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Spontaneous resolution of prenatal megalourethra
Spontaneous Resolution of Prenatal Megalourethra By Amar Nijagal, Roman M. Sydorak, Vickie A. Feldstein, Shinjiro Hirose, and Craig T. Albanese San Francisco, California
Urethral obstruction in the fetus is rare. Whereas proximal obstruction most often is caused by posterior urethral valves, causes of distal obstruction are less well recognized and can include urethral atresia, urethral webs, and anterior urethral valves. These latter abnormalities can lead to urinary retention, incontinence, enuresis, spontaneous bladder rupture, and megacystis. The authors present 3 fetuses (gestational age range, 18 to 20 weeks) in whom distal urethral obstruction was suspected by prenatal ultrasonography in the absence of a demonstrable lesion. All 3 experienced
spontaneous resolution of the presumed obstruction. On follow-up, all are alive and well with no adverse genitourinary tract sequelae. No postpartum intervention was required. J Pediatr Surg 39:1421-1423. © 2004 Elsevier Inc. All rights reserved.
D
obstruction was noted. The child is now 10 years of age and has normal renal function.
ISTAL URETHRAL obstruction is a rare congenital anomaly of the urinary tract that can result in a variety of abnormalities including urinary retention, incontinence, enuresis, spontaneous bladder rupture, and megacystis. The obstructive uropathy can lead to bilateral hydroureteronephrosis, azotemia, and end-stage renal failure.1-4 The diagnosis typically is made after birth and is suspected clinically based on symptoms of difficulty voiding (eg, dribbling on micturition, poor urinary stream), incontinence, and recurrent urinary tract infections. The diagnosis is confirmed by a voiding cystourethrography (VCUG).5 We present 3 fetuses in whom distal urethral obstruction was suspected on the basis of prenatal ultrasound findings. The observations made in these cases have implications for the prenatal evaluation and management of this condition. CASE REPORTS
Case 1 A 29-year-old gravida 2, para 1 woman was referred to our institution for evaluation of bilateral fetal hydronephrosis and megalourethra. Before referral, an ultrasound (US) examination showed a dilated fetal bladder at 14 weeks’ gestation. Follow-up US 3 weeks later showed bilateral hydronephrosis and progression of the bladder dilation. The fetus underwent serial bladder aspirations, removing 110 mL of urine at 17 weeks’ gestation and 25 mL of urine at 19 weeks. The urinary electrolytes and protein levels were normal. Upon referral, US at 20 weeks’ gestation showed normal amniotic fluid volume and a persistently dilated bladder in conjunction with bilateral hydroureteronephrosis and megalourethra. These findings were unchanged on follow-up evaluation at 22 weeks’ gestation and subsequent US. Serial US showed no progression of disease. At 36 weeks’ gestation, a 2,110-g boy was delivered. The infant had several clinical findings suggesting prune belly syndrome, including bilateral cryptorchidism and megalourethra, but without attenuation of the abdominal wall musculature. Postnatal US found normal-appearing kidneys and mild proximal ureteral dilatation. Voiding cystourethrogram showed a normal bladder without reflux. No valves or residual
INDEX WORDS: Urethral obstruction, prenatal, megalourethra, fetal hydronephrosis.
Case 2 A 26-year-old gravida 3, para 2 woman carrying a fetus at 20 weeks’ gestation was referred for evaluation of possible fetal bladder outlet obstruction. Before referral, obstruction was suspected at 16 weeks’ gestation when US examination showed a dilated bladder and bilateral hydronephrosis. A follow-up US performed 1 week later showed persistent bilateral hydronephrosis with an increase in bladder size. In addition, a cystic structure of uncertain etiology was noted. A total of 98 mL of urine was removed from the fetal bladder without complication. The urinary electrolytes were normal for gestational age. On referral to our institution, US examination showed normal amniotic fluid volume, bilateral hydroureteronephrosis, a markedly enlarged, thick-walled fetal bladder, and mildly echogenic kidneys (Fig 1). The reported cystic structure was recognized as megalourethra (Fig 2). Four days later, spontaneous resolution of the presumed obstruction was seen with a nondilated fetal bladder (Fig 3) and persistently normal amniotic fluid volume. A 3,000-g boy was born at 38 weeks’ gestation with mild bilateral hydronephrosis, megalourethra, and cryptorchidism. No postpartum intervention was required. The child is now 2 years of age and is developing normally.
