Augmentation Cystoplasty: in Pretransplant Recepients

Augmentation cystoplasty is performed to increase bladder capacity and compliance. The primary use of augmentation cystoplasty is to protect renal function, to achieve urinary continence, and often to facilitate urinary tract reconstruction (1). The most common problems necessitating bladder augmentation are neurogenic bladder dysfunction secondary to myelodysplasia, extrophy of the bladder, and posterior urethral valves. However, many other conditions may require bladder augmentation including tuberculosis, interstitial cystitis, multiple surgeries, chemotherapy and radiation therapy. Not all patients undergoing augmentation cystoplasty, especially in the pediatric population, can achieve complete emptying of their bladder by spontaneous voiding. It was the success and wide spread acceptance of clean intermittent catheterization (CIC) in the mid-1970s that made augmentation cystoplasty and continent urinary diversion possible especially in children (2). Conventional enterocystoplasty employs the use of detubularized segments of small or large bowel. Ileum, sigmoid and cecum have all been used; several studies have confirmed the reliability of these segments (3, 4). Despite the functional success of enterocystoplasty, clinical experience has demonstrated that there are numerous complications that can result from the incorporation of small and large bowel and their heterotropic epithelium into the urinary tract. To avoid some of the deleterious side effects of enterocystoplasty, several procedures have been developed to augment the bladder without the use of the bowel. These include gastrocystoplasty, the use of dilated ureter (either naturally dilated or balloon dilated), autoaugmentation and seromuscular enterocystoplasty (5, 6, 7, 8, 9). Autoaugmentation involves the excision of the detrusor muscle from the dome of the bladder allowing the epithelium to form a large diverticulum which may or may not be covered with a seromuscular gastric or sigmoid patch as a backing. In addition, recent advances in tissue engineering substrates and biomaterials have enhanced our abilities to possibly regenerate bladder tissue that is clinically useful for augmentation purposes. Generally, three classes of biomaterials have been used for engineering of genitourinary tissues; naturally derived materials, such as collagen and alginate, cellular tissue matrices such as bladder and small intestinal submucosa (SIS) and synthetic polymers such as polyglycolic acid (PGA) and polylactic acid (PLA) (10, 11, 12, 13).