Changes to these cells may be linked to a rare form of cervical cancer called adenocarcinoma. Some women may be required to have a further test because not enough cells were picked up in the first smear or because there were small cell changes in the cervix. These may, in time, return to normal of their own accord, but will have to be monitored. Laboratories check for three types of dysplasia - mild, moderate and severe dysplasia. The severity depends on how much of the cervix is affected.
Researchers are still unclear as to the causes of abnormal cells.
But they believe women who become sexually active at an early age or have a large number of sexual partners are most at risk. However, many women carry HPVs and do not develop dysplasia. There is also research suggesting a link between long-term use of the contraceptive pill and abnormal cells, but this is not conclusive. In addition, smoking is thought to increase the risk of developing cancer. This may be because it damages the immune system which protects against HPVs.