Your doctor or health provider performs a cervical smear to look for cervical and/or vaginal cells that are cancerous or potentially pre-cancerous. The smeared cells or cell suspension is placed on a glass slide, stained with a special dye, and viewed under a microscope by a cytotologist or pathologist. The test can also be used to detect vaginal or uterine infections. This allows infections to be treated promptly, thus avoiding further discomfort or more serious complications.

In the UK a woman registered with a GP receives her first invitation at the age of 25. There are three-yearly examinations between 25 and 49, and five-yearly examinations between 50 and 65. In other situations, a cervical smear may be requested if a woman has frequent sexual partners, is pregnant, or has abnormal vaginal bleeding, pain, sores, discharge, or itching. After three consecutive normal smears, it may be performed less frequently or as your doctor deems appropriate.

A "negative" smear means the cells obtained appear normal, or there is no identifiable infection. In some instances, the conventional cervical smear may be reported as "unsatisfactory" for evaluation. This may mean that cell collection was inadequate or that cells could not be clearly identified. A summary of other reported results follows.

• Unsatisfactory: inadequate sampling or other problem.
• Benign: non-cancerous cells, but smear shows infection, irritation, or normal cell repair.
• Atypical cells of uncertain significance: Abnormal changes in squamous cells or glandular cells for which the cause is undetermined.
• Low-Grade changes: infection with Human Papilloma Virus (HPV), which in some instances can be a risk for cervical cancer.
• High-Grade changes: very atypical cells that may result in cancer.
• Squamous cell carcinoma: cancer is evident and requires immediate attention.

The cervical smear is generally used as a screening test. A small percentage of abnormalities in women may go undetected with a single smear, which is why it is important to have smears regularly. The most common errors are those made in collecting the sample. The smear represents a very small sample of cells present in the vaginal area. Even for the most experienced nurse or physician, sample collection can be occasionally inadequate and a repeat may be required.

The cervical smear, when performed routinely, has been a great help in the early detection of cervical cancer, which is treatable if caught at an early stage. Early detection and treatment can prevent 80 to 90 per cent of cancers developing. The smear is also used to monitor any abnormalities or unusual findings. In many cases, these findings are part of a body's repair process and often resolve themselves without any further treatment. If you douche, tub-bathe, or use vaginal creams 48 - 72 hours prior to the examination, your test results might be "unsatisfactory." Other factors that may alter results include bleeding (menstruation), infection, drugs (such as digitalis and tetracycline), or having sexual relations within 24 hours prior to examination.

In these cases, a repeat smear may be necessary but does not necessarily mean there is a significant problem. In some instances, the use of the liquid-based techniques may eliminate some of the obscuring materials (blood and mucus) that may prevent a clear and uncluttered presentation of cervical cells. A second advantage is that the same sample may be used to perform additional testing for HPV if appropriate.