Endometrial thickness is a commonly measured parameter on routine gynaecological ultrasound and MR imaging. The appearance as well as the thickness of the endometrium will depend on whether the patient is of reproductive age or post-menopausal and if of reproductive age, at what point in the menstrual cycle they are examined.
The endometrium should be measured in the long-axis or sagittal plane. The measurement is of the thickest echogenic area from one basal endometrial interface across the endometrial canal to the other basal endometrium. Care should be taken not to include the hypo-echoic myometrium in this measurement.
Commonly accepted trans-vaginal ultrasound values are as follows.
In pre menopausal patients it significantly varies according to the stage of the menstrual cycle.
- during menstruation 1,4: 2-4 mm
- early proliferative phase (day 6-14 ): 5-7 mm
- late proliferative-pre ovulatory phase: up to 11 mm
- secretory phase: 7-16 mm
- following dilatation and curettage or spontaneous abortion: <5 mm, if it is thicker consider retained products of conception.
Will depend on the use of use of hormonal therapy/Tamoxifen
- if on no medication 5: <5 mm
- if there is vaginal bleeding, the risk of carcinoma is ~7% if endometrium is >5 mm 8
- if there is no bleeding, the risk of carcinoma is ~7% if the endometrium is >11 mm 8
- if on hormonal therapy 6: 8-15 mm upper limit
- if on Tamoxifen 3: <6 mm (although ~50% of those receiving Tamoxifen have been reported to have thickness of >8 mm 7)
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- 4. Williams PL, Laifer-narin SL, Ragavendra N. US of abnormal uterine bleeding. Radiographics. 23 (3): 703-18. doi:10.1148/rg.233025150 - Pubmed citation
- 5. Sahdev A. Imaging the endometrium in postmenopausal bleeding. BMJ. 2007;334 (7594): 635-6. doi:10.1136/bmj.39126.628924.BE - Free text at pubmed - Pubmed citation
- 6. Hulka CA, Hall DA, Mccarthy K et-al. Endometrial polyps, hyperplasia, and carcinoma in postmenopausal women: differentiation with endovaginal sonography. Radiology. 1994;191 (3): 755-8. Radiology (abstract) - Pubmed citation
- 7. Hann LE, Giess CS, Bach AM et-al. Endometrial thickness in tamoxifen-treated patients: correlation with clinical and pathologic findings. AJR Am J Roentgenol. 1997;168 (3): 657-61. AJR Am J Roentgenol (abstract) - Pubmed citation
- 8. Smith-bindman R, Weiss E, Feldstein V. How thick is too thick? When endometrial thickness should prompt biopsy in postmenopausal women without vaginal bleeding. Ultrasound Obstet Gynecol. 2004;24 (5): 558-65. doi:10.1002/uog.1704 - Pubmed citation
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