orientation

The female urethra begins at the bladder neck and runs inferiorly and anteriorly through the pelvic floor and perineal membrane. It terminates at the external urethral orifice, located in the vestibule between the labia minora, just anterior to the vaginal opening and posterior to the clitoris.

Segment	Description
Proximal	Continuous with the bladder neck at the internal urethral orifice
Middle	Traverses the urogenital diaphragm and is surrounded by the external urethral sphincter
Distal	Passes through the anterior vaginal wall and opens into the vestibule

Relations

Anterior

• Pubic symphysis
• Retropubic space (space of Retzius) lies between the symphysis and the bladder/urethra

Posterior

• Anterior wall of the vagina

Lateral

• Pubovesical ligaments and components of the pelvic floor muscles

Wall Structure

The wall of the female urethra consists of three main layers:

• Mucosa: Lined by transitional epithelium proximally and stratified squamous epithelium distally
• Submucosa: Contains venous plexuses that contribute to closure pressure and lubrication
• Muscularis: Inner longitudinal and outer circular layers of smooth muscle; surrounded by striated external urethral sphincter

Urethral Glands and Structures

• Skene’s glands (paraurethral glands): Located near the distal urethra, homologous to the male prostate, secrete into the urethra
• Urethral crest: A small longitudinal ridge sometimes visible on the posterior urethral wall

Sphincters

Internal Urethral Sphincter

• Involuntary smooth muscle
• Located at the bladder neck
• Controlled by the autonomic nervous system (primarily sympathetic)

External Urethral Sphincter

• Voluntary striated muscle
• Surrounds the middle urethra as it traverses the urogenital diaphragm
• Controlled by the pudendal nerve (S2–S4)
• Important in voluntary continence control

Blood Supply

• Arterial: Internal pudendal artery (via perineal and dorsal arteries of the clitoris), vaginal artery
• Venous: Urethral and vaginal venous plexuses, drain into internal pudendal vein

Lymphatic Drainage

• Proximal urethra: Internal iliac lymph nodes
• Distal urethra and external orifice: Superficial inguinal lymph nodes

Innervation

• Somatic: Pudendal nerve (S2–S4) — controls voluntary sphincter
• Autonomic:
  • Sympathetic: T11–L2 (via hypogastric plexus) — maintains tone of internal sphincter
  • Parasympathetic: Pelvic splanchnic nerves (S2–S4) — stimulate detrusor contraction

Clinical Significance

• Urinary Tract Infections (UTIs): The short length and proximity to the anus and vagina make the female urethra a common portal for ascending infection
• Stress Urinary Incontinence: Weakness in the pelvic floor or sphincters can lead to involuntary leakage during exertion, coughing, or sneezing
• Urethral Diverticulum: A localized outpouching of the urethral wall, often presenting with post-void dribbling or dysuria
• Urethral Caruncle: A benign vascular lesion at the external urethral orifice, typically seen in postmenopausal women
• Catheterization: Easier in females due to shorter length but must be done with care to avoid false passage or infection
• Skene’s Gland Infection: Can lead to abscess formation near the external urethral orifice
• Urethral Cancer: Rare, usually squamous cell carcinoma; may present with bleeding, dysuria, or a visible mass