siegel - female pelvis.docx

**T**ransabdominal sonography remains the imaging study of choice for the initial evaluation of gynecologic abnormalities in the pediatric population (1-5). Transvaginal and transperineal scanning can be valuable ancillary tools when a more detailed evaluation of gynecologic structures is requir...

**T**ransabdominal sonography remains the imaging study of choice for the initial evaluation of gynecologic abnormalities in the pediatric population (1-5). Transvaginal and transperineal scanning can be valuable ancillary tools when a more detailed evaluation of gynecologic structures is required. This chapter reviews the techniques for performing pelvic sonography and the sonographic features of the normal and abnormal pelvis in female infants, children, and adolescents. The roles of gray-scale and Doppler imaging are discussed in the evaluation of pelvic masses, pelvic pain, disorders of puberty, and ambiguous genitalia. Clinical and pathologic features of the common disease processes also are reviewed. **TECHNIQUE** **TRANSABDOMINAL SONOGRAPHY** Transabdominal sonography is performed with the transducer on the anterior abdominal wall at the level of the pelvis. A distended, fluid-filled urinary bladder serves as an acoustic window for scanning by displacing gas-filled bowel loops out of the field of view and facilitating visualization of the ovaries and uterus. Adequate bladder filling often can be achieved with oral intake of fluid. Bladder catheterization with instillation of sterile fluid may be needed if the patient is unable to tolerate large fluid volumes orally. Transabdominal sonography in infants and young children is best performed with a high-resolution, 5 to 12 MHz curvilinear or linear array transducer. In large children and adolescents, a 3.5- to 5-MHz transducer may be needed. Scans of the ovaries and uterus are obtained in both sagittal and transverse planes. Angling the transducer obliquely may improve visualization of the uterus. In some instances, placing the patient in a decubitus position and scanning directly over the adnexal region can improve visualization of the ovaries. **TRANSPERINEAL SONOGRAPHY** Transperineal imaging is useful in evaluating the external genitalia and lower vagina in the clinical setting of urogenital malformations, hydrometrocolpos, labial masses, and vaginal foreign bodies. The transperineal examination is performed with a high frequency linear array (8 MHz or higher) transducer, which is covered with acoustic gel and a rubber sheath, and then is placed directly against the labia minora and external urethral orifice with the patient in a supine position. If needed, a standoff pad can be placed on the perineum. **TRANSVAGINAL SONOGRAPHY** In the pediatric population, transvaginal scanning has been largely limited to adolescent patients. Candidates for this study are girls who are sexually active or use a tampon and consent orally to the study. The transvaginal examination is performed with the bladder empty. A coupling gel is applied to the face of the transducer and the transducer is covered with a rubber sheath. Lubricant is placed on the outside of the rubber sheath and then the transducer is inserted into the vagina with the patient supine and the knees gently flexed. If possible, the patient should insert the probe, which helps to minimize anxiety and pain. The transducer should be placed half to two thirds of the way into the vagina. When correctly inserted, it will not touch the cervix. When properly done, the transvaginal technique is relatively noninvasive and painless. Sagittal and coronal images are obtained by gently rotating and angling the transducer from side to side. Transvaginal sonography is accepted well by most adolescents. **Transabdominal versus Transvaginal Sonography** Transabdominal sonography shows the entire pelvis, facilitating visualization of structures located beyond the field of view of the transvaginal probe. Its major limitation is the need to fill the bladder. The advantages of transvaginal scanning are the obviation of bladder filling and improved near-field focusing, which can improve imaging of the ovaries and uterus (*Fig. 13-1*). The major limitation of this technique is a limited field of view. The depth of penetration of the ultrasound beam from the transducer face is approximately 8 to 10 cm. Thus, large or very superiorly or laterally positioned ovaries or masses may be incompletely visualized or missed. **Fig. 13-1** Normal ovarian