Overview, Etiology, and Clinical Presentation: A multicystic dysplastic kidney (MCDK) is the most common form of cystic renal dysplasia. With high-grade obstruction or atresia of the upper urinary tract (renal pelvis and/or ureter) during early renogenesis, disordered parenchymal development results in an MCDK.¹ Two types of MCDK exist: the pelvoinfundibular type (common) and the hydronephrotic type (uncommon).^2,3 MCDK can occur in half of a duplex kidney (usually the upper moiety) or in renal fusion anomalies, such as a horseshoe kidney and crossed fused renal ectopia. MCDK is sporadic in most cases, although familial cases have been described.^1,4 Vesicoureteral reflux (VUR) (both ipsilateral and contralateral) and contralateral ureteropelvic junction obstruction are common.^1,5 Long-term sequelae (e.g., infection and hypertension) are rare, because most affected kidneys either partially or completely involute on their own over time.^6–9

Imaging: On ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI), a classic MCDK is characterized by multiple cysts of various sizes (ranging from 1 mm to several cm) that do not communicate, with no normal intervening renal parenchyma (Fig. 114-1). The affected kidney may be small, normal, or enlarged.¹ Compensatory hypertrophy of the contralateral kidney often is present.¹⁰ The hydronephrotic form has cysts that communicate, mimicking pelvocaliectasis, but no normal functioning renal tissue.² The diagnosis of both classic and hydronephrotic MCDK can be confirmed by diuretic renal scintigraphy (e-Fig. 114-2) or MR urography (MRU) (e-Fig. 114-3). A voiding cystourethrogram (VCUG) may reveal VUR into a blind-ending ureter on the side of the MCDK.^11,12

Treatment: Follow-up ultrasound typically demonstrates involution of the cysts over time, eventually resulting in remnant dysplastic renal tissue that may be impossible to visualize.13,14 Immediate resection of an MCDK is rarely indicated¹⁵ and is reserved for cases in which the size of the kidney is a problem. In the past, routine nephrectomies were performed because of a fear of malignant degeneration. Current belief discounts this possibility, and as long as no other complication exists, surgery is not indicated.

Overview and Etiology: Autosomal-dominant polycystic kidney disease (ADPKD), the most common form of inherited renal cystic disease, is seen in 1 in 800 live births.16,17 Two types of ADPKD exist, each with clearly defined chromosomal mutations. The more severe form (PKD1) accounts for about 85% to 90% of cases, whereas the milder phenotype (PKD2) presents later in life, results in less morbidity, and is less common.^16,18 Cysts arise from both the renal cortex and the medulla.^16,19

Clinical Presentation: Systemic hypertension, hematuria, and slowly progressive renal insufficiency are the typical clinical manifestations.1,20 ADPKD is very rarely detected prenatally because fewer than 5% of nephrons are cystic before birth.¹ Diagnosis of ADPKD early in life portends a poor prognosis; 43% of affected persons die in the first year of life, hypertension develops in 67%, and some affected children progress rapidly to end-stage renal disease.²⁰ Because it can be difficult to delineate between autosomal-recessive and autosomal-dominant forms of polycystic kidney disease in a neonate, screening of siblings and parents may be helpful.

Imaging: The diagnosis of ADPKD usually is made on the basis of ultrasound (Fig. 114-4), although CT or MRI also can suggest it. Although the kidneys may be normal during the first decade of life, they also may contain one or more simple cysts (Fig. 114-5).^16,21 The kidneys may be abnormally enlarged and echogenic, mimicking autosomal-recessive polycystic kidney disease (ARPKD) in early life (e-Fig. 114-6).^16,22 Although it is typically a bilateral process, imaging findings may be asymmetric, and in young children they can manifest as a unilateral abnormality.^16,21,23 Microscopic cysts, as well as larger cysts that can be detected by cross-sectional imaging techniques, are common in the liver and less frequent in the pancreas, spleen, lungs, thyroid, ovaries, and testes.¹⁹ The remainder of the urinary tract is usually normal.

