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).

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

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.

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

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