UTI diagnosis

Tests used to diagnose UTI

Your healthcare provider will likely conduct testing to determine whether you have an infection. Some tests and procedures used to diagnose^[22] UTIs include:

• Urinalysis: This test involves collecting a sample of your urine for lab analysis. Your provider will look for the presence of white blood cells (which can indicate infection), red blood cells, or bacteria.
• Urine culture: Sometimes, urinalysis is followed by a urine culture. This test involves cultivating your urinary bacteria in a lab. This allows your provider to identify the bacteria that are causing your infection (and, therefore, determine what type of medication will be the most effective in treating your infection).
• Imaging tests: If you have frequent UTIs and your provider suspects that an abnormality in your urinary tract may be the cause, imaging tests like ultrasound, computerized tomography (CT) scans, or magnetic resonance imaging (MRI) may be used to look at your urinary tract.
• Cystoscopy: If you have recurrent UTIs, you may undergo a cystoscopy—a procedure that uses a long, thin tube with a lens (called a cystoscope) to look inside your bladder and urethra.

By definition^[23], a symptomatic UTI is diagnosed when at least 10⁵ colony-forming units of bacteria per milliliter are present in one urine sample. Asymptomatic bacteriuria, on the other hand, is defined by the presence of bacteria in the urine without any of the clinical signs or symptoms of a typical UTI. Once diagnosed, UTIs can be classified^[24] into two types based on where they occur in the urinary tract:

• Lower tract infections include bladder infections (cystitis) and urethral infections (urethritis).

Lower tract infections usually occur when GI bacteria enter the urinary tract through the urethra from skin-to-skin contact or spreading the bacteria through things like wiping after using the bathroom. They can also be caused by bacterial STIs, including gonorrhea and chlamydia. In males, one type of lower tract infection is prostatitis (inflammation of the prostate).

• Upper tract infections involve the upper urinary tract, including the kidneys and ureters (tubes connecting the kidneys to the bladder).

These infections, which include pyelonephritis (kidney infection), can occur when bacteria travels up the urinary tract from the bladder to the kidneys or when bacteria passed through the bloodstream accumulates in the kidneys.

Diagnosing UTIs in older adults

Because UTIs in older adults are frequently asymptomatic, they can be difficult to diagnose. If you or a loved one are suspected of having a UTI, make sure to tell a provider if any of the following symptoms^[25] are present:

• Fever over 100.5°F (38.1°C)
• Sudden pain when urinating
• Worsening frequency of urination or urgency to urinate
• Pain, tenderness, or pressure in the lower abdomen, above the pubic bone

The presence of at least two of these symptoms along with a positive urine culture can confirm the presence of a UTI.