Does a Pap Smear Test for STDs?

‘Dr, my pap smear is normal; that also means I am safe from STDs, am I right?’ This is a common question during consultation. 

Often, many patients think that pap smears and STD tests are similar as both involve ‘swabs’ from the genital region. This article aids readers in understanding what a pap smear test entails and the differences between a pap smear test and STD testing. The article also serves to facilitate readers to make informed decisions on which test is/are suitable based on individual history and risk of exposure.

What is a pap smear test?

A pap smear is a medical test procedure to screen for cervical cancer. A pap smear is performed at the bedside. Your physician will use a sterile speculum device to examine the vagina and then use a special brush to obtain cells from your cervix (neck of your womb, at the end of the vaginal tunnel).

A pap smear is offered to all sexually active ladies. Aside from detecting cervical cancer cells on pap smears, the test is also able to pick up early changes or abnormalities in cervical cells that may eventually lead to cervical cancer. Hence, a pap smear is the first step in preventing further development of cervical cancer and should be considered routinely even if a woman is completely well and asymptomatic.

What is an HPV test?

Human papillomavirus (HPV) is a common virus that affects approximately 80% of those who are sexually active at some point in their life. It can affect anyone regardless of their socioeconomic status. HPV can stay indolent for years before causing abnormal cervical changes and cervical cancer.

As more than 99% of cervical cancers are due to human papillomavirus (HPV) infection, women aged 30 and above are encouraged to go for HPV tests in conjunction with a pap smear. In some cases, your doctor may offer an HPV test rather than a pap smear. 

HPV test is a cervical swab test performed by your medical physician to screen for high-risk HPV strains that may infect the cervix. HPV test serves as a risk stratification against the development of cervical cancer. In patients found to have high-risk HPV strains, your doctor may advise you to consider HPV vaccination (if you are eligible and you have not done so), to follow up your pap smear and HPV test at closer intervals, to consider colposcopy, or even treatment option for the affected cervical region if needed. 

If you are unsure whether you require HPV testing or you have further questions regarding HPV, you can reach out to your doctor for further enquiry.

Can pap smear detect STDs?

Pap smear is a test modality used to screen for cervical cancer. The cervical cells and tissues will be swabbed with a sterile brush and stained on a smear slide. This will be reviewed under a microscope by the pathologist in the laboratory to look for any abnormal cervical tissue cells, including cancer cells. Commonly, a pap smear can pick up abnormal cell changes secondary to HPV infection. However, a pap smear does not specifically reveal which HPV strain (over 150 strains of HPV viruses) causes the abnormalities of the cells. This can be further evaluated with HPV testing.

As a pap smear involves microscopic visualisation of the tissue cells of the cervix, the presence of fungus such as Candida (commonly causing vaginal infection) can be seen.

Less commonly, infected tissue cells of the cervix due to herpes (HSV- herpes simplex virus) viral infection can be seen. Though this is usually inconclusive, your doctor may advise further HSV testing with blood and PCR swab tests.

Does a pap smear test for STD infections?

Unfortunately, a pap smear has its limitations and is unable to rule out STDs such as chlamydia, gonorrhoea, HIV, and syphilis. Although these infections can be associated with cervicitis (inflammation of the cervix), the pap smear may only reveal non-specific inflammation of the cells. One will require specific STD tests to confirm these infections. Considering specific STD tests are crucial as treatment options for different types of STD are different – you will need the correct medication and the correct dose to eradicate STD. 

Using a pap smear alone to screen for STDs is insufficient. Conversely, just doing an STD test is unable to safely rule out cervical cancer either. You are encouraged to discuss with your doctor your symptoms (if any), concerns, risk of exposure and obtain professional advice on which test(s) are suitable for you.

What does it mean if I have an abnormal pap smear? Do I need to routinely do an STD test if I have an abnormal pap smear?

It is useful to note that (not all) abnormal pap smears are associated with HPV infection. HPV can be transmitted between partners during sexual intercourse. In such cases, in a person with an abnormal pap smear, your doctor may explore with you further your sexual history and risk of exposure to other STDs such as HIV, syphilis, chlamydia, gonorrhoea, herpes, etc. In the event of the presence of risk of exposure, your doctor may offer you further STD tests. 

STD testing and pap smears are screening for different medical conditions, as discussed above. Merely doing pap smear is unable to rule out STDs; similarly, if just doing STD tests, one is not able to know whether they are safe from cervical cancer.

How can females check for STDs?

STD tests for women usually involve vaginal swab tests, urine tests, blood tests/finger prick tests. In those who may be exposed to infection over the oral region, or the anal region, you may be offered further swab tests over the affected areas. The tests are usually done at the outpatient clinics with minimal discomfort and pain. You are encouraged to discuss with your doctor your sexual history and any abnormal symptoms that you are experiencing. Your doctor can advise you on which STD tests to consider. 

What are the differences between pap smear and STD swab tests?

A pap smear is a medical test offered for all women as part of cervical cancer screening to detect abnormal changes in the cervical cells. As cervical cell changes commonly are associated with HPV infection, the pap smear results may be suggestive of HPV infection. However, it will not tell specifically which type of HPV infection it is. This will require further testing with an HPV test. Pap smear does not automatically test for HPV strains. Pap smear is the swab of the cervix, which is the neck of the womb (end of the vaginal tunnel).

STD tests allow one to detect any sexually transmitted infections such as chlamydia, gonorrhoea, trichomonas, mycoplasma, ureaplasma, etc. You should discuss your exposure risk with your doctor so that your doctor will know which tests to consider screening for. 

Is it sufficient for me to do self-testing for STDs?

There are various STD self-testing kits available in the market. However, one should be wary when considering self-testing kits, as the test needs to be done correctly. This is especially important to female self-swab tests- one may need to be more familiar with the human anatomy, resulting in inappropriate or insufficient sampling. Furthermore, different STD infections may have different incubation periods/window periods before the test kits can pick the infection up. This can lead to a false negative result.

You are encouraged to see your healthcare provider that you are comfortable with for further guidance on STD tests, especially if there is involvement of swab tests or blood tests.

If my pap smear is normal, does it mean my HIV is normal? What is the link between HIV and pap smear?

No, unfortunately, even if your pap smear test is normal, that does not rule out HIV infection. Pap smear is a cervical swab test that evaluates for abnormal cervical cell changes; it does not test specifically for STD infections, including HIV. Pap smear does not detect HIV.

A pap smear is performed with a cervical brush inserted through the vagina to your cervix by your medical professional to obtain a sample.

HIV tests, on the other hand, are performed using blood tests, finger prick tests, and even salivary tests.

HIV, also known as the human immunodeficiency virus, is a condition in which, once a person is infected, the virus will progressively destroy that person's immune system, leading to low immunity against infections and disease. A person with HIV condition increases their risk of HPV infection (or any infection). HPV infection is associated with cervical abnormalities and cervical cancer. Hence, HIV infection does increase the risk of abnormal pap smears and cervical cancer. 

What have I learnt today?

• Pap smear tests are an essential screening tool for cervical cancer for all sexually active women.
• A pap smear test does not rule out STDs and HIV infection.
• STD tests are not able to rule out cervical cancer. 
• There may be better options for screening than self-testing STDs as it depends on availability and accuracy of the test kits, methods of collecting samples, and the window period of the disease. 
• When there is a risk of exposure, one may consider both pap smear and STD testing.
• If you have doubts or uncertainties regarding which test(s) are suitable for you, you can reach out to your healthcare provider that you are comfortable with to explore your concerns and screening options.

References

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