Sonography of the Female Child's Reproductive System

The main indications for pelvic sonography in the pediatrie patient are pelvic masses, ambiguous genitalia, and amenorrhea. The uterus, vagina, and ovaries in infants and children can be easily visualized by sonography; anomalies and tumors causing the aforementioned signs and symptoms will be discussed in this article.

Examination of the entire pelvis with serial crosssectional and longitudinal scans usually requires 30 minutes. A full urinary bladder is mandatory for displacement of the intestinal loops away from the organs to be examined and to act as a "sonic window."

Figure 1. Normal sonographic appearance of uterus in two-day-old girl being examined because of ambiguous genitalia. Left Longitudinal sonogram demonstrates the uterus (ut) behind the bladder (b). Right Transverse sonogram through the uterus, which is elevating the bladder. Arrow points to strong endometrial echo due to maternal hormonal stimulation.

UTERUS AND VAGINA

When the uterus is present, it can always be identified sonographically regardless of the patient's age. The size and shape of the uterus, however, vary with age. A newborn has a large uterus (3.5 cm. in length) for the first month because of intrauterine maternal hormones. The uterus becomes progressively smaller as this hormonal effect decreases, until it reaches approximately 2.5 cm. in length. It remains at this size from infancy until puberty. During puberty, when estrogen stimulation occurs, the uterus enlarges to a length of 5-7 cm.

Figure 2. Rhabdomyosarcoma of the uterus in a four-year-old girl. Left Longitudinal midline sonogram through the bladder (b). Arrow points to solid mass elevating the bladder. Right Cystogram confirms the presence of the mass.

The normal sonographic appearance of the infantile uterus (Figure 1) presents an intermediateintensity echo pattern, with occasional stronger echoes arising from the endometrial cavity. The vagina provides a helpful means of locating the uterus, since the uterus is located posterior to the bladder and is continuous with the vagina. To detach the vagina sonographically, a longitudinal scan is performed in the midline, with the transducer angled so as to complete an arc that extends beneath the pubic symphysis.

Pathologic states. Sonography is a benign method of examining the child's vagina; however, its accuracy in diagnosing pathologic processes is poor, and suspected pathology is best determined manually and by direct visualization.

Uterine anomalies in a child generally cannot be evaluated by physical examination. In the neonate, anomalies are discovered because of fused labia, ambiguous genitalia, or a pelvic mass; in the adolescent female, because of abnormal menses or unusual maturation. They also can manifest as problems during pregnancy or at the time of delivery.

The uterus is small or absent with gonadal agenesis or dysgenesìs, hypogonadotropic state, uterine agenesis, or testicular feminization.

A large uterus may be due to hematocolpos, primary uterine tumor or tumor of the uterus that is metastatic or affected by contiguous spread, or functioning endocrine tumor causing precocious development or intrauterine pregnancy.

Hydrometrocolpos. Retention of uterine fluid may present as an abdominal mass or bulging hymen in a neonate or at puberty. In the neonate this is due to maternal estrogen's causing an increased amount of uterine fluid; at puberty it is caused by retained menstrual secretions. The differential diagnosis includes that of vaginal stenosis or atresia.

Sonographically, hydrometrocolpos appears as an echo-poor transonic pelvic mass with many internal echoes, A normal uterus and vagina cannot be identified.

Tumors. Primary tumors of the uterus and vagina are rare in children. Malignant tumors are more common than benign tumors, with the vagina a more frequent site than the uterus. Rhabdomyosarcoma of the botryoides form sarcoma botryoides) is the most common type and appears to arise from the remnants of the urogenital sinus. The bladder is the most common site of this tumor in males. The vagina is more frequently affected in females (Figure 2). Although sarcoma botryoides may originate in the uterus, it becomes involved with tumor most frequently by contiguous spread from the vagina. The presenting signs and symptoms are a bloody vaginal discharge and a pelvic mass. The diagnosis is suspected from the presence of a grapelike mass in or protruding from the vagina.

Sonography is useful in delineating the extent of the tumor and, after therapy, for detecting recurrence of the disease.

OVARIES

The normal ovaries are about 2 cm. in diameter in the prepubertal child but are larger immediately at birth because of maternal stimulation. At puberty the ovaries enlarge to 3 cm. because of estrogen stimulation.

With the bladder fully distended, the adnexa should be sonographically visualized in over 90 percent of all normal females.

Absent or hypoplastic ovaries. The absence of ovarian tissue is extremely rare and considered to bean acquired lesion. Because of the absence of the concomitant fallopian tube, the lesion is thought to be secondary to torsion and necrosis in utero.

Ovarian hypoplasia in general is associated with primary amenorrhea and occurs in patients with endocrine disturbances, intersex, and the gonadal dysgenesis syndromes.

These topics will be discussed in subsequent sections.

OVARIAN TUMORS

Ovarian tumors may be cysts, benign cystic teratomas, or malignant teratomas or carcinomas. FoIlicular, corpus luteum, and bilateral polycystic disease associated with Stein-Leventhal disease are similar sonographically. In each case the cysts are well circumscribed and echo-free, with strong posterior walls and increased through-transmission. Anterior reverberation artifacts are present in large cysts.

