Diagnosis:

A doctor can confirm if you have a urinary tract infection by testing a sample of your urine. For some younger women who are at low risk of complications, the doctor may not order a urine test and may diagnose a urinary tract infection based on the description of symptoms.

Urine Tests

Urinalysis. A urinalysis is an evaluation of various components of a urine sample. It involves looking at the urine color and clarity, using a special dipstick to do different chemical testing, and possibly inspecting some of the urine underneath a microscope. A urinalysis usually provides enough information for a doctor or nurse to start treatment.

Urine Culture. If necessary, the doctor may order a urine culture, which involves incubating and growing the bacteria contained in the urine. A urine culture can help identify the specific bacteria causing the infection, and determine which type of antibiotics to use for treatment. A urine culture may be ordered if the urinalysis does not show signs of infection but the doctor still suspects a UTI is causing the symptoms. It may also be ordered if the doctor suspects complications from the infection.

Clean-Catch Sample. To obtain an untainted urine sample, doctors usually request a so-called midstream, or clean-catch, urine sample. To provide this, the following steps are taken:

• Patients must first wash their hands thoroughly, then wash the penis or vulva and surrounding area four times, with front-to-back strokes, using a new soapy sponge each time.
• The patient must then begin urinating into the toilet and stop after a few ounces.
• The patient then positions the container to catch the middle portion of the stream. Ideally, this urine will contain only the bacteria and other evidence of the urinary tract infection.
• The patient then urinates the remainder into the toilet.
• The patient securely screws the container cap in place without touching the inside of the rim.

The sample is generally given to the doctor or sent to the laboratory for analysis.

Collection with a Catheter. Some patients (small children, elderly people, or hospitalized patients) cannot provide a urine sample. In such cases, a catheter may be inserted into the bladder to collect urine. This is the best method for providing a contaminant-free sample.

Other Tests

If the infection does not respond to treatment, the doctor may order other tests to determine what is causing symptoms. Imaging tests can help identify:

• Serious and recurrent cases of pyelonephritis
• Structural abnormalities
• Obstruction or abscess
• Possible obstruction or vesicoureteral reflux in children ages 2 - 24 months

Ultrasound. Ultrasound is a noninvasive imaging test that can be used to screen for hydronephrosis (obstructions of the flow of urine), kidney stones that predispose to infection, and kidney abscesses. In men, ultrasound can detect enlargement or abscesses of the prostate and is an accurate method for detecting incomplete emptying of the bladder, a common cause of UTI in men over age 50. In children with urinary tract infections, it also can be used to detect vesicoureteral reflux, the defect of the valve-like mechanism between the ureter and bladder.

X-Rays. Special x-rays can be used to screen for structural abnormalities, urethral narrowing, or incomplete emptying of the bladder, which can cause stagnation of urine and predispose to infection. Due to the possible risks to the fetus, x-rays are not performed on pregnant women.

• Voiding cystourethrogram is an x-ray of the bladder and urethra. To obtain a cystourethrogram, a dye, called contrast material, is injected through a catheter inserted into the urethra and passed through the bladder.
• An intravenous pyelogram (IVP) is an x-ray of the kidney. For a pyelogram, the contrast matter is injected into a vein and eliminated by the kidneys. In both cases, the dye passes through the urinary tract and reveals any obstructions or abnormalities on x-ray images.

Cystoscopy. Cystoscopy is used to detect structural abnormalities, interstitial cystitis, or masses that might not show up on x-rays during an IVP. The patient is given a light anesthetic, and the bladder is filled with water. The procedure uses a cystoscope, a flexible, tube-like instrument that the urologist inserts through the urethra into the bladder.

Computed Tomography (CT). A computed tomography (CT) scans may be used to check for kidney stones or other obstructions

Blood Cultures. If symptoms are severe, the doctor will order blood cultures to determine if the infection is in the bloodstream and threatening other parts of the body.

Ruling Out Conditions with Similar Symptoms

About half of women with symptoms of a UTI actually have some other condition, such as irritation of the urethra, vaginitis, interstitial cystitis, or sexually transmitted diseases (STDs). Some of these problems may also accompany or lead to UTIs.

Vaginitis. Vaginitis is a common vaginal infection that can be caused by a fungus (candidiasis) or bacteria. Occasionally, the infection causes frequent urination, mimicking cystitis. The typical symptoms of vaginitis are itching and an abnormal discharge.

Sexually Transmitted Diseases. Women with painful urination whose urine does not exhibit signs of bacterial growth in culture may have a sexually transmitted disease. The most common microorganism is Chlamydia trachomatis. Other STDs that may be responsible include gonorrhea and genital herpes.

Interstitial Cystitis. Interstitial cystitis (IC) is an inflammation of the bladder wall that occurs almost predominantly in women. The average age of patients with IC is 40 years old, but 25% of cases occur in women under age 30. Symptoms are very similar to cystitis, but no bacteria are present. Pain during sex is a very common complaint in these patients, and stress may intensify symptoms.

Kidney Stones. The pain of kidney stones along with blood in the urine can resemble the symptoms of pyelonephritis. There are no bacteria present with a kidney stones, however.

Thinning Urethral and Vaginal Walls. After menopause, the vaginal and urethral walls become dry and fragile, causing pain and irritation that can mimic a UTI.

Disorders in Children that Mimic UTIs. Problems that might cause painful urination in children include reactions to chemicals in bubble bath, diaper rashes, and infection from the pinworm parasite.

Prostate Conditions in Men. Prostate conditions, including prostatitis (inflammation of the prostate) and benign prostatic hyperplasia, can cause symptoms similar to urinary tract infections.