Evidence for a reflex provoking contraction of the renal pelvis (with some comments on its clinical implications).

The effect of swallowing a small quantity of water or of solid food (biscuit) on the renogram curve was observed in 177 patients. Swallowing provoked contraction of the renal pelvis in 63% of the kidneys with a pelvicalyceal system which was neither obstructed nor dilated, with expulsion of a substantial fraction of the contents within 30 s. This did not occur in obstructed or denervated kidneys, nor in patients with a high transection of the spinal cord. Evidence is adduced that this contraction is mediated reflexly. This effect may be used diagnostically to distinguish physiological dilatation from obstruction. The implications when performing and interpreting renography are discussed.