Chapter 42 GYN

Describe the changes of the endometrium throughout the normal menstrual cycle.

14. During menstruation (days 1 to 4), the endometrium appears as a hypoechoic central line representing blood and tissue. A hyperechoic endometrial echo surrounds the endometrium. If menstrual flow is heavy, the entire endometrial cavity can appear anechoic. During this phase of early menses, acoustic enhancement posterior to the endometrium may appear as it does in the luteal phase, but to a lesser degree. As menses progress (days 3 to 7), the hypoechoic echo that represented blood disappears. In the proliferative phase (days 5 to 9) the endometrium appears as a single thin stripe (the endometrial cavity) with a hypoechoic halo (the functionalis) encompassing it, creating the three-line sign. The thin surrounding hyperechoic layer of endometrium represents the basalis. In the early secretory phase (days 10 to 14), ovulation occurs. The endometrium increases in thickness and echogenicity, representing the basalis that progresses and inundates the entire endometrium. During the luteal or secretory phase, the endometrium is at its greatest thickness and echogenicity with posterior enhancement. The posterior enhancement is thought to be attributable to the increased vascularity of the endometrium.

Before a pelvic ultrasound, what pertinent information should be requested from the patient?

A complete history is critical to adequately correlate ultrasound findings with the proper differential. It is important for the sonographer to use a routine patient questionnaire requesting the following information: last menstrual period, gravidity, parity, physiologic menstrual status, hormone regimen, symptoms, history of cancer, family history of cancer, past surgeries, laboratory tests, pelvic examination findings, and previous ultrasound findings.

Premenopause

A transitional stage of 2 to 10 years before the complete cessation of the menstrual cycle.

What are the contraindications for endovaginal ultrasound?

Contraindications include patient refusal, lack of patient tolerance (usually secondary to intense pelvic pain), and age (both premenarche and menopausal). Evaluation with endovaginal scanning is exempted with patients who have an intact hymen or small vaginal canal.

Pourcelot resistive index

Doppler measurement that takes the highest systolic peak minus the highest diastolic peak divided by the highest systolic peak.

Pulsatility Index (PI)

Doppler measurement that uses peak systole minus peak diastole divided by the mean.

In a normal anteflexed uterus, visualization of the cervix is optimized by what angulation of the endovaginal transducer?

Endovaginal evaluation of the cervix and rectouterine recess is superior to the transabdominal technique. While inserting or withdrawing the transducer into or from the vaginal fornix about 2 to 3 cm from the external os, the cervix is posterior to the anechoic bladder. Improved visualization may require posterior angulation if the uterus is anteverted and anterior angulation if the uterus is retroverted.

If fluid is present within the endometrial cavity, how should the endometrial thickness be determined?

Exclude fluid within the endometrial cavity from the measurement. Measure the anterior and posterior layers separately and add the two measurements together to determine the thickness.

Describe the proper endovaginal transducer preparation before each examination.

For chemical disinfection technique, after the transducer has been soaked in a Cidex-type solution for at least 10 minutes, it is important to rinse off the transducer with water and dry it before applying the coupling gel and protective probe cover. Careful examination for air trapped under the probe cover and subsequent removal prevents artifacts. The final step of transducer preparation is adding sterile lubrication to the outer surface. If the examination is performed on an infertility patient, the use of water to lubricate the transducer is preferred, because water does not have a negative effect on sperm mobility.

Coronal Plane

Horizontal plane through the longitudinal axis of the body to image structures from anterior to posterior.

What are the four major muscle groups in the female pelvis that are visualized by ultrasound?

In the lesser or true pelvis, the iliopsoas, reproductive organs, levator ani, piriformis and obturator internus muscles can be identified.

Endometrium

Inner lining of the uterine cavity which appears as echogenic to hypoechoic on ultrasound, depending on the menstrual cycle.

Internal Os

Inner surface of the cervical os

How is the endometrium properly measured?

Measure the endometrial thickness from the highly reflective interface of the endometrium and myometrium in the sagittal view. This sonographic measurement includes both the anterior and posterior layers of the endometrium. The surrounding hypoechoic area and fluid within the endometrial cavity are not included in the measurement.

Why is it important to know the last menstrual period before beginning the ultrasound examination?

Obtaining the last menstrual period start date allows determination of the size, endometrial appearance, and ovaries as they relate to the cycle.

Cornu, Cornua

Only projection like a horn; refers to the fundus or the uterus where the fallopian tubes arise.

Menarche

Refers to the onset of menstruation and the commencement of cyclic menstrual function; usually occurs between 11-13 years of age.

Translabial Scanning

Scanning across or through the labia.

Arcuate vessels

Small vessels found along the periphery of the uterus.

Describe the sonographic technique to image the ovary.

Sonographically, the normal ovary appears as an ovoid homogeneous echodensity; follicular cysts are often present. The best sonographic marker for the ovary is identification of a follicle within the almond-shaped structure and the iliac vessels (the ovary lies anterior and medial to the vessel).

Sonohysterography (Saline Infused Sonography)

Technique that uses a catheter inserted to fill the endometrial cavity.

What is the best landmark for orientation in the female pelvis when using endovaginal sonography?

The best landmark for orientation in the female pelvis with endovaginal ultrasound is the uterus.

What is the best way to visualize the rectus abdominis muscles? How do they appear sonographically?

