Technical Considerations
The anatomy of the
bladder forms an
extraperitoneal muscular urine reservoir that lies behind the pubic symphysis
in the pelvis. A normal bladder functions through a complex coordination of
musculoskeletal, neurologic, and psychological functions that allow filling and
emptying of the bladder contents. The prime effector of continence is the
synergic relaxation of detrusor muscles and contraction of the bladder neck and
pelvic floor muscles.
The normal adult bladder accommodates 300-600
mL of urine; a central nervous system (CNS) response is usually triggered when
the volume reaches 400 mL. However, urination can be prevented by cortical
suppression of the peripheral nervous system or by voluntary contraction of the
external urethral sphincter.
Before being considered for augmentation
cystoplasty, patients should have timed voids as often as necessary to maintain
low bladder volume and pressure.
Anticholinergic medications (eg, oxybutynin,
hyoscyamine, or tolterodine) may be given to decrease detrusor instability and
symptoms of urgency. Medical management also allows increased bladder volume to
protect renal function and to decrease the chance of pyelonephritis. The
increase in bladder capacity with medical treatment has been modest (generally
< 50 mL), but some groups have found that higher doses may increase the
effect, as one study demonstrated in young children with neurogenic bladders.[7]
Lack of coordinated detrusor contraction or
increased bladder outlet obstruction (eg, external sphincter dyssynergia) can
be overcome with intermittent self-catheterization at 4- to 6-hour intervals.
This usually reduces bladder pressure and improves continence. Adult patients
should have good manual dexterity, proven by performing self-catheterization in
front of the physician. In pediatric patients, the parents must be committed to
catheterizing the child at least every 4-6 hours. Parents must be taught catheterization
before surgery.
Intermittent catheterization and
anticholinergic management are usually used in combination to accomplish
symptom-management goals, to create continence, to eliminate vesicoureteral
reflux, to prevent UTIs, and to ensure low bladder storage pressure. If these
measures fail, augmentation cystoplasty should be considered.
