Hydronephrosis Index as a New Method for the Evaluation and Follow-up of Fetal Hydronephrosis

Background: The present study was conducted to compare the efficiency of hydronephrosis index (HI) with those of pelvic anteroposterior (AP) diameter and parenchymal thickness in the diagnosis of fetal hydronephrosis in the prenatal period, as well as 1, 6, and 12 months after birth. Methods: This study was conducted on pregnant women with the pregnancy age of 30 weeks whose fetus was suspected of hydronephrosis. The study participants were collected via the consecutive sampling method. The HI, pelvic AP diameter, and parenchymal thickness were measured at the baseline and 1, 6, and 12 months after delivery using ultrasound. According to the study design, the study participants were divided into three groups. Group A consisted of cases with decreased HI and higher hydronephrosis severity. Group B was composed of subjects with relatively constant HI, and group C entailed individuals with increased HI and lower hydronephrosis severity. All of the study measurements and analyses were performed on the three study groups. Results: The results revealed a negative association between HI and pelvic AP diameter but a positive association with parenchymal thickness. On the other hand, HI showed a significant correlation with parenchymal thickness in the diagnosis and prognostic assessment of fetal hydronephrosis. Conclusion: The HI correlated with parenchymal thickness and pelvic AP diameter scores in all follow-up stages. Accordingly, HI can be concluded to be a good alternative to parenchymal thickness or pelvic AP diameter as a grading factor for hydronephrosis. It is suggested to perform further studies to carefully assess the efficiency of HI in the diagnosis, prognosis, and clinical outcome of hydronephrosis.