The Pap Smear: Why You Might Need It, Why You Might Not

By Lauren Streicher, MD Asst. Clinical ProfessorObstetrics and Gynecology The Feinberg School of Medicine

Posted on | By Lauren Streicher, MD

Pap smears are like routine car service. You’re not exactly sure what they are checking for, but you know you should do it.  Even well-informed women who know that a Pap test is primarily a screen for cervical cancer are still unsure as to whether it also checks for sexually transmitted infection, ovarian cancer, uterine cancer and general “gynecologic wellness.” So, what exactly is a Pap test?


In 1928, after spending months observing his own wife’s cervical cells under a microscope, Dr. George Papanicolaou invented the Pap smear as a method to detect cervical cancer. His discovery has stood the test of time. And Dr. Papianicolaou can be credited with the fact that cervical cancer is now a rare cause of death in the US in spite of the fact that it remains the leading cause of death in countries where Pap smears are not routinely done. (Though it seems Mary Papanicolaou should get at least some of the credit after submitting to countless Pap smears to support her husband’s research!)


Most women are familiar with the basic process: a speculum is inserted into the vagina in order to sample cells from the surface and canal of the cervix. The cells are then sent to a lab where they are checked for abnormal cell growth, also known as dysplasia, cervical intraepithelial neoplasia or CIN.


Every year, more than 3.5 million women get that stomach-dropping “Your Pap smear is abnormal” notification. But even if dysplasia is detected, the chance of a real cervical cancer is small. Out of that 3.5 million, only 13,000 are likely to have a true cancer. The rest will either ultimately be found to have nothing wrong with their cervix, or a dysplasia which is easily treated or, even more likely, goes away on its own.


If a Pap smear is abnormal, the next step is usually colposcopy, which is nothing more than a microscopic examination of the cervix done in the office. While a Pap smear samples random cells, colposcopy allows the gynecologist to inspect the surface of the cervix under magnification so that the area where the abnormality is can be targeted and biopsied. The small sample of tissue removed is then sent to a pathologist who will report one of the following:


Normal tissue

Frequently, the cervical cells are normal, which indicates that the cells reverted back to a normal growth pattern. Occasionally, abnormal cells are present, but are high up in the cervical canal, beyond the view of the colposcope, which is why a follow-up short interval Pap smear is always done.


HPV changes

Human Papilloma Virus (HPV) is responsible for dysplasia and cervical cancers. Sometimes, cellular changes indicate the presence of the virus, but there are still no actual pre-cancerous cells.


CIN I (mild dysplasia or low grade squamous intraepithelial lesions)

CIN II (moderate dysplasia or high grade squamous intraepithelial lesions)

CIN III (severe dysplasia, or high grade squamous intraepithelial lesions, also known as carcinoma in situ)


Invasive Cancer (true cancer which has infiltrated surrounding tissue and has the ability to spread)


Dysplasia is the result of infection with the HPV virus, which is sexually transmitted. Before you plot your boyfriend or husband’s murder when discovering you have been exposed to HPV, keep in mind that that exposure could have occurred years before dysplasia shows up and may have nothing to do with a current partner. 


An important distinction: Almost all women with cancer have HPV, but most women with HPV never get dysplasia or cancer. HPV is extremely common; some studies show that it is present in the cervixes of almost 80% of sexually active women. There are over 100 subtypes of HPV, but it is the high-risk subtypes that are most likely to progress to cancer. This is why if you have HPV and your gynecologist says it is no big deal, you really shouldn’t worry about it. Really.


Most women have it drilled into them that they MUST get a Pap every year, but now the annual ritual of getting a Pap smear is not necessarily annual. Initiation of Pap smears and recommendation for frequency of Pap smears have changed, and a lot of women are confused by how often they need to get one.

Guidelines are as follows:

  • Pap tests should begin at age 21
  • From 21-30, it is fine to get a pap every 3 years instead of annually as long as you are low risk, meaning you have never had moderate or severe dysplasia, cervical cancer, HIV, or have a severe medical illness that compromises your immune system. HPV testing is not necessary.
  • After age 30, every 3 years is fine, or a combination of Pap smear and HPV testing every 5 years, if both initial tests are negative. Women with a history of dysplasia or who have other risk factors should be tested more frequently.
  • After age 65, you can cross Pap smears off your “to-do” list as long as you have had a normal test for at least 10 years with the most recent test within 5 years.
  • Women who have had a hysterectomy that included removal of the cervix need not continue to get Pap tests.

Why the change? Two reasons. Most abnormal Paps have minimal potential for progression to cancer. This is particularly true for young women. In the event that a persistent dysplasia is present, the transition from pre-cancerous cells to a true cancer takes not weeks or months, but years.

So does that mean you only have to see your gynecologist every three years? Sorry, no such luck. If you don’t need a Pap, you still need to have a breast exam, STD screen, and a pelvic exam to check your uterus and ovaries. And even if you don’t need cells sampled from the cervix, your gynecologist still needs to take a peek inside to make sure your cervix and vagina look healthy.


Also, keep in mind that Pap smears don’t detect 100% of abnormalities. I biopsied a suspicious growth on a patient's cervix that turned out to be an early cancer.  Her Pap smear the year before was read as normal, and had she not come in for her annual exam, I would not have seen the growth.

Even if your car is not making funny noises and no warning lights are flashing, it’s a good idea to get the oil and brakes checked annually. Your uterus, cervix and vagina deserve the same attention. After all, if your gynecologist doesn’t look in your vagina, who’s going to? 

Article written by Lauren Streicher, MD
Asst. Clinical Professor, Obstetrics and GynecologyThe Feinberg School of Medicine