Important: This is intended as general information only. It may not apply to your specific situation.  It is not a substitute for medical advice.  If you have a question or concern, please raise it with me at your next appointment or contact me sooner if it's urgent.

Cervical Screening Test (CST)

What is the CST?

As of December 2017, the CST has replaced the pap smear as a screening test for changes in the cervix which, if left untreated, can eventually turn into cervical cancer.  The CST is a screening test - this means that it is a test performed in healthy women with no symptoms.  The purpose of a screening test is to detect problems in their early stages so that we can intervene to prevent further problems down the track. The CST is a DNA test that detects the Human Papilloma Virus - specifically, it detects versions of the virus which are associated with cancer.  This test is more reliable than the pap smear it replaced.  In Australia, it is recommended the all women over the age of 25 who have ever been sexually active should be screened.  If the CST is negative (normal), this means you don't carry any of the versions of HPV that can cause cancer.  Women with a negative test should have the test repeated every five years.  Women with abnormal test results require further investigation.  It is important to understand that an abnormal CST does not mean that you have cancer.  It just means that there is something going on and we need to have a closer look to determine whether you need treatment and how to follow you up in the future.

Women who have symptoms, such as abnormal bleeding, will usually have a CST performed as part of the initial investigation of their symptoms.  This is often done in women who are younger than 25 or women who are up to date with their screening tests.

What is HPV?

HPV is a very common virus that most people are exposed to at some point in their lives.  There are many different sorts of HPV, some of which can infect the skin in the genital area and the cells in the vagina and cervix.  Other forms of the virus are responsible for the common warts that people get on their skin in other parts of the body.  The virus is spread by skin contact during sex and almost everyone who has been sexually active will have come into contact with it.  Although, technically, it is a sexually transmitted infection (STI), it’s better to think of it as a normal part of having sex as almost everyone who does so will become infected.  Condoms, which are very effective in protecting against other STIs, offer only limited protection against HPV. 

Some forms of HPV can cause changes in the cells of the cervix.  These changes are called cervical dysplasia.  Over time, some cases of cervical dysplasia can progress to become cancer.  Not all cases of cervical dysplasia progress to cancer.  In fact, most of them don't.  However, since this is a possibility, we take all cases seriously.  Cervical cancer usually doesn’t cause any symptoms until it is very advanced which makes it difficult to treat, so it is particularly important to pick up these early changes.  Forms of HPV that can cause cancer are known as oncogenic HPV.  Different forms of HPV are numbered.  There are 14 different type of HPV associated with cancer, all of which have their own number.  HPV 16 and HPV 18 are the two forms most commonly associated with cancer.  These two are considered to be higher risk than the other oncogenic HPVs.

Most people pick up HPV after becoming sexually active but their immune system manages to detect it and gets rid of it.  However, the virus is quite good at hiding from the immune system and can persist in the cells of the vagina and cervix for many months or even years.  It not usually possible to know where your particular HPV came from or how long you have had it.  Some women carry the oncogenic HPV but don't have any cell changes.  If the virus causes cell changes, it is still possible for the immune system to clear the virus after these changes have occurred.  In a small number of cases, however, these changes progress and can, eventually, turn into cancer.

There is nothing you can do to ‘boost’ your immune system in order to make it more likely to clear the virus.  However, you can make it harder for your immune system to clear it by smoking.  There are plenty of other reasons not to smoke, of course, but it is well established that being a smoker makes it much harder for your immune system to clear HPV and, in turn, more likely that cervical dysplasia will progress to cancer. 

Some women may need, for medical reasons, to take drugs that suppress the immune system which may cause them to have persistent HPV infection.  Generally speaking, these women need to continue their medication (immunosuppressant drugs are usually only required for quite serious illnesses so stopping the medication is not an option) so they need to be followed very closely and may require more frequent screening than the general population.

CST results

The CST is reported in a way than can be confusing.  When I see you in the rooms, I will go through your report with you and explain it to you in detail.  The results are summarised as 'low risk', 'intermediate risk' and 'higher risk'.

