Abnormalities of Size or Shape

Position

●Anteversion, anteflexion (normal finding)

●Retroversion

●Straight (especially in old age, when it is more difficult to evaluate by transvaginal scanning; the fundus should be manually flexed forward)

Uterine size and shape

●Prepubertal

–2–3.3 cm long, 1 cm wide, 0.5–1 cm thick

–Cervical diameter is greater than the corpus diameter. The cervix accounts for two-thirds of total uterine length

●Nullipara

–Pear-shaped

–5–9 cm long, transverse diameter

1.6–4 cm, 3 cm thick

●Multipara

–10 × 5 × 6 cm

–Uterine corpus comprises the upper two-thirds of the total length, the cervix the lower third

●Postmenopause

–4.5 cm long, 2 cm wide, 1.5 cm thick

–Symmetrically hyperplastic

Uterine weight

●Adolescence: 44–66 g

●Childbearing age: 50–120 g

●Pregnancy: weight increases 20-fold up to 1000 g

formed. The regression phase begins several days before menstruation, as hormone production wanes and the thickness of the mucosa decreases by approximately 50% owing to fluid loss. The hormone levels decline precipitously in the desquamation phase, and the endometrial lining is sloughed. A regenerative phase follows menstruation, reinitiating the cycle.

Uterine cervix. The cervix consists mainly of connective tissue and a few smooth muscle fibers, with the result that it undergoes minimal cyclic structural changes. The cervical canal is lined by columnar epithelium and increases its diameter at midcycle. The cervical mucus becomes more fluid in response to estrogens and then more viscous again in response to increased progesterone.

Fig. 13.17 Vertical position of the uterus (UT) caused by the complete filling of the bladder (BL), ballooned cervix with the portio invaginating into the vagna (arrows). R = rectum.

Fig. 13.15 Longitudinal uterine scan posterior to the bladder. Anteflexion is clearly defined. The echogenic serosa and the linear endometrium are detectable.

Fig. 13.18 Transverse scan through the uterus and rectum.

Fig. 13.16 Retroflected uterus: the uterus (UT) lies dorsally to the bladder with retroflected corpus. Small bowel loops (B) reach more caudally behind the bladder (BL). R = rectum.

Fig. 13.19 Postpartum uterus (UT PP). Uterine length is still approximately 16 cm. BL = bladder.

Uterine Prolapse

Atypical and abnormal positions of the uterus affect the shape of the uterus as displayed by ultrasound (Fig.13.20, Fig.13.21).

Uterine Prolapse

Malformations

Uterine Aplasia, Atresia

Uterine Hypoplasia, Small Uterus

Hemangioma, Lymphoma, Angiomyoma, Myoma

Fig. 13.23 Bicornuate uterus. Arrows = uterine horns. Lateral: both ovaries.

tive endometrium) are seen in a transverse ultrasound scan through the uterine horns at midcycle, which is the best time for detecting this anomaly when it is suspected.

Myometrial Changes

Uterine Myomas

Uterine Adenomyomatosis

Uterine Sarcoma

Myomas (fibroids) are muscular tumors of the uterus, generally classified histologically as fibroleiomyomas.3 These benign tumors composed of smooth muscle and connective tissue are the most common type of genital tumor.

The formation and growth of uterine myomas depend on the functional status of the ovaries (relative estrogen dominance). Myomas do not occur in children or older women and tend to regress after menopause. Antiestrogens and progesterone inhibit their growth.

Myomas develop in the uterine corpus and cervix. They are rarely solitary and may have an intramural, subserous, submucous, or intraligamentous location. They lack a true capsule. The tumor nodules are initially round but may alter their shape owing to pressure effects. Myomas undergo structural changes over time.

Malacia, characterized by the following changes:

●Cavernous transformation, permeation by edema

●Rapid myxomatous growth

●Tense cystic appearance, resembling an ovarian cyst

●Fatty degeneration (especially in the puerperium)

●Necrotic foci due to vascular occlusion

Clinical Presentation

Myomas present clinically with bleeding abnormalities such as hypermenorrhea (usually only intramural myomas affect uterine wall contractility), menorrhagia, and metrorrhagia (caused by submucous myomas). Dysmenorrhea is caused by capsular tension or contractions and also depends on the tumor location.

●Suppuration due to infection ascending from the uterine cavity, spreading from the bowel, or transmitted by blood vessels or lymphatics; breakdown by putrefactive bacteria, especially in submucous myomas

Induration, consisting of the following changes:

●Progressive fibrous transformation, ranging to a pure fibroma

●Irregular or eggshell calcification. Fully calcified myomas may become dislodged, resulting in the “delivery” of uterine stones.

Sonographic features. Approximately 25% of all women over age 35 have uterine myo-

Myomas can also cause bladder complaints and constipation or hydronephrosis (intraligamentous myoma) ( 13.1 l–s). A ruptured myoma capsule can produce the signs and symptoms of an acute abdomen. Myomas can cause infertility. A necrotic myoma can lead to an elevated ESR.

mas.4 These tumors appear sharply circumscribed at ultrasound. Initially they are largely homogeneous and less echogenic than the rest of the myometrium owing to their copious blood supply.

Most myomas are subserous in location ( 13.1a,b), but 5% are submucous;5 these often cause bleeding abnormalities and are not palpable. Multiple myomas and diffuse myomatosis are found in many multiparous women, leading to uterine enlargement with no circumscribed nodularity ( 13.1c,d).

Degenerating myomas may appear as hyperechoic masses. Calcified myomas cast an acoustic shadow that can obscure surrounding structures ( 13.1h–j). Central necrosis, due, for

h Uterine myoma with di use calcification. UT = uterine sarcoma; BL = bladder; S = shadow.

k Uterine myoma with central hypoechoic necrosis.

Renal pelvic obstruction

i Uterine myoma with eggshell calcification and acoustic shadowing (S). BL = bladder.

j Uterine myoma with eggshell calcification (arrow). S = shadow.