Klinkhamer P J, Vooijs G P, de Haan A F
Department of Pathology, University of Nijmegen, The Netherlands.
Acta Cytol. 1988 Nov-Dec;32(6):794-800.
In a study of variability in the diagnosis of epithelial abnormalities, cervical smears with abnormalities of different severity were rescreened twice by 19 observers with an interval of six months. The observers focused on grading atypicality of squamous, squamous metaplastic and endocervical columnar epithelial cells; their results were compared (1) for the two screenings to assess intraobserver variability and (2) to "review" (final) diagnoses to assess interobserver variability. When the same observer rescreened a smear, 83.3% of the diagnoses did not differ more than one grade between two screenings; however, average intraobserver variability differed considerably for individual observers. The intraobserver variability was only slightly (not significantly) influenced by the years of experience in cytopathology of the observers. Intraobserver variability proved to be an important factor in incorrect diagnoses: 49.1% of the smears with false-negative and 52.9% with false-positive diagnoses at the first rescreening were correctly assessed at the second rescreening. Of all diagnoses made at rescreening, 80.9% were in agreement with the review diagnosis. The interobserver variability also showed considerable differences between observers; however, there was a strong influence of the experience of the observer on the interobserver variability. Atypicality grading of endocervical columnar epithelium by the observers showed a low correlation with the review diagnoses. The relatively low accuracy in the evaluation of this kind of epithelial abnormality is likely to be attributable to the low incidence of abnormal changes of endocervical columnar epithelium. The results of this study point to intraobserver variability as the main cause of false diagnoses. When wrongly diagnosed, severe epithelial abnormalities are more often underestimated than completely overlooked. Apart from training in cytopathology, the establishment of laboratory protocols for multiple screening of even minor abnormalities seem to be the most effective means of reducing the number of false diagnoses.
在一项关于上皮异常诊断变异性的研究中，19名观察者对不同严重程度异常的宫颈涂片进行了两次重新筛查，间隔时间为6个月。观察者专注于对鳞状上皮、鳞状化生上皮和宫颈管柱状上皮细胞的非典型性进行分级；将他们的结果进行了比较：（1）针对两次筛查以评估观察者内变异性，以及（2）与“复查”（最终）诊断进行比较以评估观察者间变异性。当同一名观察者对涂片进行重新筛查时，83.3%的诊断在两次筛查之间的差异不超过一个等级；然而，个体观察者的平均观察者内变异性差异很大。观察者内变异性仅受到观察者细胞病理学经验年限的轻微（不显著）影响。观察者内变异性被证明是错误诊断的一个重要因素：在首次重新筛查时假阴性诊断的涂片中有49.1%以及假阳性诊断的涂片中有52.9%在第二次重新筛查时得到了正确评估。在重新筛查时做出的所有诊断中，80.9%与复查诊断一致。观察者间变异性在观察者之间也显示出相当大的差异；然而，观察者的经验对观察者间变异性有很大影响。观察者对宫颈管柱状上皮的非典型性分级与复查诊断的相关性较低。对这种上皮异常评估的相对低准确性可能归因于宫颈管柱状上皮异常变化的低发生率。这项研究的结果指出观察者内变异性是错误诊断的主要原因。当诊断错误时，严重上皮异常更常被低估而非完全被忽视。除了细胞病理学培训外，建立针对即使是轻微异常的多次筛查的实验室方案似乎是减少错误诊断数量的最有效手段。