anatomy. **A:** Transabdominal and **B:** transvaginal approaches. Ovarian follicles are better defined on the transvaginal scan than on the transabdominal scan. *Calipers* = ovarian margins. In general, transabdominal sonography is the initial examination in a patient who has not had a previous pelvic sonogram. If the transabdominal examination is normal or it unequivocally reveals an abnormality, transvaginal sonography usually is not necessary. Transvaginal imaging can be done if the transabdominal findings are indeterminate or confusing or to better characterize an ovarian or uterine abnormality. It is particularly useful for assessing endometrial disorders. **SONOHYSTEROGRAPHY** Sonohysterography, also termed *saline-infusion sonohysterography,* is used primarily in adult women to assess the endometrial canal and its lining (6). This procedure requires the insertion of a speculum and the placement of a tiny catheter into the uterine cavity. The catheter is introduced by means of a long forceps and is inserted to the level of the fundus. The speculum is removed and the transvaginal probe, which is covered with a rubber sheath and sterile gel, is inserted into the vagina. Sterile saline is injected slowly through the catheter under sonographic guidance, and images of the uterine cavity are obtained in sagittal and coronal planes to demonstrate the endometrial canal. The indications for sonohysterography include (a) characterization of an abnormal endometrial interface suspected or detected on conventional grayscale sonography; (b) determination of the cause of abnormal uterine bleeding; and (c) characterization of congenital uterine anomalies (6). The anechoic, saline-distended endometrial cavity facilitates differentiation between intracavitary, endometrial, and submucosal abnormalities. The usefulness of this technique in prepubertal children is obviously limited. However, this technique may hold promise for characterizing congenital uterine anomalies in adolescent girls. **THREE-DIMENSIONAL ULTRASONOGRAPHY** Three-dimensional or volume sonography appears to be useful for evaluating the external uterine contour, especially the fundus, for the diagnosis of uterine anomalies (see subsequent discussion of uterine malformations) (7). It also may improve evaluation of the site of origin of a tumor and the extent of tumor invasion. **DOPPLER IMAGING** Color and pulsed Doppler sonography are used to demonstrate vascular structures in the pelvis and provide functional information about flow characteristics. Such information can be helpful in characterizing gynecologic masses and in diagnosing ectopic pregnancy and adnexal torsion. Color Doppler parameters (velocity scale, gain, sensitivity, and wall filter) should be optimized to detect low frequency shifts of slow flowing blood. Impedance can be quantified by the use of the resistive index (RI). Doppler characteristics are described in the normal and pathologic ovary in more detail in subsequent sections. **OVARIES** **NORMAL SONOGRAPHIC ANATOMY** **Prepubertal Ovary** The size and position of the ovaries and uterus are age dependent and change under hormonal influence. During fetal life, the ovaries descend from the upper abdomen into the true pelvis. At birth, they usually lie within the superior margins of the broad ligaments. On occasion, descent is arrested and the ovaries may be found anywhere from the inferior edge of the kidney down to the broad ligament. Rarely, the ovaries descend below the broad ligaments into the inguinal canal. The shape of the prepubertal ovaries is variable and they may have a round or ovoid configuration, although the majority are ovoid in shape with their craniocaudal axes paralleling the broad ligaments (8,9). Because of the variability in shape, ovarian volume, which is determined by the formula for a simple prolate ellipsoid (0.523 × width × thickness × length), is considered the best method for determining ovarian size. Mean ovarian volume in the first year of life is approximately 1.0 cm3, but may be as large as 3.0 cm3 (8,9). Volume decreases during the second year of life, averaging 0.7 cm3. The ovaries are relatively stable in size, exhibiting a mean volume of \4 cm\) and cystic (*Fig. 13-39*). Torsed cystic mass may contain internal echoes, septa, and fluid-debris levels. **Fig. 13-38** Adnexal torsion of a normal ovary. **A:** Longitudinal image shows an enlarged right ovary (*arrows*) with dilated peripheral follicles (*arrowheads*). Note that the ovary is