Medical clinics and doctors’ offices can test for some STDs, but most do not do these tests routinely. The reason why has to do with the tests themselves and the requirements of the insurance companies that approve payment for the tests. Here are some of the most common questions about testing for STDs.
How are STDs diagnosed?
A sexually transmitted infection (STI) or disease (STD) is diagnosed based on the history of symptoms provided by the patient, based on the findings on a physical examination, and based on the laboratory test that confirms the infection. To make diagnosis and treatment as simple as possible and available to as many people as possible, some rapid response type tests have been developed that can be used in community screenings and other events without a history or physical examination. These rapid response tests are usually screening tests and not ones used for accurate diagnosis. For medical people, a positive screening test means ‘take another look’.
Does the type of doctor’s practice matter?
Although almost any doctor’s office or health care center can test for STDs, you have to ask for it. Often, routine blood work along with your annual exam does not include STD testing. Even if certain STDs are included in your annual exam, this will not be the entire panel and the specific STD you are concerned about may not be included.
As uncomfortable as it may be, you should discuss with your doctor your concerns and which STDs you want to be tested for. Your healthcare provider can further advise you on the need for the test in relation to the disease you are concerned about and can advise you on whether or not follow-up testing is necessary to avoid false negative results.
Your doctor may also want to make sure that you have waited long enough after sex to get tested, as different STDs have different wait times before a test can detect the presence of the infection. According to One Medicalyou must wait two weeks before a test can detect gonorrhea or chlamydia. The withdrawal period for syphilis is one week to three months and six weeks to three months for HIV and hepatitis.
What types of tests are available?
It would be great if we could find out more about our cholesterol and chlamydia with just one sample of blood or a mouth swab. Some older tests are still used and there are new but expensive tests on the market.
Bacterial culture: This test involves placing some of the fluid from the cervix or penis onto a culture medium to see if anything grows. After 24 and 48 hours, laboratory technicians look at samples of the bacterial growth on the culture plate. This test plays an important role in detecting new strains of bacteria that become resistant to commonly used antibiotics, such as what happens with gonorrhea. A culture is often taken if initial treatment appears to have failed.
Sensitivity testing: This test may be included as part of a bacterial culture test to determine which antibiotic is most effective at curing the infection. These culture and sensitivity tests are “culture and sensitivity‘or abbreviated to C & S in common medical jargon.
Antibody tests: Our immune system responds to invaders by making small, weaponized proteins to fight the infection. These proteins, called antibodies, appear in body fluids such as blood and even more easily accessible body fluids such as urine. The downside is the risk of testing for an infection before the antibody level is high enough to show up, which will produce a false negative result.
Antigen tests: Some proteins that are part of the cell wall membrane of various viruses and bacteria can be tested directly. These are usually blood tests.
Enzyme-linked immunosorbent assay (ELISA): This test detects both bacterial antigen and the antibody. A positive result from this test will demonstrate exposure to the bacteria at some point. It does not indicate whether the current infection is caused by the bacteria. An ELISA can be used to confirm syphilis (the Treponema pallidum bacteria).
RNA testing: These expensive tests look for the genetic material, or RNA, of the germ itself.
Gram stain: An old-fashioned but effective test called a Gram stain can be done wet or dry. The cotton swab is rubbed over dry skin or wet tissues, including mucous membranes. The swab is then rubbed over a glass and a series of dyes (stains) are applied. The provider looks at the results under a microscope. Gram-positive bacteria will appear blue-purple in color and gram-negative bacteria will appear red. A Gram stain also identifies the bacteria based on shape. Gram + cocci are round in shape. Gram – rods are rod-shaped. A Gram stain is often accompanied by a sensitivity test (see above).
Viral cultures: These tests can sample an ulcer with fluid, such as a herpes lesion, and determine if a virus is present by growing it like the bacterial culture. Viral cultures are challenging and can have a high false negative rate.
Many of these specialized tests are not available in a regular doctor’s office, but require a visit to a laboratory.
What is the difference between screening tests and diagnostics?
When laboratory tests are evaluated, they must achieve a level of accuracy. They both have to find the specific germ/virus being looked for, and they have to find it every time. They also cannot call a positive if there is no infection. Each test is specific to the protein antibody, virus or germ being looked for. There is no one test that can check everything.
Audition
The cheaper and easy to use tests, such as tests that use cheek swabs and are performed in twenty minutes, are considered audition. A screening test cannot always distinguish an old infection from a new one, and they usually cannot be relied on to detect an infection early. Screening tests have a higher rate of false negatives and false positives. A false negative is a result that appears as negative when the infection is actually present. A false positive result is a positive test result when no infection is present. Screening tests are usually used to decide which people should undergo the most expensive and accurate tests diagnostic tests.
Diagnostic tests
A diagnostic test is used to diagnose a specific infection, such as bacterial or viral culture, and to ensure that the screening test did not produce a false negative or positive. Diagnostic tests can also point to specific treatments.
Why not check everything?
These bugs (viruses and bacteria) tend to travel together, but the treatments are not the same. The test for gonorrhea tells us nothing about chlamydia, although we know the two are often seen together. Treatment for one will not treat both. The HIV virus and syphilis bacteria travel together, but the diagnostic tests and treatments are different for each.
However, if there is a single positive screening test for an STD, many medical providers will recommend checking everything by using the more expensive diagnostic tests. This recommendation is made even if there are no symptoms, because some of the more troublesome germs/viruses will hide and not cause enough symptoms to worry about. The exception to this rule is herpes. These lesions are typically only cultured during an outbreak, although the virus can spread at any time.
Why not just always use the more expensive diagnostic tests?
That’s probably an exaggeration and the tests will be very expensive. This is important because insurance companies decide whether they will reimburse the costs of the test. They usually set standard guidelines for approving the test, such as symptoms, physical examination indicative of infection, or a positive screening test. They do not pay for the diagnostic tests used when there are no symptoms or physical examination results, such as a typical soreness. This means that the patient, you, ultimately has to pay the bill. Screening tests are less invasive, cheaper and usually work well.
Medical providers do not actually need to undergo laboratory tests to confirm a diagnosis. A history of symptoms and a physical examination consistent with the disease is standard practice for management. Many use laboratory tests alone to confirm the diagnosis or to evaluate if the initial treatment does not seem to be working.
When are STDs part of a normal medical examination?
There are two times when the standard of medical practice is to check everything. This is during prenatal care and care for people infected with HIV or tuberculosis. Medical clinics that specialize in diagnosing and treating STDs will usually also conduct a comprehensive examination, as those seeking answers need detailed and specific answers. Specialty clinics also tend to be at the forefront of new and emerging STDs, and this field is rapidly changing with bacteria mutating and developing antibiotic resistance.