Does the Whitaker test add to antegrade pyelography in the investigation of collecting system dilatation in renal allografts?

Significant pelvicalyceal dilatation in renal allografts is currently investigated by antegrade pyelography. However, the clinical significance of a radiologically demonstrated narrowing of the ureter is unclear. Over a 21-month period 26 of 155 renal allografts with pelvicalyceal dilatation were investigated by antegrade pyelography. In eight allografts no ureteric stenosis could be identified. Two grafts were shown to have ureteric necrosis and required surgical intervention and 16 of the other grafts appeared to have a ureteric stenosis. 15 of the 16 allografts with radiological ureteric stenosis underwent a concurrent pressure flow study to assess the functional relevance of the ureteric narrowing. As shown by a pressure rise of > 7 mmHg at a perfusion rate of 10 ml min-1, 11 of the 15 grafts were functionally obstructed and were treated by a nephrostomy catheter followed by antegrade insertion of a ureteric stent. The four grafts with a negative pressure flow study were subsequently shown on biopsy to have rejection. The diagnosis of allograft rejection was also confirmed by biopsy in seven of the eight allografts without a radiological ureteric stenosis. The last of the eight allografts was found to be cyclosporin toxic. Pelvicalyceal dilatation of renal allografts is appropriately investigated by antegrade pyelography in combination with a pressure flow study which identifies those grafts with mechanical obstruction.