Detection of residual disease by cytology in patients with cervical intraepithelial neoplasia III post‐large loop excision of the transformation zone

Abstract

To evaluate the diagnostic accuracy of cytology in detecting residual disease in patients with cervical intraepithelial neoplasia (CIN) III post-large loop excision of the transformation zone (LLETZ). This prospective study was performed between February 1994 and August 1999 at the Department of Obstetrics and Gynecology, Ramathibodi Hospital, and involved 90 patients who underwent LLETZ and had histologic confirmation of CIN III. Simple hysterectomy was performed in all patients 2-3 months after LLETZ. Two Papanicolaou smears were taken using Ayre spatula on each patient 6 weeks after LLETZ and 1 day before hysterectomy. Histologic findings of hysterectomy specimens were used as the 'gold standard'. Forty-six cases (51.1%) were found to have residual diseases: seven cases with CIN I, 11 cases with CIN II, 27 cases with CIN III and one case with invasive squamous cell carcinoma. Using the most severe diagnosis of two Papanicolaou smears performed on each patient as the cytologic diagnosis, the sensitivity, specificity, positive predictive value and negative predictive value were 28.3, 93.2, 81.3 and 55.4%, respectively. The accuracy rate was 60.0%. Residual diseases were found in 62.5 and 39.0% of cases with the presence and absence of CIN at the margin of the LLETZ specimen, respectively. Cytology using the Ayre spatula has low accuracy in detecting residual disease in the cervix post-LLETZ.