Gram stain of urethral discharge
A gram stain is a method of identifying bacteria using a special series of stains. In a gram stain of urethral discharge, a smear of fluid from the urethra is stained and then examined under the microscope.
The gram stain method can be applied to almost any specimen and is one of the most commonly used techniques for the rapid diagnosis of bacterial infections.
A urethral discharge 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. It is first stained with crystal violet stain, then iodine, then decolorized, then stained with safranin.
The stained smear is then examined under the microscope for the presence of bacteria. The color, size, and morphologic appearance (shape) of the cells help identify the infecting organism.
This test is often performed in the health care provider's office.
The sensation of pressure or burning may be present when the cotton swab is in contact with the urethra.
The test is performed when an abnormal urethral discharge is present. It may be performed if infection with a sexually transmitted disease is suspected.
No presence of organisms is normal.
Abnormal results may indicate infection with gonorrhea or other infections.
There are no risks.
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.
Reviewed By: Kenneth Wener, M.D., Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Boston, MA. Review provided by VeriMed Healthcare Network.