Bladder outlet obstruction is a condition in which the opening between the bladder and the urethra is partially or completely blocked. This allows only some urine, or sometimes none at all, to empty from the bladder.

What is going on in the body?

When the flow of urine is first blocked, the bladder responds by thickening the bladder wall and squeezing harder to push urine out. But if the blockage lasts a long time, the bladder begins to fail and the bladder wall thins out.

What are the causes and risks of the condition?

Bladder outlet obstruction is rare in women. But, when its does occur, it is usually caused by neurological disorders or a very large, sagging bladder. Bladder outlet obstruction is very common in older men. It is usually caused by an enlarged prostate from benign prostatic hyperplasia or prostate cancer.

Other causes, which are also more common in men, include:

All men, as long as they still have their testicles and are producing testosterone, develop some degree of enlarged prostate as they get older. Prostate cancer is also very common. People who smoke and are exposed to certain chemicals are at increased risk of developing bladder tumors and urethral cancer. Urethral strictures can occur as a result of prior surgery or recurrent episodes of urethritis, an infection of the urethra.