Size of the Uterus

Ashley Davidoff MD

The Common Vein copyright 2008

Introduction

In the postmenarchal non gravid state the upper part of the adult uterus measures about 8cm. in length, 4 cm. in A-P dimension, and nearly 6 cm. in transverse dimension;  it weighs from about 35gms in the virgin state to up to 200 gms in the postpartum state, and has a correlative volume of between 75-200ccs.   It is slightly smaller than the heart and the mature uterus is described as the size of a woman’s fist.   

The nature and structure of the uterus allows it to change its size dramatically from  the size of a pear or maybe an avocado where it is confined to the deep pelvis to an organ that reaches the umbilicus when at peak pregnancy.  

The myometrium measures between 1.5-2.5cms thick, and the endometrium measures from 1-8mms and sometimes up to 10mms thick.   

The size of the cervix length 2.5cms transverse 5 cms antero-posterior 2.5 cms weight volume

At Birth

The body of the uterus is similar in size to the cervix.  Its overall size is 2.3-4.6 cms. (Nalaboff)

At Birth (left) and at Maturity (right)

This diagram in the coronal plane demonstrates the differences in size of the uterus at birth (left) and the mature, post menarche uterus (right). There is not only a difference in the absolute size but the ratio of the size body to the cervix changes as well. At birth the cervix is about the same size as the body of the uterus and post menarche the cervix is about 1/4 to 1/3 the size the body. Courtesy Ashley Davidoff MD  Copyright 2010  All rights reserved 96266b15b01h02.83sc

 Adulthood

Pregnancy

Non Gravid, 32 Week Pregnancy, and Post Cesarean Section

The series of CT scans from different patients are reconstructed in the sagittal plane to show the mature uterus in the non-gravid state (a,d) with a 32 week pregnancy (b,e), and in the postpartum, post cesarean section state (c,f). In the nongravid adult the uterus the craniocaudad span (c-c) measures about 9cms and the anteroposterior (A-P) dimension it measures 4.5cms The uterus containing the 32week pregnancy measures 24cms (c-c) by 16cms (A-P). In the post cesarean section patient the uterus measures 17cms (c-c) by 9cms (A-P). Courtesy Ashley Davidoff MD Copyright 2010 All rights reserved 78093c08.8s

Old Age

Old and Young

The sagittaly reconstructed CT of a 82 year old female (a,b) is placed in comparison to a similar view in an 25 year old female (c,d),and size change is the most obvious difference. In the older patient the craniocaudad span (c-c) is about 5cms and A-P dimension is 1.5cms, and in the younger patient it is about 9cms in c-c span and 4.5cms in A-P dimension. The endometrial stripe in the older patient is not really visible but is drawn in a s a less than 1mms line and in the younger patient it is obvious and measures about a 1cms. In both instances the uterus is buoyed and cushioned by partly filled bladder (yellow) Note also the difference in the density of the bones, the degenerative changes in the spine and the calcification in the older patient of the distal abdominal aorta. Courtesy Ashley Davidoff MD Copyright 2010 All rights reserved 83564c03.8s

Ultrasound of the Post Menopausal 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.  Courtesy Ashley Davidoff MD Copyright 2010 All rights reserved 84711c01.8s

Size and the Menstrual Cycle

The cyclical changes of the menstrual cycle present a continual change of events controlled by a series of integrated hormonal events.  These changes are most easily observed in the endometrium by ultrasound.

During the menses, the endometrium sheds and becomes thinner, the junctional zone is irregulalrly thick, and the myometrium loses water and thins.

In the periovulatory phase the myometrium and endometrium start to thicken, and the junctional zone becomes more easily identified (Kido)

There are 3 distinct zones or parts of the uterus which vary in size and character during each of the menstrual phases.

Endometrial Changes During the Cycle

During the follicular phase (proliferative phase) which occurs in the first half of the cycle, and after the shedding of the endometrial lining, there is a rise in estrogen which causes the endometrial lining to start to thicken.  In mid cycle after ovulation, luteinizing hormone is released, which heralds in the luteal phase (aka secretory phase). Progesterone now rises and further proliferation of the endometrium occurs.  In the absence of pregnancy progesterone levels and estrogen levels fall, and the endometrium sheds. The cervical canal has a maximal dimension of 8mms.

