Risk Factors for Urinary Tract Infections

Some people are more likely to get a UTI than others, but about one of every five women will develop a UTI in her lifetime. Women have more UTIs than men do. It may be because women's urethra is relatively short, which allows bacteria quick access to the bladder. It may also be because a women's urethral opening is near sources of bacteria from the anus and vagina.

For many women, sexual intercourse seems to trigger an infection. According to several studies, women who use a diaphragm are more likely to develop a UTI than women who use other forms of birth control. Recently, researchers found that women whose partners use a condom with a spermicidal foam tend to have growth of E. coli bacteria in their vagina. Unlubricated condoms or condoms with a spermicidal foam increase irritation and help bacteria cause symptoms of a UTI. Other options include using lubricated condoms without spermicide or a nonspermicidal lubricant.

Women are at a higher risk for UTIs after they experience menopause. The walls of the urinary tract become thinner after menopause, which weakens their mucous linings. The mucous linings are then less able to resist bacteria. The muscles of the bladder also become less elastic (or cannot stretch the way they used to) and the bladder may not empty completely. This can contribute to a UTI.

Any abnormality of the urinary tract that blocks the flow of urine (a kidney stone, for example) makes an infection more likely. A common source of infection is catheters, or tubes placed in the bladder to help people who are unconscious or critically ill to urinate. Bacteria on the catheter can infect the bladder, so hospital staff take special care to keep the catheter sterile and to remove it as soon as possible. People with diabetes also have a higher risk of a UTI because of changes in the immune system. Any disorder that suppresses the immune system, like diabetes, raises the risk of a UTI.