Last checked September 2026 against 18 sources · Editorial policy
Endometrial thickening after menopause
After menopause, the endometrial wall, or uterine lining, is normally thin: 2.9 mm on average in women not taking HRT. If you have bleeding, a lining over 4 mm usually needs a biopsy, because 4 mm or less rules out endometrial cancer with over 99% certainty. Without bleeding, a thicker lining doesn't routinely need tests. The most common causes of thickening are polyps, HRT and hyperplasia; cancer is less common.
A lining over 4 mm after menopause with bleeding usually needs further tests. What causes thickening, what's normal on HRT, and the next steps.
Thickened endometrium after menopause: expectation vs reality
What people often expect
“A thickened lining on an ultrasound means cancer”
What the evidence shows
Usually it doesn't. Polyps, hyperplasia and HRT are more common causes. In a decision analysis, women with bleeding and a lining over 5 mm had about a 7.3% risk of cancer, and women without bleeding and a lining over 11 mm about 6.7%. When 82 women without bleeding had surgery for a thick lining thought to be a polyp, 68 had a benign polyp and none had cancer. Whether you've had bleeding matters most.
Endometrial thickness after menopause explained
What is endometrial thickness? The uterine wall explained
The endometrium is the lining of the uterus, also called the womb lining. Before menopause it builds up and sheds during each period; after menopause, with little estrogen, it becomes thin. Endometrial thickness is measured on a transvaginal ultrasound as the thickest part of the lining, front to back, on a lengthwise view of the uterus. Fluid inside the uterus isn't counted. An axial uterus, obesity, fibroids, adenomyosis or previous surgery can make the measurement less reliable.
Normal endometrial thickness after menopause
In a meta-analysis of 32 studies with 11,100 postmenopausal women without bleeding and not taking HRT, the average endometrial thickness was 2.9 mm. In those women, the rates of endometrial cancer and atypical hyperplasia were low, at 0.62% and 0.59%. A lining of 4 mm or less is the usual reassuring cut-off when there's bleeding. HRT, especially sequential HRT, makes the lining thicker, so different reference values apply.
Endometrial thickness with bleeding: the 4 mm rule
If you have bleeding after menopause, ACOG says a lining of 4 mm or less has a greater than 99% negative predictive value for endometrial cancer, so a first bleed with a thin lining often needs no more tests. A lining over 4 mm needs a biopsy. A European meta-analysis of individual patient data suggested an even stricter 3 mm cut-off. Rare types of cancer can occur with a lining under 3 mm, so bleeding that persists or returns needs a biopsy whatever the thickness.
Learn more →Thickened endometrium without bleeding
ACOG says a lining over 4 mm found by chance in a postmenopausal woman without bleeding doesn't routinely need further tests, although your risk factors should be considered. In 1,750 women without bleeding, a lining of 6 mm or less excluded cancer 99.94% of the time. A decision analysis suggested a biopsy when the lining is over 11 mm, where the cancer risk was about 6.7%, compared with 0.002% below it. Ultrasound isn't a screening test for cancer.
What causes a thickened endometrium after menopause
Polyps are a common cause: they become more common with age, obesity and tamoxifen, and 13% of randomly selected postmenopausal Danish women had one without bleeding. Endometrial hyperplasia, a genuine thickening of the lining, can be caused by HRT, high estrogen levels or being overweight. HRT itself thickens the lining. Less often, the cause is endometrial cancer, which is more likely with obesity, diabetes, tamoxifen, late menopause and some types of HRT.
Endometrial thickness on HRT
HRT thickens the endometrium, and the type matters. In one trial, after 6 months the average lining was 8.5 mm on continuous sequential HRT but 3.6 mm on continuous combined HRT, where 91% of women had a lining of 4 mm or less. Women on HRT need different reference values, and on sequential HRT the scan is most informative in the estrogen-only part of the cycle. Polyps were found in 16.3% of women on HRT.
Learn more →Endometrial hyperplasia: types and cancer risk
Hyperplasia is split by whether abnormal (atypical) cells are present. In a study of 7,947 women with hyperplasia, the risk of it becoming cancer over 19 years was 4.6% without atypical cells, but 27.5% with them. That's why hyperplasia without atypia may be treated with progestogen or simply monitored, while atypical hyperplasia is usually treated with a hysterectomy. Hyperplasia is often found because of bleeding, which is the main reason to report any bleeding after menopause.
Normal endometrial thickness in perimenopause
Before menopause, the lining builds up and sheds with each cycle, so there's no single normal value, and the postmenopausal cut-offs don't apply. In perimenopause, transvaginal ultrasound is the first step for irregular or heavy bleeding, to look for causes such as polyps and fibroids, which become more common with age. A biopsy or hysteroscopy is planned based on what the scan shows.
