You may have a false-negative urine culture if you have been taking antibiotics.
A urine culture is a lab test to check for bacteria or other germs in a urine sample.
How the Test is Performed
Most of the time, the sample will be collected as a clean catch urine sample in your health care provider's office or your home. You will use a special kit to collect the urine.
A urine sample can also be taken by inserting a thin rubber tube (catheter) through the urethra into the bladder. This is done by someone in your provider's office or at the hospital. The urine drains into a sterile container, and the catheter is removed.
Rarely, your provider may collect a urine sample by inserting a needle through the skin of your lower abdomen into your bladder.
The urine is taken to a lab to determine which, if any, bacteria or yeast are present in the urine. This takes 24 to 48 hours.
How the Test will Feel
When the catheter is inserted, you may feel pressure. A special gel is used to numb the urethra.
How to Prepare for the Test
If possible, collect the sample when urine has been in your bladder for 2 to 3 hours.
"Normal growth" is a normal result. This means that there is no infection.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
There is a very rare risk of a hole (perforation) in the urethra or bladder if your provider uses a catheter.
What Abnormal Results Mean
A "positive" or abnormal test is when bacteria or yeast are found in the culture. This likely means that you have a urinary tract infection or bladder infection.
Other tests may help your provider know which bacteria or yeast are causing the infection and which antibiotics will best treat it.
Sometimes more than one type of bacteria, or only a small amount, may be found in the culture.
Why the Test is Performed
Your provider may order this test if you have symptoms of a urinary tract infection or bladder infection, such as pain or burning when urinating.
You also may have a urine culture after you have been treated for an infection. This is to make sure that all of the bacteria are gone.
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