The use of renal scintigraphy in assessing the potential for recovery in the obstructed renal tract in children.

Abstract

To assess the value of renal scintigraphy with 99mTc-dimercaptosuccinic acid (DMSA) in predicting functional recovery after the surgical relief of obstructed kidneys in children. Patients and methods Forty-three children underwent surgery to relieve upper urinary tract obstruction; 37 had pelvi-ureteric junction obstruction and six had vesico-ureteric junction obstruction. The indication for surgery was a combination of an obstructed renogram with symptoms of either pain or pyelonephritis. Most children (41) had < 40% function on the affected side before surgery, with just two having hyperfunction (> 55%). In all patients intravenous urography before surgery showed hydronephrosis, and a micturating cystogram was used to exclude coexisting reflux in the presence of an associated megaureter. Diuretic renography (using 99mTc-mercaptoacetyl triglycine or 123I-hippuran) and DMSA scintigraphy were both carried out before surgery and the renography repeated 6 months afterward. The renographic drainage curves improved from obstructed to unobstructed or 'dilated unobstructed' on all postoperative studies. Regression analysis showed that preoperative DMSA scan was an excellent predictor of outcome (P < 0.001) whilst the preoperative renogram was a relatively poor predictor of the functional result. In four patients where the initial renographic function was < 10%, DMSA scintigraphy predicted correctly the capacity for recovery in three and the inability to improve in the fourth. Conclusion Before surgery, DMSA scintigraphy in children with upper urinary tract obstruction is a more useful estimate of probable long-term renal function than value from diuresis renography. If there is doubt about the desirability of reconstructive surgery, a DMSA scan may eliminate the need for more invasive methods of estimating recovery, e.g. a period of nephrostomy drainage.