Learn more →Endometriosis after menopause
Endometriosis symptoms usually stop after menopause, but not always, and pain can start at any stage of life. It's less studied after menopause, and surgery remains the main treatment. Rarely, endometriosis becomes cancerous after menopause: a review of 90 published cases found a mean age of 55.8, and about 65% had a history of endometriosis. HRT choices need care if you've had endometriosis.
Endometrial thickness by the numbers
From the studies on this page
negative predictive value of a lining of 4 mm or less for cancer in women with bleeding
>99%
of randomly selected postmenopausal women without bleeding had an endometrial polyp
13%
of women with hyperplasia without atypical cells developed cancer over 19 years
4.6%
2.9 mm
Thickness cut-offs only apply after menopause and when you're not on HRT. They're a guide for deciding on a biopsy, not a diagnosis.
What happens next with a thickened endometrium
Watchful waiting for a thick lining without bleeding
First stepIf a thicker lining was found by chance and you haven't had any bleeding, ACOG says it doesn't need routine further tests, although your doctor should weigh your risk factors, such as obesity, diabetes or tamoxifen use. Any bleeding from then on should be reported straight away, because bleeding is the warning sign that matters.
Biopsy for a thickened endometrium with bleeding
First stepWith bleeding and a lining over 4 mm, the next step is a sample of the lining. An office biopsy with a thin tube is the usual first choice, but it fails or gives too little tissue in some women, about 10.4% for one common device. If it's inconclusive, a hysteroscopy with dilation and curettage lets the doctor see and sample the lining directly.
Removing endometrial polyps
If this is the causeIf a polyp is causing the thickening, it's usually removed by hysteroscopic polypectomy, an effective and safe procedure that can often be done in a clinic without general anesthesia. Small polyps that cause no symptoms can sometimes be watched. The removed tissue is checked in a lab.
Progestogen for endometrial hyperplasia
If this is the causeHyperplasia without atypical cells may need no treatment, progestogen tablets, or a hormonal IUS that releases progestogen into the uterus. The long-term cancer risk without atypia is under 5%. Atypical hyperplasia carries a risk of 27.5% over 19 years, so a total hysterectomy is often recommended.
Adjusting HRT for a thickened lining
If this is the causeIf HRT is thickening the lining or causing bleeding, changing or stopping it is often enough. Your doctor may adjust the progestogen dose or switch between sequential and continuous combined HRT. Continuous combined HRT gave a much thinner lining than sequential HRT in one trial, 3.6 mm versus 8.5 mm on average.
Reaching a healthy weight
First stepExcess weight raises estrogen levels, which can thicken the lining and increase the risk of hyperplasia and uterine cancer. The NHS advises keeping to a healthy weight, staying active and eating a balanced diet to lower your chance of uterine cancer, and talking to a doctor about which HRT is best for you.
When a thickened uterine lining needs a doctor
Urgent: Any bleeding after menopause
Always get it checked, even spotting or a single episode. An ultrasound to measure the lining is usually the first test.
More →Urgent: Bleeding that keeps coming back, even with a thin lining
Go back to your doctor. Persistent or recurrent bleeding needs a biopsy whatever the thickness.
A thickened lining reported on a scan
Ask your doctor what it means for you, especially if you have risk factors such as obesity, diabetes or tamoxifen use.
Bleeding on HRT for more than 6 months
See your doctor. Bleeding that's heavier or starts after you'd stopped bleeding also needs checking.
More →
Endometrial thickening after menopause: questions women ask
What is a normal endometrial thickness after menopause?
In women not taking HRT and without bleeding, the average is about 2.9 mm. If you have bleeding, 4 mm or less is considered reassuring. Without bleeding, a thicker lining found by chance doesn't routinely need tests, and one analysis used 11 mm as the point to consider a biopsy.
Is 5 mm endometrial thickness normal after menopause?
It depends on whether you've bled. With bleeding, anything over 4 mm usually means a biopsy is recommended. Without bleeding, 5 mm doesn't routinely need further tests: in 1,750 women without bleeding, a lining of 6 mm or less excluded cancer 99.94% of the time. On HRT, 5 mm can be normal.
What endometrial thickness is concerning after menopause?
With bleeding, over 4 mm, or any thickness if bleeding keeps coming back. Without bleeding, there's no agreed cut-off: ACOG advises an individual assessment, and one decision analysis suggested a biopsy above 11 mm, where cancer risk was about 6.7%.
Does a thickened endometrium mean cancer?
Usually not. Polyps, hyperplasia and HRT are more common causes. In 82 women without bleeding who had surgery for a suspected polyp, none had cancer. Among women with bleeding and a lining over 5 mm, the cancer risk was about 7.3%. A biopsy is the only way to be sure.
What causes a thickened uterine lining after menopause?
