Primary Vesico-Ureteral Reflux: Comparison of Factors between Infants and Children

PURPOSE The association of age, sex and renal parenchymal damage (RPD) in vesicoureteral reflux (VUR) is well known. We compared various factors between infants and children in a cohort of patients with primary VUR. MATERIALS AND METHODS Medical records of 147 patients diagnosed as VUR between 1997 and 2010 were reviewed. Of these children 91 (61.9%) were boys and 56 (38.1%) were girls. 99 (67.3%) of the 147 patients were younger (Group 1), and 48 (32.7%) were older than 1 year (Group 2). The impact of patient's gender and age as well as VUR grade on RPD were analyzed in each patient. The Fisher's exact test and chi square test was done with SPSS ver. 12.0 (SPSS Inc., Chicago, IL, USA). RESULTS VUR was unilateral in 88 patients (59.9%) and bilateral in 59 patients (40.1%). Abnormal renal scan was found in 78 (37.7%) renal units. The incidence of VUR was significantly higher in male in group 1 (p<0.01) and in female in group 2 (p<0.01). The incidence of abnormal renal scan was significantly higher in intermediate and high grade VUR comparing low grade VUR in group 1 (p=0.042). In both group, abnormal renal scan didn't show any difference between male and female statistically (p>0.05). CONCLUSIONS Our data showed that VUR in infant was significantly higher in male than in female, whereas VUR in children was significantly higher in female. This may be due to that characteristic of a population where neonatal circumcision is not a common procedure in infant and urinary tract infections are more common in female children. Further study may be needed to identify gender difference in RPD in infant with high grade reflux.