Why an abnormal Pap smear doesn't always mean you have cancer

• An abnormal Pap smear means some percentage of your cervix cells appear abnormal in shape or size.
• In most cases, an abnormal Pap smear does not indicate cancer and is in fact caused by HPV.
• If you have an abnormal Pap result, your doctor may order further testing like a biopsy.

A Papanicolaou test, commonly called a Pap smear, tests for abnormal cells in your cervix - the area connecting the uterus to the vagina - and determines if these cells may be precancerous (called dysplasia) or cancerous. The goal of a Pap smear is to detect abnormalities before they become cancer. It may take up to three weeks to get your Pap smear results back.

An abnormal Pap smear result indicates some cervical cells appear irregular. But, that doesn't always mean cells are cancerous. Every year around three million people receive abnormal Pap results, but less than 1% of them are diagnosed with cervical cancer.

Here's what you need to know about abnormal Pap smear results and why it doesn't always mean you should worry.

What does an abnormal Pap smear mean?

A healthy cervix contains cells that are flat and thin, akin to microscopic fish scales. An abnormal Pap smear means that some percentage of cells collected during the test look abnormal in size, shape, or other characteristics.

How many abnormal cells there are and how abnormal the cells appear determines how results are graded, says Sarah Feldman, MD, a gynecologic oncologist at Brigham and Women's Hospital. There are three grades of abnormality:

• High-grade: Cells that can have moderate to severe changes and are more likely to be precancerous or cancerous.
• Low-grade: Changes that are less severe.
• ASCUS: cells appear slightly abnormal, but not to the degree of being clearly precancerous. Your doctor may order another Pap smear.

An abnormal Pap smear may lead to a biopsy to gather more information and confirm or deny the results of the test. So, even if you have a high-grade Pap, your diagnosis could be changed to a low-grade after the biopsy results.

What causes an abnormal Pap smear?

If your Pap smear is abnormal, that usually does not mean you have cervical cancer. In fact, in most cases, an abnormal Pap smear is caused by the human papillomavirus infection or HPV, says Monica Well Rosen, MD, an assistant professor at Michigan Medicine Voigtlander Women's hospital.

HPV is a very common sexually transmitted disease affecting about 80% of sexually active people at some time in their life. There are over 200 variations and 14 that are considered high risk for cancer, but only two types lead to a majority of cervical cancer cases. Therefore, if your abnormal Pap smear indicates HPV, the chances of developing cervical cancer are still slim.

In most cases, an HPV infection will resolve itself within six to twelve months, but during that time can cause changes to the cervix. Most low-grade changes will disappear over time, but higher-grade changes may persist and become precancerous.

Important: It is best to prevent HPV in the first place, which is why medical experts highly suggest you get the HPV vaccine. This protects against multiple types of HPV, including the two known to cause a majority of cancer cases.

It's important to catch changes in the cervix early to prevent them from progressing to cancer, says Rosen. That's why it's essential to get Pap smears regularly. You should start regular Pap smears at the age of 21, and continue having the test every three years, or every five years after 30.

There may be other causes to an abnormal Pap smear as well, including:

• Yeast infections, or other inflammation due to infections
• Herpes, a sexually transmitted disease
• Recent sexual activity as sex could obscure abnormal cells
• Menopause, aging can cause cell changes, which isn't necessarily dangerous
• Poor sample where your cells that the doctor tested may be inconclusive, so you may need another Pap smear.

What the research says: Some people believe there is a relationship between stress and abnormal Pap smears, but more studies are needed. One large 2012 study found women who tested high in stress did not have significant abnormal Pap smears. It concluded there was no evidence to support that stress or depression has any impact.

What happens after an abnormal pap?

In the case of an abnormal Pap smear, there may be some follow-up tests after the results.

HPV test: Depending on the sample, a doctor may be able to run an HPV test with your Pap smear sample. This is called co-testing. Otherwise, they will test cells from the cervix with the use of a speculum, the same tool used for your Pap smear to open up your vagina. For people over 30, HPV tests are scheduled every few years along with your Pap smear.

Colposcopy: This test is often run if results are high-grade or if abnormalities are found in combination with an HPV positive test. With a magnifying instrument called a colposcope, your doctor will closely examine your cervix for abnormal areas. The procedure takes about 15 to 20 minutes and only further examines your cervix. If the doctor spots anything abnormal, then they will move on to a biopsy.

Cone biopsy If the colposcopy finds suspicious areas, then the doctor may conduct minor surgery to remove abnormal areas. The sample is then analyzed for cancer. You will be put under a general anesthetic for the procedure which lasts around 15 minutes.

If the biopsy confirms cancer, depending on the patient, you could choose to have your uterus removed, also known as a hysterectomy, says Rosen. If the cancer is affecting only a small portion of the cervix, the patient may opt for a trachelectomy to remove just that section. Or, patients may undergo chemotherapy depending on the severity of cancer.

Insider's takeaway

A Pap smear can help determine if you have abnormal cells in your cervix that are cancerous or could lead to cancer.

Abnormal cells can be high-grade, which means the changes in your cervix are severe, or low-grade, which means the changes are less so. The results can also be unclear, which means you may need more testing.

Keep in mind that abnormal Pap smears are common but rarely indicate cancer. Most abnormal test results are due to an HPV infection, which is mostly mild and goes away with time.

If you have an abnormal Pap result, you may take an HPV test or your doctor may perform further tests like a biopsy.