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GYNOCOLOGY – ULTRASOUND

INTRODUCTION

The uterus is a pear-shaped, retroperitoneal organ that lies anterior to the rectum, posterior to the urinary bladder, and is bounded laterally by the broad ligaments . Its primary function is to provide a place for the products of conception to implant and develop.

The uterus can be divided into four major divisions: fundus, corpus, isthmus, and cervix.

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The largest part of the uterus is the corpus, or body. The corpus is located inferior to the fundus. The isthmus is the area located between the corpus and the cervix.

During pregnancy, the isthmus may be referred to as the lower uterine segment.

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The cervix is the rigid component of the uterus that is located inferior to the isthmus, and it is the portion of the uterus that projects into the vagina.

The cervix is marked superiorly by the internal os, which is in contact with the isthmus, and inferiorly by the external os, which is in close contact with the vagina.

Uterus parts

Fundus. The uppermost and widest part of your uterus. It connects fallopian tubes.

Corpus. The main body of uterus. This is where a fertilized egg implants during pregnancy.

Isthmus. The part of uterus between corpus and cervix. It’s where uterus starts to narrow or thin.

Cervix. The lowest part of uterus. cervix opens to vagina.

LAYERS

The uterine wall consists of three layers . The outermost layer is referred to as the serosal layer or perimetrium, which is continuous with the fascia of the pelvis.

The middle layer is the myometrium or muscular layer, which constitutes the bulk of the uterine tissue, providing the area where contractile motion occurs.

The inner mucosal layer of the uterus is referred to as the endometrium. The endometrium can be further divided into a deep or basal layer and a superficial or functional layer

The thickness of the basal layer is typically consistent, although minimal changes may occur throughout the menstrual cycle.

The functional layer of the endometrium is the component that is shed during menstruation; thus, the thickness of the functional layer of endometrium will vary during the menstrual cycle as a result of hormonal stimulation

The endometrial cavity, also referred to as the uterine cavity, is located between the two functional layers of the endometrium.

This cavity is contiguous with the lumen of the fallopian tubes laterally, and the cervix inferiorly.

Uterine Size and Shape

The size and shape of the uterus depends on the age of the patient, parity, and the presence of pathology or congenital anomalies that may alter its contour.

The normal neonatal uterus is tubular in appearance and may exhibit distinct endometrial echoes in the first week of life as a result of maternal hormone stimulation.

Following the neonatal period, the cervical anteroposterior 579 diameter is equal to or slightly greater than that of the uterine fundus

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The uterus grows minimally during prepubertal years, whereas after puberty, the uterine fundus becomes much larger than the cervix, consequently providing the pear-shaped appearance of the normal adult uterus.

Following menopause, the uterus typically becomes much smaller than the premenopausal uterus

Uterine Positions

The uterine position within the pelvis is variable The normal position of the uterus is considered to be anteversion or anteflexion.

Anteversion describes the uterine position in which the body tilts forward or anteriorly, forming a 90-degree angle with the vagina.

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Anteflexion of the uterus denotes the position in which the uterine body folds forward, possibly coming in contact with the cervix.

Retroversion of the uterus is the position in which the uterine body tilts backward or posteriorly, without a bend where the cervix and body meet.

Retroflexion is the uterine position that results in the uterine body tilting backward and actually coming in contact with the cervix

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The uterus may also be oriented more to the left or right of the midline, resulting in a variation between anatomic midline and functional midline.

The uterus that is located more on the left is referred to as a levoverted uterus, whereas the uterus that is located on the right is referred to as dextroverted uterus

Uterus position

Retroverted uterus. Commonly called a tipped or tilted uterus. This is when your uterus is tilted or tipped backward so it curves toward your spine instead of forward toward your abdomen.

Anteflexed uterus. Your uterus is anteflexed when it’s bent forward. The tilt is severe and can put pressure on your abdomen or bladder and cause painful symptoms.

