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Posterior urethral valves
Pediatric Surgical Images Edited by Geoffrey K. Blair, MD
Posterior Urethral Valves By A.E. Perks, A.E. MacNeily, and G.K. Blair
P
OSTERIOR URETHRAL VALVES (PUV) occur in 1 in 5,000 male births and result in congenital bladder outlet obstruction. It represents an anomalous membrane that radiates anteriorly and distally from the verumontanum to the membranous urethra. The valve has a small opening posteriorly so that during voiding, the fused anterior portion bulges distally. It occurs early during fetal development exposing the urinary tract to high pressures that can lead to permanent maldevelopment of the kidneys and bladder. PUV may present at birth as an abdominal mass (secondary to hydronephrosis or a thick-walled, distended bladder), urinary ascites, or respiratory distress with hypoplastic lungs. If undetected at birth, the neonate may go on to have urosepsis, failure to thrive, renal insufficiency, and only occasionally a dribbling urinary stream. Delayed diagnosis as a child occurs during investigation for anatomic causes of urinary tract infections or voiding dysfunction, ie, urinary incontinence (Fig 1). Renal-bladder ultrasonography provides an accurate, noninvasive screening tool for PUV. Findings include bilateral or unilateral hydroureteronephrosis (88%) and an abnormal bladder (87%) that may be thickened, trabeculated or significantly distended. Sensitivity is 95% for suspecting posterior urethral valves and becomes more sensitive in older children. Other findings include echogenic kidneys and renal cysts as evidence of renal dysplasia and urinary ascites. Whether echogenic kidneys on initial ultrasound scan predict for poor renal function is still debatable. On the contrary, urinary ascites has been found to correlate with good prognosis. Voiding cystourethrogram (VCUG) is the gold standard for the radiographic diagnosis of PUV (Figs 1 and 4). When urinary ascites or perinephric urinomas result, VCUG may show the site of extravasation, often at the renal fornix. Secondary vesicoureteral reflux occurs in one third of cases. Good prognostic features include unilateral high-grade reflux, perinephric urinomas, and urinary ascites. All of these findings are believed to act as a pressure popoff, which help to preserve renal function. With the advent of screening gestational ultrasonog-
Journal of Pediatric Surgery, Vol 37, No 7 (July), 2002: pp 1105-1107
raphy, many cases now are being detected antenatally. Findings in the fetus include unilateral or bilateral hydronephrosis or a distended, thick-walled bladder; occasionally, a dilated or thickened prostatic urethra is seen. There may be associated oligohydramnios and renal cortical echogenicity. Controversy exists surrounding the role of fetal intervention and in utero urinary tract decompression. Many believe that renal dysplasia is an early event before the time of fetal intervention. Currently, in-utero vesicoamniotic shunt placement or primary fetal valve ablation should be restricted to controlled trials, and current standards of practice recommend urinary diversion at the time of birth. Initial management is to divert urinary flow by placing a feeding tube or foley catheter per urethra. Once the patient is stable, valve ablation is performed endoscopically. In neonates too small to allow endoscopic management, vesicostomy is an acceptable form of diversion for the first year of life. PUV often causes permanent damage to the urinary tract. Even with early intervention, it often results in unrelenting, progressive renal insufficiency requiring dialysis and renal transplantation. Many patients develop permanent bladder dysfunction, typically urinary incontinence. Two to three percent die during the neonatal period of respiratory insufficiency (pulmonary hypoplasia carries a 50% mortality rate). Patients with a poorly compliant, small bladder may require future anticholinergic medication, clean intermittent catheterizations, or bladder augmentation to help control urinary incontinence. Overall, approximately 1/3 to 1⁄2 of valve patients will progress to chronic renal insufficiency by their adolescent years. Submitted by A.E. Perks, MD, A.E. MacNeily, MD, and G.K. Blair, MD, Department of Surgery, British Columbia Children’s Hospital, Vancouver, BC Canada. Submissions to Pediatric Surgical Images should be sent to Geoffrey K. Blair, MD, Departments of Surgery, British Columbia’s Children’s Hospital, Vancouver, BC, Canada V6H 3V4. Copyright 2002, Elsevier Science (USA). All rights reserved. 0022-3468/02/3707-0035$35.00/0 doi:10.1053/jpsu.2002.33886 1105
Fig 1. Voiding cystourethrography (VCUG) was diagnostic for PUV in a 10-month-old boy who presented late with a urinary tract infection and otherwise normal voiding history. Characteristic findings on oblique VCUG show urethral obstruction below the verumontanum (long arrow) sometimes seen as a bulging membrane anteriorly with a perforation posteriorly, dilatation of the posterior urethra proximal to the membrane (double arrow), a narrowed, thickened bladder neck (short arrow), and a dilated or trabeculated bladder.