Case 3 A 31-year-old gravida 1, para 0 woman was evaluated by routine US at 18 weeks’ gestation. The fetus had bilateral hydronephrosis, a dilated bladder, and a dilated urethra. The amniotic fluid volume was normal. Results from maternal serum AFP testing and amniocentesis were normal. Six days later, a follow-up US was performed, showing a
From the Fetal Treatment Center and the Departments of Surgery and Radiology, University of California, San Francisco Medical Center, San Francisco, CA. Address reprint requests to Craig T. Albanese, MD, Fetal Treatment Center, University of California, San Francisco, 513 Parnassus Ave, HSW-1601, San Francisco, CA 94143-0570. © 2004 Elsevier Inc. All rights reserved. 0022-3468/04/3909-0024$30.00/0 doi:10.1016/j.jpedsurg.2004.05.026
Journal of Pediatric Surgery, Vol 39, No 9 (September), 2004: pp 1421-1423
1421
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NIJAGAL ET AL
Fig 1. Coronal sonogram through the fetal abdomen and pelvis shows a markedly dilated urinary bladder (B) and bilateral hydroureters (u). There is bilateral hydronephrosis, and the kidneys (arrows) are mildly echogenic. The quantity of amniotic fluid (AF) is normal.
normal-sized bladder and no hydronephrosis. The urethra no longer appeared dilated. At 26 weeks’ gestation, a repeat US was done, again showing normal kidneys, bladder, nondilated urethra, and normal amniotic fluid volume. The male infant was delivered at term. A postnatal US showed normal kidneys without hydronephrosis. At 2 years of age, the child is doing well and is developing normally.
DISCUSSION
Obstructive anomalies of the fetal urinary tract occur in approximately 1% of all pregnancies. Fortunately, only 1 in 500 of these anomalies have any clinical significance. Lower urinary tract obstructions typically involve the abnormal development of the penile urethra in boys, with posterior urethral valves being the most common cause of early obstruction. Ultrasonographic signs of urethral obstruction include (1) dilatation of the urinary system, (2) changes within the fetal bladder, (3)
Fig 2. The fetal penile urethra is markedly dilated and appears as a fluid-filled tubular structure (arrows).
Fig 3. Follow-up transaxial sonogram through the fetal pelvis shows interval decompression of the bladder (B), which shows a markedly thickened wall (arrowheads). There are persistent bilateral hydroureters (u) and normal amniotic fluid volume (AF).
changes in the echostructure of renal parenchyma, and (4) decreased amniotic fluid volume.6 Proximal urethral dilatation (sonographic key-hole sign) is a sign of posterior urethral valves (PUV), whereas a dilated penile urethra is consistent with distal urethral obstruction. Complete obstruction prevents the fetal urine from entering the amniotic space causing oligohydramnios and can result in compression deformities of the face and limbs and, more importantly, lead to renal failure, pulmonary insufficiency, and mortality.2 In cases in which oligohydramnios has developed and kidney function is impaired (as measured by urinary electrolytes), fetal intervention such as vesicoamniotic shunting may be justified.7 The 3 patients presented here had signs of urethral obstruction, including bilateral hydroureteronephrosis, bladder dilation, and a dilated distal urethra. The presence of normal amniotic fluid volume suggested potential partial obstruction. The sonographic observation of the dilated penile urethra, recognized as a fluid-filled, nonvascular, tubular structure distinguished these cases from the more proximal PUV. Potential etiologies for this lower urinary tract obstruction included urethral atresia, urethral webs, or anterior urethral valve. However, postnatal evaluation was not able to determine the etiology of the abnormalities. Two of the 3 fetuses underwent bladder aspirations before referral. It is uncertain whether these maneuvers were necessary or ultimately therapeutic. Given that there was no evidence of oligohydramnios or cystic changes in the kidney, and urinary electrolytes were normal, further fetal intervention was not indicated.
