15 Sonography of the Female Genital Tract

10.1055/b-0035-122531

15 Sonography of the Female Genital Tract

Willemijn Klein

The female genital tract consists of the vagina, cervix, uterus, and ovaries. Pathology of the female genital tract in children is uncommon or often not yet apparent, and therefore an ultrasound (US) examination of this area is rarely requested. If requests are made in our university hospital, the examination in neonates is mostly for large ovarian cysts or ambiguous genitals, in young girls mostly for tumors, and in teenagers for tumors and amenorrhea.

US views of these structures are optimal when obtained through a filled or half-full bladder, which provides an acoustic window and pushes the air-filled bowels aside. If necessary, this can be accomplished in neonates by retrograde filling through a catheter. In neonates and small children, a linear high-frequency probe (4–12 MHz) gives high-resolution images; in larger children and adolescents, a curved array probe is used (3–6 MHz).

In the case of congenital anomalies, magnetic resonance (MR) imaging provides a better delineation of the anatomy than does US. Some of these anomalies are shown only with MR images.

15.1 Normal Anatomy and Variants

In the first days after birth, the uterus and ovaries of female neonates are remarkably prominent because of stimulation by maternal hormones. The cervix is equal in size to the fundus or slightly larger ( Fig. 15.1 ). The myometrium is thick, and the endometrial lining is visible ( Fig. 15.2 ). The ovarian follicles of the neonate may be large ( Fig. 15.3 ). After a few days, the size decreases and remains small for the next years. There will be a slow growth of these organs in relation to age and weight. During these years, the endometrium is usually not apparent and the follicles are small (up to 1 cm; Fig. 15.4 ). In the prepubertal years (usually from 9 years on), the uterus and ovaries increase in size more rapidly. The fundus grows larger than the cervix, which will cause a pear-shaped appearance ( Fig. 15.5 ). At puberty, the female genital tract will reach adult values, and the endometrium will be visible as an echogenic lining that varies with the phases of the menstrual cycle ( Fig. 15.6 ).

**Fig. 15.1** **a, b** Normal large uterus and cervix in a female neonate several hours after birth. a Sagittal ultrasound. b Transverse ultrasound. *White arrow*, uterus with echogenic endometrium; *open arrow*, bladder; *arrowhead*, rectum.

**Fig. 15.2** This transverse ultrasound shows the normal uterus in a female neonate. The uterus is large because of stimulation by maternal hormones. The myometrium is thickened. The echogenic lining in the cavum is the endometrium (*arrow*).

**Fig. 15.3** Fifteen-day-old neonatal girl with an asymptomatic large ovarian cyst. *Open arrow*, ovarian cyst; *white arrowhead*, bladder; *open arrowhead*, uterus.

**Fig. 15.4** Normal uterus in a 10-year-old girl. The uterus is small, and the endometrium is not visible. *White arrow*, uterus; *open arrow*, vagina.

**Fig. 15.5** Normal aspect of the uterus in a healthy postmenarchal 14-year-old girl. The myometrium is thickened. The free fluid in the cavum of Douglas is physiologic. In this case, the endometrium is not visible. Visibility depends on the cycle stage. *White arrow*, uterus; *open arrow*, vagina; *white arrowhead*, free fluid.

**Fig. 15.6** **a, b** Normal aspect of the uterus of a 14-year-old girl. a Transverse image. The uterus (*white arrow*) has an echogenic endometrium. The right ovary has a small cyst (*open arrow*). b Sagittal image.

15.1.1 Normal Measurements

Normal values for the uterus and ovaries are shown in Table 15.1 . The volumes were calculated with the formula for an ellipsoid: length × width × height × 0.523.