Fig 3. Renal bladder ultrasound scan (A) A thick-walled bladder in longitudinal section (double arrow) with marked ascitic fluid posterior to the bladder (long arrow). (B) An echogenic left kidney (double arrow) with pelviectasis (long arrow) and associated perinephric fluid collection (short arrow). Findings represent a forniceal rupture with infected urinary ascites.
Fig 2. Abdominal radiograph. Typical findings of urinary ascites in a neonate show centrally positioned distended loops of bowel, ground glass appearance, and bulging flanks.
Fig 4. VCUG confirms PUV and shows, on an anterio-posterior view, a trabeculated bladder wall (arrow) and absence of vesicoureteral reflux.
PEDIATRIC SURGICAL IMAGES
ILLUSTRATIVE CASE OF PUV
A 21-day-old boy presented to the emergency department with feeding difficulty, irritability, and failure to thrive. History showed a gradually distending abdomen over 2 weeks. Gestational ultrasound scan had been normal, and he had no voiding or stooling difficulties. Radiologic investigations are seen in Fig 2-4. The patient went to the intensive care unit for management of enterococcal sepsis, azotemia (serum creatinine ⫽ 278 umol/L), and urinary ascites. A 6F Foley catheter per urethra drained 60 mL of cloudy urine. Serum creatinine normalized over the next 72 hours. A large left perinephric abscess complicated his course in the hospital, and he required open surgical drainage in
1107
conjunction with transurethral valve ablation. The Foley catheter was removed on postoperative day 2, and he was able to void well with a good stream. SELECTED READING Herman TE, Siegel MJ: Special imaging casebook. Posterior urethral valves. J Perinatol 13:76-78, 1993 Williams CR, Perez LM, Joseph DB: Accuracy of renal-bladder ultrasonography as a screening method to suggest posterior urethral valves. J Urol 165:2245-2247, 2001 Macpherson RI, Leithiser RE, Gordon L, et al: Posterior urethral valves: An update and review. Radiographics 6:753-791, 1986 Karmarkar SJ: Long-term results of surgery for posterior urethral valves: A review. Pediatr Surg Int 17:8-10 2001 Dinneen MD, Duffy PG: Posterior urethral valves. Br J Urol 78:275281, 1996
Posterior Urethral Valves By A.E. Perks, A.E. MacNeily, and G.K. Blair
P
OSTERIOR URETHRAL VALVES (PUV) occur in 1 in 5,000 male births and result in congenital bladder outlet obstruction. It represents an anomalous membrane that radiates anteriorly and distally from the verumontanum to the membranous urethra. The valve has a small opening posteriorly so that during voiding, the fused anterior portion bulges distally. It occurs early during fetal development exposing the urinary tract to high pressures that can lead to permanent maldevelopment of the kidneys and bladder. PUV may present at birth as an abdominal mass (secondary to hydronephrosis or a thick-walled, distended bladder), urinary ascites, or respiratory distress with hypoplastic lungs. If undetected at birth, the neonate may go on to have urosepsis, failure to thrive, renal insufficiency, and only occasionally a dribbling urinary stream. Delayed diagnosis as a child occurs during investigation for anatomic causes of urinary tract infections or voiding dysfunction, ie, urinary incontinence (Fig 1). Renal-bladder ultrasonography provides an accurate, noninvasive screening tool for PUV. Findings include bilateral or unilateral hydroureteronephrosis (88%) and an abnormal bladder (87%) that may be thickened, trabeculated or significantly distended. Sensitivity is 95% for suspecting posterior urethral valves and becomes more sensitive in older children. Other findings include echogenic kidneys and renal cysts as evidence of renal dysplasia and urinary ascites. Whether echogenic kidneys on initial ultrasound scan predict for poor renal function is still debatable. On the contrary, urinary ascites has been found to correlate with good prognosis. Voiding cystourethrogram (VCUG) is the gold standard for the radiographic diagnosis of PUV (Figs 1 and 4). When urinary ascites or perinephric urinomas result, VCUG may show the site of extravasation, often at the renal fornix. Secondary vesicoureteral reflux occurs in one third of cases. Good prognostic features include unilateral high-grade reflux, perinephric urinomas, and urinary ascites. All of these findings are believed to act as a pressure popoff, which help to preserve renal function. With the advent of screening gestational ultrasonog-
Journal of Pediatric Surgery, Vol 37, No 7 (July), 2002: pp 1105-1107
