Is 8mm endometrial thickness normal

Is 8mm endometrial thickness normal DEFAULT

Measuring Endometrial Thickness in Postmenopausal Women

All gynecologists should understand the importance of certain markers at each stage of a patient's life, such as endometrial thickness in postmenopausal women. But what is the best way to measure the endometrium? And when might a patient need this exam in the first place?

Author and practicing gynecologist Dr. Steven Goldstein answered our questions about this assessment, including the best method to use and the role of ultrasound.

Q: Why might a clinician need to measure endometrial thickness in postmenopausal patients?

A: A healthy, postmenopausal woman doesn't generally need this measured. The whole purpose of measuring the thickness of the endometrium is to check the cause of unexplained bleeding: a thin, distinct endometrium in women with bleeding excludes the possibility of cancer. There are some who believe that if an endometrium measures thick in a non-bleeding patient, intervention is needed, but this is not at all the case.

A: In most women, an endometrial echo of less than or equal to 4 mm is considered normal. In higher-risk patients with bleeding, even thinner endometrial echoes may require intervention.

Q: What associated symptoms might a postmenopausal woman with an abnormal endometrium experience?

A: There is good evidence that as many as 17 percent of postmenopausal women will have a so-called thick endometrial echo. The majority of these echoes reveal asymptomatic polyps. One study found that in post-menopausal women with endometrial polyps that haven't bled, the incidence of cancer was 1 in 288.

In the absence of bleeding, endometrial thickness is not automatically a cause for intervention. However, on a case-by-case basis, a clinician may want to further investigate a thick endometrial echo in the presence of risk factors such as obesity, polycystic ovarian syndrome, hypertension and diabetes.

Q: How does ultrasound play a role in measuring endometrial thickness?

A: The main role of ultrasound is to exclude significant tissue or its high negative predictive value. There is no documented prospective trial showing that a thick endometrial echo needs intervention if the patient is healthy and has no bleeding.

Some studies have implied that the thicker the endometrial echo, the more dangerous, but that's not always true. Most endometrial cancers bleed relatively early with thinner echoes. The thickest endometrial echoes tend to be simple hyperplasia or inactive polyps.

Q: What are the key anatomical features a clinician should look for on ultrasound?

A: The key is to measure at a right angle to the endometrial echo on a long-axis view of the uterus (the anteroposterior, or AP, view) at the thickest portion, which is usually about a centimeter from the fundus. Besides thickness, clinicians can look at the irregularity and heterogeneity of the endometrium. If color Doppler is used, sometimes the presence of a central feeder vessel can reveal an endometrial polyp.

Q: What other providers or treatment options might a patient need to seek out after this exam?

A: When it comes to postmenopausal endometrial thickness, in an average-risk woman with postmenopausal bleeding, a thin, distinct echo of less than 4 mm would require no further intervention, nor would an endometrial echo of less than 3 mm in virtually any other woman.

If an endometrial echo cannot be adequately visualized secondary to coexisting fibroids, adenomyosis, axial uterus, previous surgery or marked obesity, then the next step is often saline infusionsonohysterography (SIS) to better delineate the endometrial contents and distinguish global from focal pathology. This is because global pathology may allow for a blind biopsy, whereas focal pathology should be biopsied under direct visualization with a hysteroscopic procedure.

Q: What should clinicians keep in mind when assessing and treating older women?

A: Postmenopausal women who have bleeding can be evaluated primarily with transvaginal ultrasound. A thin, distinct echo excludes significant tissue — that means less than or equal to 4 mm in an average-risk woman, or less than 3 mm in virtually any woman. If necessary, use SIS to distinguish global from focal pathology and determine the next steps. Finally, a complete ultrasound examination should always include evaluation of the cul-de-sac as well as the adnexal regions, and a search for any adnexal pathology.

Answers have been condensed and edited for clarity.

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Cobra's picture
5 Dec 2018 16:53

Endometrial thickness of 9mm

5 Dec 2018 16:53

so just had a scan and was told have endometrial thickness of 9mm, I have had some lower pain and brown dishcharge that smelt.. Had a biopsy done today now it’s the waiting game. I am really worried..

Tessa63's picture
5 Dec 2018 21:42

Endometrial thickness of 9mm

5 Dec 2018 21:42 in response to Cobra

Hi I have just been for a biopsy today the lining thickness was 13.5 I'm worried sick I don't know what to do to cope till the results come back next week...have you had your results back? Take care T x

Sundial's picture
5 Dec 2018 23:31

Endometrial thickness of 9mm

5 Dec 2018 23:31 in response to Tessa63

Hi both and welcome.

Thickened endometrium can be the result of other things beside cancer so keep an open mind if you can.  My endometrium was 16mm when I had my scan in April. Now mine was a results of endometrial cancer but if caught early it is very treatable. I had a full hysterectomy, lymph nodes removed and three sessions of internal radiotherapy, finishing in early October. I’m now on four monthly check ups and living life to the full, having just returned from a fanatic, two week cruise to the Canary Islands, 

Waiiting for results for me was the most difficult and stressful, once I knew and a plan was explained to me things settled. I tried to keep busy and distract myself but eventually I saw my gp who prescribed a low dose of diazepam I took only one a day of the six I could take but it did the trick. Once I had my results I did not need them.  When all else failed the people on here were and still are very supportive. 

