[Upper urinary tract video-urodynamics. Current indications].

Abstract

OBJECTIVES: Upper urinary tract videourodynamic studies were first described in the second half of the 20th century (years 60-70). The antegrade pyelogram with constant pressure and controlled flow received the name of its author, "Vela Navarrete test" (1982), who currently refers to it as video-urodynamic study of the upper urinary tract. It is the simultaneous study of pressure, flow, and dynamic x-ray of the upper urinary tract and it keeps same indications than the original design, in spite of the appearance of new dynamic and static imaging techniques (ultrasound, CT scan, MRI, radioisotope studies). The continued practice of video urodynamic study of the upper urinary tract in the FJD prompted an update of the procedure reviewing its current indications. METHODS: Patient is positioned in the prone decubitus on an x-ray table with video. After punctioning renal cavities with fine needle, video urodynamic tests are performed: pyelomanometry, basal pyelic pressure (basic urodynamics study), pressure changes after induced diuresis, and pressure-flow studies. 10-20 ml of urine are obtained for biochemical tests (creatinine, electrolytes, osmolarity,...), which give information about the functional viability of the renal unit, cytology or microbiological tests. Finally, the study concludes with an antegrade pyelogram, a fluoroscopic study of the radiological anatomy which provides morphologic and dynamic data of the upper urinary tract. In the Urodynamics Unit of the FJD, urologists perform 30-40 studies per year. We analyzed retrospectively all studies performed over the last five years (1999-2005) for various pathological entities of kidney dilation. (Table I). RESULTS: Structural and dynamic data obtained by the studies offered conclusive information in most of them facilitating the decision for surgery or observation (Table II). CONCLUSIONS: The interpretation of the upper urinary tract video-urodynamic study is based on radiological and dynamic findings. Flow-controlled pyelogram enables determining the existence of obstruction, dilation volume, and ureteral peristaltic behaviour. Constant pressure enables quantification of obstruction. The video urodynamic study of the upper urinary tract is easy to perform, well tolerated and may be repeated as many times as required, mainly if nephrostomy tube is placed for more prolonged evaluations. It offers excellent anatomical, dynamic, and etiological information about the upper urinary tract, and furthermore conclusive, with minimal risk.