The interrelationship between vesico-ureteric reflux, trigonal abnormalities and a bifid pelvicalyceal collecting system: a family study.

3 investigations have been undertaken to study the interrelationship between a bifid pelvicalyceal collecting system, vesico-ureteric reflux and lateral ectopia of the ureteric orifice. Firstly, in 30 families investigated to confirm the familial incidence of bifid and double ureters there were 3 families in which siblings were found with primary reflux. Secondly, reflux was found in 62 of 110 patients investigated with a duplex pelvicalyceal system. Reflux was to the ipsilateral kidney in 48 patients but occurred to the contralateral kidney, unaffected by duplicity, in 14. This high incidence of reflux is related to lateral ectopia of the ureteric orifice which may be either bilateral or unilateral. Thirdly, the incidence of a bifid pelvicalyceal system was determined in the parents and siblings of a series of 32 patients with primary reflux. The results support the hypothesis that primary reflux may be inherited by an autosomal dominant gene of variable penetrance in a manner similar to the inheritance of a duplex urinary tract. Thus there is a direct genetic relationship between primary vesico-ureteric reflux, lateral ectopia of the ureteric orifices and a duplex pelvicalyceal system.