Uterine Polyps and Endometrial Thickening: What’s the Connection?

What Are Uterine Polyps?

Also known as endometrial polyps, uterine polyps are growths attached to the inner wall of the uterus that extend into the uterine cavity. They are formed after the cells lining the endometrium, which is the inner lining of the uterus, start to overgrow. While most of the time, uterine polyps are non-cancerous in nature, i.e. benign, some can be malignant or turn cancerous over time.

In size, uterine polyps can range from a few millimetres to several centimetres, and a woman can have one or more such growths at the same time. While they can occur at any stage of the reproductive age, polyps are more common in women aged 40 to 50. Sometimes, they can also happen after menopause. Age plays a huge role in the development of these polyps.

The chances of a woman getting uterine polyps increase in the following cases:

• They take drugs used to treat breast cancer.
• They are going through Hormone Replacement Therapy (HRT) since it involves a high dose of oestrogen.
• They are overweight or obese, with a body mass index of 30 or higher.
• They struggle with hypertension or high blood pressure.
• They have Lynch syndrome or Cowden syndrome.

What Is Endometrial Thickening?

When the lining of your uterus, also known as the endometrium, becomes thicker than usual, the condition is known as endometrial hyperplasia. This is the lining that sheds during a menstrual period and the tissue from which the foetus develops.

Now, the endometrium naturally varies in thickness throughout the menstrual cycle. During the follicular phase, increasing oestrogen levels stimulate the lining to grow and thicken. In the luteal phase, the progesterone stabilises the lining, and during menstruation, it is eventually removed from your body.

When the endometrial lining thickens abnormally, it is known as endometrial hyperplasia. This thickening is beyond what is appropriate for a woman’s hormonal status and stage of the cycle.

Can Uterine Polyps Cause Endometrial Thickening?

The relationship between uterine polyps and endometrial thickening is well-recognised. Understanding it will help with accurate diagnosis and appropriate management of the two gynaecological conditions.

First, uterine polyps are made up of endometrial tissue. Their physical presence within the uterine cavity adds to the total measurable bulk of the uterine lining. Secondly, these polyps arise from localised endometrial overgrowth driven by excessive estrogen stimulation. That same hormonal environment can simultaneously cause generalised thickening of the endometrium elsewhere in the uterus. Clearly, both the polyps and true endometrial hyperplasia frequently share an underlying hormonal cause and often co-exist.

What Are The Symptoms To Look Out For?

Uterine polyps and endometrial thickening can share many overlapping symptoms. The ones that are most commonly reported include:

• Irregular or unpredictable menstrual bleeding
• Unusually heavy periods
• Intermenstrual bleeding
• Postmenopausal bleeding
• Bleeding after intercourse
• Pelvic discomfort or a sensation of pressure
• Difficulty conceiving
• History of recurrent miscarriage

While larger polyps can cause a dull ache in the abdomen or lower back, pain is not usually a prominent symptom of uterine polyps. It is important to note that many women with uterine polyps experience no symptoms whatsoever. These growths are often discovered incidentally during an ultrasound carried out for an unrelated reason.

Is Endometrial Thickening Caused By Uterine Polyps Dangerous?

When an increased endometrial thickness measurement is caused solely by the physical presence of a benign uterine polyp, it does not necessarily carry a cancer risk. However, it is still important that you have the polyp removed from your body and examined to confirm if it was really non-cancerous or if it had the potential to turn malignant.

Genuine clinical concern can arise in the following cases:

• The polyp contains atypical hyperplastic or malignant cells
• True diffuse endometrial hyperplasia with atypia coexists alongside the polyp
• The woman is post-menopausal

How Doctors Diagnose The Two Conditions

The approach to diagnosis usually proceeds in steps, starting with imaging investigations and proceeding as needed.

