Risk factors

Some people are more likely than others to develop bladder infections or recurrent urinary tract infections. Women are one such group. A key reason is physical anatomy. Women have a shorter urethra, which cuts down on the distance bacteria must travel to reach the bladder.

Women at greatest risk of UTIs include those who:

• Are sexually active. Sexual intercourse can result in bacteria being pushed into the urethra.
• Use certain types of birth control. Women who use diaphragms are at increased risk of a UTI. Diaphragms that contain spermicidal agents further increase your risk.
• Are pregnant. Hormonal changes during pregnancy may increase the risk of a bladder infection.
• Have experienced menopause. Altered hormone levels in postmenopausal women are often associated with UTIs.

Other risk factors in both men and women include:

• Interference with the flow of urine. This can occur in conditions such as a stone in the bladder or, in men, an enlarged prostate.
• Changes in the immune system. This can happen with certain conditions, such as diabetes, HIV infection and cancer treatment. A depressed immune system increases the risk of bacterial and, in some cases, viral bladder infections.
• Prolonged use of bladder catheters. These tubes may be needed in people with chronic illnesses or in older adults. Prolonged use can result in increased vulnerability to bacterial infections as well as bladder tissue damage.

In men without any predisposing health issues, cystitis is rare.