Eur Radiol (2004) 14:L107–L122 DOI 10.1007/s00330-003-2036-z

I. Gassner T. E. Geley

Published online: 30 January 2004 © Springer-Verlag 2004 ECR 2004 – Categorical Course “Pediatric Radiology”

I. Gassner (✉) · T. E. Geley Department of Pediatrics, University Hospital Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria e-mail: [email protected] Tel.: +43-512-5043600 Fax: +43-512-5045293

P E D I AT R I C

Ultrasound of female genital anomalies

Abstract Congenital anomalies of the female genital tract result from müllerian duct anomalies and/or abnormalities of the urogenital sinus or cloaca. Due to the close developmental relationship between the genital and the urinary tracts, association of anomalies in both systems are common. This article reviews the appearance of developmental anomalies of the female urinary and genital tracts and points out common associated malformations to allow an early and complete sonographic assessment of affected infant.

Introduction Understanding the development of the urogenital system is required to comprehend the full spectrum of congenital anomalies of the female genitalia (Fig. 1). The presence or absence of the Y chromosome determines differentiation of the gonads into either testes or ovaries. In the absence of an Y chromosome, zygotes with two or more X chromosomes will develop ovaries and female internal and external genitalia. The internal genital organs as well as the lower urinary system originate from two paired urogenital structures that develop in both sexes: the mesonephric ducts (wolffian ducts) and the paramesonephric ducts (müllerian ducts) [1]. Congenital anomalies of the female genital tract result from müllerian duct anomalies and/or abnormalities of the urogenital sinus or cloaca. The müllerian ducts are divided into two segments demarcated by the insertion of the ligamentum inguinale which eventually becomes the round ligament. The distal segments of the müllerian ducts move towards the midline and soon fuse into a single tube, the uterovaginal canal. The resulting septum

Keywords Ultrasound · Female genitalia · Uterus anomalies · Imperforate hymen · Vaginal atresia · Urogenital sinus · Cloacal malformation · Ovarian cyst · Multicystic dysplastic kidney disease

that divides the uterovaginal canal disappears soon after that. Failure of fusion of the müllerian ducts results in a wide variety of fusion abnormalities of the uterus, cervix, and vagina [2]. The development of the vagina is induced by the fusion of the uterovaginal canal with the urogenital sinus. Bilateral endodermal evaginations, the sinovaginal bulbs, form in the area of the müllerian tubercle and proliferate into the primitive vaginal plate. Canalization of this plate starts at the urogenital sinus forming the vaginal epithelium and the entire wall of the distal third of the vagina. The non-epithelial components of the proximal two-thirds of the vagina, however, are of uterovaginal canal origin [3]. Development of the urinary systems starts with the ureteral bud arising from the distal segment of the wolffian duct. The ureteral bud grows dorsally and soon becomes connected with the primordium of the permanent kidney or metanephric blastema to eventually form the ureter, the renal pelvis, calices, and the intrarenal collecting ducts, and acts as an inducer of differentiation of the renal blastema into the adult kidney. In females the wolf-

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Sonographic features of the uterus in neonate, prepubertal, and pubertal girls

Fig. 1a–d Embryology. Schematic presentation of the embryology of the female genitourinary tract. a The mesonephric ducts (wolffian ducts ) connect the mesonephros to the cloaca. b At approximately 5 weeks of gestational age, the ureteric bud originates from the wolffian duct, reaches the metanephros, and induces its differentiation into the kidney while the mesonephros degenerates. The müllerian ducts fuse at approximately 7–9 weeks in the midline to form the uterovaginal canal. c At 8 weeks, the uterovaginal canal reaches the urogenital sinus at the müllerian tubercle. The urogenital sinus results from the separation of the cloaca into urogenital sinus and rectum. d The vagina becomes patent at approximately 22 weeks. The wolffian ducts are resorbed and remnants are referred to as Gartner’s duct

fian duct is finally resorbed leaving only scattered remnants forming an interrupted channel alongside the Fallopian tubes, the proximal uterus, within the cervix and the anterolateral wall of the vagina, ending at or just above the level of the hymen. These remnants are then referred to as Gartner’s duct. Development of the external genital organs, the urethra and the anus, involve transformation processes of the internal and external cloaca, which are separated by the cloacal membrane in a transverse plane [4, 5]. The urorectal septum is formed by fusion of the surrounding extraembryonic mesoderm of the yolk sac and allantois. The tip of this septum marks the cranial border of the cloaca and subdivides the internal cloaca into the urogenital sinus and the anorectal canal [6]. The process of partitioning then spreads caudally into the external cloaca. The perineal mound (i.e., the tip of the urorectal septum) separates the urogenital sinus from the anus. The inner genital folds proliferate to form the perineum and the labia minora, whereas the outer genital folds develop into the labia majora.