Size Normal

46315 uterus endometrium shape normal anatomy USscan Davidoff MD

Atrophic Endometrium

46323 LMP 20 years ago uterus endometrium shape size normal anatomy USscan Davidoff MD

 Myometrial Changes

The myometrium is largest in the second half of the cycle – the midsecretory phase.  The myometrium is thickest at this time due to mild edema, but this is not easily observed by imaging techniques.

Junctional Zone Changes

During the midsecretory phase the junctional zone thins out.

In the post menopausal woman the average size of the uterus is 5cms in craniocaudad span by 2cms.(Fleischer )

In virgin state the uterus is flattened antero-posteriorly and is pyriform in shape, with the apex directed downward and backward. The bladder is to anterior and rectum is related to it posteriorly. It is a pelvic organ suspended by broad ligament and round ligament superiorly to pelvic fibrous tissue inferiorly.

Size of the Uterus Over Time

The sagittal diagram of the uterus and vagina through time shows an anteverted uterus at birth, through youth as it slowly matures and enlarges, entering spring as it reaches maturity, summer time when it bears fruit, and then through fall as it starts to involute in the postmenopausal period, and finally in its winter when it shrivels. In this view the uterus vagina, and the internal cavity starting in the endometrial cavity, coursing through the cervix and then into the collapsed vaginal cavity is exemplified. Courtesy Ashley Davidoff MD Copyright 2010 All rights reserved 96268b.51kc02Lh.8s

Normal Uterine Size: By ultrasound, the normal postmenarchal nulliparous uterus is 5-8 cm in length, 1.5-3 cm thick, 2.5-5 cm. wide.

Changes in the Endometrial Stripe

During the menstrual cycle the ultrasound appearance can characterise and date the phase of the cycle. (Nalaboff) Following menses there is a thin echogenic line which measures between 1-4mms, (Nalaboff) which progressively thickens and changes to a multilayered configuration. On ultrasound the measurement is from echogenic border to echogenic border in the sagittal plane.

In the proliferative phase (day6-14) the endometrium thickens to 5-7mmsand becomes more echogenic than the myometrium.This reflects growth of the endometrial glands blood vessels and stroma, stimulated by estrogen production by the ovarian follicles. This proliferative endometrium is structurally and functionallly prepared for implantation of the fertilised egg. In the late proliferative phase (periovulatory phase), the endometrium becomes multilayered, with an echogenic basal layer, hypoechoic inner functional layer and a thinFollowing ovulation, the endometrium is under the influence of progesterone secretion by the corpus luteum. The endometrial glands fill up with mucus. The resulting appearance of the endometrium is a thick echogenic structure (secretory phase) The endometrium is at its thickest at this stage (< 14mm). As luteinizing hormone levels fall in the latter phase of the cycle, the level of progesterone falls, and there is shedding of the endometrium. Thus, the cyclical changes of the endometrium (invisible, thin echogenic, multi-layered, thick echogenic) reflect the phases of the menstrual cycle. “Transvaginal ultrasound revealing an endometrial stripe of less than 5 mm is reassuring and essentially rules out cancer (3). An endometrial stripe greater than 4 mm necessitates endometrial sampling, preferably with in-office use of a Pipelle endometrial suction curette or similar device”

In pregnancy

During Pregnancy the uterus gradually enlarges

Post Partum Uterus

Then mean size of the uterus 24hours after delivery is 14X 7cms. (Garagiola)

BicornuateAngle divergence >105 degrees

In virgin state the uterus is flattened antero-posteriorly and is pyriform in shape, with the apex directed downward and backward. The bladder is to anterior and rectum is related to it posteriorly. It is a pelvic organ suspended by broad ligament and round ligament superiorly to pelvic fibrous tissue inferiorly.   The uterus measures about 7.5 cm. in length, 5 cm. in breadth, at its upper part, and nearly 2.5 cm. in thickness; it weighs from 30 to 40 gms. It is divisible into two portions. On the surface, about midway between the apex and base, is a slight constriction, known as the isthmus, and corresponding to this in the interior is a narrowing of the uterine cavity, the internal orifice of the uterus. The portion above the isthmus is termed the body, and that below, the cervix. The part of the body which lies above a plane passing through the points of entrance of the uterine tubes is known as the fundus. Cervix has

