Weefselonderzoek van het baarmoederslijmvlies

Endometrial tissues used to be classified by the World Health Organisation 1994 hyperplasia classification (WHO94). This classification is based on morphological features of architectural complexity and nuclear atypia. The WHO94 classification has four categories of risk classification for hyperplasia: 1) simple hyperplasia (SH), 2) complex hyperplasia (CH), 3) simple hyperplasia with atypia (SAH), and 4) complex hyperplasia with atypia (CAH).A newer method is classification with the endometrial intraepithelial neoplasia (EIN) system. This system is based on constellation of quantitative morphological measures associated with clonality. The diagnosis of EIN must meet five criteria in a single fragment, including architectural gland crowding, altered cytology, minimum size of 1 mm, exclusion of carcinoma, and exclusion of mimics. The diagnosis of EIN can be summarized as a focus of clustered endometrial glands exceeding a gland to stroma ratio of 1:1, which have altered cytology from the background endometrium, and which comprise a sufficient volume of 1 mm. These pathologic criteria were used to develop three disease categories: 1) benign, 2) endometrial intraepithelial neoplasia, and 3) malignant endometrial disease. One of the major strengths of the EIN system is its correlation to outcome: a biopsy diagnosis of EIN imparts a 45-fold increased risk of progression to carcinoma after the first year. After the diagnosis EIN hormonal treatment or a hysterectomy is advised. Endometrium samples were formally obtained through dilatation and curettage (D&C) for which general anaesthesia is warranted. Nowadays, office endometrium sampling (OES) is the first diagnostic step in women presenting with pre or postmenopausal abnormal uterine bleeding, in women with abnormal ultrasonographic features of the endometrium, in women with abnormal smears and in women with a hereditary increased risk of endometrial cancer, like Lynch syndrome. To our knowledge no study is performed to examine the accuracy of EIN in an OES. Neither is information available on the hazard of finding an endometrium carcinoma within twelve months after the diagnosis of EIN in an OES.
This study is an exploratory observational multicentre prospective clinical cohort study. Women aged 40 years and polder, with any indication for endometrial sampling, visiting the Bravis hospital (Bergen op Zoom),Albert Schweitzer hospital (Dordrecht), Fransiscus Gasthuis (Rotterdam) or the Erasmus MC (Rotterdam) will be asked for consent.

Office endometrial sampling is not suitable to diagnose EIN due to the small amount of tissue obtained.

Since data on the prevalence of EIN in OES was not available we started recruitment without a pre-set of patients needed to include. Interim analyses showed that we need approximately 500 participants to have about 25 EIN diagnosis. Therefor we expect that accrual can stop end 2019.

Women with a planned, standard samplig procedure are recruited. No additional interventions are done for the purpose of the study.