Correlation of ureteral orifice position with renal morphology

Double ureters and kidneys have provided models for the comparison of radiographic appearances and the microstructure of each renal segment, as well as the correlation with the position of the corresponding ureteral orifice. An orifice located within the limits of the normal vesical trigone portends normal renal radiography and morphology. Orifices outside the normal limits of the trigone signify accompanying renal malformations in the corresponding kidneys, such as hypoplasia or aplasia of nephrons that are often difficult to determine histologically but that give rise to thin kidneys and clubbed calices, dysplasia of nephrons and abnormal interstitial tissue and blood vessels, all of which are detected more readily on microscopic examination. The more abnormal the orifice is in location and characteristics the more abnormal are the ureteral and renal segments. The correlation also applies to upper tracts when they are associated with lower tract anomalies, such as congenital urethral valves, neuropathic bladders of myelomeningocele patients and paraureteral diverticula.