Chlamydia

Formal Name

Chlamydia trachomatis

This article was last reviewed on

28 April 2022.

This article waslast modified on 28 April 2022.

At a Glance

Why Get Tested?

To screen for or diagnose chlamydia infection

When To Get Tested?

If you are sexually active and have one or more risk factors for developing chlamydia, or have symptoms of infection e.g. discharge from the vagina or penis.

Sample Required?

Your health care team may use a swab to take a sample of cells or secretion from the infected area, or you may be asked to provide a urine sample. Women may be asked for a self taken vaginal swab.

Test Preparation Needed?

Tell your healthcare provider about any use of antibiotics or, for women, douches or vaginal creams; you may be asked to avoid using these within 24 hours before testing vaginal samples since they may affect test results. Menstruation will not affect results. For a urine sample, you may be instructed to wait one to two hours after you last urinated before collecting the sample. Follow any instructions you are given.

On average it takes 7 working days for the blood test results to come back from the hospital, depending on the exact tests requested. Some specialist test results may take longer, if samples have to be sent to a reference (specialist) laboratory. The X-ray & scan results may take longer. If you are registered to use the online services of your local practice, you may be able to access your results online. Your GP practice will be able to provide specific details.

If the doctor wants to see you about the result(s), you will be offered an appointment. If you are concerned about your test results, you will need to arrange an appointment with your doctor so that all relevant information including age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), can be considered.

Lab Tests Online-UK is an educational website designed to provide patients and carers with information on laboratory tests used in medical care. We are not a laboratory and are unable to comment on an individual's health and treatment.

Reference ranges are dependent on many factors, including patient age, sex, sample population, and test method, and numeric test results can have different meanings in different laboratories.

For these reasons, you will not find reference ranges for the majority of tests described on this web site. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the test(s) to obtain the reference range if you do not have the lab report.

For more information on reference ranges, please read Reference Ranges and What They Mean.

What is being tested?

The test is looking for evidence of infection by the bacterium Chlamydia trachomatis, the most common bacterial sexually transmitted disease (STD) in the United Kingdom.

Common Questions

How is it used?
The test is used in two ways:

to diagnose the cause of symptoms, and

to screen sexually active people for infection with the bacterium.

A definitive diagnosis is important because chlamydia can resemble gonorrhoea, and the two infections require different antibiotic treatment.
When is it requested?

A doctor may request the test if you have symptoms such as vaginal discharge and abdominal pain (for women) or unusual discharge from the penis or pain on urination (for men). However, about 70% of infected women and 50% of infected men show no active symptoms, but can still infect a sexual partner without knowing.
Risk factors for Chlamydia infection include age under 25 years, having new or multiple sexual partners, having sex with someone who has other partners, and not using barrier contraceptives such as condoms. You may wish, or your doctor may suggest, that you be screened for the infection if you have any of these risk factors.
What does the test result mean?

A positive test indicates an active infection that requires treatment with a course of antibiotics.
Is there anything else I should know?

Chlamydia is often called “the silent epidemic” because infections are very common yet many people do not know that they are infected. Chlamydia is especially widespread among young people under the age of 25. A National Chlamydia Screening Programme is underway in England, to screen for the infection in asymptomatic sexually active men and women under 25 years of age. The aim of the programme is to reduce infection rates and spread of the disease, to so reduce the consequences of untreated infections.

Chlamydia is easily treated, but if left untreated, it can cause severe reproductive and other health problems, particularly in women. If you are infected, your sexual partner(s) should also be tested and treated as well.

People who are infected have a higher risk of developing other sexually transmitted diseases, including a 3 to 5 times greater risk of acquiring HIV if exposed to it.

The diagnosis of a sexually transmitted disease should not be ruled out if the test is negative; patients' clinical symptoms and history should also be considered.
What are the symptoms of chlamydia?

Most infected people have no symptoms, so they do not seek treatment. For women, symptoms (if they occur) include bleeding between menstrual periods and after sexual intercourse, abdominal pain, painful intercourse, and an abnormal vaginal discharge. For men, symptoms include pus or milky discharge from the penis. Both sexes can experience painful or frequent urination.
What will happen if I don’t get treated?

If left untreated, women may develop pelvic inflammatory disease (PID) from areas of infection that start on the cervix but that can spread to the fallopian tubes and ovaries. This can cause infertility infertility and increase the risk of tubal or ectopic pregnancy, which may be fatal. Women who are infected and pregnant may experience heavy bleeding before delivery and premature rupture of the membranes. Men may develop pain and swelling of the testicles due to epididymitis and may become sterile. Both sexes may develop rectal itching and red, swollen, itchy eyes and arthritis.
How is chlamydia transmitted?

It is generally transmitted through sexual contact (oral, vaginal, or anal) with an infected partner. An infected mother can spread the disease to her baby during childbirth. These babies are in danger of developing conjunctivitis (an inflammation of the eyes that can threaten eyesight) and pneumonia.
How is it treated?

Chlamydia can be easily treated with a course of antibiotics.
How can it be prevented?

Sexually active men and women can reduce their risk of chlamydia by reducing their numbers of partners and by using condoms correctly and consistently during sexual intercourse.

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