Causes and Diagnoses

Causes of Urinary Tract Infections

Normal urine is sterile, without any bacteria, viruses or fungi. A UTI happens when germs, often from the digestive tract, get into the urethra and start to multiply.

Most UTIs are caused by E. coli bacteria, which occur naturally in the digestive tract.

Diagnosing urinary tract infections

Your physician will review your medical history and do a physical exam. Other tests may include:

  • Urinalysis: This test checks for blood cells, germs (like bacteria) or excess protein in the urine.
  • Urine culture: This test attempts to grow potential bacteria or yeast found in the urine to help in diagnosing and treating the infection.

If UTIs become a repeated problem, other tests may be used to see if the urinary tract is normal. These tests may include:

  • Cystourethroscopy: Also known as a cystoscopy, this test examines the inside of your bladder and urethra. It is often used to diagnose and evaluate urinary tract disorders, such as urinary tract inflammation, kidney or bladder stones and bladder tumors.
  • Kidney and bladder ultrasound: Using high-frequency sound waves, this test shows the size and shape of the bladder and the kidneys, and checks for a mass, stones, cysts, blockages and abnormalities.
  • CT scan: This test uses X-rays and a computer to make detailed images of the urinary tract.