46355

46355 uterus endometrial cavity shape normal anatomy Davidoff MD

Uterine Atrophy in an 86 year old patient

75922c03 86 year old female with back pain age aging uterus atrophy small normal aging process grade 1 spondylolisthesis of L5 on S1 discogenic disease degenerative disease vacuum phenomenon CTscan Courtesy Ashley Davidoff MD 75917 75922c01 75922c02 75922c03

Normal Post Menopausal Uterus (a,b) Post Menopausal Endometrial Carcinoma (c,d)

The first CTscan (a,b) is from an 86 year old patient with a small but normal post menopausal uterus showing characteristic vascular calcification. The second CT (c,d) is from an 83F year old patient with distended endometrial cavity (orange in d) uterine carcinoma code uterus size enlarged postmenopausal carcinoma obstructed thick free fluid CTscan Courtesy Ashley Davidoff MD copyright 2009 all rights 83731c01.8S reserved

Enlarged Uterus and Endometrial Cavity

83F year old with distended endometrial cavity uterine carcinoma code uterus size enlarged postmenopausal carcinoma obstructed thick free fluid CTscan Courtesy Ashley Davidoff MD copyright 2009 all rights reserved 83731.8s

Obstructed Uterus with Pyometria

46 year old female with obstructed uterus and fluid filled endometrial cavity with pockets of air caused by cervical carcinoma complicated by pyometria. CT cervix uterus carcinoma cancer obstruction enlargement size air CTscan Courtesy Ashley Davidoff MD Copyright 2009 all rights reserved 83682c01b.8s

Enlarged Uterus  – Expanded Cavity

The ultrasound of a 58 year female with expanded endometrial cavity is shown. The cavity is filled with heterogenous material (green) representing a combination of tumor, fluid necrotic material and blood. Pathology showed adenocarcinoma, endometriod type, grade I/III with tumor necrosis. In this iamge a small portion of normal appearing endometrium is shown in pink. Tumor involvement with the right ureter and secondary hydronephrosis of the right kidney is present. code uterus carcinoma kidney hydronephrosis CTscan USscan Courtesy Ashley Davidoff Copyright 2009 all rights reserved 83510c03.8s

Adenomyosis Thickened Junctional Zone Enlarged Uterus

This T2 weighted MRI of a 41 year old female shows thickened junctional zone (light maroon) of the uterus measuring up to 12 mms characteristic of adenomyosis code uterus junctional zone thickened enlarged MRI T2 weighted Adenomyosis the uterus Courrtesy Ashey Davidoff MD copyright 2009

Enlarged and Obstructed Uterus – Cancer of the Cervix

83648c02.8s 46 year old female with obstructed uterus and fluid filled endometrial cavity with pockets of air caused by cervical carcinoma complicated by pyometria CT cervix uterus hematometra hematometria pyometra pyometria hydrocolpos hematocolpos CTscan Courtesy Ashley Davidoff MD Copyright 2009 all rights reserved

references

Fleischer AC, Kepple DM. Normal pelvic anatomy as depicted by various sonographic techniques. In: Fleischer AC, Javitt MC, Jeffrey RB, Jones HW, III, eds. Clinical gynecologic imaging. Philadelphia, Pa: Lippincott-Raven, 1997; 10-41.

(Kido)

Garagiola)

Postpartum and 18months Later

The CTscan is from a 26 year old female showing breasts and uterus in a post partum post cesarian section state (a,c) and then 18months later (c,d). The transverse dimension of the uterus in the post partum state is about 11cms, while 18months later is about 5cms. Her breasts in the post partum state are enlarged with prominent glandular tissue (a), and in the post partum state are reduced in size and glandular volume (b). Surgical footprints are noted in the subcutaneous tissue in c following her cesarian section. A cervical fibroid is suggested post partum image (d). Courtesy Ashley Davidoff copyright 2009 83354c.8s

Supernormal

The T2 weighted MRI from a 44 year old patient with 32 week twin gestation in the sagittal plane (a) and in the coronal plane (b) revealing a uterus that measures 30cms in craniocaudad span, by 18cms A-P, by 26cms in the transverse plane. Courtesy Ashley Davidoff MD Copyright 2010 All rights reserved 88845c01.8s