[Value of Whitaker's test in children for the diagnosis of an upper urinary tract obstruction].

Upper urinary tract pressure was measured during constant rate perfusion (10 ml/min in children and 5 ml/min in infants), and with the bladder maintained empty by an indwelling catheter. Pressure was measured simultaneously in the bladder and upper urinary tract when bladder hypertonia was suspected, determination of bladder pressure being of particular importance in patients with moderately elevated endopyelic pressure. The term differential pressure is used to denote the value obtained by subtracting endovesical from pyelic pressure. A value less than 12 cm of differential pressure is considered as being normal, one of 20 cm as markedly elevated, and those between 12 and 20 cm as of doubtful significance. Whitaker test was performed in 27 patients, with practically no complications. Differential pressure was normal in 21 cases. The short-term maximum 1 year follow-up course in the most chronic cases was radiologically and functionally stable, without signs of worsening of the disorder. Five of the 6 cases with elevated pressure readings were operated upon. The value of isotopic exploration in cases with unaltered renal function is unquestioned, but direct measurement of upper urinary tract pressure is a valid procedure in difficult cases.