Prune Belly (Triad) Syndrome

DAVID B. JOSEPH

Triad syndrome—the clinical association of a thin flaccid abdominal wall, undescended testes, and bladder hypertrophy with hydroureters—was originally described in 1895 by Parker (1). Shortly thereafter, Osler (2) presented a similar constellation of findings in a child he described as having the appearance of “a wrinkled prune.” From that point, “prune belly” has unfortunately become synonymous with this syndrome. This clinical manifestation is also known as the Eagle-Barrett syndrome and the abdominal muscular deficiency syndrome. By classic description, the triad syndrome occurs in boys. However, 5% of patients are girls presenting with similar physical findings, with the obvious exception of the gonadal abnormality. The incidence of triad syndrome in the United States is approximately 1/26,000 live births of which 50% are white, 31% African American, and 10% Hispanic (3). Most cases are sporadic, although a familial occurrence has been described and might be influenced by the HNF1β gene (4,5).

Approximately three quarters of children with classic triad syndrome will have other associated anomalies. Urethral abnormalities, including atresia and megalourethra, have been reported but are not required as part of the triad. Urethral atresia is usually associated with a patent urachus. The most common skeletal abnormality is a thoracic deformity resulting in a protruded upper sternum, depressed lower sternum, and splayed ribs. Other less frequent skeletal deformities include talipes equinovarus, congenital hip dislocation, calcaneus valgus, polydactyly, syndactyly, arthrogryposis, scoliosis, and lordosis. Intestinal malformations are noted in approximately
one-third of children and most often are due to defective fixation or malrotation of the midgut. Cardiac atrial or ventricular septal defects, patent ductus, and teratology of Fallot have been reported in approximately 15% of children (4). Oral manifestations that included enamel hypoplasia and jaw bone abnormalities have become recently appreciated and possibly due to chronic renal insufficiency (6). The perinatal mortality remains substantial most often due to prematurity and pulmonary complications (3).

DIAGNOSIS

The diagnosis of triad syndrome can be established in utero with fetal sonography. However, similar findings can be identified in a fetus with posterior urethral valves or the megacystis-megaureters syndrome. Close inspection for thinned, deficient, or absent abdominal wall musculature should hedge the differential diagnosis to that of the triad syndrome. In utero diagnosis allows for a planned neonatal investigation. Triad syndrome is typically obvious at birth with the pathognomonic physical findings of a loose, lax, wrinkled abdominal wall; flared chest; and undescended testes.

Several classifications of the triad syndrome have been established based on severity and initial clinical presentation. There is no single classification system that incorporates the total spectrum of this syndrome. For practical purposes, children can be grouped into severe, moderate, or mild presentations. With a severe presentation, survival is often limited by significant respiratory compromise due to pulmonary immaturity and dysplasia, as well as extensive renal dysplasia, resulting in a Potter-like syndrome. Children described with moderate involvement have combined renal and respiratory insufficiency, mandating close observation and early intervention to minimize the sequelae of pulmonary and renal compromise. The combination of increased bilateral renal echogenicity on sonography, chronic urinary tract infections (UTIs), and a nadir serum creatine of >0.7 mg per dL are prognostic for renal failure (7). Monitoring of the urinary system is necessary to prevent progressive renal deterioration due to stagnation of urinary flow, UTIs, and possible urinary tract obstruction. Urinary tract reconstruction may play an important role in limiting long-term morbidity. Children with mild involvement do not suffer from respiratory or renal compromise. While long-term follow-up is necessary, operative intervention is often limited to orchiopexy and abdominal wall reconstruction.

A team approach consisting of a pediatric urologist, neonatologist, nephrologist, pulmonologist, and cardiologist is required to maximize the outcome. The initial cardiorespiratory status of the neonate must be established. The baby should undergo a chest X-ray and, when indicated, cardiac sonography. Urologic evaluation commences with abdominal sonography and a baseline chemistry profile. Both the upper and lower urinary tract should be assessed. Attention should be placed on the degree of hydronephrosis, the volume of renal parenchyma, and its echogenicity. Often, there will be a disproportionate degree of distal ureteral dilation and megacystis compared to dilation of the proximal ureter and kidney. On occasion, a marked transition of ureteral dilation is noted. If the infant is clinically stable with normal renal function and is voiding per urethra or draining through a patent urachus, further diagnostic testing can be placed on hold.

Children with renal insufficiency require further imaging to differentiate renal dysplasia and stagnant urine flow from true obstruction. The MAG-3 renal scan has limitations in the newborn period but remains the most objective diagnostic tool. The voiding cystourethrogram can assess vesicoureteral reflux and the effectiveness of bladder emptying. The neonate with triad syndrome and hydroureteronephrosis is susceptible to bacteriuria and can quickly become symptomatic. Bacteriuria is often persistent and difficult to clear. Therefore, it is of utmost importance that any invasive lower urinary tract imaging be performed in a sterile environment, with the child receiving pre- and postprocedural antibiotics.