**Table 15.1** Uterine and ovarian volumes
Age	Number of healthy girls	Uterus, mL (SD)	Number of healthy girls	Ovary, mL (SD)
0–1 month	15	3.4 (1.2)	6	0.5 (0.4)
3 months	7	0.9 (0.2)	4	0.4 (0.1)
1 year	19	1.0 (0.2)	6	0.5 (0.2)
3 years	26	1.0 (0.3)	17	0.7 (0.4)
5 years	26	1.0 (0.3)	13	0.7 (0.5)
7 years	28	0.9 (0.3)	15	0.8 (0.6)
9 years	18	1.3 (0.4)	12	0.6 (0.4)
11 years	16	1.9 (0.9)	10	1.3 (1.0)
13 years	8	11.0 (10.5)	8	3.7 (2.1)
15 years	15	21.2 (13.5)	9	6.7 (4.8)
Source: Van Rijn RR, Robben S. Normal values. In: Van Rijn RR, Blickman JG, eds. Differential Diagnosis in Pediatric Imaging. New York, NY: Thieme Medical Publishers; 2011:625–660.

15.2 Pathology

15.2.1 Congenital Anomalies

Congenital anomalies of the female genital tract are the result of abnormalities in the development of the paramesonephric (Müllerian) ducts, and to a much lesser degree the mesonephric (Wolffian) ducts, urogenital sinus, and/or cloaca. The upper parts of the paramesonephric ducts form the fallopian tubes. The lower parts fuse in the midline in a process called lateral fusion. They form the uterus and upper part of the vagina (Müllerian tubercle). The lower part of the vagina develops from the urogenital sinus. The lower part is separated from the upper part by the hymen, which thins and perforates in the perinatal period. The close relation of the paramesonephros with the mesonephros and metanephros makes a combination of genital and urinary tract anomalies likely. Therefore, during a US examination of the female genital tract in search of congenital anomalies, one should always visualize the kidneys and bladder as well. The reverse is also true; when a congenital renal anomaly, such as a horseshoe kidney, multicystic kidney, or duplex system, is detected, the uterus should be visualized as well because in approximately 10% of cases there will also be an abnormal formation of the genitals.

Müllerian Duct Anomalies

In considering the embryologic development of the female genital tract ( Fig. 15.7 ), congenital malformations in this area can be classified as follows:

Müllerian agenesis, in which there is a defect in the caudal portion of the Müllerian ducts;
Disorders of lateral fusion, in which the fusion of the two Müllerian ducts is incomplete; and
Disorders of vertical fusion, caused by malfusion between the Müllerian tubercle and urogenital sinus.

Fig. 15.7 Drawing of the embryologic development of the female genital system. The paramesonephric ducts (Müllerian ducts; arrow) fuse caudad to cephalad to form the proximal vagina and uterus. The unfused cephalic parts become the fallopian tubes. The caudal end comes in contact with the urogenital sinus (yellow; arrowhead). The vagina is formed partly by the urogenital sinus and partly by the paramesonephric ducts.

First category: In Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, the vagina (or proximal two-thirds) is absent, in combination with absence or abnormalities of the uterus and frequently abnormalities of the urinary tract. In addition, the ovaries may be absent, malformed, or in a high location (maldescensus). The presentation is usually in pubertal girls with primary amenorrhea. MR imaging is needed to clearly visualize the rudimentary uterus and ovaries ( Fig. 15.8 , Fig. 15.9 , Fig. 15.10 ). There is an association with renal anomalies, and skeletal abnormalities may also occur.

**Fig. 15.8** **a–c** Hypoplastic vagina in a teenage girl with Mayer-Rokitansky-Küster (MRK) syndrome. She came to the hospital with primary amenorrhea. a Image showing the hypoplastic uterus behind the filled bladder (*arrow*). b Magnetic resonance image sagittal T2 sequence nicely depicts the hypoplastic vagina (*arrow*), which was not found on ultrasound. c The hypoplastic uterus (*arrow*).

**Fig. 15.9** **a, b** Hypoplastic uterus and hypoplastic proximal vagina in a girl with primary amenorrhea. The hypoplastic vagina and uterus are consistent with Mayer-Rokitansky-Küster (MRK) syndrome. She had normal ovaries (*not visible in these images*). a Sagittal magnetic resonance (MR) image T2 sequence showing the hypoplastic uterus (*white arrow*) and proximal vagina (*open arrow*). b Transverse MR image T2 sequence shows the hypoplastic uterus (*white arrow*).

