Aims For the diagnostic workup of postmenopausal bleeding, histological examination of the endometrium is frequently performed. Failure of endometrial sampling due to insufficient material is often reported but objective criteria for quality assessment of endometrial biopsies are lacking. The aim of the present study is to evaluate the association between the amount of tissue obtained by endometrial sampling and the diagnostic accuracy, and to establish a cut-off level for a minimal amount of tissue required for a conclusive diagnosis.
Methods For this retrospective cohort study, clinicopathological data and Pipelle endometrial sampling slides of 139 patients who were treated with hysterectomy were collected. The surface of evaluable endometrial tissue was measured by means of structured digital assessment. The correlation between the predictive values in relation to the endometrial tissue surface was calculated for different cut-off values.
Results The median endometrial tissue surface was 4.7 mm2 (range 0.4–156.4) for benign endometrium, 27.8 mm2 (range 0.0–208.4) for premalignant endometrium and 43.8 mm2 (range 0.0–223.6) for malignant endometrium. There was a significant association between the endometrial tissue surface and the correctness of diagnosis. A minimal endometrial tissue surface of 35 mm2 could be defined, for positive and negative predictive values of 92.6% and 85.7%, respectively.
Conclusions The diagnostic accuracy of Pipelle endometrial sampling is associated with the amount of endometrial tissue surface, with a minimal cut-off value of 35 mm2 required to classify an endometrial sample as conclusive. Quantification of endometrial tissue can contribute to standardisation of quality assessment of endometrial samplings.
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Handling editor Dhirendra Govender
Contributors CR scored the endometrial samples, wrote the statistical analysis plan, analysed the data and drafted the paper. NCMV scored the endometrial samples and revised the paper. JB provided intellectual support, revised the analysed data and revised the paper. LFAGM provided intellectual support and revised the paper. LJMvdP wrote the research plan and designed the data collection tools and revised the paper. JMAP coordinated the study, analysed the data and revised the paper.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Coded data are available from the original study. Both clinical data, pathological characteristics from the first biopsy and from the hysterectomy are available. Pathological characteristics from the second biopsy are, if applicable available, but non-published. Original digitalised slides are available with the measured surface selected. These data are available to the research team. All available data can be obtained by contacting the corresponding author.
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