posterior to the bladder (B). **B:** Color Doppler image shows absence of blood flow in the ovary. The color signal adjacent to the ovary is in the soft tissue. Volume of the right ovary was 50 cm3. Volume of the left ovary was 4.9 cm3. **Fig. 13-39 A**dnexal torsion secondary to a cystadenoma. **A:** Longitudinal view in a 14-year-old girl demonstrates a large cystic mass (M) arising from the left ovary (*arrow*), which is cephalad to the bladder (BL). **B:** More lateral longitudinal image shows a heterogeneous mass (*arrows*) with a target appearance representing a twisted vascular pedicle. Surgery revealed a torsed ovary with a cystadenoma. Left ovarian volume was 191.3 cm3. Right ovarian volume was 8.7 cm3. The adnexal ratio was 22. Other features of adnexal torsion are a midline position of the ovary posterior to or above the bladder (see *Figs. 13-38A* and *13-39A*), a twisted vascular pedicle, ipsilateral deviation of the uterus to the side of the torsion, and acoustic enhancement, reflecting vascular engorgement and stromal edema (50-52,54). The twisted vascular pedicle can appear as a round or beaked structure with multiple concentric hypo- and hyperechoic stripes (target appearance *Fig. 13-39C*) or as a tubular structure with internal heterogeneity (see *Fig. 13-10C*) (50,51). ***Doppler Imaging*** Doppler findings can be variable and include little or no intraovarian venous flow (earliest sign), absent arterial flow (see *Fig. 13-38B*), and absent or reversed diastolic flow (53). However, arterial flow can be present in ovarian torsion due to the dual blood supply from both the uterine and ovarian arteries (*Fig. 13-40*). If the gray-scale appearance is typical of ovarian torsion, regardless of the color flow pattern, one should suggest a diagnosis of torsion. **Fig. 13-40** Adnexal torsion. Doppler image shows preserved arterial flow in a torsed ovary. **Isolated Tubal Torsion** Isolated torsion of the fallopian tube is a rare cause of acute lower quadrant pain mimicking adnexal torsion in pubertal girls (55). The right tube is more frequently involved than the left. Sonography demonstrates a dilated fallopian tube that may contain low-level internal echoes and thickened walls and mucosal folds (*Fig. 13-41*). The ovaries usually appear normal and show flow on Doppler imaging (55,56). **Fig. 13-41** Torsion of the fallopian tube. **A:** Longitudinal image in an adolescent girl with acute right lower quadrant pain shows a dilated right fallopian tube (*calipers*). **B:** Color Doppler image shows a normal right ovary (O) with a stimulated follicle (F). **Massive Edema of the Ovary** Massive edema is the result of partial or intermittent torsion of the ovarian pedicle, resulting in obstruction of venous and lymphatic drainage but not arterial perfusion. Histologic examination shows marked stromal edema and normal follicles (57). The typical clinical presentation is intermittent lower abdominal pain, sometimes of several months duration, although the pain can be acute in onset. The sonographic findings are a large ovary with heterogeneous internal echogenicity and increased acoustic enhancement. Small cortical follicles may be observed (58,59). Arterial flow is present but may be diminished. Differentiation between massive edema and torsion is difficult and often requires laparotomy. **UTERUS, CERVIX, AND VAGINA** **NORMAL ANATOMY** Similar to the ovaries, uterine size and shape varies with patient age and menstrual status. Uterine length is measured from the top of the fundus to the bottom of the cervix in the sagittal scan plane. The anteroposterior (AP) measurement is obtained perpendicular to the longitudinal plane, usually on the same image as the longitudinal measurement. Width can be obtained on either a coronal or transverse view (*Fig. 13-42*) (60). **Fig. 13-42** Uterine measurements. **A:** Longitudinal view demonstrates measurement of uterine length from top of the fundus to bottom of the cervix (*calipers 1*) and measurement of anteroposterior diameter perpendicular to the length measurement (*calipers 2*). **B:** Transverse image demonstrates measurement of uterine width (*calipers*). **Prepubertal Uterus** The neonatal uterus is prominent for several weeks after birth, as the result of in utero maternal hormone stimulation. It has a volume up to 4 cm3 and a tubular shape with the AP diameter of the cervix equal to or slightly greater that of the fundus (*Fig. 13-43A*) (61,62). The endometrial cavity is visualized in almost all