ABSTRACT
Selection criteria and the pathophysiology of these various conditions are detailed elsewhere, but in general there
is little benefit to reconstructing a renal unit with less than 10 percent of total function on a differential renal scan. There are no data to indicate the ‘correct’ cut-off, below which nephrectomy should be performed, but it should be recognized that in most cases associated with a congenital condition, function less than 10-15 percent will seldom increase despite successful surgery. The actual threshold used varies widely and is largely a matter of individual preference. The complete absence of function on a renal scan is a good indication that it is reasonable to remove the affected unit. If it is more practical simply to achieve urinary drainage or absence of reflux, removal is not considered essential. The long-term risks of leaving a poorly functioning renal unit remain incompletely defined and for this reason some practitioners elect to remove the
affected renal unit. Alternatively, some base the decision on whether the affected unit has sufficient function for the patient to be able to avoid dialysis if the contralateral unit were lost. This may be excessively stringent, in that it is generally felt that 30 percent function is required to avoid dialysis, but most surgeons would probably preserve a kidney with much less function. Perhaps optimistically, our practice has been to use a relative functional contribution of 10 percent of total uptake as the cut-off for renal salvage versus removal. It must be recognized that this is an arbitrary distinction that is not based on any outcome data.
