Relative indications for surgery include UTI, low DRF on initial renogram, palpable giant HN, concern over noncompliance with follow-up imaging protocols and family preference in cases of persistent HGHN requiring repeated renographic
Jayanthi et al., "Contradictory supranormal differential renal function during nuclear renographic
investigation ofhydroureteronephrosis," Journal of Urology, vol.
 Using renographic
criteria, obstruction can only be diagnosed if the patient has a decrease in DRF of more that 10% on the affected side on serial studies.
Of all renal units, 79 (65%) showed renographic
evidence of obstruction ([T.sup.1/2] >20 minutes).