What is a Urinary Tract Infection?

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What is a urinary tract infection?

A urinary tract infection (UTI) is an infection in one of the parts of your body where urine is made, stored, or passed out of your body. UTIs are very common in women. About 1 in 2 women will have a UTI in their life.

Where can a UTI occur?

The urinary tract includes the kidneys, where urine is made; the bladder, where urine is stored; and the urethra, which is the tube that passes urine from the bladder out of your body. The picture on the next page shows the parts of your body that make up the urinary tract. The most common place for a UTI is in your bladder. This may also be called a bladder infection or cystitis. You can also get a UTI in your kidney. This infection, which is called pyelonephritis, is less common than a UTI in your bladder and more serious.

What causes UTIs?

Most UTIs are caused by bacteria (germs) that are normally present in your intestines or on the skin around your anus and vagina, where they do not cause harm. The bacteria can get close to your urethra when you wipe yourself after urinating. The bacteria travel up the urethra to the bladder, where they attach to the bladder wall and grow. As the bacteria grow and your body fights the infection, your bladder becomes irritated and painful. After 24 to 48 hours, you start to have UTI symptoms. If the bacteria travel to your kidneys, you will start to have symptoms of pyelonephritis.

What are the symptoms of a UTI?

The symptoms of a bladder infection may include:

  • Burning or pain when you urinate
  • A feeling of pressure or pain in your bladder
  • A feeling like you have to urinate more often than usual, but when you try, there is little or no urine
  • Cloudy urine

If you have pyelonephritis, you may or may not have the symptoms of a bladder infection listed above. The symptoms of pyelonephritis are:

  • Lower back pain
  • High fever (temperature of 101°F or greater)
  • Nausea or vomiting
  • Chills or sweats

Why am I more likely to get a UTI if I am pregnant?

Pregnancy makes the urethra more relaxed (open), which makes it easier for bacteria to enter. As the baby grows during pregnancy, your uterus (womb) gets bigger and puts pressure on the bladder and urethra. Pregnant women often are not able to empty their bladders completely. When a small amount of urine is left in the bladder after urinating, bacteria can grow more easily.

What is asymptomatic bacteriuria?

Asymptomatic bacteriuria is when you have bacteria in the bladder but no symptoms of a UTI. About 1 of every 4 women who have asymptomatic bacteriuria in pregnancy will later have a painful UTI. A few women with asymptomatic bacteriuria will get pyelonephritis, which is a serious illness during pregnancy. Asymptomatic bacteriuria also increases your chance of having preterm labor.

Your health care provider will test a urine sample early in pregnancy to see if you have bacteria in your urinary tract. If you have asymptomatic bacteriuria during pregnancy, your health care provider will give you a prescription for an antibiotic to kill the bacteria in your urinary tract. Fortunately, there are several antibiotics that treat UTIs and are safe for you and your baby if taken during pregnancy. Women who are not pregnant do not need to be tested or treated for asymptomatic bacteriuria.

What is the treatment for a UTI?

Antibiotics are needed to treat a UTI and kill the bacteria that are present. When you have a UTI, it is important to take all of the medicine given, even though your symptoms will probably go away before you are done taking the pills. If you skip pills or only take some of the medicine, you may get another UTI that is more serious than the first one. If you are also having pain when you urinate, you may be given the name of a medicine you can get at a pharmacy that will numb your bladder and stop it from having spasms. This medicine is also safe for both you and your baby if used during pregnancy.

What can I do to prevent UTIs?

  • Drink 6 to 8 glasses of water every day. This helps flush out your bladder.
  • Urinate several times each day (every 2 to 3 hours). When you feel the urge to urinate, go right away.
  • Urinate after having sex. This helps flush out any bacteria that may have been moved up to your urethra.

The Urinary Tract


Reprinted with permission from Jones & Bartlett Learning.

For More Information

Office on Women’s Health, US Department of Health and Human Services


National Institute of Diabetes and Digestive and Kidney Diseases



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