Accuracy of the diagnosis in suspected intraepithelial neoplasia of the cervix.

520 patients with a preoperative diagnosis of cervical intraepithelial neoplasia (CIN) were operated. The diagnoses obtained by colposcopically directed biopsy and endocervical curettage were compared with those obtained by cone biopsy or/and hysterectomy. Underdiagnosis occurred in 18.9% of the cases, if severe dysplasia and carcinoma in situ were considered to be separate conditions. When these two diagnoses were combined as CIN 3 the underdiagnosis rate declined to 11.0%. CIN 3 changed to invasive carcinoma in 1.5% and to microinvasive carcinoma in 4.4% of the cases. The preoperative diagnosis of CIN seems not to be accurate enough to make cone biopsy totally unnecessary as a complementary diagnostic step.