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Ear drainage culture

Definition

An ear drainage culture is a laboratory test to check for infection-causing substances in a sample of fluid, pus, wax, or blood from the ear.

See also: Ear drainage

Alternative Names

Culture - ear drainage

How the test is performed

A sample of ear drainage is needed. Your health care provider will use a cotton swab to collect the sample from inside the outer ear canal. In some cases, a sample is collected from the middle ear during ear surgery.

The sample is sent to a laboratory and placed on a special dish (culture media).

The lab team checks the dish every day to see if bacteria, fungi, or viruses have grown. Further tests may be done to specifically identify any substances and determine the best treatment.

How to prepare for the test

No preparation is needed for a lab culture.

How the test will feel

No pain is associated with using a cotton swab to take a sample of drainage from the outer ear. However, ear pain may be present if the ear is infected.

Ear surgery is performed under general anesthesia, which means you are asleep and feel no pain. See: myringotomy.

Why the test is performed

The test may be done if you or your child has:

• An ear infection that is not responding to treatment
• An infection of the outer ear (otitis externa)
• An ear infection with a ruptured eardrum and draining fluid

It may also be done as a routine part of myringotomy.

Note: Ear infections are diagnosed based on symptoms rather than using a culture.

Normal Values

The test is normal if there is no growth on the culture.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

Abnormal results may be a sign of infection by bacteria, virus, or fungus.

The test results may reveal which specific organism is causing the infection and help your doctor decide on appropriate treatment.

What the risks are

No risks are involved with swabbing the ear canal. For risks related to ear surgery, see myringotomy.

Special considerations

Ear drainage culture is usually not done because of contamination concerns and difficulty linking a bacteria to the infection. Normal bacteria will likely grow on the ear fluid sent for culture.

References

Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.