SPONTANEOUS RESOLUTION OF MEGALOURETHRA
1423
Rather, a “watch and wait” strategy was undertaken. Should oligohydramnios have developed, a percutaneously placed vesicoamniotic shunt would have been a therapeutic option. However, because of spontaneous resolution in 1 case and no progression of disease in the other 2 cases, no intervention was needed. We speculate that the preservation of renal function in these patients can be attributed to the timely resolution of a presumed distal urethral obstruction. These are the first cases of spontaneous resolution of megalourethra that have been recorded.
The cases presented offer insight into the etiology and potential for prenatal recognition of distal urethral obstruction. Targeted sonographic assessment of the fetal gender and urethra in cases of bladder outlet obstruction can yield insight into the pathogenesis and natural history of distal urethral obstruction and may help assess its true incidence and course. Level of obstruction may correlate with the severity of disease. Observation with serial US examinations and intervention only when oligohydramnios develops appears to be an appropriate strategy.
REFERENCES 1. Blumberg N, Malette TJ: Anterior urethral valve: Complications and treatment. J Urol 108:486-488, 1972 2. Aygun C, Guven O, Tekin MI, et al: Anterior urethral valve as a cause of end-stage renal disease. Int J Urol 8:141-143, 2001 3. Glazier DB, Underberg-Davis SJ, Cummings KB, et al: Neonatal bladder rupture due to anterior urethral valves. Br J Urol 80:819-820, 1997 4. Firlit RS, Firlit CF, King LR: Obstructing anterior urethral valves in children. J Urol 119:819-821, 1978
5. Zia-ul-Miraj M: Anterior urethral valves: A rare cause of infravesical obstruction in children. J Pediatr Surg 35:556-558, 2000 6. Oliveira EA, Diniz JS, Cabral AC, et al: Predictive factors of fetal urethral obstruction: A multivariate analysis. Fetal Diagn Ther 15:180186, 2000 7. Holmes N, Harrison MR, Baskin LS: Fetal surgery for posterior urethral valves: Long-term postnatal outcomes. Pediatrics 108:E7, 2001
Urethral obstruction in the fetus is rare. Whereas proximal obstruction most often is caused by posterior urethral valves, causes of distal obstruction are less well recognized and can include urethral atresia, urethral webs, and anterior urethral valves. These latter abnormalities can lead to urinary retention, incontinence, enuresis, spontaneous bladder rupture, and megacystis. The authors present 3 fetuses (gestational age range, 18 to 20 weeks) in whom distal urethral obstruction was suspected by prenatal ultrasonography in the absence of a demonstrable lesion. All 3 experienced
spontaneous resolution of the presumed obstruction. On follow-up, all are alive and well with no adverse genitourinary tract sequelae. No postpartum intervention was required. J Pediatr Surg 39:1421-1423. © 2004 Elsevier Inc. All rights reserved.
D
obstruction was noted. The child is now 10 years of age and has normal renal function.
ISTAL URETHRAL obstruction is a rare congenital anomaly of the urinary tract that can result in a variety of abnormalities including urinary retention, incontinence, enuresis, spontaneous bladder rupture, and megacystis. The obstructive uropathy can lead to bilateral hydroureteronephrosis, azotemia, and end-stage renal failure.1-4 The diagnosis typically is made after birth and is suspected clinically based on symptoms of difficulty voiding (eg, dribbling on micturition, poor urinary stream), incontinence, and recurrent urinary tract infections. The diagnosis is confirmed by a voiding cystourethrography (VCUG).5 We present 3 fetuses in whom distal urethral obstruction was suspected on the basis of prenatal ultrasound findings. The observations made in these cases have implications for the prenatal evaluation and management of this condition. CASE REPORTS
Case 1 A 29-year-old gravida 2, para 1 woman was referred to our institution for evaluation of bilateral fetal hydronephrosis and megalourethra. Before referral, an ultrasound (US) examination showed a dilated fetal bladder at 14 weeks’ gestation. Follow-up US 3 weeks later showed bilateral hydronephrosis and progression of the bladder dilation. The fetus underwent serial bladder aspirations, removing 110 mL of urine at 17 weeks’ gestation and 25 mL of urine at 19 weeks. The urinary electrolytes and protein levels were normal. Upon referral, US at 20 weeks’ gestation showed normal amniotic fluid volume and a persistently dilated bladder in conjunction with bilateral hydroureteronephrosis and megalourethra. These findings were unchanged on follow-up evaluation at 22 weeks’ gestation and subsequent US. Serial US showed no progression of disease. At 36 weeks’ gestation, a 2,110-g boy was delivered. The infant had several clinical findings suggesting prune belly syndrome, including bilateral cryptorchidism and megalourethra, but without attenuation of the abdominal wall musculature. Postnatal US found normal-appearing kidneys and mild proximal ureteral dilatation. Voiding cystourethrogram showed a normal bladder without reflux. No valves or residual
INDEX WORDS: Urethral obstruction, prenatal, megalourethra, fetal hydronephrosis.
