A double-layer endometrial thickness of 4 mm or less in a postmenopausal woman with bleeding has a very low risk of cancer; above that, or when the endometrium cannot be seen well, sampling or hysteroscopy follows.
Orient first
- The threshold applies to women not on HRT or tamoxifen (verify the cut-off your gynaecologists use: 3–5 mm).
- Focal thickening or a polyp needs a stalk and feeding vessel search.
- Tamoxifen produces subendometrial cystic change that mimics thickening.
Acquire the study
- Transvaginal ultrasound, sagittal plane through the full length of the cavity; colour Doppler at low scale; saline infusion sonohysterography for focal lesions.
The manoeuvre
- Sagittal view: double-layer endometrial thickness in mm at the thickest point, excluding intracavitary fluid.
- Endometrial texture: homogeneous vs heterogeneous; endometrial-myometrial junction regular or interrupted.
- Colour Doppler: single feeding vessel (polyp) vs multiple or disorganised vessels (concerning).
- Intracavitary fluid: measure the two layers separately.
- Adnexa and cervix.
What confirms it
- Thickness above threshold or a focal lesion — reported for sampling; cancer is confirmed histologically.
What licenses you to exclude it
- A clearly visualised, homogeneous endometrium ≤ 4 mm makes cancer very unlikely in a first episode; persistent bleeding still needs assessment.
The classic misread
- Accepting an incompletely visualised endometrium as "thin".
- Measuring intracavitary fluid as endometrium.
- Applying the threshold to women on tamoxifen.