During normal growth and development the uterus and ovaries undergo a series of changes in size and configuration. Under the influence of maternal and placental hormones the neonatal uterus is remarkably prominent with a thick myometrium and a definable endometrial lining [7]. The fundus to cervix ratio is 1:2 with a distinct border between cervix and fundus (Fig. 2). A uterus didelphys or bicornuate can therefore readily be demonstrated (Fig. 3). At 2–3 months of age, the uterus regresses to its prepubertal size and tubular configuration with a fundus to cervix ratio of 1:1. The endometrium is usually not visualized making it difficult to evaluate uterine anomalies at this developmental stage (Fig. 4). This prepubertal uterine configuration is maintained until estrogen stimulation at the onset of puberty leads to an increase in uterine size and to a fundus to cervix ratio of 3:1. The post-pubertal uterus has the adult pear-shaped appearance and the echogenicity and thickness of the endometrial lining varies according to the menstrual cycle (Fig. 5) [8]. High-resolution, real-time sonography has become the first-step imaging technique for the evaluation of the pelvis in infants, children, and adolescencents. Using the filled bladder as an acoustic window, the internal genital organs as well as the lower urinary tract can be easily evaluated. In infants and young children who are not able to maintain a full bladder, filling of the bladder with sterile saline solution via a 5- to 8-F feeding tube might be necessary. The same principle can also be used to outline the vagina (water vaginography), the rectum (water enema), or the urogenital sinus in complex congenital anomalies of the genitourinary tract (Figs. 2, 6, 7, 10). A transperineal sonographic approach should always be considered in cases of anomalies of the lower pelvis, since it allows an excellent documentation of the urethra, the periurethral soft tissue, the rectum, and the distal genital tract (Figs. 8, 10, 12). Müllerian duct anomalies Based upon the embryological development of the female genital system uterovaginal malformations are classified as müllerian agenesis in cases of a developmental defect of the caudal portion of the müllerian ducts (Mayer-Rokitansky-Küster-Hauser syndrome), disorders of the lateral fusion resulting from failure of the two müllerian ducts to fuse, and disorders of the vertical fusion that are caused by faults in the union between the müllerian tubercle and derivatives of the urogenital sinus (transverse vaginal septum, cervical agenesis, disorders of the hymen).

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Fig. 2a–d Normal neonatal uterus. a–c Longitudinal sonograms: the cervix and fundus are clearly discernible. The cervix (open arrowheads) has a greater diameter and length than fundus (closed arrowheads). There is a small amount of fluid within the endometrial canal at the junction of fundus and cervix (asterisk). Single nabothian cyst in the cervix (closed arrow). The inner layer of myometrium is hypoechoic (subendometrial halo). Echogenic endometrial glands (open arrows). In the fluid distended vagina cervical mucus adherent to the vaginal part of cervix is visible (M). d Transverse scan at the level of the fundus shows the uterine horns (area where the tubes enter the uterus; curved arrows)

The Mayer-Rokitansky-Küster-Hauser syndrome is characterized by the absence of the entire or more frequently the proximal two-thirds of the vagina, absence or abnormalities of the uterus, and malformations of the upper urinary tract (Fig. 11) [9, 10]. Two types of the syndrome are described. Type A (typical form) shows normally appearing external genitalia, but no vagina or uterus. The fallopian tubes, ovaries, and kidneys are normal. In type B (atypical form) the uterus may be normal except for the lack of a conduit to the introitus, or may be rudimentary commonly showing disorders of the lateral fusion with aplasia of one or both uterine horns, or asymmetry of the horns if both are present; however, any of the lateral or vertical fusion abnormalities with or without obstruction may be seen. The

