Abstract
This study was undertaken to evaluate if distension of the urinary bladder can cause reversible distension of the pelvicalyceal system of the kidneys. Ultrasound examinations on 72 healthy individuals with distended bladders showed a 13.9% incidence of mild (Grade 1) and a 2.8% incidence of moderate (Grade 2) hydronephrosis which disappeared when the bladder was emptied. Altered ureteral peristaltic patterns resulting from elevated intravesicular pressure and anatomic changes at the ureterovesical junction may provide a physiologic explanation for the transient hydronephrosis observed. A finding of moderate or severe hydronephrosis irrespective of the degree of bladder distension should alert the sonographer to the likely presence of obstructive uropathy.