OVARIES AND FALLOPIAN TUBES - ULTRASOUND


KEY WORDS

Adnexal Mass: a lump in tissue of the adnexa of uterus,

either benign or cancerous, simple or complex.

ABOUT THE PROCEDURE

The ovaries can be evaluated using transabdominal or transvaginal imaging. Transvaginal probes are of higher frequency, which generally results in better resolution of the ovaries; however, the examiner must be careful not to mistake pelvic structures, such as muscles or echogenic bowel loops, for normal ovaries. Attention to the following characteristics is therefore important to note when routinely evaluating the ovaries:

  • Size (measure in 3 dimensions)

  • Location (relative to the uterus and iliac vessels)

  • Echogenicity (isoechoic to uterus)

  • Presence of follicles

Characteristics of Adnexal Masses on Sonography

The diagnosis of an adnexal mass can be difficult and challenging. Neoplasms, abscesses, and hemorrhagic masses may have similar sonographic appearances. Attention to the following ultrasound characteristics together with clinical correlation will help with for- mulating a differential diagnosis:

  • Location (relative to uterus and ovaries)

  • Size (measure in three dimensions)

  • Echogenicity (hyperechoic, hypoechoic, anechoic)

  • Homogeneity (homogeneous or inhomogeneous)

  • Borders (smooth or irregular)

  • Shape(round, oval, tubular)

  • Posterior acoustic enhancement or sound attenuation

  • Presence of shadowing

  • Vascularity (presence of flow within structure)

  • Presence of peristalsis or changes in size or shape (seen with bowel)

  • Compressibility (seen with bowel)

  • Displacement of pelvic organs, structures, or vessels

  • Indentation of urinary bladder (to distinguish mass from bowel)

  • Fixation of mass on postvoid images (lack of movement)

  • Associated findings (presence of free fluid or lymphadenopathy)

Normal Sonography of the Ovaries

  • Ovoid/almond shape

  • Normally located anterior to internal iliac vessels

  • Position can vary dependent on size and location of uterus and degree of bladder filling.

  • Homogeneous midlevel echoes

  • Immature follicles seen as multiple anechoic structures on ranging in size from 0.5–18 mm

  • Mature follicle range in size from 20–25 mm at the time of ovulation

  • Pelvic muscles and echogenic bowel loops may mimic normal ovaries

Ovarian Mean Dimensions

  • Postmenopausal female (2 × 2 × 1 cm or smaller)

  • Menstruating female (3 × 2 × 2 cm)

  • Prepubertal female (1 × 1 × 1 cm)

PATHOLOGY

Ovarian Cyst (Simple)

  • Round, anechoic, smooth-walled structure (Figure 14-5)

  • Unilocular

  • Posterior acoustic enhancement

Ovarian Cyst (Complex)

Meets the criteria for a cyst with any of the following internal appearance(s):

  • Thin or thick septations (echogenic hair-like strands within the cyst)

  • Multilocular compartments (cluster of cysts)

  • Fluid–fluid layers (hyperechoic and hypoechoic layers within a cyst)

  • May have reverberation artifact (low-level echoes on anterior aspect of cyst)

  • Internal low-level echoes representing infection or hemorrhage

Hemorrhagic Cyst

Hemorrhagic cysts have a spectrum of sonographic appearances time dependent on clot hemolysis. These include the following:

  • Cyst with fine level echoes (appearance more commonly related to endometriomas)

  • Multiple septations

  • Solid hyperechoic mass (acute hemorrhage)

  • Cyst with solid component (haemorrhage on anterior or posterior portion of cyst as clot retracts)

  • Absence of color flow Doppler within cyst

  • Reduced posterior acoustic enhancement

  • All of these appearances can mimic benign or malignant ovarian tumors or abscess.

Types of Functional Ovarian Cysts:

Follicular Cyst

  • Mature follicle that did not involute

  • Generally greater than 25 mm and may become large

  • Usually unilateral

Corpus Luteum Cyst

  • Associated with early pregnancy (10–12 weeks)

  • Usually involutes by 12 weeks gestation

  • Unilateral

  • Measures 4.0–6.0 cm

Theca Luteal Cyst

  • Associated with hydatidiform mole

  • Associated with ovarian hyperstimulation syndrome

  • Largest functional cyst

  • Bilateral and multilocular

  • Generally greater than 5 cm

Paraovarian Cyst

  • Arise from broad ligament

  • Can mimic ovarian cysts

  • Size range from 4–8 cm

  • Cyst seen separate from ovary may represent paraovarian cyst

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