What causes urethral strictures?

Any inflammation of urethra can result in scarring, which then can lead to a stricture or a narrowing of the urethra. Trauma, infection, tumors, surgeries, or any other cause of scarring may lead to urethral narrowing or stricture. Mechanical narrowing of the urethra without scar formation (developmental causes or prostate enlargement) can also narrow the urethra.