Augmentation Cystoplasty Technique

Candidates for bladder augmentation have 2 less invasive surgical options available to them that may be considered before augmentation cystoplasty is carried out:

• Cystoscopic injection of onabotulinumtoxinA

• Sacral nerve stimulation (SNS; also referred to as sacral neuromodulation) ^[22]

OnabotulinumtoxinA injections are used in some patients with overactive bladders and may benefit bladder-augmentation candidates. Some small studies have shown significant increases in bladder volumes, often exceeding those seen with oral medications. ^{[23, 24, 25]} However, this treatment may not be adequate or durable in patients with extremely reduced bladder compliance or volume. These injections have improved quality-of-life scores in many patients who have neurogenic incontinence despite oral anticholinergic therapy. ^[26]

In a small study of 26 children with neurogenic bladders refractory to conventional treatment, repeated injections of onabotulinumtoxinA failed to produce sufficient changes in urodynamic variables, with urinary continence achieved after the first, second, and third injections of 50%, 77%, and 75%, respectively. ^[27]

A study by Anquetil et al suggested that in patients with spinal cord injury who have a refractory overactive detrusor, those who undergo augmentation cystoplasty have a better quality of life than do those who are treated with botulinum toxin. Among the 14 patients in the study who received botulinum toxin injections and the 16 who underwent augmentation cystoplasty, the latter group scored higher on the Qualiveen-30 questionnaire. Moreover, 14 patients in the augmentation cystoplasty group (87.5%) were completely continent, compared with just 6 patients who received botulinum toxin (42.9%). ^[28]

SNS is a minimally invasive technique that has markedly improved bladder volume, urge symptoms, and incontinence rates in patients with detrusor overactivity and urge urinary incontinence. It has also been shown to help patients with urinary retention who have high residual volumes after voiding.

In the first stage of SNS, tunneled leads are placed, usually in the S3 foramen. After a trial of efficacy with an external device, the implantable neuromodulator is implanted in the second stage. Initial experience has shown SNS to be promising as a means of averting major surgery in adult and pediatric patients who would otherwise be candidates for augmentation cystoplasty. Long-term follow-up is limited, but the available evidence suggests that SNS should be a durable option. ^[29]

When medical treatment, behavioral modifications, and other less invasive options all fail, formal surgical therapy with augmentation cystoplasty is warranted. Failure is defined as debilitating urinary symptoms (eg, frequency, urgency, or incontinence) or high bladder-storage pressures (>40 cm H₂O) that risk damage to the renal parenchyma.

Counsel patients regarding the risks, benefits, requirements, and lifestyle impact of the operation. When deciding among urinary conduit diversion, orthotopic bladder substitution, and augmentation cystoplasty, take into account the patient’s renal function, serum acid or base status, and potential need for dialysis. Also consider procedures that can be performed as alternatives or as adjuncts to augmentation cystoplasty, including sling procedures, urethral lengthening, appendicovesicostomy, and bladder neck closure.

Either of the following 2 methods can be used to prepare the bladder:

• A U-shaped flap can be lifted with its base anterior on the bladder

• The bladder can be opened via a sagittal incision extending from an anterior position posteriorly to the trigone

If part of the bladder is being removed to prevent symptom recurrence (as, for instance, in patients with interstitial cystitis), the bulk of the bladder may be excised around the trigone. In this case, an orthotopic bladder substitution or continent urinary diversion may be a better option. The anastomosis should be widely patent so as not to create a poorly draining diverticulum.

General principles of using enteric segments

A standard midline laparotomy incision is most often used, though a lower abdominal transverse incision can be used for some nongastric enteric segments.

Before dividing the intestine, test the mobility of the segment to ensure that it will reach the bladder without tension. Always create a vascular arcade within the mesentery to the isolated bowel segment. After reestablishing the continuity of bowel segments, mesenteric defects should be closed to prevent internal hernia formation. To prevent ischemic necrosis, small bowel should not be divided more than 8 cm from an arcade artery.

The abdomen should be packed and draped carefully to prevent contamination of the surgical field with enteric contents. Enteric segments should be irrigated thoroughly to remove gastrointestinal (GI) contents.

Intestinal segments should be detubularized by incising them with a cautery on the antimesenteric side to create a rectangular surface and to minimize forceful contractions in the augmented bladder (see the image below).

