Hydronephrosis and pyelonephritis in a pregnant woman: a proposal of MR urography clinical applications

Introduction. MR urography has been used satisfactorily to evaluate kidneys, pelvicaliceal system, ureters and bladder, this technique has the advantage of not using ionizing radiation and also the potential to provide functional information as CT or even more. Case report. We present a case of a 25-years-old pregnant woman with right lumbar pain and probable urolithiasis, the static fluid MR urography demonstrate extrinsic ureteral compression by the pregnant uterus at the lower third bilaterally but predominantly right as well as, right kidney hydronephrosis and pyelonephritis, with the direction of an MR specialized radiologist, pelvic complementary images were taken in order to evaluate the ureter-bladder junction without evidence of urolithiasis. Discussion. MR urography is based in two different imaging strategies basically, which can be used in a complementary manner to cover the mayor aspects in the diagnosis of the upper urinary tract diseases. The first technique utilizes unenhanced heavily T2-weighted pulse sequences to obtain static-fluid images of the urinary tract, even if the renal excretory function is abnormal. The second MR urography technique is analogous to conventional intravenous urography and is called excretory MR urography, in which is necessary to administer intravenously a non-nephrotoxic gadolinium chelate and after its renal excretion, the gadolinium-enhanced urine is visualized using fast T1-weighted fat saturated sequences. Magnetic resonance urography protocol performed in combination with standard MR imaging offers a potential to reduce the need for invasive pyelography.