The endometrial stripe, otherwise known as the endometrial lining or endometrium, is a complex structure of the womb with its own microenvironment that allows it to perform tits unique function: to allow implantation of embryo, leading to pregnancy. The cells and tissue that make up this stripe is not found anywhere else in the normal woman’s body, except the inner lining of the womb; when it does appear elsewhere, it becomes a disease.
Every menstrual cycle begins with the uterus shedding its inner lining that has built up from the previous cycle. Estrogen produced by the eggs in the ovaries directly stimulates the lining to thicken, in preparation for a possible implantation of embryo when the maturing egg is released for fertilisation later on in the cycle. When this lining is exposed to abnormal levels of hormones (including estrogen), its growth may become abnormal, especially in certain women who are prone to developing conditions such as polyps or pre-cancerous changes.
When the endometrial lining invades beyond its normal boundaries, either into the muscle wall of the womb, or even beyond the womb itself, disease states of adenomyosis and endometriosis are formed. These are very common diseases affecting many women, with variable symptoms, such as painful menstruation, painful passage of urine / stools, painful sex, chronic pelvic pain and infertility. Some may not experience any symptoms at all.
Symptoms of endometrial stripe disease often include abnormal bleeding: regular heavy menstruation, irregular menstruation, prolonged menstrual bleed, bleeding in the middle of cycle, bleeding after sexual intercourse, markedly reduced or even total absence of menstruation, etc. Any such symptoms experienced (persistently) should alert the lady of possible disease of the endometrium and she should seek help from a gynaecologist.
How is the Endometrium evaluated?
The gynaecologist will conduct a thorough review of your menstrual history and risk profile for developing diseases of the endometrium. Then, complemented with a bedside ultrasound scan of the womb and ovaries, the endometrium can be clinically evaluated. The main objective of clinical assessment is to categorise the patient into high risk or low risk of developing endometrial disease; thereafter, the decision for a biopsy of the endometrium can be made.
The ultrasound scan (especially a transvaginal one), will allow the gynaecologist to measure the thickness of the endometrial stripe, which should not exceed 14mm, even during the part of the menstrual cycle when the stripe is expected to be the thickest (the limit for post-menopausal women should be less than 5mm). In experienced hands, the appearance of the endometrial stripe may also shed light on the health of the womb lining. Pre-cancerous changes and presence of polyps may be picked up or at least suspected.
Biopsy of the endometrium is the gold standard for determining the diagnosis. The biopsy may be taken in the clinic with the patient fully awake, or under anaesthesia with an endoscopic instrument (hysteroscopy). The harvested specimen will be sent to the lab for the pathologist to perform microscopic examination, to confirm the nature of the tissue and to determine if polyps, cancer and pre-cancer are present.
The Center for Disease Control and Prevention (CDC) lists five cancers that impact women's reproductive system. Cervical, ovarian, uterine, vaginal, and vulvar cancers afflict women in the United States, with uterine cancer affecting 50,600 women per year. Endometrial or uterine cancer is more frequent in women after menopause when the endometrium should be very thin (less than 5mm); hence any menopausal woman with endometrial thickness of 5mm or more should be evaluated carefully, preferably with a biopsy.
Women who do not ovulate regularly during their reproductive years (20-50 years) are at risk of having cancerous change in their endometrium. A well-known condition that affects of such groups of women is Poly-Cystic Ovarian Syndrome (PCOS). Hence women with PCOS should continue regular follow up with their gynaecologists to look for signs of such cancers forming and also consider preventive treatment wherever appropriate.
Signs and Symptoms of Endometrial Disease
The following symptoms are indicative of possible endometrial disease:
- Bleeding after menopause
- Irregular menstrual bleeding
- Heavy menstrual bleeding
- Prolonged menstrual bleeding
- Bleeding after sex
- Bleeding unexpectedly during the second half of menstrual cycle
- Markedly reduced menstrual bleeding, or absent menstruation
- Menstrual cycles longer than 35-40 days
Can Endometrial Cancer be prevented?
Although certain women are more prone to develop endometrial cancer than others, the primary stimulant for causing the endometrium to change into cancer is estrogen. Estrogen is produced in every healthy woman before menopause. The impact of estrogen on the endometrium can be counteracted by progesterone, which as also a hormone produced by ovulating women. When this balance of hormone production is lost, cancer or pre-cancer may occur.
As estrogen is fat-soluble, overweight or obese women are likely to have higher amounts of estrogen present in their bodies, hence they have a higher chance of developing endometrial cancer. Also, obese women are less likely to ovulate regular, which is another risk factor for developing cancer of the endometrium. Certain drugs may also directly stimulate the endometrium to change towards cancer / pre-cancer, such as Tamoxifen.
Diabetes is found to be another significant risk factor for developing endometrial cancer. The exact mechanism is unknown, but it may be related to obesity as well.
As estrogen is pivotal to the development of endometrial cancer for most cases, reducing the exposure to estrogen is the key to prevention of this dreaded disease:
- Pregnancy (high progesterone to counter estrogen effect)
- Breastfeeding (reduction of estrogen production)
- Combined oral contraceptive pills (contains progesterone)
- Loss of weight (less estrogen stored in fats)
- Progesterone-containing contraceptives: combined pills, Mirena intra-uterine device, progesterone implants, etc
Endometrial hyperplasia is considered the precursor of endometrial cancer. Depending on the severity of the hyperplasia, the treatment varies from cyclical progesterone or Mirena intra-uterine device, to removal of the womb. During the course of conservative treatment, regular biopsies of the endometrium is required to ensure disease response and not let cancer progression go unnoticed.
Your gynaecologist will be able to assist you in determining the best treatment choice for you.
Questions to ask your doctor
The following are just a few of the essential questions you should ask your doctor about your endometrial health:
- 1. Does my endometrium look normal?
- 2. What are my risks of developing endometrial hyperplasia or cancer?
- 3. What can I do to reduce my risks of endometrial cancer?
- 4. How can I optimise my endometrial lining for pregnancy?
- 5. Do I need to do a biopsy of my endometrium?
The endometrium is a structure that is easily assessed by an experienced gynaecologist with a simple bedside ultrasound scan. Different conditions of the endometrium may be detected by scan and subsequent decisions for biopsy may be undertaken for confirmation. Endometrial hyperplasia is usually curable, with the correct treatment regime for the specific individual. Develop a treatment plan with your physician. Regular follow-up with your specialist is essential to monitor for disease improvement / progression.