Treatment: Although renal function is generally maintained during childhood, ADPKD is responsible for the need for chronic dialysis in 10% to 12% of adult patients.¹ Hypertension should be managed medically to prevent long-term complications. About 12% to 15% of patients with ADPKD have an intracranial aneurysm, most often arising from the circle of Willis.^19,23–25 Screening MR angiography usually is not performed in childhood, however, because aneurysm rupture is rare in this period.

Overview: ARPKD is a rare disorder (occurring in 1 : 20,000 live births) that affects both kidneys.26,27 Genetic studies have localized the inheritance of ARPKD to chromosome 6p.^27,28 The PKHD1 gene is expressed in fetal and adult kidneys and livers, the two major sites affected by the disease.²⁸ Approximately 1 in 70 persons are a carrier for this condition.^26,27

Clinical Presentation: ARPKD has been subdivided into categories based on clinical presentation. The perinatal and neonatal forms, which have the poorest prognosis, are associated with severe renal dysfunction and minimal hepatic portal tract fibrosis. Affected children often die of the disease early in life.27,29 Infantile and juvenile forms are associated with less severe renal dysfunction and more significant hepatic fibrosis.²⁷ The degrees of renal and hepatic abnormalities tend to be inversely proportional.^17,27 A number of children with ARPKD also have Caroli disease (see Chapter 88).²⁷

Pathology: Histologically, the kidneys have a spongelike appearance, replaced by myriad minute 1- to 2-mm cysts of relatively uniform size, representing markedly dilated and elongated collecting ducts.1,27 These cysts radiate from the hilum to the surface of the kidney without a clear demarcation between the medulla and cortex. Fibrosis is present in the renal interstitium. Children with significant hepatic involvement are at increased risk for complications related to portal hypertension, and ascending cholangitis can lead to sepsis and death.²⁷

Imaging: Abdominal radiography in the neonatal period commonly reveals bilateral abdominal or flank masses with centralized gas-filled bowel loops. The lungs may appear small because of a combination of pulmonary hypoplasia and mass effect from marked nephromegaly (e-Fig. 114-7).²⁷

On ultrasound, affected neonatal kidneys tend to be smoothly enlarged (frequently more than four standard deviations above the mean expected length for age), are hyperechoic as a result of the multiple acoustic interfaces at the walls of the dilated ducts, and have poor corticomedullary differentiation (e-Fig. 114-8).^1,27,29,30 On occasion, discrete cysts (solitary or multiple) of variable size (most commonly <1 cm) may be seen (Fig. 114-9).^26,30 A sonolucent rim may be seen at the periphery of the kidney, especially in older infants, as a result of cortical compression and relative sparing.^26,27 Contrast-enhanced CT (Fig. 114-10) or MRI show delayed opacification of the renal parenchyma with a prolonged and striated nephrogram. When studied with MRI, the dilated tubules in affected kidneys appear linear and hyperintense on T2-weighted imaging, radiating from the medulla toward the cortex (Fig. 114-11).³¹

Treatment: Eighty-six percent of patients who survive beyond 1 month of age are alive at 1 year, and 67% are alive at 15 years.³² In infants who have initially adequate (although not normal) renal function, the disease may not be detected until later in the first decade, when ultrasound is being performed for unrelated purposes. Systemic renovascular hypertension may occur and require medical management.^17,27 Persons with ARPKD who have severely impaired renal function eventually will require renal replacement therapy, either dialysis or renal transplantation.

Overview, Etiology, and Clinical Presentation: A calyceal diverticulum represents a focal outpouching of the renal collecting system that is located within the renal parenchyma and that contains urine.³³ This condition has an incidence of 3.3-4.5 : 1000 in children, based on excretory urography.^34–36 Calyceal diverticula are likely developmental in origin; they are lined with urothelium and surrounded by muscularis mucosa.^33,35 Although these structures most commonly are an incidental finding, they can be associated with both infection and calculus formation as a result of urinary stasis.^33,35,37

