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Gram stain of urethral discharge

Definition

A gram stain of urethral discharge is a test used to identify bacteria in fluid from the tube that drains urine from the bladder (urethra).

Alternative Names

Urethral discharge Gram stain

How the test is performed

Fluid from the urethra is collected on a cotton swab. A sample from this swab is applied in a very thin layer to a microscope slide. A series of stains called a gram stain is applied to the specimen.

The stained smear is then examined under the microscope for the presence of bacteria. The color, size, and shape of the cells help identify the organism causing the infection.

How to prepare for the test

This test is often performed in the health care provider's office.

How the test will feel

You may feel pressure or burning when the cotton swab touches the urethra.

Why the test is performed

The test is performed when an abnormal urethral discharge is present. It may be performed if a sexually transmitted disease is suspected.

Normal Values

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.

What abnormal results mean

Abnormal results may indicate gonorrhea or other infections.

What the risks are

There are no risks.

Special considerations

A culture of the specimen (urethral discharge culture ) should be performed in addition to the gram stain. More sophisticated diagnostic tests (such as PCR tests) are sometimes also done.

References

McCormack WM. Urethritis. In: Mandell GL, Bennett JE, Dolin R, eds. . 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 106.

Cohen MS. Approach to the patient with a sexually transmitted disease. In: Goldman L, Ausiello D, eds. . 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 293.

Encyclopedia content is provided as information only and not intended to replace the advice and instruction from your personal physician.