| Abstract|| |
Hydronephrosis is probably the most common congenital abnormality detected prenatally by ultrasonography This study was performed to determine the cause and outcome of prenatal hydronephrosis in our hospital. A total of 45 infants, with 57 prenatally hydronephrotic renal units, were enrolled into this study. For the purpose of this study, the degree of hydronephrosis was defined as mild, moderate or severe. Postnatal ultrasonography was performed as soon as possible in those with bilateral hyronephrosis and 3-7 days after birth in those with unilateral hydronephrosis. Voiding cystourethrogram was performed in 6-8 weeks time. In the absence of vesicoureteral reflux (VUR), Diethylenetriamene penta acetate scan was performed to exclude obstructive uropathy. There were 29 males and 16 females (male:female ratio 1.8:1), and unilateral and bilateral hydronephrosis were seen in 33 (73%) and 12 (27%) of the cases, respectively. Hydronephrosis was caused by ureteropelvic junction obstruction (UPJO) in 20 (44.5%), VUR in 10 (22.2%), ureterovesical junction obstruction in four (8.9 %), posteriorurethral valves in four (8.9 %), UPJO with VUR in two (4.4%) and non-VUR non-obstructive in one (2.2%). During follow-up, 16 patients (35.5%) required operative intervention while seven (15.5%) improved spontaneously. Fetal hydronephrosis needs close follow-up during both antenatal and postnatal periods. In this study, the most common cause for hydronephrosis were UPJO and VUR. Also seen in this study is the noteworthy point that mild fetal hydronephrosis is relatively benign and does not require surgical intervention in most cases and surgery should be performed only if there is renal function compromise. Prenatal consultation with a pediatric nephrologist and urologist is useful in decreasing parental anxiety and facilitating postnatal management.
|How to cite this article:|
Asl AS, Maleknejad S. Clinical outcome and follow-up of prenatal hydronephrosis. Saudi J Kidney Dis Transpl 2012;23:526-31
| Introduction|| |
Prenatal ultrasonographic detection of fetal genitourinary abnormalities was first reported in 1970 by Garrett et al.  Prenatal hydronephrosis is diagnosed at an incidence of 1:100 to 1:500 by ultrasonographic studies. ,, By renal ultrasound examination, urological anomalies may be demonstrated in 1-2% of fetuses and in about 0.5% of newborns.  Shokeir et al as well as Garne et al reported that two to nine neo-nates per 1000 newborns births have urogenital anomaly, and 50-87% of these at births have urogenital anomaly, with 50-87% of these having hydronephrosis. ,, Data from a large European database for surveillance of congenital malformations showed an overall prevalence of congenital hydronephrosis as 11.5 cases per 10,000 births. 
When a fetus is identified with a suspected urinary tract abnormality, the goals of management should include determining the differential diagnosis, assessment of associated anomalies and determining the fetal and postnatal risk of the malformations. ,,,,, Prenatal consultation with a pediatric nephrologist and urologist is useful in decreasing parental anxiety and facilitating postnatal management.  The detection of fetal hydronephrosis presents a diagnostic and therapeutic dilemma. For these reasons, a retrospective study was performed to determine the cause and outcome of 45 infants with prenatal hydronephrosis in our hospital.
| Patients and Methods|| |
We retrospectively analyzed the case records of 45 infants (29 male, 16 female) with 57 prenatally diagnosed hydronephrotic renal units who were referred to our hospital between 2006 and 2009. Prenatal hydronephrosis was defined based on prenatal sonography that was performed after the 20 th week of gestation. Postnatal ultrasound was performed in 3-7 days after the delivery to confirm the presence of hydronephrosis. For the purpose of this study, the degrees of hydronephrosis was classified as mild, moderate or severe hydronephrosis when the anteroposterior pelvic diameter (APPD) was 5-9 mm, 10-14 mm and ≥15 mm, respectively, according to antenatal sonographic measurements. At birth, infants had undergone complete physical examination to exclude any other congenital anomalies. In infants with history of prenatal hydronephrosis, antibiotic prophylaxis was started if a voiding cytourethrogram (VCUG) was requested (moderate and severe cases). VCUG was per-formed after six to eight weeks in infants with unilateral hydronephrosis and as soon as possible in those with bilateral hyronephrosis to rule out posterior urethral valves and other abnormalities. In the absence of vesicoureteral reflux (VUR), a DTPA scan was performed to exclude obstructive uropathy. Following this, postnatal follow-up was performed for these infants by serial sonography and radionuclide scan to assess differential function. The statistical analysis for measuring the confidence intervals was carried out using WinPepi software V9.9.
| Results|| |
Forty-five infants, 29 males and 16 females (male:female ratio 1.8:1 ) with 57 dilated renal units were included in this study. The left kidney kidney was more commonly involved (left: 21, right: 12). Mild hydronephrosis was present in 13 (23%), moderate hydronephrosis in 28 (49%) and severe hydronephrosis in 16 (28%) of the dilated kidney units. The average age of mothers ranged from 17 to 43 years (mean age 25.6 years). The demographic data are given in [Table 1].
|Table 1: Demographic data and anteroposterior pelvic diameter (APPD) of the study group.|
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Unilateral and bilateral hydronephrosis were seen in 33 (73%) and 12 (27%) of the cases, respectively. Etiologic classification of postnatally detected urologic abnormalities in hydronephrotic units in unilateral and bilateral hydronephrosis are given in [Table 2] and [Table 3].
|Table 2: Etiologic classification of postnatally detected urologic abnormalities in unilateral hydronephrosis.|
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|Table 3: Etiologic classification of postnatally detected urologic abnormalities in bilateral hydronephrosis.|
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Dilatation of the renal pelvis in the 13 renal units with mild hydronephrosis was caused by mild ureteropelvic junction obstruction (UPJO) in nine (69%) and VUR in four (31%). None of the children with mild hydronephrosis were operated, and hydronephrosis resolved spontaneously in seven renal units during the follow-up period.
