Endometrial Thickness

Endometrial Thickness Index

Standardized Clinical Cut-offs

Postmenopausal (ACOG/SOGC)

Normal Threshold≤ 4 mm

High negative predictive value for cancer

Suspicious / Action> 4 mm

Requires biopsy/histology if bleeding

Asymptomatic (No PMB)> 11 mm

May require biopsy even without bleeding

Premenopausal Reference

Menstrual Phase2–4 mm

Proliferative Phase4–8 mm

Periovulatory8–11 mm

Secretory Phase7–16 mm

Clinical Ref: For postmenopausal patients, the measurement of endometrial thickness is most accurate when taken in the midline sagittal plane, excluding any small pockets of fluid.

Guidelines & Evidence

Verified

Last Review: 2026-07-17

When to Use

Primary Clinical Uses

Triage and risk stratification for postmenopausal bleeding (PMB)

Determining the necessity for invasive endometrial sampling (biopsy or hysteroscopy)

Evaluating asymptomatic thickened endometrium found incidentally on imaging

When NOT to Use

Absolute thickness is a poor standalone screening tool for asymptomatic postmenopausal women. Routine screening for endometrial cancer using ultrasound is explicitly NOT recommended by ACOG or SGO in the absence of bleeding.

How it Works

Measurement Technique

Measured via Transvaginal Ultrasound (TVUS) in the mid-sagittal plane

Represents the maximum anteroposterior dimension of the endometrial echo (double-layer thickness)

Caliper placement: from the echogenic interface at the myometrium-endometrium junction to the contralateral interface

If intracavitary fluid is present, measure both single layers separately and sum them (do NOT include the fluid in the measurement)

Standard Thresholds (Postmenopausal)

≤ 4 mm (with PMB)	Endometrial cancer highly unlikely (NPV > 99%)
> 4 mm (with PMB)	Abnormal; requires tissue sampling
Asymptomatic	Threshold debated; frequently biopsied if > 11 mm

Last Comprehensive Review: 2026-07-17

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Endometrial Thickness