Chlamydia is diagnosed during a physical examination that includes a medical history and, in women, a pelvic examination. A physician may discuss sexual history, including number of sexual partners, past history of sexually transmitted diseases (STDs) and use of contraception.

Because chlamydia often produces no symptoms, the only conclusive way to diagnose the STD is with a laboratory test. Since the U.S. Centers for Disease Control and Prevention recommends that all sexually active women ages 25 and under receive a screening test, women may be given a test even if they have no symptoms. In addition, the U.S. Preventive Services Task Force (USPSTF) recommends that all pregnant women aged 25 years or younger be screened for the disease. However, some studies encouraged screening only in women with risk factors of the disease. Men may only be tested if they are symptomatic.

There are two types of tests that detect chlamydia:

• Culture swab. For men, the physician may insert a slim swab into the end of the penis to get a sample from the urethra (the tube that carries urine from the bladder to outside the body). For women, the physician may take a sample of mucous from the cervix or vaginal discharge with a swab. In some cases, a sample may be taken from the anus. The sample is then sent to a laboratory where it is studied for the presence of bacteria.
  
  
• Urine test. This may be performed on women and men. After collecting a sample of urine, it is sent to a laboratory where it is studied for the presence of the chlamydia bacteria.