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Fig. 5 Normal postmenarchal uterus of a 12-year-old girl. Longitudinal sonogram: pear-shaped uterus. Diameter and length of the fundus (closed arrowheads) are greater than those of the cervix (open arrowheads) Fig. 3 Bicornuate uterus. A 6-day-old female newborn with congenital segmental dilatation of the colon (C). Transverse image through the pelvis shows two separate uterine horns (arrows), bladder (B)

Fig. 4 Normal prepuberal uterus of a 4-year-old girl. The uterus is small with a fundus to cervix ratio of 1:1. B bladder, R rectum

fallopian tubes are abnormal (hypoplasia and aplasia of one or both tubes) and ovarian anomalies such as inguinal hernia containing an ovary, no descent of ovary, absence of the ovary, or streak ovaries have been reported [11]. Associated malformations are encountered in the upper urinary tract, the skeletal system, and the spinal

cord, and include hydronephrosis, agenesis, fusion, dysplasia or unilateral ectopia of the kidneys, ectopia of the ureter, vesicoureteral reflux, supernumerary, wedged or fused vertebrae, rudimentary vertebral bodies, absence or underdevelopment of one lower sacral segment and coccyx, syndactyly, absence of a digit, long proximal phalanx of digits 3 and 4, long metacarpals of digits 1–4, carpal abnormalities, hypoplasia of the tenar eminence, bilateral femoral hypoplasia, and tethered spinal cord. Sonographic evaluation aided by instillation of fluid into the bladder as well as the rectum may demonstrate the absence of vagina and uterus (Fig. 6). Magnetic resonance imaging is frequently needed to clearly document the ovaries and the rudimentary uterus [12, 13]. Spinal ultrasound in newborns and MR imaging in older girls as well as plain X-rays are required to rule out spinal cord anomalies and skeletal anomalies, respectively. Disorders of the vertical fusion of the müllerian ducts consist of transverse vaginal septa, imperforate cervix, and cervical agenesis, and result from faults in the junction between the descending müllerian ducts and the ascending urogenital sinus. In transverse septa the interruption may be complete or incomplete and occur at any level of the vagina, sometimes at multiple levels. The vagina is obliterated by fibrous connective tissue with vascular and muscular elements lined by squamous epithelium. The septum may be a thin membrane but involves more commonly a whole segment of the vagina (segmental vaginal atresia). An increased incidence of associated proximal müllerian duct anomalies is found such as lateral fusion abnormalities of the uterus, stenosis, hypoplasia, or absence of the uterus and the fallopian tubes [14].

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Fig. 6a, b Mayer-RokitanskyKüster-Hauser-syndrome in a 10-year-old girl with normal external genitalia and normal female karyotype. a Transverse and b longitudinal pelvic sonograms: between the fluid-filled rectum (R) and the bladder (B), neither vagina nor uterus is visualized

Although the hymen membrane is entirely of urogenital sinus origin, imperforate hymen is commonly listed together with defects of the vertical fusion of the müllerian ducts. Due to the embryological origin of the hymen membrane no increased incidence of müllerian duct or renal anomalies need to be expected [14]. Imperforate hymen may either be symptomatic in the newborn period or after onset of puberty when development of hydrocolpos/hydrometrocolpos or hematocolpos/hematometrocolpos, respectively, occurs. Sonographic evaluation shows the cystic dilatation of the vagina with the less distensible uterus attached to it. Internal echoes reflect cellular debris. Frequently, a fluid-debris level or a blood level can be demonstrated within the uterus or the vagina. Fluid may also be found in the peritoneal cavity due to spillage of genital secretion via the Fallopian tubes. Larger cysts may obstruct the one or both ureters resulting in hydronephrosis. A precise evaluation of the level of vaginal obstruction as well as the distance between the perineal surface and the caudal aspect of the distended vagina is best achieved by transperineal scanning (Figs. 8, 9, 12). Disorders of the lateral fusion of the distal segments of the two müllerian ducts include septate, bicornuate, didelphys, and unicornuate uterus [15]. In the absence of obstruction, these malformations are asymptomatic during childhood or at puberty. A minor and relatively common form of fusion defects of the müllerian ducts is simple septate vagina in which the vagina is divided into two lateral compartments by a midline sagittal septum without uterine anomalies. Because of the frequent association of vertical with lateral fusion anomalies, it is useful to consider vaginal anomalies according to the presence or the absence of obstruction. Nonobstructive vaginal anomalies encompass bifid vagina, longitudinal vaginal septum, and incomplete transverse septum. Among the obstructive vaginal anomalies are imperforate hymen, complete trans-