infants (\>95%) as a thin, highly echogenic line in the center of the uterus. This linear echo is caused either by mucus or secretions within the uterine cavity or by the endometrium itself. A hypoechoic halo may surround the endometrial canal, believed to represent the inner third of the myometrium, which is hypoechoic related to vascular engorgement (61). **Fig. 13-43** Normal prepubertal uterus. **A:** Neonatal uterus. Longitudinal image shows a prominent uterus (*arrowheads*) with the cervix (C) and fundus (F) having a bulbous configuration and being of similar size. Note the thin echogenic endometrial stripe (*arrows*) as a result of in utero hormonal stimulation. **B:** An 8-year-old girl. The uterus (*arrowheads*) is smaller and still tubular in configuration with no differentiation between fundus and cervix. B = bladder. As maternal hormonal levels decline over the ensuing several weeks, the uterus decreases in size, maintaining a tubular shape with no differentiation between the uterine body and cervix (uterine body-to-cervix ratio of 1:1; *Fig. 13-43B*). From infancy until approximately 7 to 8 years of age, uterine size shows little change with a mean length ranging between 3.3 and 3.6 cm, fundal width between 0.7 and 0.9 cm, and cervical width of 0.8 and volume between 2 and 3 cm3 (*Table 13-3*) (9). The endometrial canal is usually not visualized. After 7 to 8 years of age, the uterus gradually increases in length and width, with the corpus growing faster than the cervix. The endometrial canal may be visualized as a thin echogenic line on longitudinal images. It is in continuity with the vagina, which also appears as a bright midline echogenic line, reflecting apposed mucosal linings. **Table 13-3 Normal Uterine Diameters and Volume** **Age** **(yr)** **Length (cm),** **Mean (± 1 SD)** **AP Dimension of Corpus** **(cm), Mean (± 1 SD)** **AP Dimension of Cervix** **(cm), Mean (± 1 SD)** **Volume** **(cm3)** 2 3.3 (0.4) 0.7 (0.3) 0.8 (0.2) 2.0 (02) 3 3.4 (0.4) 0.6 (0.1) 0.8 (0.2) 1.6 (0.08) 4 3.3 (0.3) 0.6 (0.2) 0.9 (0.2) 2.1 (0.06) 5 3.3 (0.6) 0.8 (0.3) 0.8 (0.2) 2.4 (0.1) 6 3.2 (0.4) 0.7 (0.3) 0.8 (0.2) 1.8 (0.2) 7 3.2 (0.4) 0.8 (0.2) 0.8 (0.3) 2.3 (0.1) 8 3.6 (0.7) 0.9 (0.3) 0.8 (0.2) 3.1 (0.2) 9 3.7 (0.4) 1.0 (9.3) 0.9 (0.2) 3.7 (0.2) 10 4.0 (0.6) 1.3 (0.5) 1.1 (0.3) 6.5 (0.4) 11 4.2 (0.5) 1.3 (0.3) 1.1 (0.3) 6.7 (0.3) 12 5.4 (0.8) 1.7 (0.5) 1.4 (0.6) 16.2.(0.9) 13 5.4 (1.1) 1.6 (0.5) 1.5 (0.2) 13.2 (0.6) Ap = Anteroposterior; Sd = Standard Deviation. From Orsini LF, Salardi S, Pilu G, et al. Pelvic organs in premenarcheal girls: real-time ultrasonography. *AJR Am J Roentgenol* 1984; 153:113--116. **Pubertal Uterus** At puberty, the uterus descends with the adnexa deeper into the pelvis. The uterine fundus elongates and thickens and becomes more rounded, producing the adult pear-shaped uterus, with a uterine body-to-cervix ratio of approximately 1.5:1 (*Fig. 13-44*). The uterus reaches its adult size and configuration several years following menarche (9). The postmenarcheal uterus measures approximately 5 to 8 cm in length, 1.6 to 3 cm in maximum AP diameter, and 3.5 cm in width. At onset of menarche, the endometrium proliferates and the endometrial stripe is often visible at transabdominal sonography depending on the phase of the menstrual cycle. **Fig. 13-44** Normal pubertal uterus. Longitudinal sonogram shows a pear-shaped configuration with a fundal diameter (*arrow*) that is greater than that of the cervix (*open arrow*). The uterine body-to-cervix ratio is 1.5:1. B = bladder. **Uterine Physiology** Histologically, the endometrium is composed of a central functional layer, which thickens and sheds with each menses, and a peripheral basal layer, which remains intact throughout the cycle and contains vessels that supply the endometrium as it thickens. Endometrial thickness is measured in the AP diameter on a midline sagittal image, perpendicular to the long axis of the endometrium. The thickest portion of the endometrium should be measured. Endometrial thickness varies with the phase of the menstrual cycle. During the menstrual phase (days 1 to 5), the functionalis layer of the endometrium is shed, leaving only the basal layer subadjacent to the myometrium. The endometrium appears as a thin (up to 4 mm thickness) echogenic line, reflecting blood and sloughed tissue in the uterine canal (*Fig.