Thickened Endometrium: Causes, Symptoms & Treatment Options Explained

In short: A thickened endometrium means the lining of the uterus is thicker than expected on ultrasound. Causes include hyperplasia, polyps, early pregnancy, remains of a pregnancy and, rarely, cancer. The risk of hyperplasia turning into cancer is about 5% over 20 years, and for polyps no more than 1%. It is usually treated with progesterone for 6 months, or by removal, depending on the case.

If your ultrasound report mentioned a “thickened endometrium,” it’s completely natural to feel a little worried. This guide explains what the term means, why it can happen, and how doctors evaluate and manage it — so you can better understand your results and know what questions to ask at your next visit.

What is meant by endometrial thickening?

It means the endometrial lining appears thicker than expected on an ultrasound (vaginal or abdominal)

After menopause, the lining is normally thin; in a woman with postmenopausal bleeding, a thickness of 4 mm or more on a vaginal ultrasound needs a biopsy, and bleeding that continues needs evaluation even if the lining looks thin. — that is, thicker than what is typical at a particular stage of the menstrual cycle.

What are the causes of a thick endometrial lining on an ultrasound?

• Endometrial hyperplasia
• Polyps in the endometrium
• Early pregnancy
• Placental tissue remains after childbirth * Endometrial cancer

What is endometrial hyperplasia?

It is an irregular proliferation of endometrial glands, resulting in an increased proportion of glandular cells compared to normal endometrial cells.

Is there a risk associated with endometrial hyperplasia?

It depends on the type. Hyperplasia without atypia has a low risk (under 5 percent over 20 years) of turning into cancer. Atypical hyperplasia is more serious: the risk of cancer is much higher, and in up to 4 in 10 women a cancer is already present at the time of diagnosis.

What are the causes of endometrial hyperplasia or endometrial cancer?

Risk factors:

• Obesity
• Estrogen therapy or estrogen receptor agonists
• Polycystic ovary syndrome
• Family history
• Age over 35
• Never having a baby
• Starting menstruation at a young age
• Delayed menopause
• Diabetes and use of tamoxifen

How do endometrial polyps appear?

They appear as localized thickening of the endometrium — meaning the thickening occurs on one side, while the surrounding endometrium is thin or normal.

How can we identify endometrial thickening resulting from early pregnancy?

By performing a pregnancy hormone test (in blood or urine).

When should we suspect placental remnants in the uterus?

A recent birth followed by intermittent vaginal bleeding that does not stop despite the expected end of the postpartum period, in addition to the presence of thickening on an ultrasound consistent with placental remnants.

What are the symptoms that women experience due to thickening of the uterine lining?

• Irregular vaginal bleeding
• Abdominal pain
• Fever in cases of tumors or placental remnants

How is endometrial hyperplasia suspected?

It is suspected by measuring the thickness on a vaginal ultrasound, sometimes with a cystic appearance of the endometrium, but the diagnosis can only be confirmed by taking a sample (endometrial biopsy or hysteroscopy) and examining it under the microscope.

How is endometrial hyperplasia treated?

Depending on age, symptoms, and reproductive desire, treatment may include:

• Hyperplasia without atypia: hormonal therapy with progesterone, preferably the hormonal IUD (Mirena), for at least 6 months, with a repeat endometrial biopsy every 6 months until two biopsies in a row are normal.
• Atypical hyperplasia: total hysterectomy is recommended (the ovaries are usually removed after menopause, while in younger women this is decided individually). Women who still wish to become pregnant may be treated with progesterone under close follow-up with repeated biopsies.

What are the available progesterone forms for treatment of endometrial hyperplasia?

• Pill form
• Liquid form
• Hormonal IUD (Mirena)

How are endometrial polyps treated?

By removing them under direct vision with hysteroscopy (often possible as an outpatient procedure or with light anesthesia), rather than by blind curettage which can miss them, and confirming the diagnosis by sending the sample to a histopathology lab.

Can endometrial polyps recur?

Yes.

Can polyps transform into tumors?

Rarely. The risk is about 1 percent in women before menopause, but higher (about 4-5 percent) in women after menopause who have bleeding, which is why polyps in this group should be removed.

How is retained placental tissue managed?

• Giving antibiotics
• Performing a surgical evacuation procedure under anesthesia

How is endometrial thickening managed in the presence of a positive pregnancy hormone test?

A transvaginal ultrasound is repeated after 7–10 days to look for a gestational sac. If the gestational sac is not detected, the blood pregnancy hormone (hCG) test is repeated after 48 hours: a good rise suggests an early pregnancy in the uterus that is not yet visible, a fall suggests a pregnancy that is ending (chemical pregnancy), and a slow rise or plateau raises concern for an ectopic pregnancy. Any pain, dizziness or heavy bleeding needs urgent assessment the same day.

How is endometrial cancer treated?

Hysterectomy, followed by additional radiation or chemotherapy as needed.

If you have been told your endometrium is thicker than expected, or you’re experiencing irregular bleeding, it’s a good idea to have a thorough evaluation rather than worry alone. Dr. Najeeb Layyous and his team welcome patients seeking a clear, caring assessment and guidance on the most suitable next steps for their individual situation.

Dr Najeeb Layyous F.R.C.O.G

Consultant Obstetrician, Gynecologist and Infertility Specialist