This occurs with a much older form of ureteral reimplantation (ureter to sigmoid). See below:
Implantation of the ureters into the sigmoid colon or a vesicocolic fistula can result in a hyperchloraemic acidosis due to absorption of Cl- in exchange for HCO3- across the bowel mucosa. Absorption of urinary NH 4+ in the sigmoid colon may also contribute to the development of acidosis as metabolism of the ammonium in the liver results in production of H+. Some of these patients develop renal failure related to infection, stones or urinary obstruction. This can result in uraemic acidosis or renal tubular acidosis as well.
Acidosis is much less of a problem with an ileal conduit (acidosis incidence 2 to 20%) than it was with the older procedure of ureterosigmoidostomy (incidence 30-80%). (Incidence data from Cruz, 1997) This is because the continuous external drainage from the ileal conduit usually results in a short dwell time in the conduit with minimal time for Cl--HCO3- exchange.
