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The endometrium is the innermost lining of the uterus. Where implantation of the embryo takes place. It comprises a single-layered prismatic epithelium and cell-rich connective tissue with blood vessels that surround the uterine glands. The single-layered prismatic epithelium consists of three types of cells: secretory cells, cells with cilia, and basal cells. The uterus is one of the few organs of the human body which changes in size every month, throughout the female’s fertile years. The endometrium is mostly made up of mucosal tissue and has two layers, the stratum basalis and the stratum functionalis. The stratum basalis is attached to a layer of smooth muscle tissue of the uterus known as the myometrium. This layer serves as an anchor for the endometrium of the uterus and remains relatively unchanged. However, the second layer is dynamic and changes in response to the monthly hormone flow that guides the menstrual cycle. Because of this reason, it is called the functional layer or stratum functionalis. It is the part of the endometrium where the fertilized egg will implant if the female conceives.

Each month, as part of the period cycle, a female’s body prepares the endometrium to host the embryo. The endometrial thickness increases and decreases during the whole process. The hormones estrogen and progesterone cause these cycles of endometrial growth. They are also responsible for shedding endometrium through menstruation if the female does not get pregnant. The endometrium thickness in pregnancy plays an essential role in determining issues during pregnancy. The endometrium is the uterine lining where the embryo implants to commence pregnancy. The endometrium’s thickness changes in each pregnancy month, and it is also a parameter assessed during imaging tests, ultrasound scans. The doctor may check the endometrium thickness to determine the underlying cause of any abnormal uterine bleeding during pregnancy.

In this post, we tell you about the normal endometrium thickness during pregnancy and the various abnormal changes in the tissue’s thickness. The morphology and thickness of the endometrium remain constant before puberty and in menopause.

Normal Thickness Of The Endometrium:

According to a study conducted in Shanghai Jiaotong University, the rate of implantation, clinical pregnancy, and ongoing pregnancy was higher among women who had an endometrial thickness between 8-14mm. The pregnancy rate was negatively affected among the women with stripe’s thickness less than 7mm. The normal thickness of endometrium varies at different stages of the menstrual cycle in premenopausal women. Endometrial thickness can also be used as a predictor for normal intrauterine pregnancy if there are vaginal bleeding and sonographic diagnosis of pregnancy of unknown location.

**The following chart can give you a better idea of how the thickness of endometrium varies during the cycle: **

What Causes Thickness Of Endometrium?

Both pregnant and non-pregnant women can have an abnormally thickened endometrium due to various reasons.

In pregnant women, thickened endometrium could be due to:

• Pseudogestational sac
• Mola, which can make the endometrium look thick
• Retained products of conception
• Heterogeneously thickened endometrium, which could be due to fluid collection
• Molar pregnancy, wherein the multiple small cystic spaces make the endometrium look thickened
• Heterogeneously thickened endometrium due to an intrauterine blood clot
• Inflammation of the uterus, also called as endometritis

In non-pregnant women, it could be because of:

• Endometrial polyp, or benign protrusions on the endometrial surface
• Endometrial carcinoma that gives it a thickened appearance
• Endometrial hyperplasia or over-thickening of the endometrium
• Tamoxifen-related changes causing variable appearances of the endometrial surface
• Endometritis

What Are The Symptoms Of An Abnormally Thick Endometrium?

• Menstrual cycle shorter than 21 days or longer than 38 days
• Heavier bleeding during periods
• Spotting between periods
• Longer periods than usual

It is recommended that you visit your doctor if you are experiencing abnormal vaginal bleeding and pelvic pain.

How Is Abnormally Thick Endometrium Diagnosed?

Transvaginal ultrasound helps in identifying abnormal endometrium thickness.

How Does The Endometrium Look Like?

The endometrium looks like a dark line on an MRI or ultrasound scan, and it’s called endometrial stripe. Here is how the appearance and thickness of endometrial stripe change during the menstrual cycle,

• Menstrual and early proliferative phase: it appears as a thin and bright echogenic stripe that consists of a basal layer with minimal fluid.

• Late proliferative phase: It comprises the basal layer, middle functional layer, and the inner echogenic stripe at the center. A trilaminar appearance is seen in this phase.

• Secretory phase: Endometrium is the thickest during this phase. The stripe has fluid surrounding it and thus looks uniformly echogenic in an ultrasound.

How Is It Treated?

Treatment will depend on the cause for thickening. You should see the doctor and discuss the treatment options.

What Causes Thinning Of The Endometrium?

Thin endometrium results from the impairment of the normal growth of the endometrial tissues. The most common cause is menopause and it is natural. And, Other causes are

• Decreased blood flow to the endometrium
• Permanent damage to the basal endometrium
• Testosterone overexposure
• The resistance of estrogen by endometrium surface receptors

Can Endometrial Thickness Indicate Early Pregnancy?

According to research reports from the University of Texas Southwestern Medical Center, Endometrial thickness between 8-40mm was noted in intrauterine pregnancies of unknown location. Among this, 70% of women had an endometrial thickness between 13-25mm. This study also shows that 70% of women with ectopic pregnancy had an endometrial thickness of less than 13mm Endometrial thickness can indicate early pregnancy, be it normal or abnormal (ectopic).

Infographic : How To Improve Endometrium Function And Thickness Before Pregnancy?

Go through the infographic to learn ways to enhance endometrial functions and thickness before pregnancy. Reaching ideal endometrial thickness and functions before conception increases the chance of pregnancy. It also enhances the outcomes of assisted reproductive technologies.