In infants with an ultrasound diagnosis of upper tract dilatation, hydronephrosis could coexist with a Vesicoureteral.reflux (VUR)
In addition to the other examinations a 99mTc-MAG3-scintigraphy can be performed to differentiate a dilating reflux from an obstructive condition only. In most cases of hydronephrosis with no significant loss of percentage of renal relative uptake (RRU), no treatment is necessary but a surveillance with MAG3 can be clinically useful.
We performed a retrospective analysis of MAG3(± diuretic study) in patients who underwent two or more scans for two or more years, with the primary end point to assess the changes in scan findings during Follow-up and with the secondary end point to define the lasting of the MAG3 surveillance.
Among patients who consecutively undervent MAG3 scan in our Istitution, we selected those who performed a minimum of two scans in an interval time of 12 months. A diuretic study was added to MAG3 only in the case of a persistence of more than 75% of activity in the renal pelvis after 20/30 minutes from starting time, with the patient standing and following bladder voiding. In each scan the RRU, the diuretic response and any possible morphological renal abnormalities were reported.
From July 1994 to December 2012 224 patients performed two or more MAG3 scans (±voiding study) in an interval time ranging from 12 months to 13 years. A diuretic study was added to MAG3 only in the case of a persistence of more than 75% of activity in the renal pelvis after 20/30 minutes from starting time, with the patient standing and following bladder voiding.
175 patients underwent 2 scans, 30 patients 3 scans, 13 patients 4 scans, 6 patients 5 scans, with the median interval time period of two years between each study.
At basal study, 163 patients presented with a monolateral hydronephrosis (HYD), 61 showed a bilateral HYD. In more than one third of patients mono or bilateral upper tract obstruction were associated with other malformative conditions.
The ranges of RRU found were: 40%-53% in 130 patients (58%); 30-40% in 47 pts (21%), 20-30% in 36 pts (16%); ≤20% in 11 pts (5%).
Most patients with RRU values lower than 40% underwent surgical correction. Unrespectively to surgery, in follow-up scans RRU values remained stable in about 95% with a significant decline only in 2-3 % of cases. Except for the above mentioned patients, we observed a progressive improvement of excretory function, with an eventual normalization in about 2/3 of patients. When the follow-up was longer than 4 years we did not observed any further significant change of the findings.
In our experience a four-year time frame follow-up is enough to determine prognosis in patients with dilatation or obstruction when no decline of RRU or excretory function are observed after the second study.