verse vaginal septum, unilateral obstructive longitudinal vaginal septum, obstruction of a unilateral rudimentary horn, and atresia of the uterine cervix or the vagina. Sometimes obstructive disorders already present at birth due to accumulated genital secretion. More commonly, however, the patient seeks medical advice at puberty with cyclic abdominal pain and a pelvic mass is found. The whole spectrum of müllerian duct anomalies from the obstructed hemivagina in association with an uterus didelphys to the unicornuate uterus which reflects the extreme end of the spectrum are almost always associated with severe ipsilateral renal anomalies (renal agenesis, renal dysplasia, ectopia, ipsilateral ectopic ureter, and hydronephrosis; Fig. 7) [14, 16, 17]. One has to be aware that a multicystic dysplastic malformation of the kidney can mimic renal agenesis later in life since the multiple cysts seen in the affected infant disappear in the course of time. This strong association of müllerian duct anomalies with anomalies of the urinary tract should urge the physician to always evaluate both systems when a malformation is dedected in one of them [16, 17]. Still under maternal hormonal influence the uterus of the newborn shows a prominent myometrium with a echogenic endometrium. Sonographic evaluation can, therefore, easily document uterine duplications at that age (Figs. 3, 7, 10). Filling of the vagina via an 8-F feeding tube will further delineate the internal anatomy and patency of the vagina, the number of cervices present, and the existence of a possible cystic mass related to an obstruction. Single ectopic ureter Rarely the ureteral bud fails to separate from the wolffian ducts and a single ectopic ureter may terminate directly or via a Gartner’s duct or a Gartner’s duct cyst into the

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Fig. 7a–f Uterus didelphys with left multicystic dysplastic kidney (MCDK) and ipsilateral vaginal obstruction. a Longitudinal scan (coronal plane) of the left flank. MCDK: multiple anechoic cysts of variable size and shape which do not communicate with each other. The dilated ureter (arrows) could be traced from the MCDK to the obstructed ipsilateral left vagina. b Transverse pelvic sonogram shows two uterine fundi: right fundus (closed arrowheads),

left fundus (open arrowheads). c Transverse scan at lower level than b shows a left-sided cyst representing obstructed left vagina (LV). d, e. Longitudinal sonograms obtained after instilling saline solution in vagina demonstrate d fluid-filled patent right vagina (RV) with right uterus (arrowheads); and e atretic left vagina (LV) with left uterus (arrowheads) obstructing membrane (arrow). f Schematic representation

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Fig. 8a, b Imperforate hymen with moderate hydrocolpos. a The imperforate hymen protrudes between the labia. b Translabial sagittal scan: the vagina (V) is moderately ilated and the fluid protrudes the hymen (arrowheads) spherically

Fig. 9a–c Imperforate hymen with excessive hydrocolpos. a, b Longitudinal scans: the low-level echoes within the markedly dilated vagina (V) represent mucous secretions. a The uterus with cervix (open arrowheads) projects into the dilated vagina (V). Mucus plug (closed arrowhead) adherent to the cervical ostium. b The hydrocolpos (V) compresses the inferior vena cava (arrows). c Transverse pelvic scan, the ureters (U) are dilated due to distal ureteral compression. V hydrocolpos

bladder neck, the urethra, the vaginal vestibule, or the vagina itself. A single ectopic ureter is always associated with ipsilateral renal hypoplasia, dysplasia, or agenesis [18]. Urogenital sinus malformation The most common urogential sinus malformations a radiologist will come across are patients suffering from fe-

male hypospadias, female pseudohermaphroditism, and cloacal malformation. Urogenital sinus is suspected during physical examination of a newborn with a normally placed anus in association with either ambigous genitalia or a normal female external genitalia but only a single perineal opening within the vestibulum. It is either found isolated or in association with chromosomal and hormonal abnormalities or as a cloacal variant. Neonates with urogenital sinus frequently have ambiguous genitalia, since a main cause of this malformation is due to virilization of a female fetus or an intersex anomaly; however, urogenital sinus may also result from incomplete development of the lower vagina and the external genitalia may appear completely normal [19]. In female hypospadias the urethral meatus is positioned in the anterior wall of the vagina. Some authors regard female hypospadias as a mild form of urogenital sinus [20]. Other authors describe female hypospadias as an abnormality of the urethra itself caused by a defect in