Low risk CST
his is also sometimes describes as a negative or normal CST.  This means that none of the forms of HPV that are associated with cancer were found on your sample.  This is very reassuring.  However, it does not mean that you will never pick up one of these viruses.  You still need to have regular CSTs performed - the next one in five years.  This seems like a long time, especially as we are used to having pap smears every two years.  However, the cell changes that develop as a result of HPV take many years to progress to cancer so screening every five years is safe.

Intermediate risk CST

This means that you have been found to carry one of the viruses that can cause cancer, but not either of the two most common forms (HPV 16 or 18). Some labs report each form separately, some will report this as 'non 16/18'.  If a non 16/18 virus is detected, the lab will then (from the same sample) look at the cells included in the sample to see if they show any changes.  If there are no changes seen, you don't need further treatment immediately.  It is recommended that you repeat the CST in 12 months.  If the HPV is still there, we will need to have a closed look with a colposcopy - more about that later.  If, a year later, your immune system has cleared the virus you can return to having a CST every five years.

Higher risk CST

This means that HPV 16 or 18 was detected or one of the other oncogenic strains was found and you had some cell changes.  If you have a higher risk result, you will need to see a gynaecologist (like me) for a colposcopy.

What is a colposcopy?

Finding oncogenic HPV and even seeing some cell changes doesn’t actually make a diagnosis.  In order to do this, we need to take a closer look at the cervix.  This involves a small procedure, done in the rooms, called a colposcopy.

A colposcope is a microscope with an attached light.  Women having a colposcopy lie on a gynaecology couch to support their legs and a speculum (exactly like that used for the CST) is inserted into the vagina.  Because of the special leg supports, this is usually more comfortable than having a speculum examination on a standard bed.   I then use some dyes to (temporarily!) stain the cervix and look at the cervix with the microscope to see if I can see any abnormal areas.  If I can see anything abnormal, I will then take a small biopsy which will be sent to a laboratory to be examined by a pathologist.  Although the biopsy is very small – a couple of millimeters – it is usually big enough for a skilled pathologist to make a definitive diagnosis so that we can plan where to go from there.

There is sometime a small amount of light bleeding or spotting from the biopsy site and often a dark discharge as the dye used to stain the cervix works its way out.  It is recommended that women who have had a cervical biopsy avoid using tampons or having sex for about 48 hours or as long as the discharge persists.  Some women experience mild 'period-type' cramps for an hour or so after a biopsy.  These usually reposed well to simple pain killers like paracetamol or ibuprofen. The whole procedure takes between five and ten minutes. Although it is not comfortable, most women tolerate the procedure very well and tell me that it was better than they were expecting. 

I will, of course, tell you what I can see when I look at the cervix and what I think the diagnosis is.  The final diagnosis (and therefore the plan for follow up and treatment) will depend on the results of the biopsy.  In most cases, I can discuss this with you over the phone once the results are available.

Can I treat the HPV?

No, unfortunately we don't have a specific treatment for HPV.  We rely on your immune system finding and eliminating the virus.  However, we can treat cervical dysplasia (cell changes) to prevent them progressing to cancer. 

Treatment for cervical dysplasia

Cervical  dysplasia is divided into two categories - low grade squamous intraepithelial lesion (LSIL) and high grade squamous intraepithelial lesion (HSIL).  As you might imagine, HSIL is more concerning than LSIL 

LSIL, particularly in young women, may not require treatment.  In most cases it will resolve spontaneously.  However, it is extremely important that women with a LSIL have regular follow up. In the first instance, it is recommended that the CST and colposcopy be repeated in twelve months.  If the LSIL persists, we keep an eye on it it (usually annually) until it the virus is cleared and the cell changes resolve.  It is unlikely that the abnormality will get worse but, if it does, treatment may be required.  In older women or women with previous abnormalities or other health problems, we may move on to treatment a little earlier.

It is recommended that HSIL be treated.  This is because, over time, the cells may become significantly more abnormal and progress to become cervical cancer.  This does not happen to all cases of HSIL.  In fact, may of them will resolve without treatment.  Unfortunately, however, we are not very good at predicting which ones will resolve and which ones will progress or persist so it is recommended that all be treated.

