Metabolic consequences of urinary diversion through intestinal segments.

The use of intestinal segments in the reconstruction of the urinary tract for a variety of malignant and nonmalignant conditions is generally accepted. Metabolic derangements may result any time urine is in contact with the intestinal mucosa. Numerous studies concerning the pathophysiology of this syndrome have demonstrated that it is in large part secondary to reabsorption of urinary acid as ammonium and, to a lesser degree, to bicarbonate secretion into the urine. The syndrome of metabolic acidosis resulting from urinary diversion has been most common after ureterosigmoidostomy, often in the setting of renal insufficiency secondary to pyelonephritis and obstruction. It became a lesser clinical problem with the popularization and frequent use of conduit urinary diversions. At present, with a greater emphasis on the construction of large-capacity continent urinary diversions, there is an increased likelihood of metabolic derangements, especially in the setting of renal insufficiency. Furthermore, although the reported incidence of clinically problematic metabolic derangements is low with the newer modes of continent urinary diversion, it is impossible to assess the significance of a mild or asymptomatic acidosis, which may occur even in the setting of normal serum electrolytes. Only with close long-term follow-up can the significance of this change be determined.