The specific tests for chancroid involve taking material directly from ulcers and culturing it using a special medium for the bacteria. Blood tests designed to detect the body’s immune response (antibodies) to the infection may also help with the diagnosis. The cultures are not always positive when a person has the disease, so a negative culture is not definitive. For this reason, if the infection is strongly suspected, treatment may be started even if the culture is negative.
Newer technology using the polymerase chain reaction test, which looks for the genetic material of the bacterium, may in the near future provide an easier and more accurate way to diagnose the infection.
A person who is being tested for chancroid should simultaneously be tested for the more common causes of genital ulcers, herpes and syphilis, as well as other STDs. The less common causes of genital ulcers in the United States, lymphogranuloma venereum and donovanosis (see the sections on these topics) may also be tested for, depending upon the person’s history.