Urinary Tract Infection

A urinary tract infection (UTI) is an infection that occurs in the kidneys, ureters, bladder, and/or urethra. UTIs are usually caused by bacteria around the urethra (the entrance to the urinary tract) or in the vagina or digestive tract. Symptoms include painful urination, frequent and intense urges to urinate, and pain in the lower belly or back. Treatment typically involves an antibiotic, which can kill bacteria.

What Is a Urinary Tract Infection?

A urinary tract infection is an infection that occurs anywhere in the urinary tract. Your urinary tract is made up of organs that:
  • Collect urine
  • Store urine
  • Release urine from your body.
These organs include the kidneys, ureters, bladder, and urethra.
A urinary tract infection is a serious health problem that affects millions of people each year. Urinary tract infections are the second most common type of infection in the body, and they account for about 8.3 million doctor visits each year. Urinary tract infections are more common in women than men -- approximately 20 percent of women will develop a urinary tract infection at some point in their lives. Although urinary tract infections in men are not as common, they can be very serious when they occur (see UTI in Men for more information).

Understanding the Urinary Tract

The urinary tract consists of the kidneys, ureters, bladder, and urethra. The kidneys are two bean-shaped organs located below the ribs toward the middle of the back. The role of the kidneys is to:
  • Help control blood pressure
  • Make red blood cells
  • Keep bones strong
  • Remove extra water and wastes from the blood
  • Convert the wastes to urine.
The wastes in your blood come from the normal breakdown of active muscle and from the food that you eat. Your body uses the food for energy and self-repair and sends the wastes to the blood. If your kidneys did not remove these wastes, the wastes would build up in the blood and damage your body.
Narrow tubes called ureters carry urine from the kidneys to the bladder, which is an oval-shaped chamber in the lower abdomen. Like a balloon, the bladder's elastic walls stretch and expand to store urine and flatten back together when the urine is emptied through the urethra outside of the body.
Last reviewed by: Arthur Schoenstadt, MD
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