Megalourethra has been classified as scaphoid and fusiform (Fig. 90.1). The more common scaphoid defect is confined to the penile portion of the corpus spongiosum, resulting in a variable length of massively enlarged ventral, anterior urethra similar in appearance to a saccular diverticulum. The fusiform variety encompasses a defect of the corpus spongiosum and deficiency of one or both of the corpus cavernosum, resulting in circumferential ballooning of the urethra and generalized penile flaccidity. Megalourethra is usually an isolated defect but can present with upper urinary tract changes, including hydronephrosis, vesicoureteral reflux, and renal dysplasia. It has been reported to occur with the triad syndrome, which may represent a continuation of the abnormal mesodermal theory of development related to the triad syndrome.

FIGURE 90.1 A: Scaphoid megalourethra. Corpora spongiosum (CS) is deficient throughout the ventral aspect of penile urethra. Corpora cavernosum (CC) is normal. B: Fusiform megalourethra. Both corpora spongiosum and cavernosum are deficient. Glans (gl) is normal in both variants.

INDICATIONS FOR SURGERY

Each child presents with a unique constellation of problems resulting in its own set of considerations and requires individualized care (8). Therefore, no one treatment plan is appropriate for all children. In general, operative management can be divided into three broad areas: reconstruction of the urinary system, reconstruction of the abdominal wall, and transfer of the intra-abdominal testes to the scrotum.

Urinary Tract Reconstruction

Controversy surrounds the need for aggressive urinary tract reconstruction. Early aggressive operative intervention for all children is countered by the fact that renal dysplasia may be inherent, thus preventing any intervention from improving the functional status. In addition, imaging studies depicting significant hydroureteronephrosis do not always correlate with obstruction or the potential for symptoms, and hydroureteronephrosis by itself does not mandate reconstruction. Urinary tract reconstruction is beneficial in a child who has a component of obstructive uropathy and has been shown to have improved renal function with decompression of the urinary system. Reconstruction is also of benefit in the child who has progressive hydroureteronephrosis associated with increasing renal compromise and in the child who has recurrent symptomatic UTIs due to stagnant urine flow.

Urinary diversion plays an initial temporary role in the management of acute renal failure or sepsis. Often, children with urethral atresia or obstruction will present with a patent urachus, effectively emptying their lower tract. Infants with associated posterior urethral abnormalities resulting in obstruction or poor bladder decompression, who are not candidates for intermittent catheterization, benefit from a vesicostomy. A vesicostomy, however, may not adequately drain the upper urinary tract due to a relative obstruction of the ureter at the level of the bladder or poor urinary transport secondary to a highly compliant, adynamic ureter. Vesicostomy should be undertaken only when bladder catheterization has been shown to provide effective decompression of the upper urinary tract. Otherwise, temporary diversion of the upper urinary tract will be required. Nephrostomy tube drainage is helpful to stabilize an acute problem but long-term effectiveness is limited, resulting in a need for a more formal upper urinary tract diversion. There is a theoretical advantage in performing upper tract diversion as proximal as possible. This should maximally relieve stress to the kidney and limit stagnation of urine in a dilated tortuous ureter. However, there is often a disproportionate degree of distal versus proximal ureteral dilation that can prevent easy access of the proximal ureter.

It is compelling to perform a reduction cystoplasty during urinary reconstruction in a child with triad syndrome. However, long-term follow-up has been mixed regarding identifiable objective advantages (9,10,11). With time, the bladder will often regain its large size and lose its tone, resulting in inadequate emptying. For these reasons, it is not practical to proceed with reductive cystoplasty as the primary indication for urinary reconstruction. If a large, poorly contracting bladder results in inadequate urinary emptying, intermittent catheterization would be a more appropriate form of initial management. However, when undertaking formal urinary reconstruction with upper tract ureteral tailoring, reductive cystoplasty is practical and may provide limited improved bladder emptying (11).

Reconstruction of the Abdominal Wall

Several techniques have been devised to maximize the cosmetic benefits of abdominal wall reconstruction in children with triad syndrome. There is evidence indicating that the muscular defect is more pronounced centrally and caudally. Initial reconstructive efforts were based on removal of this abnormal tissue. While the appearance of the abdomen was improved, it was not ideal and resulted in a transverse incision and loss of the umbilicus. Monfort described preservation of the umbilicus, and others have added various modifications (12,13,14,15,16,17). Based on these approaches, abdominal wall reconstruction now allows for an excellent cosmetic and functional outcome (15,16,17,18). The benefit of abdominal wall reconstruction is dependent on the degree of abdominal wall laxity. The timing for this procedure should be based on the need for other operative intervention. If it is obvious that the child will not require upper urinary tract reconstruction, abdominal wall reconstruction can be undertaken at any time. If, however, there is the potential for upper urinary tract reconstruction, abdominal wall reconstruction should be deferred until the time of that intervention.

Only gold members can continue reading. Log In or Register to continue