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Fig. 10a–h Cloacal malformation with uterus didelphys. a Female phenotype with only a single perineal opening (catheter). b Transverse pelvic scan: right (R) and left (L) cervix uteri behind the empty bladder. c Transverse pelvic scan at lower level than b shows the right (RV) and left (LV) vagina, urethra (asterisk), and the rectocloacal fistula (arrow). d Cloacal fistula (asterisk). R rectum, V vagina. e, f Frontal and lateral view after contrast filling of

the colon via colostomy demonstrates the rectum (R) the right (RV) and left (LV) vagina, and the rectocloacal fistula (asterisk). g Transperineal sagittal scan: urethra (U), vagina (V), and rectum (R) converge to a short common cloacal channel (arrows). h Lateral view during voiding after contrast filling of bladder (B), vagina (V), and rectum (R) via three separate catheters. The short common cloacal channel (arrows) is clearly demonstrated

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Fig. 11 Schematic representation of genital anomalies encountered in Mayer-Rokitansky-Küster-Hauser syndrome. The rudimentary uterine horn consists of muscle bundles and some endometrial tissue. The tubes and ovaries are normally displayed. The perineal anatomy shows a female phenotype but no vaginal opening

Fig. 12a–c Imperforate hymen with hydrometrocolpos and ascites due to spillage of genital secretions via the fallopian tubes into the peritoneal cavity. a, b Sagittal scans: the vagina (V) as well as the uterus (U) are dilated with broad communication through the cervical ostium (open arrowheads). The vagina shows a fluid-debris level (closed arrowheads). c Distended, fluid-filled abdomen. The air-filled loops of bowel cluster in the center of the abdomen. The lateral edge of the liver (arrowheads) is visible

differentiation of either the wolffian ducts or the urogenital sinus (Fig. 13) [21, 22]. Differentiation defects of the wolffian ducts lead to the development of the more severe proximal hypospadias, whereas developmental anomalies of the urogenital sinus result in the less severe distal hypospadias. Proximal hypospadias often show a narrowing of the urethra with signs of urinary outflow obstruction and are commonly associated with cloacal anomalies and female pseudohermaphroditism [22]. Diagnostic evaluation is therefore discussed below. Distal hypospadias is more likely to have a urethra of normal diameter with no meatal stenosis and is frequently asymptomatic. The urethral meatus is on the roof of the vagina just inside the introitus and might be entirely overlooked unless attempts to catheterize the urethra, usually for radiological evaluation of the urinary tract, are frustrated by an inability to locate the meatus [23]. In these patients the urethra must be catheterized blindly. To rule out associated malformations both kidneys, the uterus, and the vagina of these patients should be examined. In most instances female pseudohermaphroditism results from exposure of a female fetus to excessive androgens. The most common causes are congenital adrenal hyperplasia (an autosomal-recessive disorder of adrenal steroidogenesis) [24], followed by placental aromatase deficiency [25], masculinizing maternal hormones, and administration of androgens to women during pregnancy. The increased level of androgens within the fetal blood stream causes virilization of the external genitalia, which may vary from minimal phallic enlargement of the clitoris to almost complete masculinization. The degree of masculinization of the fetus is thought to be related to the time and amount of androgen exposure. If the androgen stimulus is received after 12 weeks of gestation, only clitoral hypertrophy will occur [20]. Earlier androgen exposure results in urogenital sinus and a higher de-

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Fig. 13a, b Schematic representation of female hypospadia. a The perineal anatomy shows a female phenotype but no urethral opening. b The urethral meatus is on the roof of the vagina

Fig. 14a–c Congenital adrenal hyperplasia with virilization of the external genitalia and urogenital sinus with vaginal stenosis in a 1-day-old female. a Transverse scan shows an enlarged left adrenal gland with the so-called cerebriform pattern (resembling cerebral cortex). b Longitudinal pelvic scan confirms the presence of uterus (arrowheads). There is moderate hydrometrocolpos (asterisks) due to urogenital sinus with vaginal stenosis. c The bladder is catheterized. Contrast material fills the bladder (B) and during micturition the vagina (V). Stenotic vaginal communication (open arrow). Urogenital sinus opening (closed arrow)

