Colposcopy in women with a normal Papanicolaou smear

Colposcopy is usually done when the Papanicolaou smear is abnormal so that the necessity for cone biopsy is reduced. However, there is often a strong clinical suspicion of cervical neoplasia even though the smear is normal and this problem of the false negative Papanicolaou smear has not, we feel, been adequately addressed. We, therefore, examined the usefulness of colposcopy in detecting cervical neoplasia in women in whom the Papanicolaou smear was normal.

A cross-sectional design was used which included 80 patients in whom cervical neoplasia was suspected and who had undergone colposcopy in one gynaecology unit at the Christian Medical College Hospital, Vellore. The Papanicolaou smear result of these patients was then related to their diagnosis on colposcopy.

The Papanicolaou smears were normal in 56 patients and abnormal in 24. In the normal Papanicolaou smear group there were 18 women with grade I cervical intra-epithelial neoplasia and 3 with grade II lesions. In the abnormal smear group there were 8 women with grade I cervical intra-epithelial neoplasia, 9 with grade II cervical intra-epithelial neoplasia and 1 had microinvasive carcinoma. Patients with abnormal Papanicolaou smears had a relative risk of 7.8 (95% CI 2.4 to 25.8) of having a lesion more advanced than grade I cervical intra-epithelial neoplasia compared with those in whom cervical neoplasia was only suspected clinically.

When the clinician suspects cervical neoplasia but the Papanicolaou smear is negative, colposcopy reveals at least grade II cervical intra-epithelial neoplasia in 5% of patients. Such patients, therefore, need to be followed up closely or else have a colposcopy and directed biopsy.