Imaging: Abdominal radiographs may be normal or may demonstrate one or more calculi (or milk of calcium) within a calyceal diverticulum.³⁵ Upon ultrasound, such diverticula may mimic a solitary renal cyst, appearing as a round, thin-walled anechoic structure (Fig. 114-12).³⁴ They can vary in size ranging from a few millimeters to several centimeters (with a mean size around 11 mm).^35,37 They most commonly occur within the upper pole of the kidney.³³ Upon excretory phase imaging (including excretory urography, MRI, and CT), calyceal diverticula typically fill with contrast material (Fig. 114-13). A thin connection, or neck, to an adjacent calyceal fornix may or may not be identified.³⁵

Treatment: A symptomatic calyceal diverticulum may require surgical ablation. Although both lithotripsy of calculi within the diverticulum and percutaneous ablation of the cavity have decreased the invasive treatment in adults,37,38 such techniques have not yet been applied widely to children.

Overview, Etiology, and Clinical Presentation: Congenital infundibulopelvic stenosis is a very rare congenital anomaly of the renal collecting system that presents as unilateral or bilateral caliectasis. Although the exact etiology of this condition is uncertain, Lucaya et al.³⁹ hypothesized that this abnormality is a milder manifestation of the process that results in multicystic dysplastic kidney. Affected children may be predisposed to urinary tract infections, and this condition may be associated with other renal and urinary tract anomalies.³⁹

Imaging: Upon contrast-enhanced excretory phase imaging studies (including excretory urography, MRU, and CT), this condition has a specific appearance: the renal collecting system infundibula are abnormally narrowed but not entirely obliterated, and the calyces appear abnormally rounded and dilated (Fig. 114-14). The renal pelvis also appears narrowed as a result of stenosis or hypoplasia. This condition may be unilateral or bilateral. Despite the cystlike appearance of the calyces on such contrast-enhanced studies, the ultrasound appearance of the kidneys can be normal. Renal function may be normal to severely impaired.³⁹

Treatment: Most affected individuals demonstrate normal or stable renal function and do not require treatment. Surgical approaches to manage this condition have been described, including ureterocalicostomy and renal transplantation.³⁹

Overview, Etiology, and Clinical Presentation: Congenital megacalyces is a very rare anomaly of the renal collecting system that may be easily confused for hydronephrosis.⁴⁰ Calyceal involvement may be unilateral or bilateral. This abnormal calyceal dilatation is not due to urinary tract obstruction but instead is likely a result of underdevelopment/hypoplasia of the renal medullary pyramids.^41,42 Boys are more commonly affected than are girls. Associated urinary stasis may predispose affected children to urinary tract infection and urolithiasis.⁴¹

Imaging: Congenital megacalyces may be misidentified as obstructive caliectasis by ultrasound. With excretory urography, however, this condition is easily identifiable because of the presence of abnormally dilated calyces that lack normal papillary impressions, have a polygonal or faceted shape, and appear to be increased in number (20 or more calyces may be seen) (Fig. 114-15).⁴² The renal parenchyma overlying affected calyces may appear thin. The renal pelvis can be normal in caliber or mildly dilated,⁴¹ and classically, no related urinary tract obstruction should be present. This appearance of the calyces on MRU and excretory-phase CT (CT urography) also should suggest the diagnosis.

Treatment: Congenital megacalyces usually are an incidental finding that requires no specific treatment.

Overview: Ureteropelvic junction (UPJ) obstruction is the most common type of congenital urinary tract obstruction, occurring in 3 per 1000 live births. Boys are more frequently affected than are girls, and the left kidney is more commonly involved than the right kidney. About 30% of cases are bilateral, although severity of obstruction and pelvocaliectasis may be asymmetric.¹

Pathophysiology: An intrinsic narrowing (e.g., smooth muscle deficiency, increased fibrosis and collagen, stricture, valve, kinking, and altered peristalsis) occurs at the level of the UPJ, leading to dilatation of the pelvicalyceal system.1,43 On occasion, extrinsic narrowing can be seen from a crossing renal vessel in older children and adults.⁴⁴ UPJ obstruction often is seen in association with other urinary tract anomalies, such as contralateral multicystic dysplastic kidney, upper urinary tract duplication,^45,46 VUR,⁴⁷ and ureterovesical junction obstruction.⁴⁸

