Paediatric bladder augmentation and substitution: From diversions to tissue engineering.
OBJECTIVE
To review the evolution of urinary diversion, bladder augmentation and bladder replacement in the paediatric population over the past century and to outline the possible direction of future management.


METHODS
Original and review articles obtained from a PubMed search of English language publications dating from 1970 to 2001. The search terms were "bladder augmentation", "bladder substitution", "bladder autoaugmentation", "ureterocystoplasty" and "bladder engineering". The age group was "all child 0-18".


METHODS
Articles selected were those with relevance to the scope of the topic.


METHODS
The articles were analyzed with the primary focus being the problems encountered with various forms of urinary diversion, bladder augmentation and bladder replacement, and the subsequent evolution of materials and techniques.


RESULTS
Bladder tissue may need to be replaced in the paediatric population because of congenital malformation, disease or trauma. The unique structure and function of urothelium and bladder muscle make this a challenging task. Management has evolved from a mindset of attempting to divert urine from the bladder completely to that of trying to preserve what is salvageable of the organ. Historically and contemporarily, the gastrointestinal tract has provided the raw material for urinary diversion, bladder augmentation and bladder substitution. Experience, however, has highlighted the potential complications inherent in the use of the bowel in the urinary tract including mucus production, stone disease, metabolic abnormalities, growth retardation, spontaneous perforation and malignancy. However, despite these drawbacks, the bowel is the gold standard in terms of functional utility and longevity. In efforts to develop alternatives, research has focused on the use of both natural and synthetic materials. With these materials, a whole new list of potential problems has been characterized. Tissue engineering may hold promise in resolving the issues of bladder replacement or repair by providing the necessary biocompatible raw material.


CONCLUSIONS
Bowel segments have been and continue to be the clinically most useful material for urinary diversion, bladder augmentation and bladder replacement. Complications associated with the use of bowel in the urinary tract have prompted considerable research into alternative materials and methods.
Pike
John Grant
JG
Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario.