Augmentation cystoplasty uses intestinal segments to improve the storage function of the urinary bladder. The objective is to achieve a large capacity with a low pressure reservoir. Laplace's law: T=PvesR/2d.

Indications for this procedure would be poor compliance (e.g. neurogenic bladder after failed medical management), intractible detrusor instability or a small bladder capacity (e.g. post TB or post DXT).

Patient selection and pre-op considerations

• adequate renal function
• good liver function
• bladder and sphincter function assessed urodynamically. A VLPP ³ 40cmH2O is necessary for reliable continence post-op. If lower, surgical improvement of continence should be undertaken at the same operation.
• bladder emptying must be assessed - spontaneous sphincter relaxation with detrusor contraction and post void residual. Regardless of emptying efficiency, the patient must be counselled that ISC may be necessary post-op.

Pre-operative preparation

Cystoscopy is essential. In children, this can be done under the same anaesthetic but in adults, urothelial malignancy should be excluded before embarking on cystoplasty	Patient should have been taught and practised ISC
Urine culture and eradication of infection	Mechanical bowel preparation which can be challenging in neuropathics
Group and crossmatch blood	Peri-operative rehydration
Peri-operative antibiotics	TED stockings, Heparin and IPC intra-operatively

Principles of the surgical procedure

Any additional procedure such as ureteric re-implantation or culposuspension would have been determined pre-operatively.	Access - midline transperitoneal. This also gives access for omental mobilisation. Pfannenstial incision can also be used. A midline symphysis to xiphoid incision is needed for gastrocystoplasty.
Opening of the native bladder can be sagittal, stellate or by supratrigonal excision.	Adequate tension-free length of intestinal mesentery must be ensured.
The bowel segment should be detubularised and reconfigured. Reconfiguration into spherical shape ahieves maximum volume per given surface area, blunting of intestinal contraction, improved overall compliance and a shorter bowel segment is needed to achieve a given capacity.	Err on the side of too large a bladder than too small.
All reconstructions should be performed with absorbable sutures.	The retropubic space should be drained.
Omental covering is often performed and the ileum, ileo-caecum, colon or stomach may be used.

Ileocystoplasty
Fifteen to twenty centimetres from the ileo-caecal valve is spared for bile salt enteropatic circulation and B12 absorption. Continuity of the bowel is by ileo-ileostomy and 20-40 cm is required depending on the volume of the native bladder and the desired capacity. A plate/dome/cup is formed by a U S or W reconfiguration. Anastomosis to the bivalved bladder is technically easier when commenced posteriorly.

Caecoileocystoplasty
The caecum and right colon need to be mobilised along the avascular white line of Todt. For continent reservoirs and, if a stoma is to be created for ISC, the appendix can be used. If not, appendicectomy is performed. The ileo-caecal valve with a limb of ileum may be used to fashion an antireflux mechanism if implantation of the ureters is required. Bowel continuity is by ileo-colostomy.

Colocystoplasty
The sigmoid colon is used because of its mesentery. Detubularisation and reconfiguration is particularly important because the colon generates high pressures. The large bowel is reconstituted by colo-colostomy.

Gastrocystoplasty
The antrum is used based on the left gastroepiploic vascular pedicle. Continuity is maintained by Billroth I gastrodudenostomy (Leon & Ong 1972). A wedge from the body of the stomach can also be used based on either gastroepiploic artery. Mobilisation of the vascular pedicle is often necessary to avoid tension. This part of the stomach has a high acid output. Anastomosis to the bladder is in two layers and both the stomach and the bladder are drained.

Post-operative management

Early:

• NG drainage until bowel function returns
• fluid and electrolyte management
• continue anti-thrombotic measures
• pain control - epidural, CPA etc.
• frequent bladder irrigation for mucus clearance
• copious drainage should be tested for urea and creatinine
• cystogram is performed in 2-3 weeks
• SP catheter is maintained until after leak-free cystogram and established voiding or ISC
• increased oral fluid intake must be emphasised
• initial bladder emptying should be 2-3 hourly gradually building up to 4-5 hourly
• those voiding spontaneously must check their PVR regularly

Late:

• imaging for upper tract surveillance at 6 weeks and regularly thereafter (IVU, US, KUB)
• electrolyte/urea/creatinine/acid-base monitoring
• yearly endoscopy for tumour surveillance (for 5-10 years)
• adequate fluids
• regular PVR assessment
• regular bladder washout
• prompt treatment of UTI's
  
  

Complications of Cystoplasty

Intestinal obstruction - 3% incidence reported. Ensure closure of mesenteric windows.

Diarrhoea may occur temporarily especially if a long segment of ileum is used. This is more of a problem if the ileocaecal valve is used which reduces the bowel transit time.

B12 deficiency and megaloblastic anaemia. The use of the terminal 20 cm of ileum and the removal of the ileocaecal valve are predisposing factors.

Metabolic complications - ammonium chloride re-absorption and acidosis, chronic acidosis leading to bone demineralisation and growth retardation in children and, with gastrocystoplasty, hypochloraemic alkalosis.

Haematuria and dysuria syndrome - after gastrocystoplasty.

Tumour formation - at the anastomosis.

UTI's - more common in the presence of PVR. Asymptomatic bacteruria in patients on ISC should not be treated.

Stones - bladder stones may occur in up to 30% of patients. It is more common in those who cathetise through the abdominal wall because of non-dependency. Most are struvite stones. Mucus, debris and urea splitting organism infection are predisposing factors. Regular complete bladder emptying is essential.

Delayed spontaneous bladder perforation - no particular intestinal segment is more predisposed. Patients present with abdominal pain, distension, fever, sepsis, nausea and vomiting, decreased urine output and shoulder tip pain. Cystogram is diagnostic. The aetiology is unknown but catheter perforation from ISC, shearing forces from adhesions and recurrent bladder filling and emptying, transmural infection of the bowel, ischaemia and BOO have all been suggested. Treatment is laparotomy and surgical repair.

Alternatives to Augmentation Cystoplasty

Ureterocystoplasty

Detrusor Myectomy

Seromuscular enterocystoplasty

Bladder regeneration