Follicular cysts are a common cause of ovarian enlargement. These tumors are benign. Since folHcular cysts are often multiple and bilateral, the sonogram of these tumors may show several echofree regions in an ovary (Figure 3). These cysts occasionally rupture, and when they do it is common to see fluid in the cul-de-sac. Follicular cysts are often asymptomatic but may produce pain by torsion and infarction, which may lead to a misdiagnosis of an acute surgical abdomen. When this occurs on the right side, it can easily be confused with acute appendicitis. Follicular cysts usually resolve spontaneously.

Figure 3. Sonograms of abdomen of a 1 4-year-old girl with follicular cysts. Left Transverse pelvic sonogram was made when girl complained of severe right-lcwer-quadranl pain. Note the large echo-free mass and ovarian cyst (cj next to the uterus (ut). Right Longitudinal sonogram 3 cm. to the right of midline shows location of cyst below bladder (b).

Corpus luteum cysts are often asymptomatic; however, they may cause amenorrhea because of production of progesterone. The sonographic pattern is similar to the above.

Polycystic disease of the ovaries (Stein -Lev enth al syndrome) is distinguished from bilateral multiple follicular cysts by its clinical presentation of hirsutism, virilization, amenorrhea or oligomenorrhea, sterility, acne, increased lutein hormone values with low or normal follicle-stimulating hormone (Figure 4).

Benign cystic tefatomas are the most common ovarian tumors. (The term teratoma is preferable to dermoid, since these tumors usually contain endoderm, mesoderm, and ectoderm.) Although signs and symptoms of benign cystic teratomas may occur throughout childhood, they present most commonly around puberty, with a mass and/or pain due to torsion of the ovary. When these tumors occur on the right side, they can clinically be confused with appendicitis and, before the use of ultrasound, were usually misdiagnosed until surgery revealed them.

Figure 4. Sonograms of pelvic area of obese 1 5-year-old girl with amenorrhea. Left Transverse pelvic sonogram demonstrates enlarged left ovary with multiple cysts (c). Right The right ovary. A diagnosis of polycystic ovaries was made.

Sonographically, the pattern of a benign cystic teratoma varies, depending on the tissue components of the tumor. There is usually a large, illdefined mass in the adnexa. When these masses become very large, they rise out of the pelvis into the abdomen.

The majority of ovarian teratomas in childhood are predominantly cystic, producing an echo-free component with some scattered areas of high echogenicity owing to debris or the presence of solid tissue within the cyst. Fat is a common constituent of a teratoma and also accounts for densely echogenic areas (Figure 5). A careful scanning technique is necessary to identify these tumors when they are located in such a way as to blend in with thenormal pelvic fat.

Figure 5. Sonograms of a 12-year-old girl with an enlarging pelvic mass. Left Longitudinal midiine sonogram shows how the bladder (b) is being compressed by the comptex mass. Note that the mass has both very high echogenic areas (black arrows) and medium-to-low echogenic areas (white arrows). Complexity of the echoes suggests a teratoma with calcification or teeth. Right Transverse sonogram through the mass. The pathology was a cystic teratoma with bony elements and teeth.

Malignant ovarian tumors in children are very rare; when they do occur, the most common are malignant teratomas, embryon al -cell carcinomas, primary choriocarcinomas, and dysgerminomas.

Granulosa theca-cell tumors are moderately malignant and are of special interest because they may cause precocious puberty.

All these tumors present with a palpable mass and/or pain if there is torsion of the ovary.

The sonographic pattern of ovarian malignancies in children varies from almost entirely cystic with minimal echoes to purely solid and highly echogenic masses. Fluid is present in the cul-de-sac in approximately half of the patients. These sonographic findings are not specific for malignancy. However, there are secondary effects of malignant spread, such as concomitant findings of ascites or invasion of the uterus by a solid ill-circumscribed mass or by métastases to lymph nodes and /or liver.

INTERSEX

When anomalies of the genitalia are noted in the newborn, establishing the presence of a vagina, uterus, or urogenital sinus in the neonatal period permits prompt assignment of sex Table 1). Sonography is a simple procedure for obtaining this information immediately. Investigations of the sex chromatin pattern and urinary hormone excretion and biopsy of the gonads should then be carried out for definite surgical planning.

A hermaphrodite is an individual who has both ovarian and testicular tissue; the ovaries and testes may be separate on either side of the pelvis or joined as an ovotestis. The genital anatomy is variable, and the presence of a uterus depends on miillerian stimulation.

Ultrasound can identify the uterus if it is present and can occasionally visualize the gonad for biopsy. Final diagnosis requires laparotomy and confirmation of the gonad.

A female pseudohermaphrodite is a chromosomal female with ovaries but masculinized external genitalia (enlarged clitoris and prominent, fused labia). In the neonate it is most important to examine for adrenal hyperplasia. The ovaries and uterus can be sonographically identical, and sex designation must await the results of skin-chromatin-pattern and blood-sodium and -chloride tests.

