Intractable metabolic acidosis in a patient with colovesical fistula.

A 58-year-old female presented with urosepsis and faecaluria secondary to a colovesical fistula of diverticular aetiology. A plan was made for surgical repair of the fistula. Preoperatively the patient developed a hyperchloraemic metabolic acidosis, with hyperkalaemia and hyponatraemia. Renal function was normal, and a short synachten test ruled out Addison's disease. Postoperatively her acid-base physiology normalised in the absence of medical management, demonstrating that surgical intervention was responsible for resolution of the patient's metabolic acidosis. The mechanisms by which colovesical pathophysiology causes hyperchloraemic metabolic acidosis are discussed. Although diverticular disease is the most common cause of colovesical fistulae, this is the first report of such fistulae causing metabolic acidosis.