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Urinary Tract Infections

Types, Causes, and Symptoms of Urinary Tract Infection (UTI)

Overview of Urinary Tract Infection
Urinary tract infections are among the most common of bacterial infections. They occur in people of all ages, women significantly more than men.

In the United States, an estimated eight to 10 million visits are made to the physician each year for the treatment of UTIs.


Urine is formed in the kidneys, waste-filtering organs located in the mid-back, just below the rib cage. Urine leaves the kidneys and flows down the ureters, two thin tubes that empty into the bladder, the hollow, muscular organ that holds urine. The urethra is the tube that transports urine out of the body from the bladder.

Causes of Urinary Tract Infection
Most UTIs arise from bacteria that normally live in the colon and rectum, and are present in bowel movements. These bacteria cling to the opening of the urethra, begin to multiply, and travel up to the bladder. The flow of urine from the bladder usually washe s bacteria out of the body.

However, because women have a shorter urethra than men, bacteria can reach the bladder more easily and settle in the bladder wall. Much less often, bacteria spread to the kidney from the bloodstream.

Types of Urinary Tract Infection
There are three types of urinary tract infection:

  • Cystitis, the most common UTI, is an inflammation of the bladder. It almost always occurs in women. In most cases, the infection affects only the surface of the bladder and is brief and acute.
  • Pyelonephritis, more commonly known as a kidney infection, usually occurs when a lower UTI spreads to the upper tract. Occasionally, bacteria will spread to the kidney from the bloodstream. Kidney infections are much less common, but often more serious than b ladder infections.
  • Urethritis is an inflammation of the urethra. Men commonly contract urethritis through sexual intercourse with an infected partner. Urethritis may also result from trauma to the area or from a medical procedure involving a catheter, a tube inserted through th e urethra to the bladder to drain the urine.

Symptoms of Urinary Tract Infection
Symptoms may include a frequent urge to urinate, regardless of whether the bladder is full or empty, and pain and burning with urination. The urine itself may look milky or cloudy, or have a strong smell.

Women often feel an uncomfortable pressure in the pelvic area, and some men experience a feeling of fullness in the rectum. Fever may mean the infection has reached the kidneys.

Other symptoms of kidney infection include pain in the back or side below the ribs, nausea, or vomiting.

Diagnosing Urinary Tract Infection (UTI)

Urinalysis Test for UTI
Most urinary tract infections can be diagnosed with urinalysis, a test to check for bacteria in the urine. Some UTIs may require evaluation by intravenous pyelogram (IVP), which uses dye that shows up on x-ray:

  • The dye is injected through a vein and is processed by the kidneys.
  • X-rays are taken of the kidneys, ureter, and bladder as the dye passes through them. These provide a dynamic picture of the relationship between the patient's urinary system and urinary functioning.

Risks Associated with Urinalysis
This test should not be used on pregnant women or patients with kidney failure. There is a risk for an allergic reaction to standard dyes, although newer, less allergenic ones are becoming available.

Other Tests for Recurrent UTI
Patients who suffer from recurrent infections are evaluated for diagnosis by ultrasound and cystoscopy (the use of a flexible lighted tube that allows the bladder to be seen from inside the urethra).

Treating Urinary Tract Infection (UTI)

Urinary tract infections are easiest to treat when they are caught early and have not spread beyond the lower urinary tract. A course of oral antibiotics is the most common treatment for UTIs.

Severe infections that have spread beyond the bladder and affect the kidney may require antibiotic injections.

For patient referral or consultations, contact the Department of Urology at 412-692-4100.