Clinical Presentation: When UPJ obstruction is not detected prenatally, affected children commonly present with a palpable abdominal mass in the neonatal period. Older children may present with intermittent hydronephrosis and flank pain, often associated with crossing vessels. UPJ obstruction can be complicated by calculi, infection (pyonephrosis), and hemorrhage, especially when diagnosis is delayed.²⁹

Imaging: On ultrasound, abnormal dilatation of the pelvicalyceal system of varying degrees is seen, whereas the ureter is normal in caliber.1,29 Ultrasound findings suggestive of renal dysplasia may be present in cases of severe obstruction (described later). Debris within the collecting system can represent infection or hemorrhage (Fig. 114-16). Careful interrogation of the UPJ region with Doppler ultrasound may identify a crossing vessel, when present.⁴⁹ Frequently, separating dilated nonobstructed from dilated obstructed renal collecting systems is difficult by ultrasound alone.

Abdominal radiographs may show soft tissue fullness, bulging of the flank, and displacement of bowel loops from the affected side (e-Fig. 114-17). On contrast-enhanced excretory phase CT, the obstructed kidney demonstrates delayed opacification and excretion of contrast material.⁴³ CT angiography with multiplanar reformatted and three-dimensional images may be used to depict suspected crossing vessels as a cause of UPJ obstruction in older children and adults.⁵⁰

Diuretic renal scintigraphy is commonly used to evaluate UPJ obstruction; both renal function (including perfusion and differential function) and drainage are evaluated (e-Fig. 114-18).^51,52 MRU is an increasingly important tool in the evaluation of untreated and treated UPJ obstructions.⁵³ This imaging technique currently allows for the detailed assessment of urinary tract anatomy, while also providing information regarding renal function, including differential renal function, and the presence or absence of obstructive uropathy (Fig. 114-19).^53–55 Both a retrograde pyelogram and a antegrade nephrostogram also can be performed to establish the level of upper urinary tract obstruction, if clinically necessary.

Treatment: Recent literature has emphasized the conservative management of neonates with UPJ obstruction, especially with preserved renal function shown by biochemical parameters and renal scintigraphy.1,56–58 A substantial number of cases that are identified prenatally resolve spontaneously without requiring surgery.^56–58 Indications for surgery include reduced renal function, sustained increase in pelvicalyceal dilation, breakthrough infections, a solitary kidney, and severe bilateral hydronephrosis.^58,59 Treatment, if deemed necessary, usually is accomplished with a dismembered pyeloplasty.¹

Overview and Etiology: A duplex kidney consists of a single renal unit that is drained by two collecting systems. If two ureteric buds are present or the ureteric bud bifurcates before meeting the metanephric blastema, duplication of the renal collecting system and ureter occur.⁶⁰ Possibilities include a simple bifid renal pelvis, a bifid ureter (i.e., incomplete ureteral duplication), complete ureteral duplication, an ectopic ureter, and an ectopic ureterocele. Incomplete duplication of the upper urinary tract is more common than is complete duplication. Even when two ureters are present distally, they frequently enter the bladder via a common sheath.

In cases of complete ureteral duplication, one ureter takes up a near-normal position within the urinary bladder, and the other moves inferiorly with the mesonephric (Wolffian) duct into an abnormal location (e.g., the bladder neck, urethra, vagina, or perineum in girls or the ejaculatory system in boys).⁶⁰ The Weigert-Meyer rule, which is applied only to complete duplications, states that the ureter that drains the upper moiety inserts inferior and medial to the lower moiety ureter (Fig. 114-20). In addition, the ectopic ureter is more likely to be obstructed, whereas the lower moiety ureter is more likely to reflux. Extravesical ureter insertion is far more common in girls than in boys. Extravesical ureter insertions in boys are almost always above the sphincter mechanism; they can be below the sphincter mechanism in girls and present with urinary dribbling and daytime and nighttime wetness. On occasion, ectopic ureteroceles may be detected in the setting of a diminutive pelvicalyceal system, the so-called “ureterocele disproportion.”^60,61

