2. Introduction What studies done before in the topic The study : Purpose Materials and Methods Results Limitations of the study Conclusions

3. Introduction Fetal hydronephrosis is the most common anomaly detected on prenatal ultrasound, affecting 1% to 5% of pregnancies. The degree of prenatal hydronephrosis varies from mild to severe, and the degree of hydronephrosis should correlate with the severity of the underlying etiology. The lack of correlation between the two has also been well documened.

4. Lee et al recently published a meta analysis of 1,308 patients, which demonstrated that children with any degree of prenatal hydronephrosis are at significant risk for postnatal pathology. Lee et al reported that the risk of VUR was similar for all degrees of PNH.

5. Available data suggest that VUR is present in 17% to 38% of patients with PNH. While this incidence is impressive, its clinical significance has not been well described and conflicting data are found in the literature.

6. Although the differential diagnosis of PNH is broad and includes benign and pathological processes, a specific question that is debated is whether a radiological study should be performed to investigate for VUR in patients with a history of PNH. While VCUG has been reported to be safe in the neonatal period, the avoidance of urethral catheterization is preferable to the patient and his/her family.

7. the clinical significance of VUR discovered in patients with a history of PNH has not been well documented. Limited data from 2 small series suggest that VUR discovered in these cases may not be clinically significant

8. Despite its frequency, the appropriate postnatal management is not well-defined.

9. Our general clinical impression has been that a history of PNH with postnatally persistent SFU grade II hydronephrosis does not justify postnatal screening with VCUG. However, this impression has not been formally studied, and the available data do not provide clear guidelines.

10. this analysis focuses specifically on the effect of not screening patients with SFU grade II hydronephrosis on the first postnatal US. Therefore, we sought to determine whether VCUG should be performed in these patients by comparing the incidence of febrile UTI in patients with a history of PNH and postnatally persistent hydronephrosis with and without postnatal screening for VUR.