Ultrasonography of renal allografts: collecting system dilatation and its clinical significance.

Reports and ultrasound scans (658 studies) of 135 renal allografts, transplanted in the years 1987 and 1988, have been reviewed. Records of the recipients were also studied in order to determine the clinical status of the kidney at the time of each ultrasound examination and to obtain long-term follow-up of allograft function. Seventy-seven allografts (57%) never showed pelvicalyceal dilatation on 342 serial examinations. Forty-two kidneys (31%) had mild dilatation reported on at least one scan, which did not progress. However, 11 mildly dilated allografts developed moderate to severe dilatation on later examinations and these, together with 5 allografts reported as exhibiting moderate to severe hydronephrosis on their first dilated scan, were classed as moderate to severe (n = 16 = 12%). Thirty-eight patients (90%) with mild dilatation of the collecting system had no evidence of obstruction. However, in allografts with moderate to severe dilatation and poor or deteriorating function, ten patients (70%) were found to have ureteric obstruction. There was no significant difference in 1-year graft survival (87% versus 81.8%) and the median serum creatinine at 3 and 12 months after transplantation between non obstructed 'dilated' and non-dilated allografts (149 mumol/l versus 153.7 mumol/l; 139 mumol/l versus 147.3 mumol/l). All 14 obstructed allografts were salvaged with a graft survival of 85.7% at 1 year. Median serum creatine in these patients was significantly elevated at 200 mumol/l and 189 mumol/l at 3 and 12 months; P = 0.05 and 0.01 compared to dilated non-obstructed allografts. Our results indicate that grafts with moderate to severe dilatation should be urgently investigated to minimise further allograft damage.