CLINICAL PRESENTATION

Most children with VUR present in 1 of 2 distinct groups. The first group presents with hydronephrosis, often identified antenatally by ultrasound. The second group presents with clinical UTI. Even for experienced pediatricians, the diagnosis of UTI in children can be difficult.

Infection in infants can manifest as failure to thrive, with or without fever. Other features include vomiting, diarrhea, anorexia, and lethargy. Older children may report voiding symptoms or abdominal pain.

MANAGEMENT

Once the UTI is established by a suprapubic urine culture an ultrasound is recommended as first line investigation in the evaluation of VUR. The anatomy of the bladder and the dilatation of the upper tract are principally evaluated. Once the episode of UTI is treated a voiding cystourethrogram is recommended in younger children to demonstrate and grade the reflux. A nuclear renal scan (DMSA or MAG3) is done to look for renal parenchymal scars.

Majority of the VURs are treated medically. This conservative approach relies on spontaneous resolution of vesicoureteral reflux; there is an approximately 15% down gradation of reflux every year. The patient is kept on chemoprophylaxis using cephalexin for children younger than 6 months and co-trimaxazol or nitrofurantoin for older children. Urine examination and imaging is done periodically.

The indications for surgery are:

1. Unilateral gr. V or bilateral gr. IV reflux or above

2. Break through infections despite adequate chemoprophylaxis 3. Non- compliant patient

4. Fresh scars on nuclear scan

5. Correction of primary problem in secondary reflux 6. Circumcision for lower grade reflux (not established)

7. Subureteric injection of non-biodegradable material (e.g. deflux) (not established)

POSTERIOR URETHRAL VALVE (PUV) (Figs 5.31A and B) PATHOLOGY

Posterior urethral valve is an abnormal congenital obstructing membrane located within the posterior male urethra. It causes antenatal obstruction to the bladder outlet. The entire urinary tract develops in an abnormal environment of high intraluminal pressure due to mechanical obstruction. Permanent defects in the function of the kidney, ureters and bladder may result from prenatal maldevelopment and do not resolve despite adequate decompression of the urinary tract after birth. The renal insult may occur due to dysplasia, high pressure and infection.

Hydronephrosis occurs due to high backpressures, deficient development of ureteric musculature, high urinary flow due to lack of concentrating ability of the nephron or abnormalities of the vesicoureteral junction such as reflux or, rarely, ureterovesical obstruction. Vesicoureteral reflux is present in one half of patients and may be secondary to high bladder pressure or due to an abnormal ureteral orifice position caused by abnormal ureteral bud development during embryogenesis.

Bladder dysfunction is thought to be secondary to alterations in collagen deposition and the development of detrusor smooth muscle cells. These may not improve after adequate fulguration.

Several protective (pop-off) mechanisms may develop in boys with posterior urethral valve, which may lower intraluminal pressures. These include massive unilateral vesicoureteral reflux (usually associated with an ipsilateral dysplastic kidney known as vesicoureteral reflux and dysplasia syndrome), bladder diverticula, and urinary ascites.

FREQUENCY

PUV is the most common cause of lower urinary tract obstruction in male neonates; reported incidence is 1 per 8,000 to 1 per 25,000 live births.

EMBRYOLOGY

Embryologically, posterior urethral valves are thought to arise due to an abnormally anterior insertion of the mesonephric (wolffian) duct on the cloaca prior to its division into urogenital sinus and the anorectal canal. ASSOCIATED PROBLEMS: Due to bladder outlet obstruction there may be associated oligohydramnios resulting in pulmonary hypoplasia and Potter’s facies.

PRESENTATION

The clinical presentation is extremely variable. Increasingly, posterior urethral valves are identified on antenatal ultrasonography. Oligohydramnios, bilateral hydronephrosis, and incomplete emptying of a thick-walled bladder may be seen. Severely affected newborns may exhibit respiratory difficulties due to pulmonary hypoplasia.

A presentation in the neonatal period with abdominal distension due to dilated bladder, ureters, and kidneys or due to urinary ascites is also recognized. If not recognized at birth, severely affected boys often present with urosepsis, dehydration, electrolyte abnormalities, or failure to

thrive within weeks of birth. A poor urine stream may be noted. Toddlers often present with voiding dysfunction or UTI, and school-aged boys usually come to attention because of urinary incontinence.