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gree of ambiguity of the external genitalia. At birth these patients present with marked clitoral enlargement, variable degree of labioscrotal fold fusion, and rugation. The opening of the urogenital sinus at the clitoral base may mimic penile hypospadia. Urinary tract anomalies are common and encompass renal agenesia, ectopia, and cystic dysplasia as well as uni- and bilateral hydronephrosis, vesicoureteral reflux, and signs of urinary outflow obstruction [17]. The primary task of the radiologist is to demonstrate the level of communication between the vagina and the urethra, the anatomy of the internal genitalia, and to rule out kidney anomalies and adrenal gland hyperplasia. Sonographic evaluation of the patient is usually the first-step imaging technique followed by fluoroscopy using water-soluble contrast material. Transabdominal ultrasound will demonstrate the internal genitalia, the kidneys, and adrenal glands, and rule out any obstructions such as hydrocolpos and hydrometrocolpos (Fig. 14) [7]. Demonstration of enlarged adrenal glands with wavy configuration of their limbs, however, is highly suspicious of congenital adrenal hyperplasia even before biochemical or genetical data can be obtained (Fig. 14) [8]. Fluoroscopic studies with water-soluble contrast material are required to examine the exact anatomy of the malformation. Barium paste or other opaque material is useful to mark the external orifice on the perineum. The urethra and/or urogenital sinus are catheterized. If the catheter enters the bladder, voiding cystoureterography should be performed in the lateral position to demonstrate the urethra as well as the vagina during micturation and to rule out vesicoureteral reflux. If only the vagina is filled, however, the catheter should be left in place and a second catheter passed anteriorly into the urogenital sinus in an attempt to catheterize the urethra. The relative position of the vaginal orifice both to the urethra and to the vestibulum can then be demonstrated (Fig. 14).

Fig. 15a–f Schematic representation of cloacal malformation variants. a Incomplete cloacal malformation: a persistent urogenital sinus opening is found adjacent to an anteriorly placed anus. b Posterior cloaca: the urogenital sinus derives posteriorly and opens in the anterior rectal wall at the anus or immediately anterior to it. Jaramillo et al. [26] characterized the anatomy of persistent cloaca according to its urinary–cloacal or urinary–rectal communication pattern. Urinary–cloacal communication is called either urethrocloacal or vesicocloacal. c Urethrocloacal communication: the urethra empties into the proximal end of the cloaca and is well formed. d Vesicocloacal communication: the urethra is rudimentary or absent. Rectal communication is called either vaginal or cloacal. e Vaginal communication of the rectum: the rectum usually joins the vagina low on its posterior wall. f Cloacal communication of the rectum: the rectum joins the cloaca

Cloacal malformation The cloacal malformation, the most complex type of imperforate anus, is a complex congenital malformation with a common outflow of the urinary, genital, and intestinal tract into a urogenital sinus. Cloaca is exclusively seen in phenotypic females and should not be confused with cloacal exstrophy, a malformation due to a failed closure of the lower abdominal wall seen in boys and girls. The diagnosis of cloacal malformation includes a wide spectrum of pelvic and perineal anomalies [26, 27]. A persistent urogenital sinus opening with an anteriorly placed anus adjacent to it (incomplete cloaca) represents the mild variant of the spectrum. In the more severe malformations all three tracts converge inside the pelvis (Fig. 15).

The diagnosis of cloacal malformation is made when in addition to an absent anus only one perineal orifice is found between the labia (Fig. 10). The only exception would be the “incomplete cloaca” with two perineal openings. Every newborn girl with imperforate anus should be considered to have a cloacal malformation until proven otherwise. The perineal anatomy varies from an almost normal female phenotype to a rudimentary phallic structure with poorly formed labia [27]. Associated anomalies include fusion defects of the müllerian ducts [26, 28], hydronephrosis (in cases of bladder outlet obstruction) [29], renal agenesis, renal ectopia or multicystic dysplasia, bilateral vesicoureteral reflux, bladder diverticula, ectopia of the ureter [26, 30],