Intestinal segments should be sutured through their full thickness with a continuous absorbable suture, and the mucosal layer should be inverted. Forming the intestinal segment into a semispherical shape gives the augmented bladder maximal capacity and compliance. A wide anastomosis between the segment and the native bladder is important for optimal volume and drainage.

A suprapubic tube should be placed through the opened bladder and brought out through a separate skin incision. A drain is placed near the bladder as an indicator for urinary leakage.

Ileocystoplasty

The ileal segment should be based 15-20 cm away from the ileocecal valve to preserve the absorptive function of the terminal ileum. It should be between 15 and 40 cm long (usually about 25 cm), depending on patient age and the desired augmentation of bladder volume. A slightly longer segment is preferable to one that is too short.

Once the rectangular patch is formed, it is folded and sutured into a U-shaped cup; longer segments can be folded into S- or W-shaped cups (see the image below).

A vesicointestinal anastomosis is then performed in 1-2 layers with a 2-0 absorbable suture (see the image below).

Sigmoid cystoplasty

The sigmoid colon is the part of the large intestine that is most commonly used as an augmentation segment. A sigmoid segment should be 15-20 cm long. Because of the strength of sigmoid contractions, proper detubularization of this segment is of particular importance.

The surgical incision and exposure are similar to those used in ileocystoplasty. The sigmoid segment is inspected and palpated to ensure that no pathology is present. The flap is then folded and sutured into an S- or U-shaped segment and anastomosed to the bladder in 2 layers with an absorbable suture.

Ileocecocystoplasty

An ileocecal segment is often used for patients who require a catheterizable stoma. The terminal ileum is narrowed over a catheter, and the continence mechanism of the ileocecal valve is supported by imbrication and intussusception of the ileocecal junction.

Gastrocystoplasty

A midline incision is made from the xiphoid process to the pubic symphysis. A 10-20 cm wedge of anterior and posterior stomach is isolated, with the base along the greater curvature of the stomach. The apex should not extend to the lesser curvature, where branches of the vagus nerve can be damaged. The vascular segment used for the flap can be the right or left gastroepiploic artery; however, the right is often favored because it is more frequently the dominant blood supply to the stomach.

The stomach is reapproximated with 2 layers of absorbable sutures. Windows are created in the transverse mesocolon and the mesentery of the small intestine, and the gastric wedge is brought to the prepared bladder. Care should be taken to avoid twisting or angulating the vascular pedicle. The augmenting segment is anastomosed to the bladder with 2 layers of absorbable sutures.

Ureterocystoplasty

Ureterocystoplasty is possible only when the patient has massive ureteral dilation. The dilated ureter can be mobilized into the pelvis. The bladder is opened in the sagittal plane, and the posterior portion of the incision is directed toward the corresponding ureteral orifice.

The ureter is not separated from the bladder but is folded upon itself as a patching segment. It is then anastomose the ureter to the prepared bladder with an absorbable suture. If ipsilateral nephrectomy is not performed, care must be taken to the preserve proximal ureteral blood supply.

Other options

Autoaugmentation (also called detrusor myectomy) involves incising or excising the serosa and muscular components of the bladder dome and allowing the mucosa of the bladder to protrude. The mucosa may then be either left alone or supported by a cover of omentum or demucosalized bowel. Autoaugmentation can increase bladder volume and improve detrusor compliance without using enteric segments, thereby reducing surgical morbidity significantly.

Laparoscopic augmentation cystoplasty is becoming increasingly common at many institutions. The primary goal of this procedure is to adhere to the surgical principles of the open procedure outlined above. Many surgeons create a lower midline or transverse incision to perform some parts of the procedure extracorporeally and to assist with some of the reconstructive elements of the operation.

Intravenous (IV) fluids and nasogastric drainage are initially maintained for several days until the patient’s bowel function returns. Fluid status and electrolyte levels are monitored clinically. Nasogastric tube decompression is typically maintained until bowel function is recovered, though some studies have found that this does not decrease early postoperative complications.

