The primary goal of augmentation cystoplasty (AC) is a bladder that is a high-capacity, low-pressure reservoir . Potential candidates for bladder augmentation include patients that have failed medical therapy with: DLPP of approximately 40 cm H₂O or higher with signs of upper tract deterioration, incontinence secondary to detrusor overactivity, abnormal compliance leading to urinary incontinence or upper tract damage and severe autonomic dysreflexia secondary to bladder over distension.

Absolute contraindications for bladder augmentation are the inability to perform CIC (by the patient or a caregiver) and the unavailability of bowel [3]. In patients with idiopathic or neurogenic detrusor overactivity, the risk of requiring CIC after augmentation ranges from 39 to 60 % [4, 5]. The decision to augment the bladder in a patient is a multidisciplinary decision with both medical and psychosocial implications. The patient needs to understand and comply with the possibility of a lifelong, strict CIC schedule. Important factors to take into consideration before bladder augmentation are patient independence, habitus, mental illness, reliability, cognitive function, and manual dexterity. On the part of the surgeon, a long-term commitment is required for surveillance and addressing complications if needed.

The choice of segment of gastrointestinal tract used for augmentation depends on the surgeon’s experience, renal function, and the presence of factors precluding the use of various segments. In the presence of IBD or irradiated bowel, its use is a contraindication. Oftentimes AC is only one part of an operation where other concomitant procedures are done such as an antegrade enema, catheterizable stoma, and/or a continence procedure for the outlet. This may also affect the decision of what bowel segment to use.

Controversy exists in carrying out AC in patients with renal failure or LUTD as a result of interstitial cystitis (IC)/pelvic pain syndrome (BPS ). In patients with end-stage renal disease, debate exists as to the sequence of surgery, that is, should AC be performed before, after, or simultaneously with surgery for renal transplantation. The preference is often to perform the reconstruction prior to renal transplantation.

The alimentary tract was first used for AC in 1899 [6]. Initially ACs were carried out for bladder exstrophy or contracted tuberculous bladders . Over the years, the indications for AC have expanded to include all conditions that lead to low-capacity, low-compliance bladders refractory to conservative or minimally invasive therapy. Concepts that evolved over time and made AC a practical solution for patients with threatened upper urinary tracts include:

Another possibility for AC is the use of the urothelium as autoaugmentation (AA) or ureterocystoplasty . The advantages of augmenting the bladder with urothelial lining are retaining the physiologic barrier and refraining from the use of the alimentary tract and its complications, mainly mucus production, a more elaborated surgery and the risk of bowel complications.

It is difficult to arrive at conclusions regarding the success of these techniques due to a paucity of long-term reports. A study of 47 patients compared patients after AA with AC and a minimal median follow-up of 13 years. There was no difference in continence rate, upper tract status, reservoir compliance, or UTI among groups. However, following surgery, there was a significantly greater increase in bladder volume in patients with AC vs. AA [7]. More recently a study of 25 pediatric patients who had AA and were followed for a median of 6.8 years was published. Four patients had subsequent AC, all but one patient had normal renal function and 18 out of 25 were completely continent. Median bladder capacity at last follow-up was 300 mL and compliance doubled after 1 year to 10 mL/cm H₂O. This article suggested criteria for carrying out AA: 50 % or above estimated bladder capacity for patients’ age (or above 200 mL), immediate bladder recycling following surgery, and the surgical technique of hitching the detrusor flaps anteriorly and posteriorly to the rectus muscle and retroperitoneum, respectively, to prevent myotomy closure [8]. Others have not achieved good results and do not recommend this procedure [9, 10].

Since its introduction, intradetrusor BoNT-A injections have gained popularity as a minimally invasive option for the treatment of detrusor overactivity refractory to anticholinergic therapy [11]. Over the last decade, emerging data from clinical trials on patients with neurogenic detrusor overactivity have shown that this modality significantly decreases daily incontinence episodes, improves urodynamic parameters, and leads to clinically meaningful improvements in patient’s quality of life. In addition, long-term efficacy has been established with repeated injections, and side effects have been minimal [12, 13]. The increased use of BoNT-A has decreased the need for AC as patients that are refractory to medical therapy now have this option before considering AC [14, 15]. However, in patients with severely decreased bladder compliance/capacity, intravesical BoNT-A injections may not be successful. In one study of 27 patients with NDO treated with BoNT-A, 25 % had persistent urinary incontinence and 20 % ultimately underwent AC. Patients who needed subsequent AC had severely decreased bladder compliance [16].

Complications of patients following AC are usually divided into early and late.

Early complications are usually related to the surgery itself. Most common early complications cited in the literature include wound infections, vascular events, small bowel obstruction, ventriculoperitoneal shunt infection, and bleeding or persistent reservoir leakage requiring reoperation. CIC is not a complication but an expected consequence of AC [15]. The need for CIC is more frequent in AC due to neurogenic detrusor overactivity (60 %) as compared to patients with idiopathic detrusor overactivity (6 %). The need to perform CIC post-AC appears to increase with time [4].

Long-term complications as a result of AC are not rare and if untreated may lead to morbidity and potential mortality. Metabolic disturbances have been reported as a result of reabsorption of ammonium chloride or secretion of bicarbonate. These disturbances are especially significant in the presence of renal insufficiency/failure. Malignancies in augmented reservoirs have also been described. Most share common features such as a long latency period, a tendency toward adenocarcinomas as the primary histology, and development of the tumor near the enterovesical anastomosis. What is unclear is if this is primarily an issue related to the augment or the native bladder. Recent evidence suggests that congenital dysfunctional bladders are inherently prone to neoplastic transformation and are the primary risk factor for bladder cancer in this patient population [16, 17]. Mucus production may lead to reservoir stone formation and predispose to UTI with a higher incidence in those performing CIC.