Im sending a virtual squeeze from my hand to yours and hoping your results  are good.


Niki26's picture
27 Sep 2019 13:28

Endometrial thickness of 9mm

27 Sep 2019 13:28 in response to Sundial


I have just been told  by my gp my endometrium is 16mm thick and i am being fast tracked for a hysteroscopy next week. I am petrified. Does a thickness of 16mm mean it is most likely cancer? All advice and support welcome. Dont know how i will be able to wait a week for the examination

Sooky's picture
4 Jun 2020 03:18

Endometrial thickness of 9mm

4 Jun 2020 03:18 in response to Cobra

hi are you okay now.

just found this,and had a scan today where i was told my lining is thick. . i am worried now.

any advice please to help?


effy's picture
16 Jun 2020 17:41

Endometrial thickness of 9mm

16 Jun 2020 17:41 in response to Niki26


I am currently in the same situation as you were back in September. I want to know what your outcome was? 

best wishes

Niki26's picture
22 Jun 2020 00:59

Endometrial thickness of 9mm

22 Jun 2020 00:59 in response to effy

Hi Effy

I had a hysteroscopy done last year they took a biopsy of the lining and also the polyp. Thankfully all samples were clear of any abnormalities. And i was advised that at this stage even if there were any abnormalities  there were options we could take ( unlike my GP who was so unsupportive).

Whilst they performed they hysteroscopy they also inserted the mirena coil which is a hormonal coil releasing small amounts of hormone which prevents further thickening of the uterine wall.

I have basically summarised everything. My journey was a lot awful from start to end. Not in terms of hospital staff, they were wonderful but generally by my GP, then the endless waiting for tests and results etc. I had 2 hysteroscopys , 2 biopsies spinal injection to numb me waist down. I used to live on this forum looking for answers and support. I found everyone very supportive.

If you want to ask me any questions please feel free to do so, i will be more than happy to help

Good have indicated you have a thickness of 9mm well my thickness was 15mm. 

Best of luck 

Nikki x

Sparkle7's picture
22 Jun 2020 12:29

Endometrial thickness of 9mm

22 Jun 2020 12:29 in response to Niki26

Hi Nikki & Effy,

Thank you Nikki for posting all about your journey. It is reassuring to read, like you I've been reading lots of threads etc and finding out that there are many women who are/have been investigated for irregular bleeding. 

My periods went crazy in March, basically I've had 5 in ten weeks and the 5th one is still going. All this bleeding is exhausting! 

Having a hysteroscopy this afternoon after my the scan should that my linning was 15mm and contained lots of tiny cysts.

So hoping I get some answers from today and then waiting on my biopsy results. 

Hope you find some answers too Effy x x x

sam1974's picture
22 Jul 2020 13:21

Endometrial thickness of 9mm

22 Jul 2020 13:21 in response to Sparkle7

Hi Sparkle7 and everyone on here,

Its so refreshing to see im not the only one worrying about this issue.

I had a subtotal hysterectomy 6 years ago and had a bleed and excruciating bad pain in March, just before lock down. I was sent for two internal prob scans and revealed an endometrial thicking of 13mm. I've been on HRT oestrogen only for 6 years and due to lock down and not being able to be seen by anyone I was advised to take progesterone as well as the oestrogen until im seen. After 6 weeks the pain and bloating became unbearable and took myself off the progesterone. 

We're now nearly in August, hot sweats are out of control, anxiety has resulted in me being off work for 3 weeks and stomach an back pains are still looming. 

I'm terrified of whats happening inside my body. 

Is there anyone out there that has had this issue after a hysterectomy?

Best wishes


Chey's picture
28 Sep 2020 13:44

Endometrial thickness of 9mm

28 Sep 2020 13:44 in response to deezy104

Hi niki26, 

Did u get your results ? I too am currently waiting on biopsy results with 14mm thickness.  Thanks

Lou_lou's picture
1 Oct 2020 22:41

Endometrial thickness of 9mm

1 Oct 2020 22:41 in response to Chey


I am in the same boat, if been told mine is 8mm worried , been told to have a biopsy.  Any advice is welcome

Lou_lou's picture
28 Oct 2020 23:13

Endometrial thickness of 9mm

28 Oct 2020 23:13 in response to belleranges

Hello everyone

I had my biopsy under general last Wednesday.  

Surgeon told me he thought the womb was find but quote" the nabothian cysts are causing moderate concern, they did not behave as cancer when cut out and did not bleed as cancer would but I an concerned enough to send you for a CT scan which I will time with the result"

I rang today with fingers crossed but no result is back.

I was told I would get a phone call with result.

Cannot concentrate mind wonders all over the place. 

I try to read things into what he said but he did not know. 

But advice please 

I feel really bloated and sore inside from under bust down and uncomfortable my mind saying it's because it has spread .But I know they fill you with air for the procedure so worried about the pain and soreness. 

I will update you when I know more

Bless you all 

Mumsylowe's picture
29 Oct 2020 04:43

Endometrial thickness of 9mm

29 Oct 2020 04:43 in response to Lou_lou

Wow I'm not alone..  and not able to sleep. I had a hysteroscopy and curettage today. No conversation with the surgeon so no idea really what he thought.

 I was referred following a scan and initial hysteroscopy which found 9mm thickening covered in an uneven/ragged surface. Am now waiting for the results. I'm 52 and very perimenoausal. I started taking progesterone for a couple of weeks to stop the bleeding as it was horrendous. But the progesterone seemed to cause insomnia anxiety etc so am glad I'm off it now!

