← Back to CalculatorsHome
Gynaecologic Imaging
Demonstration data

Endometrial 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.

🧮 Interactive Calculator

📐 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.