Reservoir perforation occurs as a result of overdistention and noncompliance with CIC or may spontaneously occur. Diagnosis is often delayed either due to sensory deficiency in neurogenic patients or “doctors’ delay” due to its unfamiliarity among non-urologists [18, 19]. The need for re-intervention following AC is approximately 46 % [20]. Furthermore the need for subsequent open surgery following AC, in patients who need re-intervention, is approximately 50 % [21, 22]. It is important to keep in mind that clinical and radiological signs such as recurrent stone formation, new-onset hydronephrosis, UTI, urinary incontinence, or reservoir perforation may have a common denominator after AC. Poor CIC technique or noncompliance with CIC schedule may give rise to the abovementioned complications. Several studies have shown that the motivation of performing regular CIC dwindles with time [23, 24]. This underscores the importance of regular periodic clinical and radiological evaluation of patients after AC. Occasionally voiding diaries will be needed to assess reservoir functional volume and frequency of bladder evacuation. Urodynamic studies may be necessary to evaluate issues such as urinary incontinence and upper tract changes, which may be secondary to changes (or unresolved problems after the original reconstructive procedure) related to the bladder and/or outlet.

The importance of urodynamic studies prior to AC in patients with LUTD presenting with urgency, frequency, incontinence, or hydronephrosis is clear. The role of urodynamics in neurogenic LUTD, especially in spinal cord injuries, is fundamental. Several studies have shown that managing these patients on the basis of symptoms alone is misleading. Frequently the findings of urodynamic studies do not correlate with clinical symptoms [25–27]. Furthermore, urodynamics has been found to be important in the evaluation of asymptomatic patients with neurogenic LUTD secondary to spinal cord injury. In a study of 80 patients that were followed up for approximately 5½ years with yearly urodynamic studies, it was found that 96 % of patients needed treatment modifications based on these studies. In this cohort the gold standard is videourodynamics (VUD). This modality helps to clarify the consequences of the neurological insult whether it involves the bladder, outlet, or both [28, 29].

The natural history of patients with neurogenic LUTD has changed as a result of the introduction of CIC and the understanding that changes in the lower urinary tract that occur overtime lead to renal failure. Urodynamic studies have a principal role in evaluating these patients [30, 31]. Over the past three decades, in patients with spinal cord injury, the genitourinary tract has shifted from being the major cause of mortality to being the fourth in line [32, 33]. However, even with these innovations, a certain proportion of patients with neurogenic LUTD will fail conservative/minimally invasive treatment and will benefit from lower urinary tract reconstruction.

AC is an outstanding option for patients with a threatened upper urinary tract and incontinence due to refractory DO and poor compliance. Several studies have been published describing the excellent long-term outcomes of patients after AC. Some studies assessed the long-term durability of the augmented reservoir by urodynamic studies. In a study of 59 patients with heterogeneous causes for neurogenic LUTD followed up for 6.1 years, urodynamic studies were done before and 6 months after operation. Postoperatively mean bladder capacity increased from 220 to 531 mL, and mean pressure at capacity decreased from 48.9 to 15.8 cm H₂O. Complete continence was achieved in 39 patients with persistent incontinence noted in 20 patients (17 mild to moderate, 3 severe). 56 out of 59 patients used CIC. No case of deterioration in renal function was encountered during follow-up, and 53 out of 59 patients were either delighted or pleased with their current state [22].

A study of 26 patients with heterogeneous causes of neurogenic LUTD and a mean follow-up of 8 years had a 96 % complete or near-complete continence, and all were managed by CIC. At a mean of 8 years follow-up in 24 out of 26 patients, urodynamic evaluation showed a preoperative to postoperative increase in reservoir volume from a mean of 201 to 615 mL, respectively, and a decrease in maximal reservoir pressure from 81 to 20 cm H₂O. No cases of renal function deterioration were encountered during follow-up [21].

A study of 17 incontinent patients with only spinal cord-related injuries was followed up for a mean of 6.3 years after AC. 15 out of 17 patients (88.5 %) were completely continent managed by CIC. Urodynamic evaluation carried out at a mean of 5.4 years showed an increase in mean maximal cystometric capacity from mean preoperative value of 174 mL to a postoperative value of 508 mL and a decrease in mean end filling pressure from preoperative to a postoperative value of 65.5 to 18.3 cm H₂O, respectively. In this cohort during the follow-up period, no case of renal function deterioration occurred [34].

In a recent study of 19 incontinent suprasacral spinal cord injured patients, follow-up was carried out for a minimum of 10.5 years and mean of 14.7 years. All patients were incontinent before surgery and were operated by the same surgeon. Urodynamic data were available preoperatively and postoperatively at 1 year and beyond 10 years of surgery. The maximal cystometric capacity increased from a mean preoperative to 1 and 10 years postoperatively values of 229, 621, and 494 mL, respectively. On the same time scale, a mean maximal detrusor pressure decrease was seen from 81 to 41 and 28 cm H₂O, respectively. Two patients died beyond 10 years of surgery due to unrelated causes. Of the remaining 17 patients, 15 were completely dry. Of the 14 patients that completed a quality of life questionnaire, 13 patients were satisfied and would recommend AC to someone else. No cases of renal function deterioration occurred during follow-up.