Urinary Tract Infections

Urinary Tract Infections Overview

A urinary tract infection (UTI) is an infection involving the kidneys, ureters, bladder, or urethra. These are the structures that urine passes through before being eliminated from the body.

• The kidneys are a pair of small organs that lie on either side of the spine at about waist level. They have several important functions in the body, including removing wastes and excess water from the blood and eliminating them as urine.
  
  
• The ureters, 2 narrow tubes about 6 inches long, drain urine from the kidneys into the bladder.
  
  
• The bladder is a small saclike organ that collects and stores urine. When the urine reaches a certain level in the bladder, the muscle lining the bladder contracts to expel the urine.
  
  
• The urethra is a small tube connecting the bladder with the outside of the body. A muscle called the urinary sphincter, located at the junction of the bladder and the urethra, must relax at the same time the bladder contracts to expel urine.

Any part of this system can become infected. As a rule, the higher up the infection, the more serious it is.

• The upper urinary tract is composed of the kidneys and ureters. Infection in the upper urinary tract generally affects the kidneys (pyelonephritis).
  
  
• The lower urinary tract consists of the bladder and the urethra. Infection in the lower urinary tract can affect the urethra (urethritis) or the bladder (cystitis).

Urinary tract infections are usually referred to as simple or complicated.

• Simple infections occur in healthy urinary tracts and do not spread to other parts of the body. They usually go away readily with treatment.
  
  
• Complicated infections are caused by anatomic abnormalities, spread to other parts of the body, or are resistant to many antibiotics. They are more difficult to cure.

In the United States, urinary tract infections account for more than 7 million visits to medical offices and hospitals each year.

• Urinary tract infection is much more common in adults than in children, but about 1-2% of children do get urinary tract infections. Urinary tract infections in children are more likely to be serious than those in adults.
  
  
• Urinary tract infection is the most common urinary tract problem in children besides bedwetting.
  
  
• Urinary tract infection is second only to respiratory infection as the most common type of infection.
  
  
• These infections are much more common in girls and women than in boys and men younger than 50 years. The reason for this is not well understood. 
  
  
• About 40% of women and 12% of men have a urinary tract infection at some time in their life.
  
  
• Urinary tract infection is less common in men and boys than in women and girls but is more likely to be serious.