I've been signed of work as my panic and anxiety has been awful so I possibly need to have another talk to the GP. Its the not knowing heat I'm dealing either which is terrifying! Its good to know we are not alone x

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What to know about endometrial thickness

The endometrium is the lining of the uterus. It is one of the few organs in the human body that changes in size every month throughout a person’s fertile years.

Each month, as part of the menstrual cycle, the body prepares the endometrium to host an embryo. Endometrial thickness increases and decreases during the process.

Two hormones, estrogen and progesterone, prompt these cycles of endometrial growth and its shedding through menstruation if a pregnancy does not develop.

In this article, we look at the normal range for endometrial thickness, causes of changes, and when to see a doctor.

Normal thickness

The normal thickness of the endometrium changes throughout a person’s life, from childhood, through to sexual maturity, fertile years, and after menopause.

In imaging tests of young females who have not yet begun menstruating, the endometrium is present but smaller than it will be later in life.

According to the Radiological Society of North America (RSNA), the endometrium is at its thinnest during menstruation, when it usually measures between 2–4 millimeters (mm) in thickness.

The first half of the proliferative phase starts around day 6 to 14 of a person’s cycle, or the time between the end of one menstrual cycle, when bleeding stops, and before ovulation. At this phase, the endometrium begins to thicken and may measure between 5–7 mm.

As the cycle progresses and moves towards ovulation, the endometrium grows thicker, up to about 11 mm.

About 14 days into a person’s cycle, hormones trigger the release of an egg. During this secretory phase, endometrial thickness is at its greatest and can reach 16 mm.


Endometrial thickness is important in pregnancy. Healthcare experts link the best chances for a healthy, full-term pregnancy to an endometrium that is neither too thin nor too thick. This allows the embryo to implant successfully and receive the nutrition it needs. The endometrium gets thicker as the pregnancy progresses.


The RSNA also state that in healthy postmenopausal people, the endometrium typically measures about 5 mm or less.

How to measure

Ultrasound is the most common way to measure the thickness of the endometrium. It is the method that healthcare providers use first, especially if an individual has reported abnormal vaginal bleeding.

When ultrasound is not suitable, often due to the position of a person’s uterus or other health conditions, doctors use MRI.

Causes of a very thin or thick endometrial lining

The thickness of the endometrium changes during a person’s menstrual cycle, but other factors can prompt changes as well.

One of the more common causes of changes in endometrial thickness is pregnancy. Women who are having an ectopic pregnancy or who are less than 5 weeks pregnant may show signs of a thickening endometrium.

Cancer of the endometrium or the ovaries is one of the most severe conditions that can lead to an increase in endometrial thickness. According to the , endometrial cancer is the most common cancer affecting a person’s reproductive systems. Developing more often in white people than African American people, endometrial cancer is rare in females under 45. The average age at diagnosis is 60.

Other factors contributing to a greater thickness of the endometrium include:

Endometrial hyperplasia is the medical term for a condition in which the endometrium becomes too thick. This is often related to excessive levels of estrogen or estrogen-like compounds, and not enough progesterone. The condition itself is not cancer, but it can lead to the development of cancer.

It is also possible for the endometrium to be too thin. Researchers define a thin endometrium as . Typically, experts associate low readings of endometrial thickness with age. However, they report that 5% of people under 40, and 25% of people over 40 had a thin endometrium.

Possible causes of a thin endometrium include inflammation, medical treatment, or the structure and nature of the endometrium itself.


The most common signs of excessive endometrial thickness include:


Treatments for excessive endometrial thickness include progestin, a female hormone that prevents ovulation and hysterectomy.

show that it is more difficult for a pregnancy to progress when readings for endometrial thickness are low. Treatments for a thin endometrium can include:

  • estrogen
  • human chorionic gonadotrophin, which is a hormone that the placenta produces after an embryo implants in the uterus wall
  • medications and supplements used to improve blood flow

However, that these treatments are not consistently effective.

When to see a doctor

People should see their doctors if they notice abnormal vaginal bleeding, which can include:

  • spotting between period
  • unusually heavy flows
  • irregular, short blood flows
  • vaginal bleeding or spotting after menopause

People experiencing pelvic pain of unknown origin should see a doctor for evaluation and to rule out endometrial cancer. Other symptoms to watch out for are bloating and a feeling of fullness without eating much.


Paying attention to endometrial thickness can help women who are trying to become pregnant understand the best way to optimize their chances of successful conception.

Changes in endometrial thickness are common throughout a person’s life. However, if someone notices abnormal bleeding, discharge, pelvic pain, or other changes in the way their body feels, they should consult a doctor to receive proper treatment.

Endometrial cancer is one of the most severe health problems that can occur if a person’s endometrium is too thick. However, endometrial cancer has a good survival rate if diagnosed early.

Thin Endometrium Can get Pregnant? Thin Endometrium Symptoms, Causes and Treatment

Endometrial thickness is a commonly measured parameter on routine gynecological ultrasound and MRI. The appearance, as well as the thickness of the endometrium, will depend on whether the patient is of reproductive age or postmenopausal and, if of reproductive age, at what point in the menstrual cycle they are examined. 