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Fig. 16a, b Cloacal malformation with a tethered cord and b high-lying plump conus. a Longitudinal scan shows that the cord (open arrowheads) extends into the sacral canal. b Longitudinal scan shows a high-lying stubby conus (arrowheads)

lower spinal cord abnormalities, such high stubby cord or most frequently tethered cord [31, 32], anomalies of the pelvic osseous structures, such as sacral agenesis or hypoplasia, dysraphism, and pubic diastasis. Obstruction of the cloaca may occur at any level and determines whether the proximal distended urinary and/or genital system is filled solely with genital secretions or contains urine and/or meconium as well. Definitive correction of the cloaca can now be done between the age of 6 and 24 months and the prognosis of infants with cloacal malformation has improved significantly during recent years [27, 33]. Ultrasound is the most efficient first-step imaging technique in the diagnostic work-up of these patients.

Performed early after birth no or only little intestinal gas will be present and a clearer documentation of the intrapelvic structures can be obtained (Fig. 10). An abdominal mass in the neonate with cloacal malformation is almost always a distended vagina and/or uterus filled with urine and/or meconium because the path of least resistance for their egress was into the vagina instead of the cloaca [34]. Obstruction of the common outlet can lead to retrograde flow via the fallopian tubes and accumulation of intra-abdominal fluid. In cases where urine enters the rectum and colon, the meconium may calcify in utero and intraluminal calcification can be documented sonographically as well as radiologically. The distance between the blind end of the rectum and the perineum

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should be measured by transperineal ultrasound and the kidneys as well as the spinal cord documented [8]. Sonographic features of spinal anomalies, occurring with a frequency of nearly 50% in patients with cloacal malformations, are either a high-lying plump conus or a tethered cord with a thickened filum terminale (>2 mm at L5–S1), a low-ying conus medullaris (the tip of the conus lies at the level of L2 or lower), with posterior position and a restricted motion within the thecal sac. In some cases of tethered cord no distinct filum can be seen, but the spinal cord is markedly elongated, extending downward to the lower end of the dural sac (Fig. 16). After having obtained a good sonographic overview of the pelvic anatomy, radiological examination is then to be continued with plain radiographs performed a couple of hours after birth to allow accumulation of air. Gas seen in the bladder indicates a urinary–intestinal communication. A pelvic mass is usually a distended vagina and/or uterus, secondary to obstruction. If this mass contains gas, it is a sign of a rectovaginal communication. Linear calcifications in the abdomen along the peritoneal surface are signs of calcifying peritonitis, which is not necessarily a result of congenital intestinal perforation, but can occur whenever either meconium or genital secretion spills into the peritoneal cavity via the fallopian tubes [26, 35]. Granular abdominal calcifications suggest calcified intraluminal meconium (enteroliths) due to mixing of urine and meconium which are commonly associated with vaginal atresia or stenosis and recto-vesical or recto-urethral communication. The next step in the imaging process is to employ fluoroscopic studies with water-soluble contrast material to visualize the often unpredictable and erratic courses of the communications between the multiple structures, and to provide functional information about reflux and competence of the urinary sphincter (Fig. 10). Imaging during injection into the cloaca should begin in the lateral projection to display the various communications. A competent urethral sphincter can be expected when the bladder fails to opacify and vaginal obstruction or atresia is documented if contrast material fails to visualize the vagina. It might sometimes be difficult to distinguish between the bladder and the vagina. Reflux into an ureter or an urachal remnant helps to identify the bladder, and a cervical impression or a septum identifies the vagina; however, in our experience, this cervical impression is often difficult to observe. Frontal projections are useful to delineate vaginal or bladder duplications. Following the injection into the cloaca, an attempt to catheterize the bladder should be made to perform a voiding cystourethrogram, the only way to rule out vesicoureteral reflux. The rectum frequently fails to opacify after the injection of contrast material into the cloaca. In patients who have already had a colostomy, contrast material can directly be injected into the distal limb of the colostomy

