Ultrasound in suspected obstruction complicating renal transplantation.

The findings of regular ultrasound examination of 439 renal transplants in 419 patients performed during a 16-year period were reviewed to determine the significance of collecting system dilatation. Dilatation was observed in 80 cases. 34 of these proving to be obstructed. Pelvic dilatation was an insignificant finding except when appearing within a month of transplantation. One third of cases developing pelvic dilatation within a month showed progressive dilatation with obstruction subsequently confirmed. The majority of cases developing unheralded dilatation of pelvis and calyces were obstructed and all such patients require further investigation. Recurrence of dilatation following relief of obstruction was associated with recurrent obstruction in eight of nine cases. Consideration of ultrasound appearances allows more critical selection of patients for further investigation when dilatation is seen.