Upper tract urodynamics are principally used in the diagnosis of upper tract obstruction.
Antegrade perfusion studies assess the pressure drop between the renal pelvis and bladder. In the Whitaker test, the kidney is perfused with fluid at a constant rate of 10ml/min by means of a needle inserted percutaneously into the renal pelvis. A side-arm channel measures intrapelvic pressure. Intravesical pressure is measured by means of a urethral catheter.
In the unobstructed kidney, the pressure drop should be less than 15 cm of water. Values greater than 22 cm of water indicate obstruction. Intermediate values are equivocal.
Using the nephrostomy track, antegrade constrast studies may also be performed to provide anatomical information.
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