It usually involves several genetic mutations in endometrial cells, including of PTEN, a tumor suppressor gene; PIK3CA, an oncogene; and ARID1A, a gene regulating chromatin structure.

它通常涉及子宫内膜细胞的几种基因突变，包括抑癌基因PTEN、原癌基因PIK3CA，及调控染色质结构的基因ARID1A。

If it's more than 4 millimetres thick, then a biopsy or a dilation and curettage procedure is used to remove some endometrial cells and confirm the diagnosis.

如果子宫内膜厚度超过4毫米，就需要进行活检或宫颈扩张及刮宫术，来获取子宫内膜细胞以确诊。