Transvaginal Ultrasound (TVU)

This is the first-line imaging investigation that provides a measure of endometrial thickness and can show possible focal lesions that may correspond to polyps. A raised or borderline value requires further investigation but does not provide a diagnosis on its own.

Saline infusion sonography (SIS)

This involves filling the uterine cavity with sterile saline to get a better view of its structure. The method enables much higher diagnostic accuracy than a simple TVU by differentiating polyps from other conditions, such as diffuse thickening or fibroids.

Hysteroscopy

It is considered both a diagnostic and therapeutic method. A narrow, rigid, or flexible telescope is introduced via the cervix. The method allows visualising the uterine cavity, removing polyps, and performing an endometrial biopsy to study suspicious tissue.

Endometrial Biopsy

This biopsy involves sampling of endometrial tissue with the help of a special instrument introduced through the cervix. The test can be performed in outpatient settings and will help detect diffuse hyperplasia and malignancy, but not localised lesions such as polyps.

Treatment Options Available

Hysteroscopic polypectomy

The surgical excision of polyps within the uterus by using hysteroscopes is the recommended procedure when polyps need removal. This can be done under either general or local anaesthesia. All tissue obtained is sent for histopathological examination to confirm the diagnosis and rule out atypia or malignancy.

Hormonal Management

The levonorgestrel-releasing intrauterine system is recommended for the hormonal management of endometrial hyperplasia without atypia. It is generally the first-line treatment and is highly effective. It delivers progesterone directly and continuously to the uterine lining, counteracting the effects of excess oestrogen. For women who do not or cannot use an intrauterine device, oral progestogens can be a good alternative.

Surgical Management of Atypical Hyperplasia (Endometrial Thickening)

Hysterectomy, or the removal of the uterus, is the best course of action in managing atypical hyperplasia in women who have concluded childbearing because of the increased possibility of endometrial cancer. Conservative management, on the other hand, is a viable option in women who wish to maintain fertility. It involves high-dose progestogenic treatment along with biopsies.

Watch & Wait

Sometimes, especially when the uterine polyps are small, the issue may resolve spontaneously. If there are no concerning symptoms or obvious red flags, women can be managed conservatively with observation. That said, if the polyps are associated with abnormal bleeding or with endometrial thickening greater than usual, they should be removed and assessed histologically. The same goes for when uterine polyps occur in postmenopausal women.

Can Polyps Cause Endometrial Thickening After Menopause?

Yes, uterine polyps can cause endometrial thickening in women who have achieved menopause. It goes without saying that this is a concerning medical scenario. Normally, the endometrium in postmenopausal women is thin, inactive, and atrophic, measuring less than 3-5 mm. This is due to low oestrogen levels in women after menopause.

When the thickness is greater than what is considered safe, especially in women not on Hormone Replacement Therapy (HRT), it is considered abnormal and requires a prompt investigation. Postmenopausal uterine polyps are a well-documented cause of increased endometrial thickness readings, which can be a frequent explanation of postmenopausal bleeding.

The risk of a postmenopausal polyp containing malignant (cancerous) or pre-malignant (pre-cancerous) tissue is generally higher than in premenopausal women. This is why all postmenopausal polyps require removal and histological examination.

Conclusion

Uterine polyps and endometrial thickening are two gynaecological conditions that are closely interconnected and frequently share a common underlying driver, which is unopposed or excess estrogen production. Uterine polyps can directly cause an increase in the endometrial thickness simply due to their physical bulk within the uterine cavity. In some cases, they can co-exist with genuine endometrial hyperplasia. Sometimes, the polyp tissue may even undergo pre-cancerous change. While women with uterine polyps and abnormal endometrial thickening may not experience extremely apparent red flags, there are several symptoms to watch out for, including irregular, heavy, or postmenopausal bleeding.

If you are experiencing abnormal uterine bleeding or have received an imaging report noting endometrial thickening, it is best to seek gynaecological assessment as soon as you can for accurate diagnosis, appropriate treatment, and the best results.