Radiographic features


The endometrium should be measured in the long axis or sagittal plane, ideally on transvaginal scanning, with the entirety of the endometrial lining through to the endocervical canal in view. 10 The measurement is of the thickest echogenic area from one basal endometrial interface across the endometrial canal to the other basal surface. Care should be taken not to include hypoechoic myometrium or intrauterine fluid in this measurement.

The normal endometrium changes in appearance as well as in thickness throughout the menstrual cycle:

  • in the menstrual and early proliferative phase it is a thin, brightly echogenic stripe comprising of the basal layer (figure 1); minimal fluid can be appreciated endovaginally within the endometrium in the menstrual phase
  • in the late proliferative phase it develops a trilaminar appearance: outer echogenic basal layer, middle hypoechoic functional layer, and an inner echogenic stripe at the central interface (figure 2).
  • in the secretory phase it is at its thickest, up to 16 mm 10, and becomes uniformly echogenic, as the functional layer becomes edematous and isoechoic to the basal layer (figure 3); there is through transmission and posterior acoustic enhancement noted

The postmenopausal endometrium should be smooth and homogeneous.

Normal range of endometrial thickness

The designation of normal limits of endometrial thickness rests on determining at which thickness the risk of endometrial carcinoma is significantly increased.  

Whilst quantitative assessment is important, endometrial morphology and the presence of risk factors for endometrial malignancy should also be taken into account when deciding whether or not endometrial sampling is indicated.

Commonly accepted endovaginal ultrasound values are as follows:


In premenopausal patients, there is significant variation at different stages of the menstrual cycle.

  • during menstruation: 2-4 mm 1,4
  • early proliferative phase (day 6-14): 5-7 mm
  • late proliferative / preovulatory phase: up to 11 mm
  • secretory phase: 7-16 mm
  • following dilatation and curettage or spontaneous abortion: <5 mm, if it is thicker consider retained products of conception

Please note that these measurements are a guide only, as endometrial thickness may be variable from individual to individual.

Endometrial thickness can decrease with long-term combined oral contraceptive pill use 12.


The postmenopausal endometrial thickness is typically less than 5 mm in a postmenopausal woman, but different thickness cut-offs for further evaluation have been suggested.

  • vaginal bleeding (and not on tamoxifen):
    • suggested upper limit of normal is <5 mm 5
    • the risk of carcinoma is ~7% if the endometrium is >5 mm and 0.07% if the endometrium is <5 mm 8
    • on hormonal replacement therapy: upper limit is 5 mm 
  • no history of vaginal bleeding:
    • the acceptable range of endometrial thickness is less well established in this group, cut-off values of 8-11 mm have been suggested
    • the risk of carcinoma is ~7% if the endometrium is >11 mm, and 0.002% if the endometrium is <11 mm 8
  • if on tamoxifen 3: <5 mm (although ~50% of those receiving tamoxifen have been reported to have a thickness of >8 mm 7)

If a woman is not experiencing bleeding, and the endometrium is thickened, the guidelines are less clear. Either a repeat transvaginal ultrasound or a referral to a gynecologist is reasonable.


Endometrial thickness is well assessed on MRI. Measurement should be taken at a mid-sagittal slice, similar to the ultrasound assessment plane.

  • T2: normal endometrium is homogeneously hyperintense regardless of the phase of the menstrual cycle or menopausal status and well outlined by the low signal myometrial junctional zone

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See also


  • 1. Nalaboff KM, Pellerito JS, Ben-levi E. Imaging the endometrium: disease and normal variants. Radiographics. 21 (6): 1409-24. Radiographics (full text) - Pubmed citation
  • 2. Lin MC, Gosink BB, Wolf SI et-al. Endometrial thickness after menopause: effect of hormone replacement. Radiology. 1991;180 (2): 427-32. Radiology (abstract) - Pubmed citation
  • 3. Fong K, Kung R, Lytwyn A et-al. Endometrial evaluation with transvaginal US and hysterosonography in asymptomatic postmenopausal women with breast cancer receiving tamoxifen. Radiology. 2001;220 (3): 765-73. doi:10.1148/radiol.2203010011 - Pubmed citation
  • 4. Williams PL, Laifer-narin SL, Ragavendra N. US of abnormal uterine bleeding. Radiographics. 23 (3): 703-18. doi:10.1148/rg.233025150 - Pubmed citation
  • 5. Sahdev A. Imaging the endometrium in postmenopausal bleeding. BMJ. 2007;334 (7594): 635-6. doi:10.1136/bmj.39126.628924.BE - Free text at pubmed - Pubmed citation
  • 6. Hulka CA, Hall DA, Mccarthy K et-al. Endometrial polyps, hyperplasia, and carcinoma in postmenopausal women: differentiation with endovaginal sonography. Radiology. 1994;191 (3): 755-8. Radiology (abstract) - Pubmed citation
  • 7. Hann LE, Giess CS, Bach AM et-al. Endometrial thickness in tamoxifen-treated patients: correlation with clinical and pathologic findings. AJR Am J Roentgenol. 1997;168 (3): 657-61. AJR Am J Roentgenol (abstract) - Pubmed citation
  • 8. 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. doi:10.1002/uog.1704 - Pubmed citation
  • 9. J Obstet Gynaecol Can 2010; 32 (10) 990-999. SOGC Clinical Practice Guideline. No 249, October 2101.
  • 10. Gupta A, Desai A, Bhatt S. Imaging of the Endometrium: Physiologic Changes and Diseases: Women's Imaging. (2017) Radiographics : a review publication of the Radiological Society of North America, Inc. 37 (7): 2206-2207.
  • 11. T. Van Den Bosch, J. Y. Verbakel, L. Valentin, L. Wynants, B. De Cock, M. A. Pascual, F. P. G. Leone, P. Sladkevicius, J. L. Alcazar, A. Votino, R. Fruscio, C. Lanzani, C. Van Holsbeke, A. Rossi, L. Jokubkiene, M. Kudla, A. Jakab, E. Domali, E. Epstein, C. Van Pachterbeke, T. Bourne, B. Van Calster, D. Timmerman. Typical ultrasound features of various endometrial pathologies described using International Endometrial Tumor Analysis (IETA) terminology in women with abnormal uterine bleeding. (2021) Ultrasound in Obstetrics & Gynecology. 57 (1): 164. doi:10.1002/uog.22109
  • 12. Talukdar N Effect of long-term combined oral contraceptive pill use on endometrial thickness. (2012) Obstetrics and gynecology. doi:10.1097/AOG.0b013e31825ec2ee - Pubmed

