A comparison between urography and radioisotope renography in the follow-up of surgery for hydronephrosis.

The result of surgical correction of hydronephrosis caused by chronic obstruction at the pyeloureteral junction has been evaluated clinically as well as by urography and body background substracted renography performed preoperatively and up to 65 months postoperatively. The average follow-up period was 24 months. Twenty-eight patients (29 kidneys) were operated. Clinically 24 patients were improved. Urography showed regress of hydronephrosis and/or improved urinary pelvic drainage in 22 patients, whereas kidney function is judged from renography was improved in only 8 patients. Improvement in all parameters was generally most marked during the first postoperative months. Renographic improvement was seen much more often when the contralateral (non-operated) kidney was abnormal. Thus, kidney function in terms of effective renal plasma flow is rather uninfluenced by hydronephrosis surgery if the contralateral kidney is normal, whereas clinical improvement in urinary drainage is regularly obtained. This improvement in drainage is poorly registered by renography. It is concluded that renography is an important complementary method to urography, but the method cannot replace the radiological methods in the follow-up of hydronephrosis surgery.