Purpose: Duplication of the ureter and renal pelvis is the most common upper urinary tract anomaly in childhood with a reported incidence of 0.8%. Familial nature of vesicoureteral reflux (VUR) is well recognized with a prevalence of 27-51% in siblings of children with VUR and 66% rate of VUR in offsprings of parents with previously diagnosed VUR. Although VUR is known to be the most common abnormality associated with renal duplex systems, the prevalence and significance of renal duplication in familial VUR is not known. The aim of this study was to determine the prevalence and significance of duplex collecting systems in familial VUR.
Methods: Between 1998 and 2009, the parents of 237 index patients with grade III-V VUR were asked permission to screen siblings younger than 6 years old for VUR. A total of 513 children in 237 families were identified to have VUR (237 index patients, 276 siblings). Families were divided into three groups: Group I, families with only boys affected Group II, families with only girls affected and Group III, families with boys and girls affected.
Results: In 39 families (16.5%) only boys had VUR (Group I), in 89 families (37.5%) only girls had VUR (Group II) and in 109 families (46%) boys and girls were affected (Group III). Duplex collecting systems were present in 39 (7.6%) patients. The prevalence of duplex systems was significantly higher in Group I (15%) compared to Group II (6%) and Group III (6.4%), (p < 0.01). Duplex systems were present in 15% of boys in Group I and only in 4% of boys in Group III (p < 0.01). Patients with duplex systems had a significantly higher grade of VUR than patients without duplex systems (p < 0.01).
Conclusion: Families with exclusively boys affected with VUR have a higher rate of prevalence of duplex collecting systems. This has implications for genetic counseling and for modeling the inheritance of VUR.