Abdominal Sonographic Anatomy (III). By Dr. Dina Metwaly

Gynecology ultrasound (uterus & ovaries)

ULTRASOUND OF THE UTERUS & ovaries ROLE OF ULTRASOUND To examine the uterus, ovaries, cervix, vagina and adnexae. Classification of a mass identified on other modalities eg solid, cystic, mixed. Guidance of injections, aspiration or biopsy. Assistance with IVF. For diagnosis of : P/V bleeding/discharge Menorrhagia Metrorrhagia (irregular uterine bleeding) Polymenorrhea Menometrorrhagia (excessive irregular bleeding) Amenorrhea Oligomenorrhea

Excessive bowel gas can obscure the ovaries. LIMITATIONS Transvaginal scanning is contra-indicated if the patient is not yet married or cannot provide informed consent. Large patient habitus will reduce detail, particularly via the transabdominal approach. Excessive bowel gas can obscure the ovaries. Patients who are unsuitable for transvaginal scanning but cannot adequately fill their bladder for an acoustic transabdominal window. EQUIPMENT SELECTION AND TECHNIQUE Transabdominal approach initially. This will be between a 2-7MHz range curved linear array or sector probe with Colour Doppler capabilities. Transvaginal probe 4-7MHz. PATIENT PREPARATION  If possible, scan the patient in the first 10 days of the cycle. Preferably Day 5-10 for improved diagnostic accuracy in the assessment of the endometrium and ovaries. A full bladder is required . Instruct the patient to drink 1 Litre of water to be finished 1 hour before and they cannot empty their bladder before the scan. The patient empties their bladder before the transvaginal scan is started. 

SCANNING TECHNIQUE TRANS-ABDOMINAL APPROACH This is a generalized overview to identify the cervix, uterus and ovaries. Check for the orientation the uterus (anteverted V's retroverted) Assess the uterine size and shape. Assess: the myometrium endometrial status and measure the thickness: <10mm pre menopausal; <4mm post menopause or ,<6mm if post menopausal on HRT(hormonal replacement therapy) the cervix free fluid in the pouch of douglas the ovaries and adnexae bladder

Scan sagitally in the midline immediately above the pubis. Heel the probe to get the bladder over the fundus of the uterus. In this plane you should be able to assess the uterus, vagina and cervix. Zoom the image to assess and measure the endometrial thickness. Rotate into transverse and angle slightly cranially to be perpendicular to the uterus.  angle left laterally to identify the left ovary using the full bladder as an acoustic window. Examine the ovary in two planes. Now repeat this for the right ovary.

Uterus sagittal US image. Uterus TA probe positioning for longitudinal scan. Uterus sagittal US image.

Trans abdominal view of the uterus: transverse Trans abdominal view of the uterus: transverse. Both ovaries are visible (not always the case).

TRANS-VAGINAL(TV) APPROACH INSERTING THE TV PROBE Before letting the patient empty their bladder, show them the TV probe and explain the procedure. Explain the importance of a TV scan because it is the gold standard in gynaecological ultrasound because of its superior accuracy and improved diagnostic resolution. Cover the probe with a latex free TV sheath and lubricate with sterile gel on the outside. Elevate the patients bottom on a thick sponge/pillow to assist the scan. Ensure the patient is ready and get permission before inserting the probe.

If there is some resistance as the probe is being inserted, offer for the patient to help guide the probe in far enough to see the end of the fundus. When manouvering the probe to visualise the adnexae, withdraw slightly then angle the probe towards the fornix. his avoids unnecessary patient discomfort against the cervix. WIDTH OF UTERUS The Maximum Width is measured in this transverse (coronal) plane.

Transvaginal Technique Anteverted uterus. Normal TV image anteverted sagittal. The overall uterine length is evaluated in the long axis from the fundus to the cervix (external os). The depth (AP diameter) is measured from the anterior to the posterior wall and perpendicular to the length.

Retroverted transvaginal technique Retroverted uterus transvaginal scan.

Normal ultrasound appearance OF THE UTERUS The position: Central position within the pelvis. The anteverted-anteflexed uterus (AVF), with the uterine body found in the vesico-uterine space, is the most frequent situation compared with the retrovertedretroflexed uterus(RVF), when the uterine body is situated in the Douglas pouch (fig 1). The size. the length – the distance from the fundus to the internal orifice of the uterus on a sagittal view; the width – the maximum anterior-posterior distance measured in the mid portion of the uterine body also on a sagittal view; the thickness – the maximum distance measured at the level of the uterine fundus on a transverse view. The mean uterine measurements of a reproductive age patient are 70/35/50 mm, while the measurements for menopausal patient are 50/20/25. The shape. On a sagittal plane the uterus has a pyriform shape: the superior two thirds correspond to the uterine body and the inferior third to the cervix. The uterine isthmus is identified where the uterine body and cervix meet.

Uterine ultrasonographic structure: The myometrium has a homogeneous structure and has an echogenicity similar to a muscle. The hyperechoic area in the middle is the uterine cavity and can not be measured . The endometrium is evaluated on a sagittal view. When the cavity line is present the endometrium is measured from the base of its anterior layer to the base of its posterior layer (double layer). When there is intracavitary retention only one layer of the endometrium is measured (single layer thickness) The thickness and the echogenicity of the endometrium varies with the different stages of the menstrual cycle.

The Ovaries The position. Usually the ovaries are found lateral from the uterus in the ovarian fossa, behind and inside the external iliac vessels. Sometimes the ovaries are asymmetrical and mobile and change their position The shape. The ovary has an oval shape with the long axis oriented downward and forward. The ovaries have a fine contour. The size. . Two distances (the length and the width) are measured in this view and a third one (the thickness) is obtained after rotating the transducers with 90°. The mean measurements of the ovary are 30/15/15 mm, and the volume is 1.8-5.7 cm³ .

Ovarian ultrasonographic structure. The overall aspect of the ovary is hypoechoic when compared with the myometrium. Through endovaginal ultrasound two distinct areas can be observed– an echoic central area (corresponding to the stroma) – a peripheral area (corresponding to the cortex) which contains the ovarian follicles in different development stages.

Axial trans-abdominal image with the ovary lateral to the uterus. Use the full urinary bladder as an acoustic window to angle across to the ovary. Axial trans-abdominal image with the ovary lateral to the uterus.

Axial trans-vaginal scan plane. Axial trans-vaginal image.

Normal transvaginal ovary demonstration normal peripheral follicles. The uterus may be oblique and squash the ovary giving it a flattened ovoid shape.