Augmentation Cystoplasty in Children



Augmentation Cystoplasty in Children


NORA G. LEE

HANS G. POHL



Dedicated to W. H. Hendren, whose creative use of intestine in urologic reconstruction, I have been honored to observe.

Neuropathicity, bladder outlet obstruction, or embryologic abnormalities may result in a bladder too small or too hypertonic to provide normal storage and evacuation of urine. The goal of augmentation cystoplasty in the pediatric patient is to provide a sufficiently capacious reservoir that stores urine at low pressure and as a result improves urinary continence and prevents upper urinary tract deterioration. A variety of complications are possible following enterocystoplasty including, but not limited to, metabolic derangements, calculus formation, gastrointestinal disturbances, and spontaneous perforation. In this chapter, we will discuss the options for using stomach, bowel, and ureter in augmentation cystoplasty.





INDICATIONS FOR SURGERY

When urodynamic evidence exists that nonoperative measures have failed, augmentation cystoplasty is indicated. Intravesical storage pressure that has been demonstrated to be greater than 40 cm H2O is the most robust indication for augmenting the bladder. Incontinence and urinary tract infections, with or without vesicoureteral reflux, are associated symptoms that may benefit from enterocystoplasty. However, a thorough evaluation is warranted in order to ascertain what type of augmentation to perform and whether a secondary procedure is indicated in addition to enterocystoplasty to provide continence and/or prevent upper tract deterioration.


Evaluation of Anatomic and Functional Characteristics


Vesicoureteral Reflux

Vesicoureteral reflux, found in 3% to 5% of newborns with neuropathic bladder dysfunction (detrusor hypertonicity and detrusor-sphincter dyssynergia), increases in prevalence when clean intermittent catheterization (CIC) and anticholinergic medications have not been initiated at birth: 30% at age 5 years and up to 60% in older children (1,2). Conversely, vesicoureteral reflux (VUR) resolves in 30% to 55% of patients with neuropathic bladders when CIC and anticholinergics are instituted (3,4,5). Since the combination of urinary infection, detrusor hyperreflexia, and VUR poses a significant risk for renal scarring, antireflux surgery should be considered at the time of augmentation cystoplasty when reflux is high-grade or recurrent symptomatic urinary infection has occurred. However, reimplanting ureters into a thick-walled bladder is challenging technically and has been associated with postoperative ureteral obstruction, leading some to consider augmentation without ureteral reimplantation. When children with neuropathic bladders and VUR have undergone augmentation cystoplasty alone, VUR has frequently resolved or been significantly downgraded without the need for reimplantation, even in cases of high-grade VUR (6).


Sphincteric Incontinence

Sphincteric incontinence may coincide with detrusor hyperreflexia in which case a procedure to increase bladder outlet resistance is indicated at the time of augmentation. If bladder outlet surgery is entertained in conjunction with enterocystoplasty, the incontinence procedure should be performed prior to opening the peritoneal cavity in order to minimize insensible fluid loss. In addition, it is of critical importance that the surgeon ascertains that the bladder neck procedure does not make catheterization difficult because ineffective emptying can lead to any one of a number of complications, thus mitigating the benefits of enterocystoplasty.


Evaluation of the Bowel

In the child with no prior history of bowel resection or gastrointestinal comorbidity, it is generally not necessary to evaluate the intestinal tract. However, radiologic imaging is essential in patients with intestinal atresia, intestinal malrotation, and imperforate anus because it is likely that anatomic abnormalities or prior surgical intervention would obviate the use of specific bowel segments. In the most severe circumstances, urogenital and anorectal anomalies coexist (cloacal exstrophy and cloacal malformation) and require an individualized and often creative use of intestinal segments in order to provide urinary storage and emptying, evacuation of feces, and sexual function, whereas alimentary function is preserved. These cases will not be discussed because they are beyond the scope of this chapter. However, helpful references are available to assist the urologic surgeon in the proper management of these patients (7).


ALTERNATIVE THERAPY

Bladder dysfunction should initially be treated with anticholinergic medications and CIC in an effort to diminish uninhibited bladder contractions, improve compliance, and provide regular and effective bladder emptying. Also, injection of botulinum toxin into the detrusor wall has been shown to improve bladder dynamics and postpones the need for augmentation cystoplasty.


