• Extends from Bladder neck up to Meatal opening over Glance Penis
• About 20cm in length and runs through the Corpus Spongiosum
• Divided as Anterior Urethra and Posterior Urethra by Pelvic Diaphragm
• Anterior Urethra consists of Bulbar and Penile parts of Urethra
• Posterior Urethra consists of Membranous and Prostatic parts of Urethra
• Normal Diameter of Urethra is about 6mm

• Extends from Bladder neck up to the external opening in the vestibule
• About 4cm in length
• Normal Diameter of Urethra is about 6mm

• The urethra is a collapsible pipe which usually remains closed for all the time and opens when a person urinates
• Urethra being a collapsible pipe doesn’t have its diameter
• Being a collapsible pipe urethra has its two distinct properties –
  1. Elasticity – By which it can open and close
  2. Caliber – The maximum extent to which it can open

Pathology of urethral stricture starts with ulceration or wound inside the urethra. Whenever there is a wound on any surface of our body, that wound eventually heals. When it heals, it leaves a scar. The scar left is much smaller as compared to the actual size of the wound. This is called as wound contraction or cicatrization of the wound. So any wound, when it heals it contracts significantly and this contraction is by almost 40 to 80%.

When there is a wound or ulceration inside the urethra that also contracts significantly. Urethra being a very small pipe when the wound contact at the same time the whole pipe of urethra gets constricted significantly and thus the lumen becomes narrow.

A wound heals by granulation. Even in case of deeper wounds, the granulation starts from the base of the wound and when that granulation reaches up to the normal level of the skin or epithelium, the process of granulation stops at that level. Generally, the granulation never overgrows the normal level of the skin or epithelium.
The urethra is a pipe through which urine passes many times a day. Urine is acidic & it contains many salts, so it interferes with the normal healing process. Healing being a natural process, nature tries her best to heal that wound at any cost, and in that attempt, the rate of granulation significantly increases. Thus, the process of graduation, which should stop at the normal level, there is little overgrowth inside the lumen of the urethra. This overgrown tissue is called as over granulation or hyper granulation. This results in further narrowing of the lumen. Initially, the hyper granulation is soft but later it turns into fibrosis and it becomes hard. This is also called the actual scar tissue of the stricture, which results in loss of distinct qualities of urethra i.e. elasticity & caliber at that particular point.