Family doctor

Overview:

• Cervical smears are used to identify abnormal changes in the cervix
• Cervical smears take cells from the surface of the cervix for laboratory analysis
• Cervical screening should be carried out between the ages of 20 - 70
• Smears are recommended every three years for healthy women
• Women who have had high-grade abnormal cells should have yearly smears
• Cervical screening can save lives from early treatment of pre-cancerous cells
• Abnormal cells can take about 15 years to progress to cancer
• Women should not have smears during menstruation

What is a cervical smear?

A cervical smear is a test to determine if there are any early changes in the cells of the cervix, before they can progress to cancer.

The cervix is at the lower end of the uterus and connected to the top of the vagina. It is 3cm long and about 3cm wide and has a central canal that links the vagina to the interior of the uterus.

In New Zealand, about 200 women develop cervical cancer annually and these women are more likely to have infrequent cervical smears.

Why have a cervical smear?

The purpose of regular cervical smear screening is to significantly reduce the number of women who will develop cervical cancer. The cervical smear is aimed at early detection of potentially cancer forming cells (these pre-cancerous cells are called Cervical Intraepithelial Neoplasia or CIN). Effective treatment of abnormal cells then halts their progression to cancer. This progression to cancer is generally very slow and in the order of 15 years. No screening programme will however prevent all cancers.

Who needs a cervical smear?

* In New Zealand, sexually active women (including lesbians) start regular screening at age 20 years and stop at 70 years if their smears are normal.

* The usual interval is 3 yearly for women with normal smears. After her first ever cervical smear the second should be done one year later. If a woman has a five or more year gap between smears, then a further smear should be taken one year later.

* Women who are immunosuppressed (e.g. with HIV or Aids infection) should have annual cervical smears.

* Women who have had a hysterectomy with removal of the cervix fall into two groups:

1. Those who have no prior history of abnormal smears - do NOT need any more smears.
2. Those who have had abnormal cervical smears are at risk of abnormal cells occurring in the skin at the top of the vagina (vaginal vault) and smears need to be taken annually from this area.

* Some women have a form of hysterectomy whereby the uterus is removed and the cervix remains (subtotal or supracervical hysterectomy). These women should continue usual screening.

* For women with symptoms suspicious of cervical cancer, then the cervical smear is only part of the investigation. A reassuring cervical smear result in these situations cannot be used to override any clinical concerns.

How is a cervical smear done?

A cervical smear is better taken when a woman is not bleeding vaginally as blood can make the assessment difficult or impossible.

A cervical smear is performed with the woman lying on her back or side, and an instrument called a speculum, is placed gently into her vagina to allow the cervix to be seen. Cells are taken from the surface of the cervix by lightly wiping it with a plastic or wooden spatula, and sometimes a fine plastic brush. The cells are then smeared onto a glass slide which can sometimes cause uneven layering and overcrowding of cells and difficulty with accurate diagnosis. Recently there has been interest in "Thin Prep" smears which involves rinsing the collection device into a vial of preservative solution so that the cells are more evenly distributed and less likely to be obscured by blood or mucus. Preliminary studies report improved detection of abnormal cells.

Cervical smears can be taken by a doctor or approved nurse. The actual procedure usually takes less than 5 - 10 minutes.

It is important that a woman is individually aware of her result and she and the smear taker must be clear as to how the result will be communicated

What do the results of the cervical smear mean?

* Most results will be normal and the next smear will be due in 3 years.

* Sometimes the smear may be unsatisfactory. This means an accurate result is not obtained because of insufficient cells, or the cells are obscured by mucus or blood. A repeat smear is advised in 1 - 3 months.

* Some smears suggest the cervical skin is "inflamed". It is not a serious condition and usually does not require treatment.

* Occasionally an infection can be suggested on the smear and then the woman may need to have swabs taken to identify a specific infective organism, so that correct treatment is given.

* An abnormal cervical smear result means the cells have changes that can range from mildly abnormal and non-specific, to the more serious. In the vast majority of women, these changes will still be pre-cancerous and can be effectively treated. Abnormal cervical smear results will either warrant a repeat smear within 6 months or referral to a specialist for more detailed examination by colposcopy. This procedure usually takes 10 - 15 minutes and involves close inspection of the surface of the cervix with a microscope (colposcope) that can focus inside the vagina.

How reliable are smears?

There are rare occasions where a single cervix smear can appear normal when in fact there are abnormal cells present in the cervix (false normal results). The cervical screening programme makes allowances for this by having repeat smears and takes into account the long time (of around 15 years) needed before abnormal cells become cancerous. Also rarely, a cervix smear may appear abnormal, when in fact the cervical skin is normal (a false abnormal result). This situation is clarified by repeat smears and colposcopy.

It is vitally important, that if a woman has abnormal symptoms she see her doctor as soon as possible and be examined, regardless of when her most recent smear was. Symptoms to be aware of include:

* Bleeding between periods, after sex or after the menopause.

* Unusual vaginal discomfort or discharge.