In total, surgical intervention was performed in 16 patients due to progressive deterioration of kidney function and increasing severity of hydronephrosis and recurrent urinary tract infections in VUR cases. [Table 4] show the details of follow-up of patients. The operative intervention consisted of correction of UPJO in seven (43.8%), uretrovesical obstruction (UVJ) in two (12.5%), VUR in three (18.8%) and posterior uretheral valve (PUV) in four patients (25%). The remaining of the patients remained stable on follow-up (49%) by serial sonography and differential function tests.
|Table 4: The details of surgical intervention in patients with prenatal hydronephrosis|
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VUR was identified in ten infants (bilateral in three cases), giving a total of 13 renal units. Demographic data of patient with VUR are given in [Table 5]. Three children underwent surgical intervention due to breakthrough infection and high-grade reflux. In this study, dilatation of the renal pelvis was caused by UPJO in 20 (44.5%), VUR in ten (22.2%) ureterovesical junction obstruction (UVJO) in four (8.9%), PUV in four (8.9 %), UPJO with VUR in two (4.4%) and non-VUR non-obstructive in one (2.2%). In four patients (8.9%) with unilateral hydronephrosis, dilatation renal units improved spontaneously. In this study, the most common causes of hydronephrosis were UPJO followed by VUR.
| Discussion|| |
Prenatal hydronephrosis is diagnosed at an incidence of 1:100 to 1:500 by ultrasonographic studies. ,, Because a normal postnatal ultrasound scan does not preclude the presence of urinary tract abnormality, sonography was repeated at seven to ten days after birth. In most cases, there were persistent postnatal renal abnormalities when the APPD of the fetal renal pelvis measured >5 mm at 20 weeks, >8 mm at 20-30 weeks and >10 mm at >30 weeks of gestation. ,,,,, However, there is a lack of correlation between the degree of prenatal hydronephrosis and etiology, a fact that has been well documented. , In this study, the male to female ratio was 1.8:1, which was similar to other studies conducted by Miranda, Aksu, Pourissa, Garne and Cortes et al. ,,,,
In this study, dilatation of the renal pelvis was caused by UPJO in 18 (40%), VUR in 12 (26.7%), UVJO in four (8.9%), PUV in four (8.9%), UPJO with contralateral VUR in two (4.4%) and non-VUR non-obstructive in one (2.2%). In four patients (8.9%) with unilateral hydronephrosis, dilatation renal units improved spontaneously. Thus, the most common detected underlying abnormalities were UPJO (44.5%) and VUR (22.2%). Our study also showed a similar pattern when compared with studies in other centers in Iran as well as in other countries. ,,,,, The low incidence of transitory hydronephrosis is noticeable in our cases. This is possibly due to the fact that this was a tertiary care service center and majority of the neonates referred to our hospital were those with pathological hydronephrosis for further follow-up. Also, in this study, the second common abnormality was VUR (22.2%). Although controversial issues exist about the timing of postnatal cystography and whether postnatal voiding cystourethrography should be performed in infants with a history of prenatal hydronephrosis, some groups advocate postnatal cystography in any infant with a history of prenatal hydronephrosis. ,,,,, Others have questioned about this approach. A practical point for performing postnatal cystography has been mentioned as the presence of a dilated ureter or hydronephrosis of varying degrees. , Because of these controversies, my policy in this study was the later approach, and VCUG was performed in the presence of a dilated ureter or hydronephrosis of varying degrees. The available data suggest that VUR is present in 17-38% of the patients with prenatal hydronephrosis. , However, postnatal calicectasis appears to be an important predictor of VUR in children with fetal renal pelvic dilatation.  In a study by Lee et al, children with any degree of antenatal hydronephrosis were at a greater risk of postnatal pathology as compared with the normal population.  In the present study, during the entire clinical follow-up, 16 patients (35.5%) required operative intervention while seven patients with hydronephrosis improved spontaneously (15.7%). Twenty-two patients (48.8%) remained stable, as demonstrated by serial sonography and differential renal function tests, and did not need surgical intervention. These results were compatible with different studies conducted in Brazil, Turkey, Germany, Israel, Korea and Switzerland. ,,,,,, Our results show that the management of prenatally detected hydronephrosis has undergone a paradigm shift in the last decade, from early surgery to close observation until there are signs of deterioration of renal function or there is progression of hydronephrosis and operative intervention is not required for any patient with mild hydronephrosis of the kidney units.
When a fetus is identified with prenatal hydronephrosis, the goals of management should include determining the differential diagnosis, assessment of associated anomalies and determining the fetal and postnatal follow-up. In this study, the most common causes of hydronephrosis were UPJO and VUR. Also, mild fetal hydronephrosis is relatively benign and does not require surgical intervention in most cases, and surgery should be performed only if renal compromise occurs. Prenatal consultation with a pediatric nephrologist and urologist is useful in decreasing parental anxiety and facilitating postnatal management.
| Acknowledgment|| |
This study is performed with a grant made to Dr. Allaedin Asgari (pediatric urologist). The authors thank the patients and their families for their contribution to the study.
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Afshin Safaei Asl
Associate Professor, Department of Pediatrics, Guilan University of Medical Sciences, 17 Shahrivar Hospital, Namjoo Street, Rasht, Guilan
Islamic Republic of Iran
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]