Endometrial thickness

The endometrium, also known as the endometrium, is an important component of the uterus. The thickness of the endometrium is closely related to the metabolism of the female reproductive system. The endometrium will also undergo certain changes at different stages of a woman's life. Of course, no matter at which period, the endometrium has a normal thickness. Whether the endometrium is too thick or too thin, it is not a good thing for women.

1. Normal thickness of the endometrium

The normal thickness of a woman's endometrium is generally 2-10 mm, but it will change at different times. If a woman finds that her endometrial thickness is abnormal after a pre-pregnancy check-up, she should receive appropriate treatment in time, otherwise it will affect her future fertility.

Thin endometrium means that under the influence of certain estrogen, the endometrium cannot reach 8 mm during ultrasound. These factors may result in the egg not being able to implant properly, thus preventing conception from occurring as planned.

Generally speaking, the normal thickness of the endometrium ranges from 5 to 10 mm, and the thickness of the endometrium varies at different stages.

2. Thickness of the proliferative endometrium

In the early stage of hyperplasia, the endometrium appears as a thin echo line, about 4-6 mm thick. In the middle stage of hyperplasia, the endometrium gradually shows three strong echo lines, and the low echo area in between is two layers of functional endometrium with a thickness of about 8-10mm. In the late stage of hyperplasia, the three lines and two zones are more clearly visible, and the thickness of the endometrium increases to about 9-10 mm.

3. Secretory phase endometrial thickness

Early secretory phase: Day 15-19 of the menstrual cycle. During this stage, the endometrial glands are longer and more curved. Small vesicles containing glycogen begin to appear under the nuclei of glandular epithelial cells, called subnuclear vacuoles, which are histological features of the early stage of secretion.

Mid-secretory phase: Day 20-23 of the menstrual cycle. The inner membrane is thicker and more serrated than before. The apical cell membrane of the secretory epithelial cells in the gland ruptures, and the glycogen in the cells is discharged into the glandular cavity, which is called apocrine secretion. During this period, the interstitial tissue is highly edematous and loose, and the spiral arterioles proliferate and curl.

Late secretory phase: Day 24-28 of the menstrual cycle. This period is the pre-menstrual period. The endometrium becomes thickened and spongy. The openings of the endometrial glands face the organ cavity, with secretions such as glycogen overflowing, the stroma becoming looser and more edematous, and the stroma under the surface epithelial cells differentiate into hypertrophic decidual-like cells. During this stage, the spiral arterioles grow rapidly beyond the thickness of the intima, become more curved, and the vascular lumen expands. In the late secretory phase, the thickness of the endometrium is about 5 to 6 mm.

4. Endometrial Thickness During Menstruation

Days 1 to 4 of the menstrual cycle. At this time, the levels of estrogen and progesterone decrease, activating the synthesis of prostaglandins in the endometrium. Prostaglandins can stimulate the contraction of the uterine muscle layer and cause continuous spasm of the spiral arterioles in the functional layer of the endometrium, resulting in a decrease in endometrial blood flow. The area of ​​damaged, ischemic, and necrotic tissue gradually expands. Tissue degeneration and necrosis, increased permeability of the blood vessel wall, and rupture of the blood vessels lead to the formation of hematoma at the bottom of the intima, which promotes tissue necrosis and exfoliation. The degenerated and necrotic endometrium mixes with blood and is discharged to form menstrual blood. The thickness of the endometrium can reach 8-10mm.