Clinical Presentation: Clinically, incomplete duplication of the upper urinary tract may be asymptomatic or may present with urinary tract infections as a result of ureteroureteral reflux and stasis (so-called “yo-yo” reflux).⁶⁰ Children with complete duplication may present in a variety of manners, including hydronephrosis, urinary tract infection, and bladder outlet obstruction due to a large ureterocele.^60,62 Complete duplications in girls also may present with enuresis (both daytime and nocturnal wetness) as a result of insertion of the ectopic ureter into the urethra below the level of the sphincter mechanism or vagina.⁶⁰

Imaging: Ultrasound may identify a prominent renal parenchymal column that appears to separate the sinus fat, providing indirect evidence of collecting system duplication (Fig. 114-21). More commonly, complete duplications present with upper moiety hydronephrosis. Dilatation of the lower moiety can be due to VUR or, less often, concomitant UPJ obstruction (e-Fig. 114-22).^45,60 Ultrasound of the urinary bladder may show a thin-walled intraluminal cystic structure, consistent with a ureterocele (Fig. 114-23).¹ Ureteroceles can vary in size and may appear septated or multiloculated, and when they are located in the midline, it may be difficult to establish the exact side from which they arise.⁶²

In the early bladder filling phase of a VCUG examination, a smooth round filling defect is observed, consistent with a ureterocele (Fig. 114-24). Ureteroceles become more difficult to visualize as the urinary bladder distends with contrast material because of obscuration, flattening, or even eversion.^60,62 VUR into the lower moiety collecting system of a duplex kidney commonly reveals too few calyces and has a “drooping lily” appearance as a result of abnormal long-axis orientation (Fig. 114-25).⁶⁰ The normal long axis of the renal collecting system should parallel that of the ipsilateral psoas muscle. On occasion, VUR may be noted involving the upper moiety of a duplicated system (in about 11% of children), sometimes only after ureterocele incision.^60,63 VUR also can be used to discriminate incomplete from complete ureteral duplications (Fig. 114-26).

MRI (particularly MRU) provides a precise assessment of duplicated upper urinary tract anatomy (e-Fig. 114-27). A variety of T2-weighted imaging techniques can be used to image urine-filled structures, even in the setting of obstruction. MRU also allows for the assessment of renal function and the presence of obstructive uropathy and is optimal for the assessment of the extravesical ureteric insertions (e-Fig. 114-28).^60,64

Treatment: Incomplete duplications of the upper urinary tract are frequently asymptomatic and require no specific treatment. Specific treatments for upper moiety obstruction include endoscopic puncture or excision of an obstructing ureterocele, ureteroureterostomy, and upper moiety heminephrectomy in the setting of poor or absent function.60,65,66 Lower moiety dilatation due to VUR may require ureteral reimplantation, whereas dilatation due to UPJ obstruction may require surgical pyeloplasty. Multicystic dysplastic upper moieties commonly involute over time without the need for surgical intervention.⁶⁷

Overview, Etiology, and Clinical Presentation: Prune-belly syndrome, also known as Eagle-Barrett or triad syndrome, includes the constellation of bilateral cryptorchidism, anterior abdominal wall muscular deficiency, and a variety of urinary tract anomalies, including megacystis and hydroureteronephrosis.68,69 The appearance of the abdominal wall on physical examination and radiographs has a characteristic appearance. Although the pathogenesis of prune-belly syndrome is controversial, two main theories are currently suggested: (1) bladder outlet obstruction early in utero and (2) a primary mesodermal defect.^68–70 This condition is usually nonhereditary (although familial cases have been reported), almost always affects boys (3% to 5% of cases occur in girls), and is present in 1 : 29,000 to 1 : 50,000 live births.^68,69 Associated anomalies of the cardiovascular, musculoskeletal, and gastrointestinal systems also may be present.

