Urinary Tract Infection
UTIs are usually caused by bacteria and can occur in any part of the urinary tract. Symptoms of upper UTIs include pain in the upper back, chil...

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A urinary tract infection (UTI) can occur in any part of the urinary tract. Bacteria cause the vast majority of UTIs. Fungi or viruses can also cause UTIs.

UTIs are the second most common type of infection in humans. The National Kidney & Urologic Diseases Information Clearinghouse (NKUDIC) reports that UTIs account for over 8 million doctor visits annually.

What Is the Urinary Tract?

The urinary tract consists of the kidneys, ureters, bladder, and urethra.

Your kidneys are two bean-shaped organs. They are located in the abdomen on either side of the spine. The kidneys filter your blood to remove excess water, salt, potassium, urea, and other substances. You then excrete the waste products as urine.

The ureters are thin, spaghetti-shaped tubules. They carry urine from the kidney to the bladder.

The bladder is a small, balloon-shaped organ located in the pelvis. In women, the bladder is located in front of the uterus. In men, the bladder is located just above the prostate gland.

The urethra is the tube through which urine exits the bladder. The urethra in women is shorter than it is in men. In men, it has to pass through the prostate and the penis.

UTIs can involve the urethra (urethritis), bladder (cystitis), kidneys (pyelonephritis), or a combination of the three. When the kidneys are involved, a UTI can be life-threatening.

UTI Risk Factors and Causes

Anything that reduces bladder emptying or irritates the urinary tract can cause UTIs. Many factors can put you at risk of a UTI.


Blockages can make it difficult to empty the bladder and can cause a UTI. Enlarged prostate, kidney stones, and certain forms of cancer can cause obstructions.


Women are more likely to get UTIs. This is because the urethra is shorter in women than it is in men. UTIs in men are less common but tend to be more serious.

Sexual Activity

Pressure on the urinary tract during sex can move bacteria from the colon into the bladder. Most women have bacteria in their urine after intercourse. However, the body usually can get rid of these bacteria within 24 hours. Bowel bacteria may have properties that allow them to stick to the bladder.

Bathroom Hygiene

Wiping from the back to the front after going to the bathroom can lead to a UTI. This motion drags bacteria from the rectal area towards the urethra.


Spermicides can increase UTI risk. They may cause skin irritation in some women. This increases the risk of bacteria entering the bladder.


Latex condoms can cause increased friction during intercourse. They may also irritate the skin. This may increase the risk of UTI in some individuals. However, condoms are important for reducing the spread of sexually transmitted infections.


Diaphragms may put pressure on the urethra. This can decrease bladder emptying. Some studies have shown a higher risk of UTI in women who use diaphragms.


Diabetes, especially if poorly controlled, may make it more likely for someone to get a UTI.

Loss of Estrogen

After menopause, a loss of estrogen changes the normal bacteria in the vagina. This can increase the risk of UTI.

Prolonged Use of Bladder Catheters

Catheters are used when someone cannot urinate normally. These thin, flexible tubes are inserted into the bladder. They allow urine to drain into a container. Long-term catheter use can increase the risk of UTI. They may make it easier for bacteria to get into the bladder. Treatment for a catheter-associated UTI may require removal of the device.

Symptoms of UTI

Symptoms of UTI depend on what part of the urinary tract is infected.

Lower-tract UTIs affect the urethra and bladder. Symptoms of a lower-tract UTI include:

  • burning with urination
  • increased frequency of urination without passing much urine
  • bloody urine
  • cloudy urine
  • urine that looks like cola or tea
  • urine that has a strong odor
  • pelvic pain (women)
  • rectal pain (men)

Upper-tract UTIs affect the kidneys. These are potentially life threatening if bacteria move from the infected kidney into the blood. This condition is called urosepsis. Urosepsis can cause dangerously low blood pressure, shock, and death. Symptoms of upper-tract UTI include:

  • pain and tenderness in the upper back and sides
  • chills
  • fever
  • nausea
  • vomiting

Women who are pregnant and have symptoms of UTI should see their doctor right away. UTIs during pregnancy can cause high blood pressure and premature delivery. UTIs during pregnancy are also more likely to spread to the kidneys.

Diagnosis of UTI

History and physical exam may suggest you have a lower or upper UTI.

The diagnosis of a UTI requires a “clean catch” urine specimen. This is urine collected from the middle of the urinary stream. Your doctor will explain to you how to get a clean catch. The goal of a clean catch is to avoid picking up bacteria from your skin.

Your doctor will look for a large number of white blood cells in your urine. This signals an infection. Your doctor will also take a culture of your urine to test for bacteria. A culture can identify the cause of the infection. It can also help your doctor choose which treatment is right for you.

If an upper-tract UTI is suspected, you may also need a complete blood count (CBC) and blood cultures. These can make certain your infection hasn’t spread to the blood.

If you have repeated UTIs, you may need to be checked for an obstruction. Some tests for this include:

  • ultrasound
  • intravenous pyelogram (IVP), which shows the doctor your entire urinary tract by using injected dye
  • cystoscopy, which involves using a small camera to examine the bladder

During a cystoscopy, your doctor may remove a small piece of bladder tissue. This is called a biopsy. A biopsy can be used to rule out bladder cancer.

Treatment of UTI

Antibiotics are used to treat UTIs. Your doctor can treat a lower-tract UTI with oral antibiotics. Upper-tract UTIs require intravenous antibiotics (antibiotics put directly into your veins).

Sometimes, bacteria develop resistance to antibiotics. Urine cultures can help your doctor select an effective antibiotic treatment.


Researchers are trying to develop a vaccine to prevent recurrent UTIs.

In the meantime, there are simple steps you can take to help prevent UTIs. WomensHealth.gov recommends:

  • wiping from front to back after urinating or having a bowel movement
  • drinking six to eight glasses of water daily
  • drinking water after having sex
  • not holding urine for long periods of time
  • cleaning your vaginal and rectal areas daily
  • taking showers instead of baths
  • wearing pants that aren’t too tight to avoid trapping moisture
  • wearing underwear with a cotton crotch
  • While these steps are useful, they don’t guarantee that you won’t get a UTI. Contact your doctor whenever you have the symptoms of a UTI. If you have recurrent UTIs and use spermicides or a diaphragm, your doctor may recommend a different birth control.
Written by: Verneda Lights and Elizabeth Boskey, PhD
Edited by:
Medically Reviewed by: The Healthline Medical Review Team
Published: Sep 3, 2015
Published By: Healthline Networks, Inc.
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