Retroflexed uterus. Your uterus is retroflexed when it’s bent backward. The tilt puts pressure on your lower back

Congenital anomalies

• Bicornuate uterus. A heart-shaped uterus.
• Arcuate uterus. Similar to a bicornuate uterus but with less of a dip or heart shape.
• Septate uterus. When uterus is divided into two parts by a membrane.
• Unicornuate uterus. When have one fallopian tube and an irregularly shaped uterus.

Didelphys uterus. When you’re born with two uteruses

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Bicornuate uterus (Fig. 17-8). A bicornuate uterus, also referred to as bicornis unicollis, is present when the endometrium divides into two endometrial cavities, with a prominent concavity noted in the outline of the uterine fundus.

UTERINE PATHOLOGY

Adenomyosis

Adenomyosis is the invasion of endometrial tissue into the myometrium.4,7,8 The basal layer of the endometrium can often extend into the myometrium at depths of at least 2.5 mm.1,2 The involvement of Adenomyosis may be either focal or diffuse and is typically found more often within the posterior portion of the uterus

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Uterine Leiomyoma A leiomyoma is a benign, smooth muscle tumor of the uterus that may also be referred to as a fibroid or uter ine myoma. Leiomyomas are the most common benign gynecologic tumors and the leading cause of hysterec tomy and gynecologic surgery.1,7 These tumors can vary in size and may alter the shape of the uterus and have varying sonographic appearances

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Fibroids are also described sonographically by their location (Fig. 17-13). The most common location for fibroids is intramural, or within the myometrium.

A subserosal fibroid grows outward and distorts the con tour of the uterus.

Subserosal fibroids that are Pedunculated (on a stalk), or those associated with the broad ligament, could resemble adnexal masses.

This lack of blood supply results in necrosis and clinically the patient will present with acute, localized pelvic pain.

Submucosal fibroids are located adjacent to the endometrial cavity and often distort the shape of the endometrium.

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Intracavitary fibroids, the fibroids located within the uterine cavity, and submucosal fibroids usually lead to abnormal uterine bleeding because of their location in relationship to the endometrium.

Intracavitary fibroids may also extend into the cervix when pedunculated.

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Fibroid growth has been associated with estrogen stimulation and consequently their size may increase during pregnancy and reduce after menopause.

Fibroids may also impact fertility if they are intracavitary or submucosal fibroids, as the location of these fibroids may result in a higher incidence of spontaneous abortion.

Fibroids may also affect the contractile motion of the uterus, thus leading to interference with sperm migration.

A concurrent intrauterine pregnancy and fibroid can be sonographically identified and often do not result in preterm labor or early pregnancy loss.

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Alternatively, fibroids may prevent cervical dilatation during pregnancy, thus often requiring a cesarean section to be performed at the time of delivery

Leiomyosarcoma

Leiomyosarcoma is the malignant counterpart of the normally benign leiomyoma. These masses are characterized by a rapid increase in growth and are more commonly found in perimenopausal or postmenopausal woman.

Their sonographic appearance is variable and they may appear similar to a benign fibroid, with some evidence of degeneration.

Nabothian Cyst

Nabothian cysts are common findings on routine ultra sound examinations. These benign retention cysts are located within the cervix and may cause cervical enlargement on physical examination.

Nabothian cysts are classically simple but may have some internal debris or septations, which may represent hemorrhage or infection.

Nabothian cysts are typically asymptomatic and may be multiple

VAGINAL PATHOLOGY

A Gartner duct cyst may be noted within the vagina. They are typically small and located along the wall of the vagina. Gartner duct cysts are often asymptomatic.

Cervical Carcinoma

Cervical carcinoma is the most common female malignancy in women younger than age 50.

Although cervical carcinomas are not routinely diagnosed with sonography, they may be present as an inhomogeneous, enlarged cervix or as a focal mass within the cervix.

Transvaginal and transrectal imaging are methods in which sonography can be used to better visualize the cervix.