Imaging: On physical examination and radiographs, the abdominal wall of affected neonates has a characteristic wrinkled appearance with bulging of the flanks resulting from muscular deficiency (e-Fig. 114-29). VCUG allows depiction of the urinary bladder and urethral anatomy, identifies VUR, and determines whether a urachal anomaly is present. Markedly dilated, tortuous ureters are common because of a combination of muscular deficiency and VUR, which is present in approximately 75% of patients with prune-belly syndrome (Fig. 114-30).⁶⁹ Upper urinary tract obstruction typically is not present. The urinary bladder usually has a smooth wall, increased capacity (megacystis), and may contain multiple diverticula. Urethral findings include dilatation and elongation of the prostatic urethra (e-Fig. 114-31), an enlarged utricle, megalourethra (e-Fig. 114-32), and rarely urethral atresia.⁶⁸ A minority of patients with prune-belly syndrome have urethral obstruction due to an obstructing membrane or valve.⁶⁸ The primary role of ultrasound in the neonatal period is to establish the status of the kidneys. The kidneys commonly show findings compatible with renal dysplasia, including small size, abnormally increased parenchymal echogenicity, loss of corticomedullary differentiation, and cortical cysts.

Treatment: Children with prune-belly syndrome may require multiple surgical procedures. The testes should be relocated from the abdomen to the scrotum (orchiopexy) to minimize the risk of future testicular torsion and neoplasm.⁶⁸ Urethral obstruction, if present, should be surgically addressed. VUR and poor upper urinary tract drainage may be managed with chronic antibiotic prophylaxis (which is currently preferred) or surgical reimplantation of the ureters to attempt to preserve renal function. Megacystis and poor urinary bladder emptying may be treated with reduction cystoplasty or vesicostomy.⁷¹ In more severe cases, anterior abdominal wall surgical reconstruction (abdominoplasty) is performed and may improve urinary bladder emptying.^68,71 Because of chronic kidney disease and frequent underlying renal dysplasia, affected children eventually may require renal transplantation or dialysis therapy.

Overview, Etiology, and Clinical Presentation: The name “megacystis-microcolon-intestinal hypoperistalsis-malrotation syndrome” actually describes the pertinent clinical and radiologic findings. Features of this syndrome may overlap with prune-belly syndrome. This syndrome is an autosomal-recessive disorder seen mostly in girls. It presents clinically with severe abdominal distention during the neonatal period because of functional bowel obstruction and severe urinary bladder distention.72,73

Imaging: Abdominal radiography may demonstrate a large, round mass emanating from the pelvis because of megacystis. Ultrasound and VCUG show an abnormally distended urinary bladder (Fig. 114-33) and, in most cases, hydroureteronephrosis.⁷³ Urinary bladder emptying is abnormal, although no anatomic obstruction is found. Contrast enema examination reveals a severe microcolon and diminished or absent colonic peristalsis (Fig. 114-34).^72,73

Treatment: This syndrome is commonly fatal in the first year of life because of malnutrition or sepsis, unless the patient receives parenteral nutrition.72–75 Bowel transplantation has been attempted as a treatment option.⁷⁶ A cutaneous vesicostomy or suprapubic cystostomy may assist with urinary bladder drainage.⁷³

Overview: Deficiency of the anterior abdominal wall with an open, everted, incompletely formed urinary bladder is referred to as bladder exstrophy. The anterior wall of the urinary bladder and overlying skin are absent, and the rectus abdominis muscles are separated inferiorly.1,77 The remaining posterior urinary bladder wall is continuous with the skin.⁷⁷

Etiology and Clinical Presentation: Failure of migration of mesenchymal cells between ectoderm and cloaca during the fourth week of fetal life leads to incomplete closure of the midline lower anterior abdominal wall in utero, resulting in bladder exstrophy.1,77,78 This rare, unpredictable, congenital defect occurs in 1 : 10,000 to 1 : 40,000 live births and is more common in boys.¹ Upon physical examination, the ureteral orifices may be visualized draining into the posterior urinary bladder wall. Epispadias in boys and bifid clitoris in girls often are noted as well.⁷⁷ Other skeletal, scrotal, renal, spinal, and anorectal anomalies also may be present.^1,77

