There are many reasons why a woman may get a UTI. The most common causes include bacteria from the rectum and vagina, sex, or abnormalities in the urinary tract.
Bacteria
Bacteria from the bowel live on the skin near the rectum or in the vagina. These bacteria can spread and enter the urinary tract through the urethra. If they move the urethra, they may cause infections in the bladder and sometimes in other parts of the urinary tract.
Sex
Women’s anatomy makes them prone to getting UTI’s after intercourse. The opening of the urethra is in front of the vagina. During sex, bacteria near the vagina can be massaged into the urethra by the penis, fingers or devices.
Urinary tract infections also tend to occur in women who change sexual partners or begin having sex more often. Using spermicides or a diaphragm also can cause more frequent UTIs.
Abnormalities in the Urinary Tract
Infections also can occur when urine backs up instead of flowing out of the bladder. When this occurs, the bladder does not empty completely. This may be caused by:
- Blockage (a stone) in the kidneys, bladder or ureters made of a hard mass of crystals that blocks the flow of urine through the urinary tract
- A narrowed tube (or kink) in the urinary tract
- Diverticula—small pockets that bulge out of the bladder wall or out of the urethra and hold urine
- Problems with your pelvic muscles or nerves
In another condition that occurs in children, one or both ureters are abnormally short. This causes urine to back up into the kidneys. As a child grows, the ureters become longer and the problem often disappears on its own.
Other Causes
Certain other factors increase your chance of getting a UTI. You are more likely to get an infection if you:
- Are pregnant
- Had UTIs as a child
- Are past menopause
- Have diabetes
If you are pregnant and think you may have a UTI, be sure to tell your doctor promptly. If untreated, it may cause problems for you and your baby.