prior to retrograde cloacal injection. A balloon catheter is used to inject contrast material under moderate pressure to demonstrate the narrow communications between the organ systems. This technique regularly demonstrates the level of rectal occlusion and the presence of communications between intestinal, genital, and urinary tracts making further cloacal injections unnecessary (Fig. 10). Recently, MR imaging is gaining more and more acceptance in imaging congenital abnormalies of the genital tract but should be analyzed in conjunction with other imaging modalities [12]. Ovarian cysts Congenital ovarian cysts in the fetus and newborn have previously been considered uncommon. With the introduction of prenatal ultrasound the detection of both, small and large cysts, has increased. Congenital ovarian cysts can be seen after the 26th week of gestation and are usually less than 1 cm in diameter. They develop in response to maternal hormone stimulation, are filled with clear fluid, and resolve spontaneously within a few months after birth [36, 37]. Larger ovarian cysts are either caused by follicular stimulation due to maternal hormones and have been found to be associated with hypersecretion of placental hCG or increased placental permeability to hCG. Congenital ovarian cysts have also been reported in infants of diabetic mothers, in infants of mothers who had toxemia, a large placenta complicating Rh sensitization, or in infants suffering from adrenogenital syndrome [14, 38]. Great variations exist in size of ovarian cysts, and cases where they occupied nearly the whole abdomen have been reported. According to their sonographic appearance, a simple and a complex cyst have been described. Simple cysts are purely cystic without internal echoes, whereas complex cyst show a fluid-debris level, a retracting clot, or thick septae as a result of salpingo torsion and subsequent ovarian infarction or hemorrhage into a simple cyst (Figs. 17, 18, 19). Up to 30% of large simple cysts undergo torsion, which most often happens prior to birth. Torsion of an ovarian cyst occurring in postnatal life may be asymtomatic or may cause fever, irritability, vomiting, leukocytosis, and abdominal tenderness. Hemorrhage within an ovarian cyst may also occur without signs of torsion. Lower abdominal pain and tenderness are common features in these cases [14]. Controversy still exists as to whether conservative (close observation), intermediate (percutaneous needle aspiration of large simple cyst under sonographic guidance, percutaneous drainage of complex cysts), or aggressive (surgical removal) therapy is more appropriate [39]. Almost all our conservatively treated ovarian cysts subsided regardless of their sonographic appearance (Figs. 17, 18, 19). We therefore favor

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Fig. 17 Congenital ovarian cyst in a newborn of diabetic mother complicated by torsion. Longitudinal sonogram of the right hemiabdomen shows a large cyst with low-level echoes, a fluid-debris (blood) level, and an undulating thick membrane (fibrin; arrowheads). The cyst decreased in size and resolved completely

Fig. 19 Newborn with congenital ovarian cyst complicated by torsion of both the ovary and the tube. Transverse scan shows the thickened uterine tube (arrowheads)

conservative treatment in asymptomatic cases and percutaneous puncture when the cyst reaches significant space-occupying size. If surgical exploration is performed, every attempt to salvage the gonad should be made. Viable ovarian tissue may still be present, even though it may be macroscopically invisible [40]. Unilateral or bilateral ovarian follicular cysts of various size are frequently observed in girls with precocious puberty (onset of secondary sexual characteristics before 8 years of age). These cysts may either be secondary to ovarian stimulation by an increased level of circulating pituitary gonadotropins (central precocious puberty) or functional ovarian cysts similar to those seen in normal girls (partial precocious development); however, in some cases a large ovarian cyst may assume an autonomous function and be responsible for precocious puberty due to excessive estrogen production.

Fig. 18 Congenital ovarian cyst complicated by torsion. Transverse scan shows the large cyst with low-level echoes, a fluiddebris level, as well as a huge retracting clot (arrowheads). The cyst and clot resolved completely

Conclusion Developmental disorders may lead to a number of malformations of the female genital organs with malformations affecting solely the müllerian ducts being probably the least drastic changes in a girl’s anatomy. On the extreme end of the continuum of female genital malformations is urogenital sinus, which is associated with virilization of the external genitalia and cloacal malformation

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with a common outflow of the urinary, genital, and intestinal tracts. Due to the close developmental relationship, associated malformations of the inner genitalia and urinary tract need to be considered and diagnostic evaluation of both systems are mandatory in most cases. For that purpose sonography is the most useful first-step examination technique in neonates and adolescent girls. Narrowing differential diagnosis of the possible cause of urogen-

ital sinus as well as demonstration of its anatomical features in müllerian duct anomalies, cloacal malformations, ovarian cysts, and ectopic ureter can be achieved at high confidence level using contrast studies and ultrasound to asses pelvic structures and the adrenal glands; however, with the promising prospect of further improvement, MR imaging is about to challenge fluoroscopic studies in the evaluation of cloacal malformations in children.

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