There are a number of different ways that cervical dysplasia can be treated.  They all involve a small procedure to destroy or remove the abnormal cells.  This is usually done under general anaesthetic.  The most common procedure performed is called a LLETZ (which stands for Large Loop Excision of the Transformation Zone – the transformation zone is the area on the outside of the cervix where the abnormal cells are seen).  A small wire loop with an electrical current running through it is used to shave off the abnormal cells.  The electrical current cauterizes blood vessels to reduce bleeding from the cervix.  This is done in a day procedure unit.  The procedure itself only takes 10 – 15 minutes although the whole process of coming into hospital, having the anaesthetic, have the procedure and waking up enough to be able to go home again takes three to four hours.  You will usually require two days off work.  It is normal to have some mild crampy pain after the procedure and a light, bloodstained discharge for up to a few weeks after the procedure.  It’s recommended to avoid using tampons, having sex, swimming or soaking in a bath or spa until the discharge has completely settled.  If you require treatment for HSIL, I will discuss this with you in more detail.

More severe abnormalities or abnormalities that are higher up in the cervix or involve the glandular cells, may require a cone biopsy.  This involves a larger, cone shaped piece of tissue being removed from the cervix.  As well as the ability to excise a larger abnormality, this also gives the pathologist a larger piece of tissue to look at under the microscope so may be used in situations where there is uncertainty about the diagnosis or if we are particularly suspicious of an early cervical cancer.  If you find yourself in the situation, I will, of course, discuss it with you in detail.

Follow up after treatment

Treatment of cervical dysplasia removes the abnormal cells but does not specifically treat the HPV.  Often, as part of the postoperative healing process, you immune system finds the virus and clears it although this is not guaranteed.  Therefore, you will require follow up to ensure that the abnormality has resolved and to determine whether the HPV have been cleared.  Even if all the tests are reassuring, it is recommended that you be followed up for 2 years after treatment before you can be signed off a 'cured' and return to five yearly CSTs.  Routine follow up occurs at six months, 12 months and 24 months after surgery.

HPV vaccination

A vaccination against HPV – Gardasil – has been available since 2007.  Currently it offered to all year 8 students (the idea being that it would be good to vaccinate young people before they become sexually active).  The vaccination protects against four common strains of the virus, two of which are known to cause cervical cancer and two of which cause genital warts. In 2019, this will replaced with a vaccine that covers nine strains of the virus. Three doses of the vaccine are required, over a six month period. Hopefully, this will mean many fewer abnormal pap smears and cases of cervical cancer in the future.  Most of my patients are too old to participate in the government-funded year 8 immunisation programme.  It is possible to get the vaccine through your GP and I recommend this, particularly for women in their twenties who have not previously been vaccinated.  It is likely that older women have already been exposed to the virus so vaccination may not be as useful for them.  Its not necessary to have the vaccination if you are coming to see me with an abnormal CST – we already known that have been exposed to the virus (that’s what made the CST abnormal in the first place) and hopefully, over the course of observation or treatment, your immune system will clear the virus and you will become immune as a result.

Its important to remember that you still need to have pap smears even if you have been vaccinated.  This is because there are lots of different strains of the HPV virus.  The vaccine protects against four of the most common strains but you may still come into contact with one of the less common strains.

Abnormal pap smears and pregnancy

Occasionally, an abnormal CST will occur during pregnancy.  If you are pregnant and your CST is due, please let me know so that I can advise you on the best time to have it done.  It is quite safe to have a CST during pregnancy. 

If your CST shows a intermediate risk result during pregnancy, it is usually fine to wait until after delivery to investigate it further.  If a higher risk result is returned, particularly if it is found early in the pregnancy, it is usually a good idea to have a colposcopy straight away.  We don’t generally treat cervical dysplasia during pregnancy, although this can be done safely if necessary.  Because the abnormalities progress slowly, it is usually fine to wait until after delivery to think about treatment.  If you were planning to have treatment and found yourself pregnant before the procedure it’s fine, in most cases, to defer the procedure until after delivery.  However, it is important that we keep an eye on the abnormality to make sure that it doesn’t progress during the pregnancy.  It is completely safe to have a colposcopy during pregnancy.