Table 1: Gender and amniotic fluid index (AFI) in the postnatal hydronephrosis.

Data presented as number (%).

Table 2: Correlation between bladder wall thickness and grade of hydronephrosis in antenatal ultrasound.

Data presented as number (%).

Table 3: Correlation between the amniotic fluid index (AFI) and grade of hydronephrosis detected by the first postnatal ultrasound.

Data presented as number (%).

Comparing antenatal and postnatal US kidneys revealed 33 cases with mild hydronephrosis postnatal US: seven cases normal, 17 mild, eight moderate, and one severe. In moderate antenatal US, six cases were normal, 14 mild, 10 moderate, and five severe at postnatal US. In severe antenatal hydronephrosis, seven cases were normal, eight mild, 11 moderate, and 11 severe at postnatal US [Table 4].

MCUG was abnormal in three cases who had normal first postnatal US, seven cases with mild, seven cases with moderate, and seven with severe hydronephrosis in first postnatal US [Table 5]. MAG3 according to degree of hydronephrosis. The more severe the degree of hydronephrosis, the more likely MAG3 shows obstruction.

Table 6 shows the final diagnosis in these cases based on all investigations done. The diagnosis was made according to the grade of hydronephrosis using first postnatal US. Of the 20 cases found to have no hydronephrosis by first renal US, 11 had normal kidneys, two were diagnosed with reflux disease, six were diagnosed with multicystic dysplastic kidney disease and one with solitary renal cyst. Six cases had severe hydronephrosis detected at the first postnatal US; PUJ was the final diagnosis in 11 out of 17 cases. The final diagnosis in these cases included PUV in three cases, primary hydronephrosis in one case, and VUR in two cases. Oligohydramnios was seen in five cases during antenatal US, out of which three had PUJ obstruction, one had multicystic dysplastic, and one had VUR.

A total of 28 cases needed surgical intervention, which had an underlying pathological cause of hydronephrosis. The first postnatal US revealed mild, moderate, and severe hydronephrosis in four, 10, and 14 cases, respectively [Table 7]. Postoperative US at one-year-old showed improvement in the grade of hydronephrosis except for two cases that did not improve. However, all cases maintained normal renal function. Only one case had two episodes of UTI postoperatively.

Twenty-two (20.9%) cases resolved spontaneously at one-year follow-up. Twenty-six patients were cured following surgery (n = 26; 24.7%); however, the condition persisted in 52 (49.5%) patients with normal renal function. Four (3.8%) patients were lost to follow-up.

One baby who had no signs of hydronephrosis at first postnatal US developed stage 3 CKD due to grade 5 bilateral VUR, which was discovered by renal US at six months old during UTI screening. In eight cases although the first postnatal US showed no evidence of hydronephrosis, the subsequent US revealed hydronephrosis with normal renal function [Table 8].

The number of infants that underwent corrective surgery was 28 (26.6%) and the condition resolved completely in 26 (92.8%). Of those who underwent corrective surgery, 14 (50.0%) had severe, 10 (35.7%) had moderate, and four (14.2%) had mild hydronephrosis at first postnatal US.

Very few positive cultures were obtained for UTI episodes in the first year of life for those followed in our hospital. We considered most patients might have more episodes of UTI diagnosed and treated in other hospitals.

Table 8: Outcome of hydronephrosis at one-year-old (first postnatal ultrasound).

Data presented as number (%); CKD: chronic kidney disease.

Discussion

With the availability of antenatal US, a vast majority of fetal hydronephrosis are increasingly detected. However, the etiology and underlying pathology remain undefined making postnatal US evaluation essential. The antenatal diagnosis of hydronephrosis naturally causes parental anxiety during pregnancy; therefore, antenatal counseling becomes imperative to reassure them of its usual benign course or unremarkable clinical outcome.6,8

The majority of infants with hydronephrosis are male and also had severe hydronephrosis. We found no correlation between bladder wall thickness and severity of hydronephrosis in antenatal US. We also found no correlation between AFI and the severity of hydronephrosis assessed by first postnatal US. However, a large-scale study is needed to ascertain the value of these diagnostic parameters in hydronephrosis.

Our study has shown that the severity of the condition usually diminishes during the postnatal period; however, the condition may deteriorate in about a quarter of affected newborns. Parents must be made aware of this possible outcome. Moreover, we noted that only one newborn classified initially as mild hydronephrosis from the first postnatal US deteriorated to severe hydronephrosis signifying that the chances of the condition progressing from mild to severe is rare. From the moderate group, however, a slightly larger proportion, a little over a quarter, deteriorated to the severe form suggesting that the moderate and severe forms require a better management strategy to prevent worsening of the condition. This variation between antenatal and postnatal US to detect the grade of hydronephrosis makes counseling of parents crucial.

Indeed the present study found that newborns with mild and moderate hydronephrosis at first postnatal US persisted with the condition throughout the one-year study period but exhibited normal renal function. However, newborns found to have severe hydronephrosis at first postnatal US required surgical intervention to maintain their renal function.

Postnatal US must be performed for every newborn with ANH, followed by MCUG if there is any grade of hydronephrosis. If the postnatal US reveals severe hydronephrosis, MAG3 should be done for those that had normal MCUG. Yerkes et al,9 evaluated 60 infants who had less than grade 2 unilateral or bilateral hydronephrosis seen on US performed at one month of life. MCUG was positive in 15% of the infants. Similarly, we noted that two cases with normal postnatal US subsequently showed the development of VUR, which indicates the need to follow-up with US and MCUG for all newborns with ANH to detect any abnormalities at the appropriate time. Thus, there is a need to draw proper procedural guidelines and formulate criteria for healthcare providers for imaging (MCUG, MAG3) in the postnatal period.

We prescribed prophylactic antibiotics for all babies with hydronephrosis and UTI suspected in over half.

Conclusion

Antenatal US is essential for detecting hydronephrosis while postnatal US is imperative for parental counseling and management. Follow-up with US after delivery is important in any newborn with ANH regardless of normal first postnatal US as this may help to detect missed cases of VUR.

Even though newborns with ANH are at greater risk of developing renal disease, in a vast majority, the outcome appears favorable. We found no correlation between the grade of hydronephrosis and bladder wall thickness antenatally except in PUV cases. AFI in most cases did not correlate with the severity of hydronephrosis postnatally.

The majority of ANH improved spontaneously, which can reassure the family. The majority of those cases who needed surgical intervention majority recovered after surgery.

Disclosure

The authors declared no conflicts of interest. No funding received for this study.

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