Inter‐ and intra‐observer variation in the histopathological reporting of cervical squamous in traepithelial lesion susing a modified Bethesda grading system
Authors: McCluggage W.G. , Walsh M.Y. , Thornton C.M. , Hamilton P.W. , Date A. , Caughley L.M. , Bharucha H. 
Published: August 2005

Objective
1. To assess inter‐ and intra‐observer variation in the histopathological reporting of cervicalcolposcopic biopsies using a histologic modification of the cytological Bethesda grading system; 2. to determine the histologic profile of those cases which resulted in diagnostic disagreement.Methods
Consecutive cervical colposcopic biopsies (n= 125) were assessed independently by sixexperienced histopathologists. Cases were classified as normal, low grade squamous intraepitheliallesion or high grade squamous intraepithelial lesion. Six months later the process was repeated. Thedegree of inter and intra‐observer variation was assessed by kappa statistics. All cases in which therewas less than perfect inter and intra‐observer agreement were reviewed by the coordinator of thestudy.Results
In the first round of the study inter‐observer agreement was generally poor, with unweighted andweighted kappa values ranging from 0.15 to 0.58 (average 0.30)and from 0.21 to 0.61 (average 0.36)respectively. In the second round inter‐observer agreement was better, with unweighted andweighted kappa values ranging from 0.08 to 0.55(average 0–33) and from 0.22 to 0.59 (average 0.42). Ten of the 15pairs of observers achieved fair inter‐observer agreement using weighted kappaanalysis. The degree of intra‐observer agreement was better, unweighted and weighted kappa valuesranging from 0.26 to 0.61 (average 0.47) and from 0.34 to 0.62 (average 0–51) respectively. Two ofthe six participants achieved fair intra‐observer agreement and two achieved good intra‐observeragreement using weighted kappa analysis. There were marked difficulties in the separation of normalsquamous epithelium from low grade squamous intraepithelial lesion and in the separation of lowgrade from high grade squamous intraepithelial lesions. Histopathological review revealed thatmany of the difficulties in the separation of normal and low grade squamous intraepithelial lesionwere in the distinction between superficial vacuolated cells and true koilocytes. Difficulties alsoresulted in the separation of basal cell hyperplasia, inflammatory associated changes and immaturesquamous metaplasia from low grade squamous intraepithelial lesion. Conditions which resulted indifficulty in the separation of low grade and high grade squamous intraepithelial lesions includedflorid koilocytotic change and immature metaplastic squamous epithelium with atypia. In somecases, there was a full spectrum of diagnoses from normal to high grade squamous intraepitheliallesion. These were largely cases of immature metaplastic squamous epithelium with atypia and ofthin or atrophic squamous epithelium with atypia.Conclusions
Most pairs of observers can achieve fair inter‐observer agreement in the reporting ofcervical colposcopic biopsies using a modified Bethesda system. Intra‐observer agreement is alsogenerally fair to good using this system. It may be that a two tier grading system is more appropriatefor the histopathological reporting of these biopsies than the traditional three‐tier intraepithelialneoplasia (CIN) system.