Table

TABLE 1 CLINICAL INDICATIONS FOR INTERSEX DETERMINATION

In older girls, clitoral hypertrophy and hirsutism are generally due to increased androgen effect in association with adrenal adenoma or carcinoma. Sonography of the pelvis can confirm the female gender by demonstrating ovaries and a uterus when the adrenal-hormone studies are examined.

Occasionally, female pseudohermaphroditism occurs in a patient when no known cause is identified.

A male pseudohermaphrodite is an individual with testes and feminized external genital tract due to decreased androgens or poor target organs. When patients' testes are not in the scrotum, sonography has not been successful in locating them because of the variability in the places where they sometimes are found. Sonography can exclude the presence of ovaries and uterus, however.

Clitoromegaly and female externat genitalia can also be indications for use of sonography; a person with a female chromatin pattern and normal female hormone levels can have her ovaries and uterus clearly demonstrated by sonography.

PRECOCIOUS PUBERTY

The onset of normal puberty (including ovulation in girls and spermatogenesis in boys) before the age of eight is considered precocious puberty. Most often no cause is found, especially in girls, but occasionally the precocious puberty is due to central-nervous-system tumor or associated with the McCune-Albright syndrome (cafe-au-lait spots and polyostotic fibrous dysplasia). Sonography is useful in demonstrating normal pubertal reproductive organs in young girls with no apparent pathologic process.

Precocious sexual development (pseudoprecocious puberty, isosexual precocity) refers to the normal sexual maturation of puberty, including uterine bleeding but no ovulation. Ovarian and adrenal tumors account for many of the cases with this symptom complex. Granulosa-theca-cell tumor of the ovary accounts for 60 percent of ovarian tumors causing pseudoprecoció us puberty. Adrenal lesions associated with precocious sexual development are hyperplasia, adenoma, and carcinoma. The adrenal is difficult to demonstrate by sonography unless it is 2 cm. or larger.

The unusual causes that are occasionally associated with precocious sexual development in adolescents are hypothyroidism in girls and androgensecreting hepatomas in boys. The girls with hypothyroidism develop enlarged breasts but have no menses. Sonography is of no assistance in confirming the presence of either of these conditions.

PRIMARY AMENORRHEA

Primary amenorrhea exists when a girl has not started her menses by the age of 16. Delay in the appearance of the signs of secondary sexual development may have indicated an abnormality in such persons even before their failure to menstruate becomes a significant concern. Among the pathologic causes of primary amenorrhea are genital abnormalities, a failure in gonadotropin production, and intersex anomalies.

Ultrasound is not useful for evaluating the hypothalamus or pituitary gland. Diseases of the adrenal, vagina, uterus, and ovaries have been discussed previously (Table 2).

Gonadal dysgenesis syndrome represents more than one disease entity. Clinical findings vary, but sexual infantilism and poorly developed gonads are common to all of them. Pelvic sonogram demonstrates hypoplasia or nondetectable ovaries or uterus (Figure 6).

Turner's syndrome can be a cause of gonadal dysgenesis. Dwarfism, lymphedema, and congenital anomalies are often associated with the syndrome, and some Turner's-syndrome patients are mentally retarded. The diagnosis can be confirmed by a chromosomal examination.

Table

TABLE 2 CAUSES OF PRIMARY AMENORRHEA

Figure 6. Sonogram of uterus of 17-year-old girl with amenorrhea. This midline longitudinal sonogram clearly demonstrates the infantile uterus (ut) connected to the vagina (arrow). No adnexal masses can be seen.

Figure 7. Transverse pelvic sonogram in an adolescent girl with pelvic pain and fever. Fluid (f) could be demonstrated behind the uterus (ut) that contains debris echoes. These findings suggest pervie inflammatory disease.

PREGNANCY

Pregnancy in pediatrie patients is not uncommon.* Any girl over the age of nine who presents with a pelvic mass should have a pelvic sonogram to establish whether or not she is pregnant before any x-ray studies are made.

A pelvic sonogram performed on a pregnant girl before 12 weeks' gestation will demonstrate enlargement of the uterus, with a gestational sac, and echoes due to the embryo. After 1 2 weeks' gestation the placenta and fetal parts will be sonographically visible.

PELVIC INFLAMMATORY DISEASE

As sexual activity increases in teenagers, so does the incidence of pelvic inflammatory disease. Gonococcus is the most common organism cultured, followed by Staff hylococcus, Streptococcus, Escherichia coli, and Mycobacterium tuberculosis. Ultrasound demonstrates bilateral adnexal masses that are predominately echo-free. An associated finding is fluid in the cul-de-sac. In chronic forms, when the patient has been on medical treatment, a thick-walled sac with a fluid-debris level generally will be found (Figure 7).

CONCLUSION

Ultrasonic imaging offers a valuable supplement to the physical examination of the abdomen and pelvis in infants, children and adolescents. The procedure is noninvasive, and the existence of a suspect mass can be quickly confirmed.

Clinical indications for the use of pelvic sonography include suspicion of a mass, ambiguous or anomalous genitalia, primary or secondary amenorrhea, gonadal dysgenesis, precocious puberty, a need to exclude pelvic abscess from a diagnosis, and any unusual vaginal discharges.