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Urinary Tract Infections (cont.)

Exams and Tests

Diagnosis of a urinary tract infection is based on information you give about your symptoms, medical and surgical history, medications, habits, and lifestyle. A physical examination and lab tests complete the evaluation.

Your doctor may simply perform a urine dipstick test in the office. Only a few minutes are needed to obtain results. Your doctor may also send your urine to the lab for testing. These results take a few days to come back. This tells your doctor the exact bacteria causing your infection and to which antibiotics these bacteria have resistance or sensitivity. The culture is usually sent for special populations, including men, because they are less likely to get UTIs. It is not necessary to send a culture for everyone because the majority of UTIs are caused by the same bacteria.

The single most important lab test is urinalysis. A sample of your urine will be tested for signs of infection, such as the presence of white blood cells and bacteria.

In certain circumstances, your urine also may be "cultured." This means that a small amount of the urine is brushed on a sterile nutrient substance in a plastic plate. The plate is allowed to sit for a few days and then examined to see what kind of bacteria are growing on it. These bacteria are treated with different antibiotics to see which works best against them. This helps determine the best treatment for your specific infection. This is rarely necessary with a simple infection.

Blood tests usually are not required unless a complicated condition, such as pyelonephritis or kidney failure, is suspected.

You may be asked to give a clean-catch, midstream urine specimen. This avoids contamination of the urine with bacteria from your skin. You should be instructed in how to do this.

Midstream means you urinate a little into the toilet before collecting a specimen. The idea is that you don't collect the urine that comes out first, as this urine is often contaminated.

Clean-catch refers to a midstream specimen that was collected after cleaning the area of the urethral opening.

Adult women and older girls: Cleanse the area around your urethral opening gently (but completely) using a sterile wipe or soap and water. Catch the urine midstream. For some women, catheterization (inserting a tube into the bladder) may be the only way to obtain a sterile, uncontaminated specimen.

Men and boys: A sterile specimen can usually be obtained with a midstream catch. Uncircumcised males should retract the foreskin and cleanse the area before urinating.

Newborns: Urine may be obtained with a procedure in which a needle is introduced through the lower abdominal wall to draw (aspirate) urine from the bladder.

Infants and children: Either catheterization or the needle aspiration method is used.

If you cannot produce a urine specimen or are unable to follow instructions for a clean-catch specimen, your health-care provider will obtain a urine specimen by catheterizing you.

This means placing a thin tube (catheter) in your urethra to drain urine from your bladder.

The catheter usually is removed after the bladder is emptied.

The catheter may remain in place if you are very ill or if it is necessary to collect all urine or measure urine output.

Depending on their symptoms, young sexually active women could require a pelvic examination because pelvic infections can have similar symptoms as a urinary tract infection.

Men will most likely require a rectal examination so that the prostate can be checked. A prostate infection (prostatitis) requires a longer course of antibiotics than a urinary tract infection.

In some cases, an imaging test may be indicated to detect any underlying problem in the urinary tract that could cause an infection. This is usually only necessary in repeat infections or special circumstances (unusual bacteria, suspected anatomic abnormalities).

An ultrasound examination can evaluate kidney and bladder problems.

A fluoroscopic study can show any physical problems that predispose children to urinary tract infections.

Intravenous pyelogram (IVP) is a special series of X-rays that uses a contrast dye to highlight abnormalities in the urinary tract.

Cystoscopy involves insertion of a thin, flexible tube with a tiny camera on the end through the urethra into the bladder. This allows detection of abnormalities inside the bladder that might contribute to infections.

A CT scan gives a very detailed three-dimensional picture of the urinary tract.

Imaging tests are most often needed for the following groups:

Children with urinary tract infections, especially boys

Up to 50% of infants and 30% of older children with a urinary tract infection have an anatomic abnormality. The child's pediatrician should investigate this possibility.