* *13-45A*). During the proliferative phase (days 6 to 14), the endometrium increases in thickness due to estrogen effect, measuring 4 to 8 mm in diameter by the time of ovulation, a reflection of the increased tortuosity of the glandular elements. After ovulation, the inner functionalis layer appears hypoechoic, probably a reflection of stromal edema (*Fig. 13-45B*). In the secretory phase (days 15 to 28), the endometrium reaches maximal echogenicity and thickness, measuring up 15 to 16 mm (*Fig. 13-45C*), reflecting distention of the endometrial glands by mucin and glycogen. This appearance persists until the onset of menses, when the functional layer of the endometrium sloughs and the endometrium thins and the cycle repeats itself (63,64). **Fig. 13-45** Phases of endometrial development, three different patients. **A:** Menstrual phase, the endometrial canal is seen as a thin (3 mm) echogenic stripe (*cursors*). **B:** Proliferative phase, the central canal is echogenic and surrounded by the thickened, hypoechoic functionalis layer (8-mm thickness; *arrowheads*). **C:** Secretory phase, day 26. The echogenic endometrium has reached its maximal thickness, 15 mm (*calipers*). The central echogenic lining (*arrow*) and outer hypoechoic wall (*arrowheads*) of the vagina are also seen. Note in all patients the pear-shaped uterus, with a fundal diameter larger than that of the cervix. **Myometrium** The myometrium in prepubertal girls is homogeneous and hypoechoic relative to surrounding soft tissues. In postmenarcheal girls, the myometrium may have a striated appearance, showing three distinct zones: a hypoechoic inner junctional zone, a moderately echogenic intermediate zone, and a hypoechoic outer zone. The thickness of the myometrium increases slightly during the menstrual cycle. **Cervix and Vagina** The cervix is homogeneous in echotexture and similar in echogenicity to the uterine body. The prepubertal vagina is difficult to identity on sonography. The postmenarcheal vagina is characterized by a central echogenic endometrial lining and an outer hypoechoic wall (see *Fig. 13-45C*). **Doppler Imaging** The uterus is supplied by the uterine arteries, which are branches of the internal iliac arteries. The normal endometrium in prepubertal and postmenarcheal girls shows little or no flow on color Doppler imaging. In prepubertal girls, the myometrium is also avascular. In postmenarcheal girls, the myometrium exhibits varying amounts of color signal on Doppler examination (*Fig. 13-46*). **Fig. 13-46** Normal uterine color flow, adolescent uterus. Longitudinal endovaginal image shows moderate color signal in the uterine myometrium (*arrows*). O = right ovary. **CONGENITAL UTERINE MALFORMATIONS** **Embryology** The uterus, cervix, and cranial two thirds of the vagina develop from fusion of the caudal ends of the two müllerian ducts. The fallopian tubes develop from the unfused cranial ends of the ducts. The median septum formed by the fusion of the medial walls of the ducts eventually involutes and disappears by the 20th week of fetal life, resulting in a single uterine cavity (65). Uterine malformations may result from müllerian duct agenesis, failure or incomplete fusion of the müllerian ducts, or incomplete septal regression (65-69**)**. The caudal one third of the vagina develops from the sinovaginal bulb. The distal and proximal parts of the vagina ultimately fuse when the cellular cord between the two parts dissolves. Failure of the müllerian ducts to meet or canalize will result in vaginal hypoplasia or agenesis or a transverse vaginal septum (discussed below). The American Fertility Society classification scheme, which is based on the degree of failure of normal development, divides uterine anomalies into several major classes: (I) segmental agenesis or hypoplasia (cervical, fundal, tubal or combined anomalies), (II) unicornuate uterus, (III) didelphys uterus, \(IV) bicornuate uterus, (V) septate uterus, and (VI) arcuate uterus (70). Diethylstilbestrol exposure resulting in a hypoplastic uterus with an irregular T-shaped configuration (wider than it was long) was initially included in this classification system (class VII). This drug was used between 1945 and 1971 to prevent miscarriage and its teratogenic effects are no longer seen in the pediatric population. **Class I: Uterine Agenesis and Hypoplasia** Uterine agenesis and hypoplasia are the result of arrested development of the müllerian ducts bilaterally. Uterine agenesis can be an isolated finding, but it is also associated with the Mayer-Rokitansky-Küster-Hauser syndrome. The Mayer-Rokitansky-Küster-Hauser syndrome is characterized