Ashley Davidoff MD

The Common Vein Copyright 2010

Introduction

Changes Duringthe Menstrual Cycle

During the menstrual phase (days 1- 4) the the endometrium is thin and typically is seen as a single echogenic line by ultrasound examination, and measuring between 1-4mm thick reflecting the early development of glands and stroma.(Nalaboff)

During the proliferative phase (days 4-14) the endometrium is of intermediate thickness.  In the early phase as the glands, stroma and vessels start to regenerate the stripe is echogenic and slightly thicker and measures between 5-7mms thick by ultrasound.  Later as the the tissue matures in the preovulatory phase the stripe has a typical trilaminar appearance and the thickness measures up to 11mms.  (Nalaboff)

During the secretory phase (days 15-28) the endometrium is at its thickest in the midsecretory phase and has a typical homogeneously echogenic appearance. The glands are fluid filled wit mucus and glycogen and stroma is edematous resulting in through transmission.  As it starts to degenerate are of hetrogeneity in the echogenic stripe start to appear.  It usually measures between 7-16mms. (Nalaboff)

During the menses the heterogeneous shedded endometrium may be seen in the cavity mixed with fluid and blood.

Character – by Ultrasound

Junctional Zone In Early Proliferative Phase

The normal sagittal view of the uterus is a transvaginal ultrasound, in the first week after menstruation  and just prior to the next menstruation after the endometrium has been shed. It demonstrates that the endometrium becomes a single echogenic line consisting of opposing walls (orange) and is surrounded by a subendometrial halo of the junctional zone (tan). This layer is more compacted, and relatively hypovascular. This image is typical of the early proliferative phase. It is during this time that estrogen starts to rise and progesterone has fallen. The endometrium in this case measures about 3mms.

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The Complex Endometrium

Triple Stripe – Trilaminar Appearance – Preovulation

The normal sagittal view of the uterus is a transvaginal ultrasound, 2 weeks after menstruation, and just prior to ovulation. It demonstrates that the uterus and more specifically the endometrium is more complex than just a simple columnar epithelium. This is an example of the trilaminar appearance of the endometrium and is characteristic of the appearance of the endometrium in the preovulatory phase. This pahse is also called the follicular phase, or proliferative phase. It is during this time that estrogen is the dominant hormonal influence. The appearance is also known as a “triple stripe”, and conversely, its presence is seen before progesterone is produced. If present with a 9mm+ diameter, it reflects an ideal potential lining for fertilization.. In this case it measured 1.2cms.

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The Overipe Endometrium – Premenstrual

The normal sagittal view of the uterus is a transvaginal ultrasound, about 4 weeks after menstruation, and just prior to the next menstrauation when the endometrium is overripe. It demonstrates that the uterus and more specifically the endometrium is more complex than just a simple columnar epithelium. This is an example of the hyperechoic, homogeneous, thick endometrium characteristic of the secretory phase. It is during this time that progesterone is the dominant hormonal influence and estrogen influence is minimal. The endometrium in this case measures 1.2cms.

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Endometrial Stripe and Junctional Zone in the Aging Uterus

The transvaginal ultrasound is from a 62 year old post menopausal patient who presents with pelvic discomfort. The ultrasound shows a small atrophied uterus. The myometrium (dark red) junctional zone (light red) and endometrial cavity (pink) are outlined. In the sagittal plane the uterus measures 3.4cms in cranoicaudal dimension by 2.4cms in anteroposterior dimension (a,b) In the axial dimension (c,d) the uterus measures 2.4cms. The endometrial stripe is measured in the sagittal plane and measures .7mms.

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References

Nalaboff, Kenneth M. MD,  Pellerito, John S. MD and   Ben-Levi, Eran MD Imaging the Endometrium: Disease and Normal Variants RadioGraphics, 21, 1409-1424. November 2001