Case 2 A 26-year-old gravida 3, para 2 woman carrying a fetus at 20 weeks’ gestation was referred for evaluation of possible fetal bladder outlet obstruction. Before referral, obstruction was suspected at 16 weeks’ gestation when US examination showed a dilated bladder and bilateral hydronephrosis. A follow-up US performed 1 week later showed persistent bilateral hydronephrosis with an increase in bladder size. In addition, a cystic structure of uncertain etiology was noted. A total of 98 mL of urine was removed from the fetal bladder without complication. The urinary electrolytes were normal for gestational age. On referral to our institution, US examination showed normal amniotic fluid volume, bilateral hydroureteronephrosis, a markedly enlarged, thick-walled fetal bladder, and mildly echogenic kidneys (Fig 1). The reported cystic structure was recognized as megalourethra (Fig 2). Four days later, spontaneous resolution of the presumed obstruction was seen with a nondilated fetal bladder (Fig 3) and persistently normal amniotic fluid volume. A 3,000-g boy was born at 38 weeks’ gestation with mild bilateral hydronephrosis, megalourethra, and cryptorchidism. No postpartum intervention was required. The child is now 2 years of age and is developing normally.
Case 3 A 31-year-old gravida 1, para 0 woman was evaluated by routine US at 18 weeks’ gestation. The fetus had bilateral hydronephrosis, a dilated bladder, and a dilated urethra. The amniotic fluid volume was normal. Results from maternal serum AFP testing and amniocentesis were normal. Six days later, a follow-up US was performed, showing a
From the Fetal Treatment Center and the Departments of Surgery and Radiology, University of California, San Francisco Medical Center, San Francisco, CA. Address reprint requests to Craig T. Albanese, MD, Fetal Treatment Center, University of California, San Francisco, 513 Parnassus Ave, HSW-1601, San Francisco, CA 94143-0570. © 2004 Elsevier Inc. All rights reserved. 0022-3468/04/3909-0024$30.00/0 doi:10.1016/j.jpedsurg.2004.05.026
Journal of Pediatric Surgery, Vol 39, No 9 (September), 2004: pp 1421-1423
1421
1422
NIJAGAL ET AL
Fig 1. Coronal sonogram through the fetal abdomen and pelvis shows a markedly dilated urinary bladder (B) and bilateral hydroureters (u). There is bilateral hydronephrosis, and the kidneys (arrows) are mildly echogenic. The quantity of amniotic fluid (AF) is normal.
normal-sized bladder and no hydronephrosis. The urethra no longer appeared dilated. At 26 weeks’ gestation, a repeat US was done, again showing normal kidneys, bladder, nondilated urethra, and normal amniotic fluid volume. The male infant was delivered at term. A postnatal US showed normal kidneys without hydronephrosis. At 2 years of age, the child is doing well and is developing normally.