Typically, a urethral Foley catheter and a suprapubic tube are used to drain the bladder, with the latter exiting the abdomen directly or through the catheterizable stoma. The bladder should be manually irrigated 3 times daily and as needed to clear mucus from the suprapubic tube and the urethral Foley catheter. The pelvic drain can be removed when concerns about urinary leakage have been eliminated, either by low output or by fluid chemistries indicating peritoneal fluid.

The patient is discharged with the capped suprapubic tube in place and a urethral catheter draining the bladder. Taping the suprapubic tube to the abdomen can prevent unintentional manipulation. Low-dose antibiotic prophylaxis is continued for about 3 weeks postoperatively, until all catheters and drains are removed. During the first few postoperative weeks, the urethral catheter is removed, and the patient should begin catheterization at 2- to 3-hour intervals. The suprapubic tube should be irrigated 3 times daily to clear mucus.

Cystography performed 2-3 weeks after surgery should confirm the augmented bladder’s integrity before the tube is removed. To avoid false-negative findings for urinary leakage, cystography should be performed with at least 300 mL of contrast.

After removal of the suprapubic tube, patients may gradually increase the interval between intermittent catheterizations to 4 hours. They should wake up at least once per night to catheterize.

Patients without neurologic deficits may try to void, but postvoid residual volumes must be checked to ensure adequate emptying.

Perforation

Approximately 6% of patients who undergo augmentation cystoplasty experience perforation. ^[30] These patients may present with various signs and symptoms, including acute abdomen or a vague illness with nausea, vomiting, fever, or abdominal distention. Patients are generally quite ill, and sepsis and death are possible.

Neurologically impaired patients with decreased abdominal sensation may present with different symptoms or may present later in the course than patients without neurologic impairment.

Traditional or computed tomographic (CT) cystography (imaging after retrograde administration of intravesical contrast) is the best method of evaluation if the patient is clinically stable. Patients diagnosed with perforation of the augmented bladder and those who are hemodynamically unstable with suspected perforation require urgent operative exploration and repair.

Early perforation usually occurs along the anastomosis and is usually due to poor healing or technical issues. The etiology of late perforation is unclear; however, ischemia, infection, inflammation, or overdistention may be involved. Injury with self-catheterization may be responsible for some cases of perforation. Rivas et al showed in an animal model that augmented bladders stressed with infused volume tend to rupture within the dome (7 of 11 cases) and at a suture line (4 of 11 cases). ^[31]

Consultation with a neurosurgeon should be considered in patients with a ventriculoperitoneal shunt who experience bladder perforation.

Urolithiasis and mucus

Stone formation, both of the kidney and of the bladder, occurs in 18-50% of patients after augmentation. Struvite is the most common stone composition; thus, treatment should be initiated immediately for bacteriuria with urea-splitting organisms.

Other risk factors for stone formation include incomplete emptying (by poor voiding or by catheterization through a stoma) and increased mucus (which can serve as a nidus for stone formation). Large intestine creates more mucus than small intestine, and gastric patches produce little mucus. Gastrocystoplasty is also slightly protective against stones because of the increased acidity, which minimizes bacteria.

At present, there are no uniform recommendations to guide the metabolic workup in patients with augmented bladders who form stones. A 24-hour urine profile for pH, volume, citrate, calcium, phosphorous, oxalate, and sodium, along with serum electrolytes and urine culture, is appropriate. A surveillance abdominal plain film obtained annually may be used to identify a few small stones before they grow into multiple large stones that require more involved treatment.

Treatment options for stones in the augmented bladder include the following:

• Extracorporeal shockwave lithotripsy

• Endoscopic fragmentation or removal through the urethra or a catheterizable stoma

• Percutaneous fragmentation or removal

• Open surgery

In addition to serving as a nidus for urolithiasis, mucus can obstruct the outlet and increase the possibility of infection or perforation. Daily irrigation may decrease the risk of these complications. Irrigants can include tap water, saline, urea, N-acetylcysteine, or 3% sodium chloride.

Metabolic derangements

Except for stomach segments, which cause hypokalemic hypochloremic metabolic alkalosis, most intestinal segments used for augmentation cystoplasty can cause metabolic acidosis (see Table 2 below). ^[32]

Table 2. Metabolic Changes Caused By the Use of Various Tissues in Augmentation Cystoplasty (Open Table in a new window)

Jejunal segments, which are rarely used, can cause volume contraction and hyperkalemia, whereas ileal and colon segments can cause hyperchloremia. The acidosis caused by these segments is of concern in younger patients who are susceptible to growth retardation and bone density loss due to occult or recognized acidosis. The exact mechanism has yet to be elucidated, but oral bicarbonate replacement may obviate some of these effects.