Related articles: Pathology: Genitourinary

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8mm endometrial normal is thickness

How thick is too thick? When endometrial thickness should prompt biopsy in postmenopausal women without vaginal bleeding

Objective: Transvaginal sonography (TVS) is routinely performed as part of a pelvic sonogram in postmenopausal women, and images of the endometrium are frequently obtained. In women without vaginal bleeding, the threshold separating normal from abnormally thickened endometrium is not known. The aim of this study was to determine an endometrial thickness threshold that should prompt biopsy in a postmenopausal woman without vaginal bleeding.

Methods: This was a theoretical cohort of postmenopausal women aged 50 years and older who were not receiving hormone therapy. We determined the risk of cancer for a postmenopausal woman with vaginal bleeding when the endometrial thickness measures > 5 mm, and then determined the endometrial thickness in a woman without vaginal bleeding that would be associated with the same risk of cancer. We used published and unpublished data to determine the sensitivity and specificity of TVS, the incidence of endometrial cancer, the percentage of women symptomatic with vaginal bleeding, and the percentage of cancer that occurs in women without vaginal bleeding. Ranges for each estimate were included in a sensitivity analysis to determine the impact of each estimate on the overall results.

Results: In a postmenopausal woman with vaginal bleeding, the risk of cancer is approximately 7.3% if her endometrium is thick (> 5 mm) and < 0.07% if her endometrium is thin (< or = 5 mm). An 11-mm threshold yields a similar separation between those who are at high risk and those who are at low risk for endometrial cancer. In postmenopausal women without vaginal bleeding, the risk of cancer is approximately 6.7% if the endometrium is thick (> 11 mm) and 0.002% if the endometrium is thin (< or = 11 mm). The estimated risk of cancer was sensitive to the percentage of cancer cases that were estimated to occur in women without vaginal bleeding. For the base case we estimated that 15% of cancers occur in women without vaginal bleeding. When we changed the estimate to project that only 5% of cancers occur in women without vaginal bleeding, the projected risk of cancer with a thick measurement was only 2.2%, whereas when we estimated that 20% of endometrial cancers occur in women without bleeding, the projected risk of cancer with a thick measurement was 8.9%. As a woman's age increases, her risk of cancer increases at each endometrial thickness measurement. For example, using the 11 mm threshold, the risk of cancer associated with a thick endometrium increases from 4.1% at age 50 years to 9.3% at age 79 years. Varying the other estimates used in the decision analysis within plausible ranges had no substantial effect on the results.

Conclusions: In a postmenopausal woman without vaginal bleeding, if the endometrium measures > 11 mm a biopsy should be considered as the risk of cancer is 6.7%, whereas if the endometrium measures < or = 11 mm a biopsy is not needed as the risk of cancer is extremely low.

Endometrial thickness 22mm

What Is the Endometrial Stripe?

What is it?

Your uterine lining is called the endometrium. When you have an ultrasound or MRI, your endometrium will show up as a dark line on the screen. This line is sometimes referred to as the “endometrial stripe.” This term doesn’t refer to a health condition or diagnosis, but to a normal part of your body’s tissue.

Endometrial cells can appear in other parts of your body as a symptom of endometriosis, but an “endometrial stripe” specifically refers to endometrial tissue in your uterus.

This tissue will naturally change as you age and move through different reproductive stages. Read on to learn more about these changes, symptoms to watch for, and when to see your doctor.

What does the stripe usually look like?

If you’re of reproductive age, the overall appearance of your endometrial stripe will depend on where you are in your menstrual cycle.

Menstrual or early proliferative phase

The days during your period and immediately after it are called the menstrual, or early proliferative, phase. During this time, the endometrial stripe will look very thin, like a straight line.

Late proliferative phase

Your endometrial tissue will begin to thicken later in your cycle. During the late proliferative phase, the stripe may appear to be layered, with a darker line that runs through the middle. This phase ends once you’ve ovulated.

Secretory phase

The part of your cycle between when you ovulate and when your period starts is called the secretory phase. During this time, your endometrium is at its thickest. The stripe accumulates fluid around it and, on an ultrasound, will appear to be of equal density and color throughout.

How thick should the stripe be?

The normal range of thickness varies according to what stage of life you’re in.


