Disordered proliferative endometrium is a result of an anovulatory cycle that lacks ovulation and leads to high levels of estrogen from low progesterone levels. The University of Virginia School of Medicine describes anovulation as the absence of ovulation during the reproductive years, not including pregnancy, and is the most common cause of dysfunctional uterine bleeding. Anovulation commonly occurs at menarche and at menopause.
The exact cause of anovulation is not fully understood, according to the University of Virginia School of Medicine. In the absence of progesterone, the spiral arterioles do not develop properly. Once estrogen levels decline, there is a loss of stromal fluid and potential break-through bleeding occurs. However, in some cases when there is no drop in estrogen levels, bleeding can still occur because the necessary blood flow to the proliferative endometrium is not steady.
In a histological test, doctors can determine that there is estrogen stimulation but no progesterone production. When endometrial glands are proliferative, a histology report shows changes in the shape and structure, which are subtle. One of these mild changes is cystic dilation. When the stroma is broken down, pieces of isolated glands do not secrete, notes the University of Virginia School of Medicine.