Diuresis renography. The need for an additional view after gravity-assisted drainage.

The role of diuresis renography (DR) in the evaluation of pelvi-ureteric junction obstruction is well established. However, problems may be encountered when applying this technique to patients after pyeloplasty because of the role of gravity-assisted drainage (GAD) in this post-operative group. Twenty-three radionuclide studies that were performed in 21 children were reviewed. All children underwent standard DR and all then had an additional view performed after GAD. In 12 children evaluated in a preoperative assessment for possible obstruction, 5 were obstructed on both DR and after GAD, 1 was equivocal on DR but drained after GAD, and 6 were not obstructed in either part of the study. In 11 children assessed after pyeloplasty, 5 were obstructed on DR but not obstructed on GAD, 3 were not obstructed in both studies, 1 was obstructed in both, and 2 were equivocal on DR but not obstructed after GAD. It can be concluded that when assessing patients, particularly those who have undergone pyeloplasty, DR should be supplemented with an additional view acquired after gravity-assisted drainage.