by complete vaginal atresia, with 90% of patients having associated cervical and uterine agenesis. In the remaining patients, the uterus is hypoplastic or duplicated (69). The remnant uterine structures can be functional (containing an endometrial layer) or nonfunctional (absence of an endometrial layer). Complete uterine agenesis presents as primary amenorrhea. If a functional remnant is present, patients may present with cyclic abdominal pain due to hematometra (71). The syndrome is associated with renal and skeletal anomalies. The acronym for the associated anomalies is MURCS (MÜllerian duct aplasia, Renal dysplasia, Cervical Somite anomalies). Affected patients have a normal female karyotype, external genitalia, and secondary sexual development. Sonographic findings are normal ovaries, absence of the cervix and upper vagina, and an absent or small uterus with poorly differentiated zonal anatomy (*Fig. 13-47*) (66-69). There may be a small distal vaginal pouch because the distal vagina is derived from the urogenital sinus. **Fig. 13-47** Müllerian hypoplasia, a 5-year-old girl with Mayer-Rokitansky-Küster-Hauser syndrome. **A:** Longitudinal image shows a small left uterine horn containing a 5 mm endometrial stripe (*arrow*). **B:** Coronal fast spin-echo T2-weighted magnetic resonance image shows the left-sided functional uterus (*short arrow*) and a rounded soft tissue mass (*long arrow*), with a signal intensity similar to that of the myometrium and no endometrial stripe on the right, presumed to be a uterine remnant. The vagina is atretic. (Reproduced from Junqueira BL, Allen LM, Spitzer RF, et al. Mullerian duct anomalies and mimics in children and adolescents: correlative intraoperative assessment with clinical imaging. *Radiographics* 2009; 29:1085--1103s; with permission.) Differential diagnostic considerations for amenorrhea are Turner syndrome, true hermaphroditism, and the androgen insensitivity syndrome (previously called testicular feminization syndrome; see discussion below on amenorrhea). **Class II: Unicornuate Uterus** The unicornuate uterus results from arrested development of one of the two müllerian ducts. There is a single-horned uterus that communicates with a single cervix and normal vagina. In most patients, there is a contralateral rudimentary horn with or without functioning endometrium. The rudimentary horn may or may not communicate with the developed uterine horn (72). Unicornuate uterus does not require treatment unless functional endometrial tissue within a noncommunicating horn causes endometriosistype symptoms or hematometra. The diagnosis can be suggested on sonography when there are two horns of different sizes (*Fig. 13-48*) or when there is a single horn that is curved, elongated, and laterally located (i.e., banana-shaped uterus). The developed uterine horn shows normal zonal anatomy (66-69,72). **Fig. 13-48** Unicornuate uterus with a noncommunicating rudimentary horn. **A:** Transverse sonogram shows a hypoplastic left uterine horn (*arrowhead*), which lacks an endometrial lining and does not communicate with the laterally deviated right uterine horn (*arrow*). The right uterine horn has a dilated endometrial canal (E) with low-level echoes representing blood products. **B:** Fat-saturated T2- weighted magnetic resonance image shows a noncommunicating hypoplastic left horn (*arrowhead*) and blood in the endoemterial cavity (E) of the right uterine horn (*arrow*). Hematometra was secondary to vaginal atresia. **Class III: Uterus Didelphys** Uterus didelphys is due to complete non-fusion of the müllerian ducts (*Fig.* *13-49*). There are two separate, widely divergent, non-communicating uterine horns, each with normal zonal anatomy, two cervices, and two vaginas (*Fig. 13-50*). Each horn has a fusifrom shape and convex lateral margins. A complete or partial longitudinal vaginal septum may be present (66-69). Affected patients are usually asymptomatic unless the vaginal septum obstructs one of the vaginas, leading to hematocolpos and producing cyclic pelvic pain at onset of menarche. Renal agenesis is common in patients with an obstructing vaginal septum. There is no surgical repair for uterus didelphys. **Fig. 13-49** Müllerian duct fusion anomalies. **A:** Didelphys uterus: two uteri, two cervices, two vaginas. **B:** Bicornuate uterus bicollis: two uteri, two cervices, one vagina. **C:** Bicornuate uterus unicollis: two uteri, one cervix, one vagina. **D:** Septate uterus: single uterus divided by a septum. (Adapted