Gynaecologic Imaging
Live dataEndometrial Thickness
Interprets transvaginal endometrial thickness against menopausal status and bleeding history to decide whether tissue sampling is warranted.
Endometrial thickness is measured as the maximal double-layer (bilayer) width on a midline sagittal transvaginal image, excluding any intracavitary fluid. Its interpretation depends heavily on menopausal status and, in postmenopausal women, on whether there is bleeding, because the pre-test probability of endometrial cancer differs.
📐 Formula
Double-layer thickness measured on midline sagittal TVUS; thresholds by bleeding status
🎯 When to Use
- Postmenopausal bleeding — the primary indication, to triage for endometrial sampling.
- Incidental thickened endometrium in an asymptomatic postmenopausal woman.
- Assessing the endometrium in premenopausal women (interpreted against cycle phase).
⚙️ How It Works
- Obtain a midline sagittal TVUS image and measure the maximal double-layer thickness perpendicular to the cavity.
- Exclude intracavitary fluid; if fluid is present, measure each single layer and sum.
- Apply the threshold appropriate to the bleeding and menopausal context.
📊 Interpreting the Result
- Postmenopausal with bleeding: ≤4 mm has a very high negative predictive value for cancer; >4 mm warrants tissue sampling or further evaluation.
- Postmenopausal without bleeding: no validated threshold, but >11 mm is often used as a trigger to consider further evaluation.
- Premenopausal: thickness varies physiologically with cycle phase (thin post-menstrual to ~16 mm in the secretory phase); interpret against timing rather than a fixed cut-off.
⚠️ Limitations & Pitfalls
- The 4 mm rule applies only to postmenopausal bleeding; applying it elsewhere causes over-investigation.
- Tamoxifen, adhesions and poor image quality reduce reliability; saline infusion sonography or hysteroscopy may be needed.
- A non-measurable or indistinct endometrium in a bleeding postmenopausal woman still requires further evaluation regardless of apparent thickness.
📚 References
- ACR Appropriateness Criteria: Abnormal Uterine Bleeding. American College of Radiology.
- Goldstein SR. The role of transvaginal ultrasound or endometrial biopsy in the evaluation of the menopausal endometrium. Am J Obstet Gynecol. 2009;201(1):5-11.
- ACOG Committee Opinion No. 734: The Role of Transvaginal Ultrasonography in Evaluating the Endometrium of Women With Postmenopausal Bleeding. 2018.
⚕️ For clinical decision support only. Always verify calculations and apply clinical judgment.