raphy, many cases now are being detected antenatally. Findings in the fetus include unilateral or bilateral hydronephrosis or a distended, thick-walled bladder; occasionally, a dilated or thickened prostatic urethra is seen. There may be associated oligohydramnios and renal cortical echogenicity. Controversy exists surrounding the role of fetal intervention and in utero urinary tract decompression. Many believe that renal dysplasia is an early event before the time of fetal intervention. Currently, in-utero vesicoamniotic shunt placement or primary fetal valve ablation should be restricted to controlled trials, and current standards of practice recommend urinary diversion at the time of birth. Initial management is to divert urinary flow by placing a feeding tube or foley catheter per urethra. Once the patient is stable, valve ablation is performed endoscopically. In neonates too small to allow endoscopic management, vesicostomy is an acceptable form of diversion for the first year of life. PUV often causes permanent damage to the urinary tract. Even with early intervention, it often results in unrelenting, progressive renal insufficiency requiring dialysis and renal transplantation. Many patients develop permanent bladder dysfunction, typically urinary incontinence. Two to three percent die during the neonatal period of respiratory insufficiency (pulmonary hypoplasia carries a 50% mortality rate). Patients with a poorly compliant, small bladder may require future anticholinergic medication, clean intermittent catheterizations, or bladder augmentation to help control urinary incontinence. Overall, approximately 1/3 to 1⁄2 of valve patients will progress to chronic renal insufficiency by their adolescent years. Submitted by A.E. Perks, MD, A.E. MacNeily, MD, and G.K. Blair, MD, Department of Surgery, British Columbia Children’s Hospital, Vancouver, BC Canada. Submissions to Pediatric Surgical Images should be sent to Geoffrey K. Blair, MD, Departments of Surgery, British Columbia’s Children’s Hospital, Vancouver, BC, Canada V6H 3V4. Copyright 2002, Elsevier Science (USA). All rights reserved. 0022-3468/02/3707-0035$35.00/0 doi:10.1053/jpsu.2002.33886 1105
Fig 1. Voiding cystourethrography (VCUG) was diagnostic for PUV in a 10-month-old boy who presented late with a urinary tract infection and otherwise normal voiding history. Characteristic findings on oblique VCUG show urethral obstruction below the verumontanum (long arrow) sometimes seen as a bulging membrane anteriorly with a perforation posteriorly, dilatation of the posterior urethra proximal to the membrane (double arrow), a narrowed, thickened bladder neck (short arrow), and a dilated or trabeculated bladder.
Fig 3. Renal bladder ultrasound scan (A) A thick-walled bladder in longitudinal section (double arrow) with marked ascitic fluid posterior to the bladder (long arrow). (B) An echogenic left kidney (double arrow) with pelviectasis (long arrow) and associated perinephric fluid collection (short arrow). Findings represent a forniceal rupture with infected urinary ascites.
Fig 2. Abdominal radiograph. Typical findings of urinary ascites in a neonate show centrally positioned distended loops of bowel, ground glass appearance, and bulging flanks.
Fig 4. VCUG confirms PUV and shows, on an anterio-posterior view, a trabeculated bladder wall (arrow) and absence of vesicoureteral reflux.
PEDIATRIC SURGICAL IMAGES
ILLUSTRATIVE CASE OF PUV
A 21-day-old boy presented to the emergency department with feeding difficulty, irritability, and failure to thrive. History showed a gradually distending abdomen over 2 weeks. Gestational ultrasound scan had been normal, and he had no voiding or stooling difficulties. Radiologic investigations are seen in Fig 2-4. The patient went to the intensive care unit for management of enterococcal sepsis, azotemia (serum creatinine ⫽ 278 umol/L), and urinary ascites. A 6F Foley catheter per urethra drained 60 mL of cloudy urine. Serum creatinine normalized over the next 72 hours. A large left perinephric abscess complicated his course in the hospital, and he required open surgical drainage in
1107
conjunction with transurethral valve ablation. The Foley catheter was removed on postoperative day 2, and he was able to void well with a good stream. SELECTED READING Herman TE, Siegel MJ: Special imaging casebook. Posterior urethral valves. J Perinatol 13:76-78, 1993 Williams CR, Perez LM, Joseph DB: Accuracy of renal-bladder ultrasonography as a screening method to suggest posterior urethral valves. J Urol 165:2245-2247, 2001 Macpherson RI, Leithiser RE, Gordon L, et al: Posterior urethral valves: An update and review. Radiographics 6:753-791, 1986 Karmarkar SJ: Long-term results of surgery for posterior urethral valves: A review. Pediatr Surg Int 17:8-10 2001 Dinneen MD, Duffy PG: Posterior urethral valves. Br J Urol 78:275281, 1996