The most common causes are polyps, HRT and endometrial hyperplasia, which is linked to high estrogen levels and being overweight. Tamoxifen also raises the risk of polyps and uterine cancer. Less often, the cause is endometrial cancer.
What is a normal endometrial thickness on HRT?
It depends on the type. In one trial, after 6 months the average was 8.5 mm on continuous sequential HRT and 3.6 mm on continuous combined HRT. Doctors use different reference values for women on HRT, and on sequential HRT the scan is best timed in the estrogen-only part of the cycle.
How is a thickened endometrium treated?
It depends on the cause. Polyps are removed through the cervix. Hyperplasia without atypical cells may be monitored or treated with progestogen tablets or a hormonal IUS. Atypical hyperplasia and cancer are usually treated with a hysterectomy. If HRT is the cause, adjusting it may be enough.
What is a normal endometrial thickness in perimenopause or premenopausal women?
There's no single normal value, because the lining still builds up and sheds with your cycle, and the postmenopausal cut-offs don't apply. In perimenopause, ultrasound is used to look for causes of abnormal bleeding such as polyps and fibroids rather than to compare against a fixed number.
How is endometrial thickness measured?
With a transvaginal ultrasound, where a small probe is placed in the vagina. The sonographer measures the thickest part of the lining from front to back. Obesity, fibroids or previous surgery can make it harder to see, in which case a sonohysterography, hysteroscopy or biopsy may be used instead.
Can you get endometriosis after menopause?
Yes, although symptoms usually stop after menopause. Endometriosis pain can start or continue at any stage of life. Surgery is the main treatment after menopause, and HRT choices need care. Rarely, endometriosis can become cancerous after menopause, so new pelvic pain should be checked.
Sources
- Breijer MC, Peeters JA, Opmeer BC, et al. Capacity of endometrial thickness measurement to diagnose endometrial carcinoma in asymptomatic postmenopausal women: a systematic review and meta-analysis. Ultrasound Obstet Gynecol. 2012;40(6):621-9.
- American College of Obstetricians and Gynecologists. Committee Opinion No. 734: The role of transvaginal ultrasonography in evaluating the endometrium of women with postmenopausal bleeding. Obstet Gynecol. 2018;131(5):e124-e129.
- NHS. Postmenopausal bleeding.
- Smith-Bindman R, Weiss E, Feldstein V. How thick is too thick? When endometrial thickness should prompt biopsy in postmenopausal women without vaginal bleeding. Ultrasound Obstet Gynecol. 2004;24(5):558-65.
- NHS. Hysterectomy.
- Office on Women's Health, US Department of Health and Human Services. Menopause basics.
- Van den Bosch T, Van Schoubroeck D, Ameye L, et al. Ultrasound assessment of endometrial thickness and endometrial polyps in women on hormonal replacement therapy. Am J Obstet Gynecol. 2003;188(5):1249-53.
- Timmermans A, Opmeer BC, Khan KS, et al. Endometrial thickness measurement for detecting endometrial cancer in women with postmenopausal bleeding: a systematic review and meta-analysis. Obstet Gynecol. 2010;116(1):160-167.
- Han MN, Munro MG. Endometrial Polyps. Obstet Gynecol. 2026.
- NHS. Womb (uterus) cancer: causes.
- Affinito P, Palomba S, Pellicano M, et al. Ultrasonographic measurement of endometrial thickness during hormonal replacement therapy in postmenopausal women. Ultrasound Obstet Gynecol. 1998;11(5):343-6.
- Lacey JV Jr, Sherman ME, Rush BB, et al. Absolute risk of endometrial carcinoma during 20-year follow-up among women with endometrial hyperplasia. J Clin Oncol. 2010;28(5):788-92.
- Dreisler E, Frandsen CS, Ulrich L. Perimenopausal abnormal uterine bleeding. Maturitas. 2024;184:107944.
- NHS. Endometriosis.
- Cassani C, Tedeschi S, Cucinella L, et al. Menopause and endometriosis. Maturitas. 2024;190:108129.
- Giannella L, Marconi C, Di Giuseppe J, et al. Malignant Transformation of Postmenopausal Endometriosis: A Systematic Review of the Literature. Cancers (Basel). 2021;13(16):4026.
- NHS. Womb (uterus) cancer: tests and next steps.
- NHS. Side effects of hormone replacement therapy (HRT).
See our editorial policy.
Related guides
Bleeding after menopause
Any bleeding 12+ months after your last period needs a doctor's check. Common causes (atrophy, polyps, HRT), l…
Postmenopause
Postmenopause begins 12 months after your last period. Which symptoms continue, long-term bone and heart risks…
HRT side effects
Breast tenderness, bloating, spotting and headaches are common in the first 3 months and usually settle. Serio…
Fibroids in perimenopause and after menopause
Fibroids mainly cause problems before menopause and are a common cause of heavy bleeding in perimenopause. Tre…