Caution in Interpreting Diethylenetriamine Pentaacetic Acid Renal Scan in Renal Failure

Abstract

Since the invention and use of dynamic radionuclide renal imaging techniques, the diagnosis of urinary tract obstruction has become easier. Amongst this, diuretic renogram using Technetium 99 m Diethylenetriaminepenta-Acetic acid (99 mTc-DTPA) is the most widely used for detecting upper urinary tract obstruction. This is even widely used amongst paediatric population for its higher diagnostic success. But, even these techniques might misdiagnose or may reveal incomplete data of the renal derangement causing increased morbidity and mortality. We present a case of a 34-year-old male patient with impaired renal function for which DTPA scan was done twice, which revealed partial obstructive nephropathy with hydronephrosis of left kidney. But a retrograde pyelogram was performed which showed complete obstruction at the upper part of the ureteric segments. This required a robot assisted pelvi-ureteric anastomosis to release the hydronephrosis. Here the DTPA scan findings were misleading on both occasions. This does emphasise the need for an array of investigations to evaluate or exclude any clinical suspicion.

Keywords

• obstructive nephropathy
• percutaneous nephrostomy
• pelvi-ureteric anastomosis