from Colodny AH. Disorders of the female genitalia. In: Kelalis PP, King LR, Belman B, eds. *Clinical pediatric urology*. Philadelphia, PA: WB Saunders, 1985:888--903.) **Fig. 13-50** Uterus didelphys, two patients. **A:** Transverse image in a 1-day-old girl with an imperforate anus shows two widely divergent, noncommunicating uteri (*arrows*) with stimulated endometrial stripes (*arrowheads*) related to maternal hormonal stimulation. R = meconium filled rectum. **B:** Transverse view more caudally demonstrates two dilated vaginas with internal echoes related to blood products secondary to maternal stimulation (*arrows*). Vaginal orifices were stenotic bilaterally. B = bladder. **C:** Transverse image of a 16 year-old-girl with irregular menses shows two separate uterine horns (*arrows*). The right endometrial canal is larger than the left (*arrowheads*). **D:** Computed tomography scan also shows two uteri (*arrows*) with a fluid-filled right endometrial canal corresponding to blood products. **Class IV: Bicornuate Uterus** Bicornuate uterus results when there is partial failure of fusion of the müllerian ducts (*Fig. 13-49*). There are two symmetric uterine horns that are fused caudally and communicate with each other, usually at the level of the uterine isthmus. The upper surface of the uterine fundus has a concave fundal contour with a deep cleft (\>1 cm), and the uterine cavities are divided by myometrium (*Fig. 13-51*). The central myometrium may extend to the level of the internal cervical os (bicornuate unicollis, one vagina, one cervix, and two uterine corpora) or to the external cervical os (bicornuate bicollis, one vagina, two cervices, and two uterine corpora). Each horn has a fusiform shape and normal zonal anatomy (66-69). Affected patients are usually asymptomatic. The bicornuate uterus usually does not require surgical repair. **Fig. 13-51** Bicornuate uterus. Transverse transabdominal image shows concave indentation of the uterine fundus (*arrow*) and two uterine horns (RT, LT) of similar size. The uterine horns are divided by myometrium. An endometrial stripe (*arrowhead*) is seen in the left uterine horn. The concave fundal cleft helps separate bicornuate from septate uterus. *Calipers =* margins of uterine horns. The bicornuate bicollis uterus is distinguished from didelphys uterus because it demonstrates some degree of fusion between the two horns, whereas in the didelphys uterus, the two horns and cervices are separated completely. In addition, the horns of the bicornuate uteri are often not fully developed and are smaller than those of didelphys uteri. **Class V: Septate Uterus** The septate uterus is the most common müllerian anomaly and results from partial or complete failure of resorption of the septum between the two müllerian ducts. There is a single uterus, cervix, and vagina, with a septum dividing the uterus into two endometrial-lined cavities (66-69). Affected patients are usually asymptomatic, although they have an increased incidence of spontaneous abortions. Treatment, if needed, is resection of the septum. At sonography, the upper surface of the uterine fundus can have a convex, flat, or minimally concave (\ 80% of cases), but it can be secondary to pituitary gland and hypothalamic tumors (88,89). Prolonged exposure to sex steroids from any source also can cause central precocious puberty. Peripheral or pseudosexual precocity is gonadotropin independent and results from peripheral production of estrogens, resulting in ovarian follicular development and uterine growth. Estradiol levels are increased, but serum gonadotropin levels are low or normal, so ovulation and true menses do not occur. The causes include functioning ovarian cysts; ovarian neoplasms (granulosa-theca cell tumors, arrhenoblastomas, thecomas, and choriocarcinomas); adrenal adenomas and carcinomas; neurofibromatosis; McCune-Albright syndrome (fibrous dysplasia and cutaneous pigmentation); and ingestion of estrogen compounds (88,89). Sonography is used to determine ovarian and uterine size. In both central and peripheral precocious puberty, the uterus can have an adult morphology (i.e., dominance of the corpus over the cervix) and a stimulated, echogenic endometrial canal (*Fig. 13-65*). In central precocious puberty, both ovaries will be enlarged. Mean ovarian volume is approximately 4.6 cm3 (11). In pseudosexual precocity, a unilateral ovarian cyst or tumor can be seen (*Fig.* *13-66* and see *Fig. 13-28*). The presence of small follicles (\