title: An unrecognised case of metabolic acidosis following neobladder augmentation cystoplasty.
abstract: BACKGROUND
  We present a case where there was a delay in the diagnosis of severe metabolic acidosis in a patient with an orthotopic neobladder. There are a growing number of patients with orthotopic neobladders and a wider range of clinicians are encountering these patients. A delay in the diagnosis can lead to significant morbidity but if identified early it can be easily treated.
  
  
  METHODS
  A 59-year old patient with a recent neobladder augmentation cystoplasty was admitted under the medical team with a metabolic acidosis which was incorrectly presumed to be secondary to urosepsis. His condition rapidly deteriorated until a surgical review identified hyperchloremic metabolic acidosis secondary to neobladder augmentation. The patient required admission to the intensive care unit where he was treated with intravenous alkalising therapy which produced rapid metabolic improvement. Following a full recovery, he underwent neo-bladder excision and ileal conduit formation.
  
  
  CONCLUSIONS
  Hyperchloraemic metabolic acidosis develops due to the bowel segment absorbing urinary constituents including ammonium, hydrogen ions and chloride in exchange for sodium and bicarbonate. It can be diagnosed by careful interpretation of the arterial blood gas and calculation of the anion gap. This hyperchloraemic metabolic acidosis can be corrected with alkalizing agents combined with catheterisation.
  
  
  CONCLUSIONS
  Hyperchloremic metabolic acidosis is a well-established complication of urinary diversion. Patient with orthotopic neobladder with high residual urine and large capacity are at even higher risk of metabolic acidosis. This information should be clearly documented in the post-operative discharge documentation to ensure early recognition by non-specialists.
authors.affiliation: Guy's and St Thomas' NHS Foundation Trust, Urology Centre, Great Maze Pond, London SE1 9RT, United Kingdom. Electronic address: eldredevans@doctors.org.uk.
authors.forename: David
authors.initials: D
authors.lastname: Eldred-Evans
authors.affiliation: Guy's and St Thomas' NHS Foundation Trust, Urology Centre, Great Maze Pond, London SE1 9RT, United Kingdom. Electronic address: fahdkhan@doctors.org.uk.
authors.forename: Fahd
authors.initials: F
authors.lastname: Khan
authors.affiliation: Department of Urology, Darent Valley Hospital, Dartford, Kent DA2 8DA, United Kingdom. Electronic address: jsabbaraju@yahoo.com.
authors.forename: Jay
authors.initials: J
authors.lastname: Abbaraju
authors.affiliation: Department of Urology, Darent Valley Hospital, Dartford, Kent DA2 8DA, United Kingdom. Electronic address: Seshadri.Sriprasad@dvh.nhs.uk.
authors.forename: Seshadri
authors.initials: S
authors.lastname: Sriprasad
keywords: Metabolic acidosis; Neobladder; Urinary diversion