Before puberty, the endometrial stripe looks like a thin line all month long. In some cases, it may not yet be detectable by an ultrasound.


For women of reproductive age, the endometrial stripe thickens and thins according to their menstrual cycle. The stripe can be anywhere from slightly less than 1 millimeter (mm) to slightly more than 16 mm in size. It all depends on what phase of menstruation you’re experiencing when the measurement is taken.

Average measurements are as follows:

  • During your period: 2 to 4 mm
  • Early proliferative phase: 5 to 7 mm
  • Late proliferative phase: Up to 11 mm
  • Secretory phase: Up to 16 mm


When pregnancy occurs, a fertilized egg will implant into the endometrium while it is at its thickest. Imaging tests done during early pregnancy may show an endometrial stripe of 2 mm or more.

In a routine pregnancy, the endometrial stripe will become home to the growing fetus. The stripe will eventually be obscured by a gestational sac and placenta.


The endometrial stripe is thicker than usual after childbirth. That’s because blood clots and old tissue can linger after delivery.

These remnants are seen after 24 percent of pregnancies. They’re particularly common after cesarean delivery.

The endometrial stripe should return to its regular cycle of thinning and thickening when your period cycle resumes.


The thickness of the endometrium stabilizes after you reach menopause.

If you’re close to reaching menopause but still have occasional vaginal bleeding, the average stripe is less than 5 mm thick.

If you no longer experience any vaginal bleeding, an endometrial stripe above 4 mm or more is considered to be an indication for endometrial cancer.

What causes abnormally thick tissue?

Unless you’re experiencing unusual symptoms, thick endometrial tissue generally isn’t a cause for concern. In some cases, a thick endometrial stripe may be a sign of:


Endometrial polyps are tissue abnormalities found in the uterus. These polyps make the endometrium appear thicker in a sonogram. In most cases, polyps are benign. In a of cases, endometrial polyps can become malignant.


Uterine fibroids can attach to the endometrium and make it look thicker. Fibroids are extremely common, of women developing them at some point before they turn 50.

Tamoxifen use

Tamoxifen (Nolvadex) is a drug used to treat breast cancer. include early menopause and changes in the way your endometrium thickens and thins.

Endometrial hyperplasia

Endometrial hyperplasia occurs when your endometrial glands cause the tissue to grow more quickly. This condition is more common in women who have reached menopause. In some cases, endometrial hyperplasia can become malignant.

Endometrial cancer

According to the American Cancer Society, almost start in the endometrial cells. Having an abnormally thick endometrium could be an early sign of cancer. Other symptoms include heavy, frequent, or otherwise irregular bleeding, irregular discharge after menopause, and lower abdominal or pelvic pain.

What causes abnormally thin tissue?

Unless you’re experiencing unusual symptoms, thin endometrial tissue generally isn’t a cause for concern. In some cases, a thin endometrial stripe may be a sign of:


Your endometrium will stop its monthly thinning and thickening during and after menopause.


Low estrogen levels can lead to a condition called endometrial atrophy. Most often, this is connected to the onset of menopause. Hormone imbalances, eating disorders, and autoimmune conditions can also lead to atrophy in younger women. When your body has a low estrogen level, your endometrial tissue may not become thick enough for an egg to implant.

What symptoms are associated with abnormalities in tissue?

When endometrial cells grow at an abnormal rate, other symptoms can result.

If you have a thicker than normal endometrial stripe, these symptoms may include:

  • breakthrough bleeding between periods
  • extremely painful periods
  • difficulty getting pregnant
  • menstrual cycles that are shorter than 24 days or longer than 38 days
  • heavy bleeding during your period

If your endometrium is thinner than normal, you may have some of the same symptoms associated with thicker tissue. You may also experience:

If you’re experiencing any of these symptoms, make an appointment with your doctor. They may recommend an ultrasound or other diagnostic test to determine the cause.

Talk to your doctor

Don’t hesitate to ask your doctor questions about your reproductive health. Your doctor can review your medical history and discuss what’s normal for you.

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Evaluation of endometrial thickness in postmenopausal women by using 3.0-T MRI



Junko NakamuraI; Takeharu YoshikawaII; Eriko MaedaII; Hiroyuki AkaiIII; Hiroshi OhtsuIV; Naoto HayashiII; Kuni OhtomoI

IDepartment of Radiology, Graduate School of Medicine, The University of Tokyo, Japan
IIDepartment of Computational Diagnostic Radiology and Preventive Medicine, The University of Tokyo Hospital, Japan
IIIDepartment of Radiology, Research Hospital The Institute of Medical Science, The University of Tokyo, Japan
IVDepartment of Clinical Trial Data Management, The University of Tokyo Hospital, Japan





BACKGROUND: The accepted threshold for normal endometrial thickness is 5 mm; lesions with endometrial thickness < 5 mm are considered benign, whilst those > 5 mm are considered malignant. However, endometrium ≥ 5 mm on transvaginal ultrasonography in postmenopausal woman is considered as asymptomatic endometrial thickening. However, recent studies suggest that asymptomatic endometrial thickness of even 8 mm - 11 mm in postmenopausal women may be normal.
OBJECTIVES: The present study investigated the normal endometrial thickness range in 297 asymptomatic postmenopausal women using 3.0-T magnetic resonance imaging (MRI) T2-weighted sagittal images measured retrospectively by a single radiologist.
METHOD: The data were classified according to patient age and postmenopausal duration, and the medical records and follow-up MR images were reviewed to assess the clinical outcome.
RESULTS: The mean endometrial thickness was 2.4 ± 0.1 mm (range: 0.1-11.6). The endometrium in 21 of 297 subjects was ≥ 5 mm thick. Follow-up MR images were obtained in 17 of these 21 women, and their endometrial thickness was found to have decreased in all of them. To date, none of the subjects has been diagnosed with endometrial cancer.
CONCLUSION: Although 5 mm is considered the conservative threshold of normal endometrial thickness on MRI of postmenopausal women, this figure should not, to avoid excessive false-positive diagnoses, be assumed as an indication of malignancy.




