Endometrial Lining Scan
Endometrial Lining Ultrasound Scan
£197
Endometrial Lining Scan is a gynaecological Ultrasound assessment of your endometrium (the lining of the womb) designed to assess its structure, thickness, how it correlates with where you are in your cycle or responsiveness to treatment stimulation, as well as its shape, to ensure normal appearances. Also, we will assess the womb, ovaries, fallopian tubes, and surrounding structures. This type of scan aims to ensure normal thickness of the lining of the womb to appropriately time natural conception or any form of assisted conception (such as IVF), as well as to rule out any structural cause that might explain difficulty conceiving, recurrent miscarriages, generalized pelvic pain or any other related issue.
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Endometrial Thickness (Uterine Lining) – Normal Range by Cycle & Menopause
Endometrial thickness (also called the endometrial lining or endometrial stripe) is the ultrasound measurement of the womb’s inner lining. Normal size changes throughout the menstrual cycle, and differs in perimenopause and postmenopause. It can also be influenced by HRT, tamoxifen, PCOS, endometrial polyps, hyperplasia, and pregnancy.
Quick Reference: Normal Endometrial Thickness (mm)
Premenopausal (Natural Cycles)
- Menstruation (Day 1–4): 2–4 mm (thin, shedding)
- Early proliferative (Day 5–9): 5–7 mm
- Late proliferative / pre-ovulation (Day 10–14): 7–11 mm
- Secretory / luteal phase (Day 15–28): 10–16 mm (can be up to ~16–18 mm near peak)
Fertility note: Many pregnancies occur with an endometrium ≥7–8 mm around ovulation; the “triple-line” pattern also matters.
Perimenopause
Variable; interpret with symptoms and cycle timing. Diffuse ≥16 mm outside the secretory phase or any focal thickening merits specialist review.
Postmenopausal
- With bleeding (PMB): ≤4 mm is generally low risk; >4 mm requires evaluation (often biopsy).
- Without bleeding: ≤3–5 mm is typical; >11 mm often merits assessment, especially with risk factors.
- On HRT: Continuous combined: usually ≤5 mm. Sequential HRT: may be thicker (often ≤8 mm) around the “withdrawal bleed”.
Conversion tip: 10 mm = 1.0 cm; 15 mm = 1.5 cm.
Endometrial Thickness by Cycle Day (Typical Ranges)
| Cycle day | Usual appearance | Typical thickness (mm) |
|---|---|---|
| Day 2–3 | Menstrual, thin | 2–4 |
| Day 5–7 | Early proliferative | 5–7 |
| Day 8–10 | Mid proliferative (emerging triple-line) | 6–9 |
| Day 11–13 | Late proliferative / peri-ovulatory | 7–11 |
| Day 14–21 | Early secretory | 10–14 |
| Day 22–28 | Mid/late secretory (echogenic, uniform) | 12–16 (±18) |
What Do Specific Measurements Mean?
- 6 mm: Normal in early/mid-cycle premenopause. Postmenopause: borderline/high—interpret with symptoms (bleeding? HRT?).
- 7 mm: Normal in luteal premenopause. Postmenopause with bleeding: usually investigate.
- 9–11 mm: Common late proliferative/secretory in cycling women. Postmenopause: investigate, especially if bleeding.
- 13–15 mm: Can be physiological in secretory phase. If outside that phase or with abnormal bleeding, consider polyp/hyperplasia → gynaecology review. Postmenopause: abnormal → evaluate.
- ≥16–20+ mm: Cycling: thick—check timing/symptoms; rule out polyp, hyperplasia, pregnancy. Postmenopause: abnormal until proven otherwise → urgent assessment.
When to worry about endometrial thickness: postmenopausal bleeding with stripe >4 mm; any focal/heterogeneous thickening or cystic foci; premenopausal thickness ≥16 mm outside luteal phase with heavy/irregular bleeding or risk factors (obesity, PCOS, tamoxifen, unopposed oestrogen).
Thickened Endometrium – Common Causes
- Normal physiology: secretory-phase thickening, early pregnancy
- Benign lesions: endometrial polyp, submucosal fibroid
- Hormonal: HRT, tamoxifen, PCOS, anovulation, unopposed oestrogen
- Inflammatory/retained tissue: endometritis, retained products
- Endometrial hyperplasia (with/without atypia)
- Endometrial cancer (risk higher with age, obesity, diabetes, Lynch syndrome—especially if postmenopausal bleeding)
How We Measure the Endometrium on Ultrasound
Transvaginal ultrasound (TVUS) provides the most accurate endometrium measurement: the double-layer thickness (anterior + posterior) is measured in the sagittal plane at the thickest point. The report also comments on homogeneous vs heterogeneous echotexture, cystic foci, vascularity, and any focal mass (polyp). In pregnancy, the lining is decidualised; thickness is not used to stage pregnancy.
FAQs
What is normal endometrial thickness (mm/cm)?
Premenopausal: varies with the cycle (~2–16 mm). Postmenopausal without bleeding: typically ≤3–5 mm. With postmenopausal bleeding: ≤4 mm is considered low risk; thicker linings warrant evaluation. (10 mm = 1.0 cm.)
Can a thick endometrium be normal?
Yes—during the secretory phase or early pregnancy. Context and ultrasound pattern matter.
Is 13–15 mm endometrial thickness normal?
Often physiological in the secretory phase of cycling women. Outside that phase or with abnormal bleeding, evaluate for polyp or hyperplasia. In postmenopausal women, it is abnormal and needs assessment.
Does HRT or tamoxifen change the normal range?
Yes. Continuous combined HRT commonly ≤5 mm; sequential HRT can be thicker (often ≤8 mm) around the withdrawal bleed. Tamoxifen can cause cystic changes; clinical context guides biopsy.
What is an ideal endometrial thickness for pregnancy?
Many successful pregnancies occur with ≥7–8 mm around ovulation, but pattern (triple-line), hormones, and uterine health are equally important.
When to Seek Further Tests
Arrange review if you have: postmenopausal bleeding, endometrial thickness >4 mm with PMB, focal mass/heterogeneous stripe, suspected polyp, or persistent heavy/irregular bleeding in premenopause. Next steps may include repeat TVUS at the correct cycle phase, saline infusion sonography (SIS), endometrial biopsy, or hysteroscopy & polypectomy.