PRENATAL MANAGEMENT

Prenatal intervention is limited to a few centers. Options include percutaneous placement of a vesicoamniotic shunt, open fetal surgery, and fetal cystoscopic ablation. Significant complications may occur, resulting in maternal or fetal morbidity as well as fetal loss. Pulmonary function has been shown to benefit from the reversal of oligohydramnios, but no renal benefit has been noted.

POSTNATAL MANAGEMENT

Postnatally, the baby is examined for respiratory distress and presence of bladder and renal mass (unilateral or bilateral). An ultrasound is repeated to look for hydroureteronephrosis, bladder wall thickness, dilatation of posterior urethra and presence of urinary ascites. In the absence of urosepsis, renal failure or urinary ascites the baby can be taken for a voiding cystourethrogram (VCUG), cystoscopy and valve fulguration, preferably in the same sitting. The VCUG shows a dilated posterior urethra, which is suggestive of a PUV. It may also show an irregular walled, small capacity bladder and vesicoureteral reflux. The valve is confirmed on cystourethroscopy and fulgurated.

Figs 5.31A and B: Posterior urethral valve: (A) Diagrammatic representation (B) cystourethrogram shows dilatation of posterior urethra, small capacity irregular bladder and vesicourethral reflux

However, in very sick patients where there is presence of urosepsis, urinary ascites or renal failure (defined as a serum creatinine > 1 mg%) the baby (or child) is kept on bladder drainage (suprapubic or urethral) and intravenous antibiotics. If it improves on bladder drainage, VCUG and valve fulguration is done. In about 15 percent cases no improvement occurs. These patients are subjected to bilateral ureterostomies with plan for valve fulguration and urinary tract reconstruction later.

A B

PROGNOSIS

The prognosis is determined by a number of factors such as renal functions at the time of presentation, improvement of renal functions on bladder drainage, presence and grade of vesicoureteric reflux, intercurrent infections and adequacy of fulguration. It is important to understand that the obstruction to the bladder outlet is a chronic one and occurs at a time when the urinary tract musculature is undergoing developmental changes. Therefore, many irreversible changes result in the bladder muscles that persist after an adequate fulguration. These have a bearing on the final outcome and may require additional therapy (pharmacological or surgical) to bring down the urinary tract pressure and provide complete drainage to the bladder.

BLADDER EXSTROPHY—EPISPADIAS (Figs 5.32, 5.33A and B) The exstrophy-epispadias complex comprises a spectrum of congenital abnormalities that includes classic bladder exstrophy, epispadias, cloacal exstrophy, and several variants.

FREQUENCY

Prevalence of classic bladder exstrophy is 3.3 per 100,000 births; male epispadias occurs in 1 in 117,000 births, female epispadias in 1 in 484,000 births, and cloacal exstrophy in 1 in 200,000-400,000 births.

PATHOLOGY

Abdomen: Classic bladder exstrophy: The bladder is open on the lower abdomen, with mucosa fully exposed through a triangular fascial defect. Urine can be seen dribbling from the ureteric orifices, which can be identified on close examination. The distance between the umbilicus and anus is foreshortened. Rectus muscles diverge distally, attaching to the widely separated pubic bones. Indirect inguinal hernias are frequent (>80 percent of males, >10% of females) due to wide inguinal rings and the lack of an oblique inguinal canal.

Fig. 5.32: Bladder extrophy and epispadias in male

GENITALIA

Classic bladder exstrophy and Epispadias (male): The phallus is short and broad with upward curvature (dorsal chordee). The glans lies open and flat like a spade, and the dorsal component of the foreskin is absent. The urethral plate extends the length of the phallus without a roof. The bladder plate and urethral plate are in continuity. The anus is anteriorly displaced.

MUSCULOSKELETAL

Musculoskeletal abnormalities occur mostly in classic bladder exstrophy and more severe variants.

The pubic symphysis is widely separated. Divergent rectus muscles remain attached to the pubis. External rotation of the innominate bones results in a waddling gait in ambulatory patients but does not appear to result in orthopedic problems later in life.

EMBRYOLOGY

Failure of mesenchyme to migrate between the ectodermal and endodermal layers of the lower abdominal wall leads to instability and rupture of the cloacal membrane leading to this complex of infraumbilical anomalies.