DISCUSSION
Obstructive anomalies of the fetal urinary tract occur in approximately 1% of all pregnancies. Fortunately, only 1 in 500 of these anomalies have any clinical significance. Lower urinary tract obstructions typically involve the abnormal development of the penile urethra in boys, with posterior urethral valves being the most common cause of early obstruction. Ultrasonographic signs of urethral obstruction include (1) dilatation of the urinary system, (2) changes within the fetal bladder, (3)
Fig 2. The fetal penile urethra is markedly dilated and appears as a fluid-filled tubular structure (arrows).
Fig 3. Follow-up transaxial sonogram through the fetal pelvis shows interval decompression of the bladder (B), which shows a markedly thickened wall (arrowheads). There are persistent bilateral hydroureters (u) and normal amniotic fluid volume (AF).
changes in the echostructure of renal parenchyma, and (4) decreased amniotic fluid volume.6 Proximal urethral dilatation (sonographic key-hole sign) is a sign of posterior urethral valves (PUV), whereas a dilated penile urethra is consistent with distal urethral obstruction. Complete obstruction prevents the fetal urine from entering the amniotic space causing oligohydramnios and can result in compression deformities of the face and limbs and, more importantly, lead to renal failure, pulmonary insufficiency, and mortality.2 In cases in which oligohydramnios has developed and kidney function is impaired (as measured by urinary electrolytes), fetal intervention such as vesicoamniotic shunting may be justified.7 The 3 patients presented here had signs of urethral obstruction, including bilateral hydroureteronephrosis, bladder dilation, and a dilated distal urethra. The presence of normal amniotic fluid volume suggested potential partial obstruction. The sonographic observation of the dilated penile urethra, recognized as a fluid-filled, nonvascular, tubular structure distinguished these cases from the more proximal PUV. Potential etiologies for this lower urinary tract obstruction included urethral atresia, urethral webs, or anterior urethral valve. However, postnatal evaluation was not able to determine the etiology of the abnormalities. Two of the 3 fetuses underwent bladder aspirations before referral. It is uncertain whether these maneuvers were necessary or ultimately therapeutic. Given that there was no evidence of oligohydramnios or cystic changes in the kidney, and urinary electrolytes were normal, further fetal intervention was not indicated.
SPONTANEOUS RESOLUTION OF MEGALOURETHRA
1423
Rather, a “watch and wait” strategy was undertaken. Should oligohydramnios have developed, a percutaneously placed vesicoamniotic shunt would have been a therapeutic option. However, because of spontaneous resolution in 1 case and no progression of disease in the other 2 cases, no intervention was needed. We speculate that the preservation of renal function in these patients can be attributed to the timely resolution of a presumed distal urethral obstruction. These are the first cases of spontaneous resolution of megalourethra that have been recorded.
The cases presented offer insight into the etiology and potential for prenatal recognition of distal urethral obstruction. Targeted sonographic assessment of the fetal gender and urethra in cases of bladder outlet obstruction can yield insight into the pathogenesis and natural history of distal urethral obstruction and may help assess its true incidence and course. Level of obstruction may correlate with the severity of disease. Observation with serial US examinations and intervention only when oligohydramnios develops appears to be an appropriate strategy.
REFERENCES 1. Blumberg N, Malette TJ: Anterior urethral valve: Complications and treatment. J Urol 108:486-488, 1972 2. Aygun C, Guven O, Tekin MI, et al: Anterior urethral valve as a cause of end-stage renal disease. Int J Urol 8:141-143, 2001 3. Glazier DB, Underberg-Davis SJ, Cummings KB, et al: Neonatal bladder rupture due to anterior urethral valves. Br J Urol 80:819-820, 1997 4. Firlit RS, Firlit CF, King LR: Obstructing anterior urethral valves in children. J Urol 119:819-821, 1978
5. Zia-ul-Miraj M: Anterior urethral valves: A rare cause of infravesical obstruction in children. J Pediatr Surg 35:556-558, 2000 6. Oliveira EA, Diniz JS, Cabral AC, et al: Predictive factors of fetal urethral obstruction: A multivariate analysis. Fetal Diagn Ther 15:180186, 2000 7. Holmes N, Harrison MR, Baskin LS: Fetal surgery for posterior urethral valves: Long-term postnatal outcomes. Pediatrics 108:E7, 2001