The urethra (Japanese: 尿道, nyōdō) is the tubular organ that carries urine from the bladder out of the body. Its structure differs greatly between the sexes, and its role in sexual function, its status as an erogenous zone, and its infection risk are all strongly shaped by these anatomical differences.

The male urethra

The male urethra is about 18–22 cm long, running from the bladder neck to the urethral opening at the tip of the penis. It divides anatomically into four parts. The prostatic urethra is where semen enters from the seminal vesicles and prostate, with the paired ejaculatory ducts opening at the seminal colliculus on its posterior wall. The membranous urethra is the shortest part, passing through the external sphincter, about 1–2 cm long. The bulbar and penile urethra run within the corpus spongiosum and are the longest. The external opening is a vertical slit at the tip of the glans.

At ejaculation, semen fills the prostatic urethra, the bladder neck closes, and contraction of the bulbocavernosus and ischiocavernosus muscles expels the semen. The urethra thus serves the dual function of urinary and ejaculatory passage, fundamentally different from the female urethra. Running along the underside of the penis, the urethra passes just beneath the frenulum; for many men the region around the urethral opening at the glans is highly sensitive, and licking or light touch there can produce strong pleasure.

The female urethra

The female urethra is about 3–5 cm long, a fifth the length of the male urethra. It is a short tube from the bladder neck to the external opening in front of the vaginal opening, serving urinary function only (separate from the reproductive tract). The external opening lies about 2–3 cm below the clitoris, just above the vaginal opening. The Skene’s glands (paraurethral glands) open on either side, and these glands are studied in connection with female ejaculation (squirting); some researchers call the Skene’s glands the “female prostate” and position them as the source of female ejaculate, though academic consensus is still forming.

The short female urethra means the distance from the opening to the bladder is short and bacteria reach it easily, the main reason women are markedly more prone to cystitis (urinary tract infection) than men. Urination after intercourse is recommended for UTI prevention for this reason.

The urethral opening as erogenous zone

The urethral opening is sometimes discussed as a direct erogenous zone. In both sexes the mucosa around the external opening carries abundant nerve endings, and sensitivity rises with arousal. In men, stimulating the urethral opening during sex or masturbation is recognised as a means of heightening pleasure. In women, the opening adjoins the clitoris and vaginal opening and is seen as part of a “front-side erogenous network”; the female urethra and anterior vaginal wall are closely apposed, and some researchers consider so-called G-spot stimulation to act through the spongy tissue around the urethra.

Urethral play: pleasure and danger

“Urethral play,” or sounding, is a sexual practice of inserting an object into the urethra. The implements are metal or silicone rods called sounds, often repurposed stainless-steel medical instruments, with the sensation of urethral dilation and fullness enjoyed as pleasure. Urethral play carries serious health risks: urethritis, cystitis, and pyelonephritis from unclean instruments, migration or breakage of objects, bleeding, and the formation of urethral strictures have all been reported. The urethra is a delicate mucosa-lined tube, and injury makes it an easy entry route for sexually transmitted infection. Practitioners are advised that instrument sterilisation, ample lubrication, and management of insertion depth are essential. Urethral insertion in women is anatomically more difficult, and instances are fewer than in men.

Related terms

• Penis
• Clitoris
• G-spot
• Anus
• Frenulum