Imaging: Radiographs show abnormal pubic symphyseal widening (Fig. 114-35).^77,79 The hips may be dislocated. Renal imaging is most commonly normal at birth.⁷⁷ Recently, MRI has been used to assess pelvic anatomy after bladder exstrophy repair.⁸⁰

Treatment: The prognosis for bladder exstrophy is generally good. Although certain patients may be amenable to complete primary closure,⁸¹ others may require multiple surgeries involving the genitourinary and skeletal systems early in life. An increased incidence of adenocarcinoma of the bladder later in life is found compared with age-matched control subjects.^1,82

Overview, Etiology, and Clinical Presentation: Cloacal exstrophy is a nonhereditary constellation of congenital anomalies that involves the anterior abdominal wall and multiple organ systems. This condition is a result of maldevelopment of the cloacal membrane during organogenesis. The infraumbilical cloacal membrane persists, which interferes with normal infraumbilical anterior abdominal wall closure and leads to failure of urogenital septum separation from the rectum. Two hemibladders are separated by ileocecal bowel mucosa.⁸³ The terminal ileum prolapses through the exposed cecum (sometimes called an “elephant trunk” deformity).⁸³ Associated anomalies include omphalocele, abnormal genitalia, a two-vessel umbilical cord, closed spinal defects, and renal abnormalities.

Imaging: Radiographs may demonstrate a variety of abnormalities, including abnormal widening of the pubic symphysis, lumbosacral spine anomalies, developmental dysplasia of the hip, and clubfoot. Imaging of the kidneys may reveal agenesis or ectopia, and various Müllerian anomalies may be detected in the pelvis (Fig. 114-36 and Box 114-2). Ultrasound and MRI imaging of the spine commonly reveal spinal dysraphism and spinal cord tethering (e-Fig. 114-37). At some point, upper gastrointestinal series evaluation should be performed because midgut malrotation may be present in up to 30% of affected children.⁸³

Treatment: This condition commonly requires a multistage approach to surgical reconstruction.⁸⁴ Advances in surgical technique and supportive care have improved survival and functional outcomes.

Overview, Etiology, and Clinical Presentation: Cloacal malformation is diagnosed when the urinary, genital, and gastrointestinal tracts all come together to form a single outflow channel of variable length.62,85 On physical examination, the perineum has a single opening that eliminates urine, feces, and genital tract secretions.⁸⁵ Unlike with cloacal exstrophy, the anterior abdominal wall is intact.⁶² Although the etiology of this congenital anomaly is not entirely understood, it is thought to be the result of failure of urorectal septum to join the cloacal membrane in utero.⁶² This condition only affects 1 : 40,000 to 1 : 50,000 phenotypic newborn girls.⁸⁵

Imaging: Contrast injection through a catheter placed within the single perineal orifice under fluoroscopic observation can be used to confirm the diagnosis and definitely characterize perineal anatomy.62,85 Jaramillo et al.⁸⁵ divided these malformations into urethral and vaginal subtypes based on the appearance of the common channel. Numerous genitourinary tract abnormalities may be seen in the setting of cloacal malformation, including VUR, ureteral ectopia, urinary bladder diverticula, urinary bladder duplication, urachal anomalies, urethral duplication, and a variety of uterine and vaginal anomalies.⁸⁵ Renal abnormalities may include agenesis, obstruction, and horseshoe kidney, whereas osseous abnormalities may include widening of the pubic symphysis and partial sacral agenesis. Abnormalities of the spinal cord may be present and are best characterized by ultrasound or MRI (Fig. 114-38). Contrast material injection through the distal limb of a diverting colostomy also may be performed to further assess perineal anatomy.^62,85

Treatment: The goals of surgery are to achieve urinary and fecal continence and to preserve future sexual function. The surgical approach depends, at least in part, on the length of the common channel. A diverting colostomy may be performed soon after birth as a temporizing measure. Hematocolpos/hydrocolpos due to vaginal obstruction should be drained when present. Posterior sagittal anorectovaginourethroplasty often is performed to definitely repair the entire malformation with good results, although laparotomy also may be required.⁸⁶