**Fig. 15.10** **a–e** Five-year-old girl with abdominal pain. a On ultrasound, a lymphangioma is seen in the right upper abdomen(*open arrow*). b In the left inguinal region, there is some free fluid (*open arrow*) and also a small uterus (*white arrowhead*). c Magnetic resonance (MR) image T2 space sequence nicely depicts the lymphangioma (*open arrow*). d During the MR imaging procedure, the girl was crying constantly, which provoked the bilateral inguinal hernias (*open arrows*). e Image shows the bilateral inguinal hernias (*open arrows*), as well as the hypoplastic uterus. At surgery, the lymphangioma was removed completely. The hypoplastic uterus was confirmed. The inguinal hernias both contained normal ovaries; the ovaries were placed intra-abdominally and the herniations closed. This girl had familial Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome.

Second category: When correct lateral fusion of the Müllerian ducts fails to occur, there will be a septate, bicornuate, didelphys, or unicornuate uterus ( Fig. 15.11 , Fig. 15.12 , Fig. 15.13 , Fig. 15.14 , Fig. 15.15 , Fig. 15.16 ). A minor fusion defect is a vertical septum in the vagina ( Fig. 15.17 ). Girls with these defects will often be asymptomatic until reproductive age ( Fig. 15.18 ). MR imaging is a better imaging modality than US to delineate the exact anatomy of these disorders.

**Fig. 15.11** Ultrasonography of a 15-year-old girl with stomach pain, in whom a uterus didelphys was found coincidentally. RT, right uterus (*white arrow*); LT, left uterus(*open arrow*). (Courtesy of Professor Rebecca Stein-Wexler, UC Davis Children’s Hospital, Sacramento, CA USA.)

**Fig. 15.12** A young girl underwent an ultrasound examination for a urinary tract infection. Coincidentally, a uterus didelphys was found. UT, uterus.

**Fig. 15.13** This girl was born with a cloacal malformation (see also **Fig. 15.21** ). Ultrasound of the uterus didelphys (*arrows*) at the age of 18 months.

**Fig. 15.14** Young woman with primary infertility, caused by a uterus didelphys. She had a normal vagina. This transverse magnetic resonance image shows the two uteri (*arrows*).

**Fig. 15.15** **a–d** Girl with primary amenorrhea and monthly abdominal pain lasting 3 days. Hydrometrocolpos was relieved before magnetic resonance imaging. a Uterus didelphys (*arrows*). b Two cervices (*arrows*). c Two vaginas. The right vagina is aplastic (*white arrow*) and the left vagina is mostly aplastic, with 4 cm hypoplastic (*open arrow*). d Coronal view of the uterus didelphys and bicollis with blood products in both sides, consistent with hydrometrocolpos (*arrows*). This girl also had a congenital trachea abnormality and normal kidneys.

**Fig. 15.16** Young woman with primary infertility. A hysterosalpingogram shows a septate uterus.

**Fig. 15.17** Teenager with an asymptomatic septum in the uterus and vagina (*open arrowheads*).

**Fig. 15.18** **a, b a** A young woman found to have a uterus didelphys (not previously known) and a pregnancy in the right uterine horn (*white arrow*). The left uterus also has stimulated endometrium (*open arrow*). b There are two vaginas (*white arrows*). A premature delivery was performed at 28 weeks via cesarean section because of the abnormal genital tract anatomy.

Third category: Disorders of vertical fusion are imperforate hymen, transverse vaginal septum, and atresia of the cervix or vagina. Vertical defects may be obstructive, and therefore symptoms occur at an earlier age. Symptoms of hydrocolpos may develop after birth because of the accumulation of genital secretions. However, symptoms usually occur at puberty with cyclic abdominal pain without menstruation. Vertical fusion defects are associated with lateral fusion defects. Rarely, there is a triad of uterus didelphys, obstructed hemivagina, and ipsilateral renal agenesis, the Herlyn-Werner-Wunderlich syndrome ( Fig. 15.19 and Fig. 15.20 ).