Endometrial abnormalities pose diagnostic challenges for radiologists and gynaecologists. The endometrial appearance is influenced by several factors, such as age, menstrual status, pregnancy and hormonal therapy. Amongst these, menstrual status is potentially the most influential factor affecting endometrial thickness.

Although the accepted normal value for endometrial thickness is < 5 mm,1, 2 endometrium ≥ 5 mm on transvaginal ultrasonography (TVUS) imaging in a postmenopausal woman is considered asymptomatic endometrial thickening.3, 4, 5 Current literature concerning TVUS imaging suggests that asymptomatic endometrial thickness of 8 mm - 11 mm in a postmenopausal woman may be normal.6, 7, 8, 9, 10

TVUS may be ideal for reliable and cost-effective evaluation of the female reproductive tract and can measure several parameters including endometrial thickness, endometrial pattern and the endometrial and subendometrial perfusion.11 By using three-dimensional ultrasonography (3D US), any plane through an organ can be obtained, and a volume image can be recorded and further analysed in several ways, including navigation, multiplanar display, surface rendering or volume calculation.11, 12, 13 There remains no doubt that TVUS and 3D US are feasible, cost-effective and reliable modalities.

Magnetic resonance imaging (MRI) findings often correlate with US findings. Although MRI is an objective method with higher reproducibility than US, it is not first choice for asymptomatic or general patient screening, mainly because of its cost and scanning time. Therefore, screening pelvic MRI is confined to expensive private programmes, and data detailing the endometrial thickness in normal postmenopausal woman are inadequate. Furthermore, there have not been any studies assessing endometrial thickness on MRI in a sufficiently large study population. The present study investigated endometrial thickness in postmenopausal women by using MRI and correlating the findings to their menstrual activity and age.


Research method and design

Study design

The present investigation evaluated and compared endometrial thickness in postmenopausal women by using a 3.0-T MRI system. The study was approved by our institutional review board, and written informed consent was obtained from all subjects.

Subject selection

The study population comprised 679 consecutive women aged 27 to 83 years, who underwent a health-screening programme including pelvic MRI at our institution from April 2007 to February 2008. Each patient completed a medical questionnaire on menstruation, medication use and medical history.

The following were the exclusion criteria: (1) premenopausal status (174 women), (2) unclear menstrual history (72 women), (3) history of hormonal therapy or breast cancer (16 women), (4) history of severe gynaecological disease (7 women), (5) myomatous uterus or massive endometriosis with diffuse deviation or endometrial deviation (31 women) (Figure 1), and (6) hysterectomy (82 women). The remaining 297 postmenopausal women were enrolled in the study and the data classified by patient age and menstrual activity.



Magnetic resonance imaging

All of the subjects underwent pelvic MRI as part of a health-screening programme with a 3.0-T MRI system (Signa Excite, GE Healthcare UK, Buckinghamshire, England). Fast spin-echo (FSE) sagittal T2-weighted imaging was performed (repetition time: 8000 ms; effective echo time 91.5 ms; field of view 28 cm). The acquisition matrix for the FSE images was 384 x 320 with a 6 mm section thickness and a 0.547 mm intersection gap.

Magnetic resonance image analysis

A single radiologist retrospectively measured the endometrial thickness on sagittal T2-weighted images at the thickest site between the two basal layers on the anterior and posterior uterine walls (Figure 2).



Follow-up evaluation

The medical records were reviewed to assess clinical outcomes. In subjects with an endometrium ≥ 5 mm, the endometrial thickness was also measured on any available follow-up MR images.



Endometrial thickness of the 297 postmenopausal women (mean age 63 years; range 50-83) was 2.4 ± 0.1 mm (mean ± standard deviation) and ranged between 0.1 and 11.6 mm (Figure 3). Their endometrial thickness was poorly correlated with patient age (r = 0.026, p = 0.652) (Figure 3) and postmenopausal duration (r = 0.031, p = 0.583 (Figure 4).





The endometrium was ≥ 5 mm in 21 of 297 (7.1%) postmenopausal women. Three (1.0%) of the 21 women had an endometrium > 10 mm. Two of these women were referred to the gynaecology department following MRI, and one was diagnosed with endometrial hyperplasia, while no malignancy was detected in the second woman (class 1). Follow-up gynaecological examination could not be performed in the remaining case. Follow-up MRI was performed in 17 of 21 women with endometrial thickness ≥ 5 mm and showed a decreased endometrial thickness in all of them. None of the subjects was diagnosed with endometrial cancer on follow-up examination.



