Ammonia intoxication following ureterosigmoidostomy in a patient with liver disease

Metabolic and Nutritional Consequences of Urinary Diversion Using Intestinal Segments to Reconstruct the Urinary Tract

Intestinal segments in various forms have been used to reconstruct the urinary tract since the mid-1800s. Currently, many different forms of continent and incontinent diversion options exist. Incorporating bowel mucosa within the urinary tract leads to predictable metabolic and nutritional consequences. The use of ileum or colon can cause a hyperchloremic metabolic acidosis, vitamin B12 deficiency, osteoporosis, fat malabsorption, urinary calculi, and ammoniagenic encephalopathy. Due to metabolic and nutritional consequences associated with the use of jejunum and gastric segments, the use of these bowel segments is not recommended.

Noncirrhotic hyperammonaemic encephalopathy

Adult hyperammonaemia is associated with severe liver disease in 90% of cases. In the remainder, noncirrhotic causes should be considered. Measurements of serum ammonia level must be part of the basic work-up in all patients presenting with encephalopathy of unknown origin, even when liver function is normal. Clinician awareness of noncirrhotic hyperammonaemic encephalopathy can contribute to early diagnosis and the initiation of sometimes life-saving treatment. This review focuses on the physiology, aetiology and underlying mechanisms of noncirrhotic hyperammonaemic encephalopathy and discusses the available treatment modalities.

Acid-base and electrolyte disorders after urinary diversion

The use of bowel in urologic reconstructive procedures may result in numerous short and long-term complications, including well-described acid-base and electrolyte disorders. Many of these metabolic alterations are influenced by how solute absorption occurs across the particular bowel segment chosen for reconstruction. Solute absorption is impacted by: (1) the segment of bowel used, (2) the surface area of bowel used, (3) the time of retention of urine, (4) the concentration of solutes in the urine, (5) renal function, and (6) the pH and osmolality of the urine. These factors affect the type and amount of solutes absorbed, as well as the severity of metabolic complications that develop.

Metabolic complications of urinary diversions: an overview

Patients with urinary diversions present unique challenges to internists who have an important role in their long-term management. Advances in surgical techniques over the past 30 years have given rise to a number of urinary diversion procedures that use various intestinal segments. In its normal function, the intestine absorbs water and solutes. When placed in contact with the urinary stream, the intestine can create numerous metabolic abnormalities. These include bone disease, hepatobiliary disease, infection, malignancy, neurologic complications, nutritional deficiencies, and a number of electrolyte and acid-base disorders. An overview of these metabolic abnormalities and their causes is provided, as well as recommendations for screening and management of patients.

Metabolic complications of continent urinary diversions

The advent of modem reconstructive techniques in urologic surgery has allowed a wide use of intestinal segments in young and older patients. Intestinal conduits and reservoirs can produce a series of complications due to hydroelectrolytic disturbances, alterations of acid-base balance and of bone and hepatic metabolism, intestinal malabsorption. The severity of clinical features depends on the quantity of solute exchanges through the mucosa of the intestinal segment used and on the “age” of the conduit or reservoir.

Hyperammoniemic coma in a patient with ureterosigmoidostomy and normal liver function

Hyperammoniemic encephalopathy has been reported after ureterosigmoidostomy. Its development is related to a problem of bacterial overgrowth and, most often, is favored by the presence of an underlying liver dysfunction. We report the case of a 43-year-old woman with a ureterosigmoidostomy done 28 years earlier who developed hyperammoniemic coma induced by an acute rectocolitis and in the absence of any detectable liver dysfunction. Neither administration of Lactilol and neomycin nor rectal tube drainage were effective; systemic antimicrobial therapy effective against the urease-producing gram-negative bacilli was required and led to a decrease in serum ammonia levels and a dramatic clinical improvement.

Ammonia levels in paediatric ureterosigmoidostomy patients: a screen for hyperammonaemia?

Hyperammonaemia in the urological patient is a rare and potentially grave condition. It has been reported most frequently in association with ureterosigmoidostomy, where clinical neurological symptoms have developed abruptly in association with markedly elevated plasma ammonia levels. The purpose of this study was to determine whether ureterosigmoidostomy patients might have subclinically elevated plasma ammonia levels, which would put them at risk of subsequently developing hyperammonaemic encephalopathy. Both urine and plasma ammonia levels were assayed in 10 asymptomatic paediatric urological patients with ureterosigmoidostomy. Ten paediatric colocystoplasty patients served as controls. Urine pH and urine ammonia levels were significantly higher in the ureterosigmoidostomy group. There was no significant difference in plasma ammonia levels between ureterosigmoidostomy and colocystoplasty patients. In none of the patients was the plasma ammonia level elevated, but 1 ureterosigmoidostomy patient had an exceedingly high urine ammonia level. It was concluded that an annual serum ammonia level in an asymptomatic ureterosigmoidostomy patient is probably not a valuable screen for subclinical hyperammonaemia.

Hyperammonaemic coma in ureterosigmoid urinary diversion

We report on a patient with ureterosigmoid anastomosis, who presented with recurrent episodes of confusion, agitation and aggressive behaviour, culminating in coma. Investigations revealed profound hyperammonaemia, which responded to treatment with sodium benzoate and sodium phenylacetate. No definite cause was found for the abnormality, apart from possible urinary tract infection. The patient remains well on a protein restricted diet with mildly elevated levels of plasma ammonia.

Hyperammonemic coma due to Proteus infection

Hyperammonemic coma without liver disease or associated deficiencies in urea cycle enzymes is rare. We report a case and discuss the pathophysiological findings of hyperammonemic coma secondary to Proteus mirabilis urinary tract infection.

Ammoniagenic coma following ureterosigmoidostomy

Ammoniagenic coma or episodic stupor is a rare complication of ureterosigmoidostomy. We report a case with the unusual features of normal liver function and normal liver biopsy. With extremely rare exception, ammoniagenic coma will not occur in the presence of normal ornithine-urea cycle synthesis in the liver.