The effect of flexible ureterorenoscopy on renal function.
Submitted as partial fulfilment of the requirements for the MSc in Urology, 2005.
Flexible ureterorenoscopy is essential in the diagnosis and treatment of upper tract disease. However the effects on renal function have been poorly studied. To test this scientifically, I have carried out radionuclide studies before and after flexible ureterorenoscopy for urolithiasis. The hypothesis states that there is no significant reduction in renal function in adults undergoing flexible ureterorenoscopy for urolithiasis.
Using 51Cr-EDTA and 99mTc-DMSA radiopharmaceuticals, the split function glomerular filtration rate was calculated before and within 24 hours after flexible ureterorenoscopy in the department of Urology at Guy's and St. Thomas' Hospital. Treatment to the stones and post-operative care was standard. Any patient with a significant deterioration in renal function post-operatively was invited to have further scans within six months.
Between June 2002 and December 2003, 25 patients were recruited into the trial of which 20 completed it. Of these 20 patients, the mean age was 48.7 years and mean stone burden was 11.8mm. There were no statistical differences in any of the means of the measured parameters. One patient appears to have suffered a significant reduction in split renal function and he also suffered a creatinine rise. These improved with time. Five further patients appear to have had some reduction in renal function although the split function remained similar or improved. This may be as a result of nephrotoxic medication, starvation or anaesthesia. Two patients showed an improvement in their split function that probably represents relief of obstruction.
Thirteen patients were rendered stone-free at follow-up while three patients required further ureterorenoscopy and one required extracorporeal shockwave lithotripsy. One patient suffered post-operative sepsis and a further patient developed a DVT.
That six patients developed some reduction in renal function is of concern although only one may be attributable to the procedure itself, which improved with time. In conclusion, the results support the hypothesis and there is no conclusive evidence that flexible ureterorenoscopy causes significant short or long-term deterioration in renal function.