FUNCTIONAL OBSTRUCTIVE UROPATHY

            Boy, 8 year old, underwent live donor  kidney transplantation. A 99m Tc-MAG-3 scintigraphy was requested to evaluate the graft function. Kidney in right inferior abdominal quadrant with increased volume. Initially it can be seen a photopenic area in the pelvis and chalyces due to dilation (Min 1).  At 15 min, retention in the excretory system. Little excretion into the bladder. The kidney renogram depicts severe retention and that of the bladder is flat up until diuretic administration (black arrow), which induces a complete washout of the tracer.

            This is a functional pattern, relatively common and may ease spontaneously very often. Ureteral obstruction requiring surgery occurs in 1-10% of renal transplants and may be due to a clot, calculus, stenosis or extrinsic compression by hematoma or lymphocele. If compression is incomplete and renal function is partially damaged, the diuretic renogram, as in the native kidneys, can help distinguish between obstructed and functional obstruction as in the case presented above.

References:

Etchebere, Elba, Ramos Celso Dario y Camargo, Edwaldo. Trasplante Renal.p: 425-433 en: Medicina Nuclear Aplicaciones Clínicas. Eds: I. Carrio - P. González. Editorial Masson, Barcelona España, 2003.

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