The endometrial thickness was successfully measured in 297 postmenopausal women using 3.0-T MRI. US is commonly used for gynaecological examination because of its convenience and non-invasiveness; however, it has drawbacks. Because US examination depends on operator skill, examinations must be performed by experienced staff with adequate training and skills. Therefore, accurate measurement of endometrial thickness can be difficult if US image quality is suboptimal. Furthermore, US is a poorly reproducible modality, and retrospective evaluation is difficult. In comparison, MRI is highly reproducible and can be re-evaluated at any time. In the present study, MRI was not directly compared with TVUS. Further studies are required to determine whether a single T2 sagittal sequence is equivalent to TVUS for assessing endometrial thickness.

The present analysis examined whether an endometrial thickness ≥ 5 mm in postmenopausal women is abnormal in a large sample population. Our findings support previous US studies stating that asymptomatic endometrial thickness of 8 mm - 11 mm is most probably normal.6, 7, 8, 9, 10 In addition, the incidence of endometrial thickening (≥ 4.5 mm) in postmenopausal women ranges from 3% to 17%,3, 4, 5 while the incidence of endometrial cancer in an unselected postmenopausal population is reportedly 1.3 to 1.7/1000 women.14, 15, 16 Some studies assert that there is no evidence supporting routine screening for asymptomatic endometrial thickening,17, 18, 19, 20 and it remains debatable whether an endometrium ≥ 5 mm should always be considered abnormal.

In the present study, particular attention was focused on the 21 of 297 (7.1%) postmenopausal women with an endometrium ≥ 5 mm. No cases of malignancy were diagnosed, and only one case (0.3%) of hyperplasia was detected. In follow-up MRI of 17 of the 21 subjects, the endometrium was thinner in all 17 cases; to date, none of the subjects has been diagnosed with endometrial cancer. The incidence of postmenopausal women with endometrium ≥ 5 mm in the present study closely coincided with previous studies.

Similarly to previous studies, our results suggest that there is no evidence supporting routine screening for asymptomatic endometrial thickening,17, 18, 19, 20, 21 and instead suggest the possibility of a risk of over-diagnosis in postmenopausal women with an endometrium ≥ 5 mm identified as abnormal without considering other risk factors. In 2010, Goldstein22 recommended that postmenopausal asymptomatic endometrial thickening should be evaluated on a case-by-case basis. Even in an elderly patient with endometrium ≥ 5 mm and a long postmenopausal period, it is inappropriate to consider the condition abnormal if she is asymptomatic.

The correlation between endometrial thickness, age and postmenopausal duration was also assessed. The results showed that endometrial thickness correlated poorly with postmenopausal duration and patient age. Further studies are required to determine the MRI cut-off to accurately exclude neoplasia. Future studies performing limited MRI examinations prior to endometrial biopsy in patients with endometrial hyperplasia or suspected of having endometrial carcinoma are planned.


Limitations of the study

The present study has several limitations. The intra-observer error is unknown because all measurements were performed visually by one radiologist. Furthermore, the study does not compare MR and US images in the same subject. Some studies report consistent endometrial thickness on MRI and US compared with histologic measurement in hysterectomy specimens,23, 24, 25 whilst others report a slight but consistent difference between the two modalities.26 The third limitation is that endometrial thickness could not be measured correctly on sagittal T2-weighted images owing to postmenopausal haemorrhage; in such cases, a follow-up MRI may be desirable.

In addition to these technical limitations, the cost-effectiveness of MRI is also a concern. MRI is an impractical screening tool to evaluate endometrial thickness because it is more costly than TVUS or 3D US. The cost to diagnose an instance of discrepancy was reportedly estimated at $7200, and routine CT, MRI and tumour markers are not necessary in all patients.27 Therefore, it is clear that US is more suitable for screening of endometrial thickness, and MRI should not be used routinely. However, the present results can assist clinicians to correctly interpret MR images performed following an initial screening test.



Endometrial thickness in postmenopausal women was measured using 3.0-T MRI. The mean thickness was 2.4 mm, and 5 mm thick in 7% of patients, but none developed endometrial cancer. The commonly used criterion of ≥ 5 mm endometrial thickness as a possible sign of malignancy may result in an excessive number of false-positives; therefore, a new standard for postmenopausal endometrial thickness should be established.



We thank Dr J. Maharajh and Dr A. Mitha for their help in compiling the images.

Competing interests

The authors declare that they have no financial or personal relationship(s) that may have inappropriately influenced them in writing this article.

Authors' contributions

Guarantors of integrity of entire study, J.N. (The University of Tokyo), T.Y. (The University of Tokyo Hospital), K.O. (The University of Tokyo); study concept/study design or data acquisition or data analysis/interpretation, J.N., T.Y., E.M. (The University of Tokyo Hospital), H.A. (The University of Tokyo), N.H. (The University of Tokyo Hospital), K.O. Manuscript drafting or manuscript intellectual content, all authors; manuscript final version approval, all authors; literature research, J.N., T.Y., E.M., H.A., N.H. and K.O.; statistical analysis, H.O. (The University of Tokyo Hospital); and manuscript editing, J.N., T.Y., E.M., H.A., N.H., K.O.



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Junko Nakamura
The University of Tokyo
Hospital, Department of Radiology
7-3-1 Hongo, Bunkyo-ku
Tokyo 113-8655, Japan
Email:[email protected]

Received: 05 Mar. 2014
Accepted: 26 Sept. 2014
Published: 11 Dec. 2014


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