What Is an Endocervical Gram Stain (EGS)?

An endocervical gram stain (EGS) is a diagnostic test that checks for abnormal bacteria around the cervix. It involves taking a small tissue sample from the cervix, applying it to a slide, and then staining the sample using special dyes. A laboratory specialist can then identify any bacteria that appear in the endocervical gram stain to help diagnose infections or diseases.

For this test, your doctor will take a small sample of tissue from the opening of the uterus called the cervical canal. They’ll then send it to a laboratory. At the laboratory, a specialist will apply a number of different stains, including a gram stain, to the sample. These stains help them to identify bacteria that are present. The specialist will check the shape, size, and color of the bacteria to determine if it’s abnormal.

An endocervical gram stain is a common way to check for sexually transmitted infections (STIs), such as gonorrhea and chlamydia. It can also help confirm gonococcal arthritis, which is a complication of gonorrhea that causes joint inflammation, or swelling.

An endocervical gram stain may also be known as a gram stain of the cervix.

An endocervical gram stain checks for abnormal bacteria in or around the cervix. Your doctor may also perform this test if they suspect you have an STI. An endocervical gram stain can detect STIs such as:

  • gonorrhea, which is a common STI with painful urination and abnormal discharge
  • bacterial vaginosis, which is characterized by a fish-like odor and grayish discharge
  • chlamydia, which is the most commonly diagnosed STI, doesn’t always show symptoms, and may cause painful intercourse and urination
  • gonococcal arthritis, which is an inflammation of a joint caused by a gonorrhea infection

An endocervical gram stain is very similar to a Pap smear, which is also done using a swab and a speculum. You may find the test to be a little uncomfortable or awkward. However, you shouldn’t feel any pain.

Don’t douche (clean your vaginal area with special washes) for 24 hours before the endocervical gram stain. Douching may mask the bacteria in the cervix.

An endocervical gram stain will generally consist of a few basic steps:

  1. You’ll change into a gown and lie down on a table with your feet in stirrups at the end of the table.
  2. Your doctor will use a metal or plastic instrument called a speculum to gently stretch your vaginal muscles open. This will allow them to get a better view of your cervix.
  3. Your doctor will clean your cervix so there’s no discharge.
  4. They’ll then place a sterile, dry cotton swab against the cervical canal. They may also rotate the swab and leave it in for a few seconds to allow bacteria to settle on it.
  5. Your doctor will remove the swab and speculum, and then you can change into your clothing.
  6. Your doctor will send the swab to a laboratory. A technician will rub the swab against a slide and stain it with a gram stain. The laboratory technician will then study the stain under a microscope to look for any abnormal bacteria.

Your doctor will contact you with any abnormal test results. Some doctors don’t call when test results are normal. You may want to ask your doctor about their notification procedures.

An endocervical gram stain is a simple test. There are no risks or complications associated with an EGS. However, an EGS may cause a little bit of bleeding if your cervix is inflamed.

A normal test result means that the specialist found no abnormal bacteria on your EGS. Normal test result ranges may vary depending on the laboratory.

If you receive an abnormal test result, follow the guidance of your doctor. They may ask you to come back in for a follow-up examination or further testing.

Many STIs can be treated with antibiotics.

If you do have an STI, you should contact any sexual partners and encourage them to seek testing and treatment. They may have no symptoms but still have an STI and unknowingly spread it.

Ask your doctor if you have any questions about your EGS results.