Genital herpes can be difficult to diagnose because signs and symptoms vary widely among individual patients.

The condition may be diagnosed during a physical examination or routine gynecological examination if sores are visible to the naked eye. However, laboratory tests may be needed to confirm a diagnosis, especially if other symptoms are not present.

A viral culture is one such laboratory test. To perform a culture, a sample is obtained by swabbing or scraping a new sore. The sample is placed in a culture that also contains healthy cells. When examined under a microscope after several days, the cells show changes that may indicate the presence of the herpes simplex virus.

However, the specimen must be collected from a new sore, usually within 48 hours after it appears. After 48 hours, the test is not reliable because the sores begin to heal and there may not be adequate virus on the skin to make a diagnosis.

Blood tests have recently become a more popular test because they do not require the presence of sores. The test is conducted on a small amount of blood taken from the arm or finger. The tests look for specific antibodies, which are substances used by the immune system to identify and destroy foreign objects such as bacteria and viruses. Although the results may not be available for several weeks, they can identify whether a person has herpes simplex virus 1 (HSV-1) or herpes simplex virus 2 (HSV-2). However, a blood test cannot distinguish between an acute or active infection or one that has occurred in the past.

The U.S. Food and Drug Administration (FDA) has recently revised rules that could make herpes virus tests cheaper and more widely available. In addition, the FDA is proposing to reclassify herpes tests to a class that has fewer regulations. In doing so, more medical facilities and offices could offer the tests due to lower training requirements of personnel. In addition, companies may be able to develop and market new tests for the virus.