A penis swab is a long, thin tool that medical professionals such as urologists and primary care doctors use to test men for certain sexually transmitted diseases (STDs). The test itself also is often referred to as a penis swab. During the test a doctor sticks the swab into the male urethra to get a sample from a patient. The location of the male urethra leads many men to find this test slightly painful. The pain with urination that may follow a penis swab test is only temporary, while leaving an STD untreated can cause permanent damage to person's body.

The design of a penis swab is long and thin. The male urethra is not as easily accessible to doctors as the female urethra is, and it is accessed through the tip of the penis. This specific swab is designed to deal with the design of the male anatomy so doctors can perform the testing both safely and correctly. Although much more slender than an ear swab, a penile swab does have a similar cotton tip on the end.

The test known as the penis swab is most commonly done to diagnose the STDs gonorrhea and chlamydia. A doctor must use precision and accuracy when performing a swab test if he wants to achieve accurate results. The swab needs to go into the male urethra by at least 3 cm in most cases. Once the penis swab is safely inside the urethra, a doctor will rotate it multiple times to make sure that adequate urethral cells make it onto the swab. When the swab is removed from the patient's body, it is immediately placed in a sterile bag or container to be sent to a lab for testing.

Penile swabs are disposable items. The swabs typically come individually packaged. Doctors and nurses will open each swab while wearing sterile exam gloves to make sure they do not contaminate the swab. Any foreign substance on a penis swab, whether it is from the patient or the doctor, can invalidate test results.

Men who are afraid to go to the doctor for a penile swab test because of embarrassment or other personal reasons can order a penis swab test kit online. Most of these kits will include a clean penile swab, a container to put the swab in once the test is complete and packaging to send the sample to a lab when finished. Users of an at-home kit should make sure to follow the directions exactly to avoid injuring the penis or accidentally tainting test results.