In addition, patients with baseline renal insufficiency are at significantly greater risk for the development of marked serum acidosis. This can manifest as weakness, fatigue, thirst, and failure to thrive. Screening for patients who need bicarbonate replacement is also helpful in this setting.

Because of the effects on volume and electrolytes, the use of jejunal segments is typically avoided in bladder augmentation, urinary reservoirs, and urinary conduits. The use of gastric segments may decrease the potential need for bicarbonate replacement in patients with renal insufficiency who have acidosis; however, severe metabolic derangements may still develop. Rink et al reported on episodes of severe hypokalemic hypochloremic metabolic alkalosis developing after GI illness. ^[33]

Hypercontractility and hypocontractility

Hypercontractility and poor compliance are more common with the use of sigmoid bowel segments but can occur with any segment despite adequate detubularization. In some cases, this complication can necessitate reaugmentation.

Hypocontractility of the augmented bladder with incomplete voiding is also a possibility that patients should understand before surgery. Patients must be physically and emotionally prepared to perform intermittent catheterization for life.

Incontinence

Incontinence may occur if the enteric segment used for augmentation provides insufficient volume or has forceful contractions. Preoperative assessment of urine output is helpful in determining the desired volume for the augmented bladder. In addition, proper detubularization is crucial to prevent forceful contractions of the enteric segment, especially when sigmoid colon is used.

Retained mucus or stones may reduce the effective volume of the augmented bladder, and urine may leak through a poorly constructed catheterizable stoma. Urinary tract infection (UTI) may also lead to detrusor instability and incontinence. Poor outlet resistance at the bladder neck or external sphincter will cause urinary leakage if it is not diagnosed before augmentation cystoplasty and addressed at the time of surgery.

Hematuria/dysuria syndrome

A symptom complex characterized by hematuria, dysuria, or both occurs with voiding or catheterization in as many as 33% of patients after augmentation gastrocystoplasty. Continence is particularly important in patients with gastrocystoplasty because of the perineal and peristomal skin irritation that can occur as a consequence of low urine pH. Patients with renal insufficiency, low urine volume (acting as acid buffer), incontinence, and a sensate abdomen and pelvis may be at an increased risk for this syndrome.

Treatment options include type II histamine blockers or proton pump blockers, and failed medical treatment may necessitate takedown and reaugmentation with ileum.

Malignancy

Augmented bladders appear to be at greater risk for malignancy. ^[34] Adenocarcinoma is the most commonly observed tumor, and all segments seem to be associated with the same level of risk. The average time to malignancy after augmentation is around 2 decades, but cancer has been found as early as 4 years after surgery.

For this reason, some begin surveillance cystoscopy as soon as 2 years after surgery. Filmer and Spencer recommend that patients with augmentation cystoplasty undergo yearly cytology and endoscopy and that they undergo biopsy beginning 10 years after surgery. ^[35] Some advocate general anesthesia during surveillance cystoscopy, on the grounds that thorough examination is crucial and should not be limited by patient discomfort.

Small bowel obstruction

Approximately 3% of patients may develop a small bowel obstruction at any time after augmentation cystoplasty. Parastomal hernia, internal hernia, and volvulus can also occur.

Diarrhea

Diarrhea can result from the removal of the ileocecal valve from the intestinal tract in the course of the augmentation procedure. This is more likely in pediatric patients with neurogenic bladder and intestinal dysfunction. Removal of the ileocecal valve may yield a decreased stool transit time or may allow retrograde colonization of the distal small intestine, with fat malabsorption in this segment. Increased delivery of bile salt to the colon may cause secretory diarrhea.

Other complications

The removal of the terminal ileum from the alimentary tract leads to compromised vitamin B-12 and bile salt reabsorption. In addition, retrograde colonization of colonic bacteria into the small bowel can interfere with absorption. These can lead to megaloblastic anemia and diarrhea.

Early satiety after gastrocystoplasty is uncommon and is usually self-resolving.