To determine whether colposcopy
is reliable in diagnosing cervical intraepithelial neoplasia
in women who have undergone a previous cervical excision biopsy
Materials and Methods.
A prospective study of women attending the colposcopy
clinic at the University Hospital of North Staffordshire was performed between January 1998 and December 1999.
A clear histological diagnosis of the grade of cervical intraepithelial neoplasia
was available for 469 in the treatment-naive group and 58 in the treatment group. κ
coefficients comparing the colposcopic impression (negative, low-grade, high-grade, or invasion) with histological diagnosis showed that there was no difference between the treatment-naive group, weighted κ
= 0.46, and the previous treatment group, weighted κ
= 0.47. The sensitivity, specificity, positive predictive value, and negative predictive value of colposcopy
for any cervical diseasein the treatment-naive women were 93.9%, 51.9%, 96.7%, and 34.1%, respectively, compared with 77.6%, 66.7%, 86.4%, and 35.3% in previously treated women. The sensitivity of colposcopy
fell when it was used to differentiate normal and low-grade disease from high-grade disease and invasion: 82.4%, 55.9%, 82.6%, and 49.6% for treatment-naive women, compared with 61.5%, 84.2%, 60.0% and 51.6%, respectively, for the previous treatment group.
Previous treatment to the cervix does not seem to impair the ability of colposcopy
to differentiate normal cervix from all grades of cervical abnormality in women where the squamocolumnar junction is visible. However, there is a suggestion that the sensitivity of colposcopy
to differentiate negative/low-grade disease from high-grade disease/invasion is lower in previously treated women.