The best way to image the rectus abdominis muscles is with a transabdominal scan across the transverse plane of the pelvis. These muscles are symmetric and superficial in the abdominal wall.

S/D Ratio

The difference between peak systole and end diastole.

Menstruation

The endometrial canal appears as a hypoechoic central line. (Days 1-4)

Early Proliferative Phase

The endometrial canal appears as a single thin stripe. (days 5-9)

Secretory (Luteal) Phase

The endometrium is at it greatest thickness and echogenicity with posterior enhancement. ( Days 15-28)

In an endovaginal examination of the pelvis, describe how you would angle the transducer to image the fundus of the uterus and cervix.

The handle of the transducer should be pushed downward (toward the bed) to best image the fundus of the uterus. In the presence of shadowing, gently rock the transducer side to side to eliminate air interference that may be causing the air pockets and shadowing to occur. To image the cervix of the uterus, slightly withdraw the transducer and angle the handle of the transducer upward.

Myometrium

The middle layer of the uterine cavity that appears very homogenous with ultrasound. (The Muscle Layer)

What blood vessels are routinely visualized within the myometrium of the uterus?

The myometrium of the uterus should have a homogeneous echotexture with smooth-walled borders. Note, measure, and document any areas of increased or decreased echotextures. Do not mistake the normal arcuate vessels in the periphery of the uterus for pathology. These vessels bifurcate into radial branches, which supply blood throughout the uterus. These vessels are most often demonstrated 1 to 3 weeks after onset of the last menses. Just before the onset of menses and during menses, these vessels are less apparent. The vasodilating actions of estrogens on the uterus during midcycle and the vasoconstricting hormonal influences during the late luteal phase before menses explain the normal dynamic changes of these vessels.

How is the ovary measured?

The ovary is measured in the sagittal or longitudinal plane at its longest length and anteroposterior dimension. In transverse or coronal scans, the width is measured at the widest point.

What are the best landmarks to use to image the ovaries with ultrasound?

The sonographer could begin to image the ovaries by scanning the fundus of the uterus and angling the transducer to the right or left adnexal area. The iliac vessels are usually posterior to the ovaries. If follicular cysts are present along the periphery of the ovary, the structure is easier to image.

What are the three anatomic areas of the uterus?

The three anatomic areas of the uterus are the cervix, body, and fundus.

What three layers compose the uterus?

The three layers of the uterus are the endometrium, myometrium, and serosal layer.

How is the uterus properly measured?

The transabdominal technique is the best way to measure the cervical-fundal dimension of the uterus in the longitudinal plane. Oblique angulation may be needed to elongate and measure the entire length of the longitudinal plane of the uterus. Always measure the length from the distal end of the fundus to the distal end of the cervix. Either the transabdominal or endovaginal scanning technique may be used to measure the width and anteroposterior dimensions of the uterus. Because of the proximity of the uterus to the broad ligament and surrounding vessels, it may be difficult to delineate the lateral borders of the uterus. Color Doppler or changing post-processing controls may help delineate these borders.

What is the purpose of a full bladder when using the transabdominal scanning technique?

The transabdominal technique requires the urinary bladder to be adequately filled. Instruction should be given to the patient to finish at least 32 oz. of fluid 1 hour before examination time and not to empty her bladder before the scheduled appointment. The full bladder displaces bowel and "flattens" the anteflexed uterus slightly so it is more perpendicular to the transducer angle. The distended bladder also becomes an acoustic window to view pelvic anatomy and pathology. The bladder is considered optimally full when it covers the fundus of the normal-sized uterus, although an overdistended bladder may compress, distort, and displace anatomy beyond the focal zone of the transducer.

Describe the placement of the transducer to obtain and document a spectral Doppler tracing of the uterine and ovarian arteries.

The uterine artery is best demonstrated with Doppler as the transducer is angled toward the fundus of the uterus. The ovarian flow is best demonstrated as the transducer is angled lateral to the ovary.

Premenarche

Time period in young girls before the onset of menstruation.

What is the best landmark for the ovary?

To better characterize the ovary and its contents and to visualize those ovaries that are nonvisible transabdominally, endovaginal scanning is superior. Typically, the ovary is located just lateral to the uterus and anteromedial to the internal iliac vessels, which can be used as a landmark to localize the ovary. Use the contralateral side of the bladder as a window when scanning transabdominally. Endovaginally, the ovaries are easiest to locate in the coronal plane lateral to the cornua. However, it is common to find the ovaries located above the uterus or posterior in the rectouterine cul-de-sac area.

When using the endovaginal scanning technique, what labeling terms are used to represent the scanning planes?

When inserting the transducer in the sagittal plane, the flat part of the transducer is along the top surface of the handle so the beam projects in the midline anteroposterior aspect of the body. This is termed sagittal. From the sagittal plane, the transducer is limited in motion because of the vagina. True parasagittal planes are never obtained, but angulation from this central point is considered sagittal imaging. The transducer is then rotated 90 degrees counterclockwise to obtain coronal images.

Menopause

When menses have ceased permanently.

Late Proliferative Phase

When ovulation occurs. (Days 10-14)

Saline or Contrast

__________ is inserted to fill the endometrial cavity for the purpose of demonstrating abnormalities with in the cavity or uterine tubes.