What is a urodynamics study of upper urinary tract?

The urodynamic study of the upper urinary tract is a urologic procedure whose objective is to complement the information obtained by excretion urography in selected cases of documented or suspected upper tract obstruction. The procedure has several steps, all of which can be done by antegrade transcutaneous puncture of the kidney. The first and most important step consists of the simultaneous analysis of resting pelvic pressure, solute concentration in aspirated urine from the renal pelvis, and antegrade pyelogram. This set of data makes up the basic urodynamic evaluation and will be sufficient in many cases for diagnostic and prognostic purposes. However, in selected circumstances of equivocal dilatation or severe kidney atrophy, more complementary information can be gained using antegrade flow studies or temporary diversion by needle nephrostomy, respectively. These conclusions have been based on more than 300 urodynamic evaluations done by the author.