SURGICAL TECHNIQUE


Preoperative Counseling

Preoperative preparation must include a thorough review of the anticipated goals of the surgery with the parent and patient, when he or she is an older child or adolescent. During this meeting, the family’s ability to comply with the postoperative care of a bladder augmented with bowel must be assessed. When CIC has been performed preoperatively, the postoperative catheterization and irrigations are more readily adhered to. Urinary infection, bladder calculi, or perforation may result when routine emptying and augment cleansing is not performed regularly. Table 107.1 outlines the most common complications of augmentation cystoplasty in the early and late postoperative periods. Some complications are specific to the method of augmentation cystoplasty performed, but the most serious, perforation, occurs whenever CIC is not rigorously performed and is not restricted to any one type of enterocystoplasty.


Preoperative Bowel Preparation

The patient with neurogenic bladder dysfunction is likely to have coexistent constipation, thus necessitating that the bowel
preparation be started well in advance. The patient should be contacted with explicit instructions to begin clear liquids at home 2 days prior to surgery and to arrive early for a preoperative admission 1 day prior to surgery. Intravenous fluids should be started at the same time that the patient begins ingestion (orally or by nasogastric tube) of GoLYTELY solution (Table 107.2). Enemas and oral antibiotics are administered as well following completion of the GoLYTELY prep, depending on the severity of the patient’s fecal load and estimated efficacy of the oral bowel prep. For patients with marginal renal function, the use of phosphate containing laxatives is contraindicated. Instead, twice-daily oral administration of polyethylene glycol 3350 beginning 3 days preoperatively as an adjunct to a clear liquid diet is sufficient to clear most children.








TABLE 107.1 TYPES AND INCIDENCES OF COMPLICATIONS FOLLOWING PEDIATRIC AUGMENTATION CYSTOPLASTY



























Preoperative Counseling and Informed Consent


Bleeding (pelvic hematoma)


Infection (more common after colonic than ileal anastomosis)


Small bowel obstruction


Urinary leak


Ureteral stricture


Vesicoureteral reflux


Bladder calculi


Metabolic abnormalities


Poor somatic growth


Hematuria-dysuria syndrome


Excoriation around stoma site



Selection of Bowel Segment to Use

There is no ideal segment of bowel for augmentation cystoplasty; each has a set of characteristics that are advantages or liabilities depending on the clinical scenario (Table 107.3). The following section will review the aspects of each intestinal segment that sets it apart from the remainder in the context of the results and complications following enterocystoplasty. It should be noted that none of these complications are seen following ureterocystoplasty, making it the ideal tissue for bladder augmentation (8,9). However, it is a procedure ideally performed in a patient with a severely dilated ureter that subtends a nonfunctioning kidney. Ironically, most patients with neuropathic bladder dysfunction rarely present with such anatomy as a result of close followup and the early institution of anticholinergic medications and CIC. Currently, boys with posterior urethral valves are most likely to present with severely hydronephrotic kidneys and massively dilated ureters that can be used to augment the bladder. In those circumstances, ureterocystoplasty has achieved comparable capacity and compliance as with enterocystoplasty (8).








TABLE 107.2 COMMONLY UTILIZED BOWEL CLEANSING PERFORMED PRIOR TO AUGMENTATION CYSTOPLASTY







































GoLYTELY-Based Bowel Prep


Weight (kg)


Volume infused every 10 min (mL)


Total volume infused (mL)


<10


80


1,100


10-20


100


1,600


20-30


140


2,200


30-40


180


2,900


40-50


200


3,200


>50


240


4,000


Neomycin base 25 mg/kg × 3


Erythromycin base 20 mg/kg × 3


Saline enemas until clear



Intraoperative Preparation of the Patient

The patient is positioned supine on the operating table. General anesthesia with endotracheal intubation is mandatory; however, if no spinal abnormality exists that contraindicates the use of an epidural catheter, consideration should be given to regional anesthesia as well. The surgical field is prepared and draped from the xiphoid process inferiorly, including the genitalia. A Foley catheter is inserted urethrally. A midline incision is created beginning at the symphysis pubis an extending superiorly toward the umbilicus. In order to avoid the insensible loss of heat and water from peritoneal surfaces, it is recommended that any concomitant procedures on the bladder or bladder neck be performed through a limited incision that does not enter the peritoneal space. Retraction can be provided by either a Denis Browne or Bookwalter retractor at this point.


Preparation of the Bladder for Cystoplasty

When a continent diversion is not planned, a midline cystotomy suffices to prepare the bladder for augmentation (Fig. 107.1). Ureteral reimplants can be easily performed at this point. However, when a continent catheterizable stoma is planned, either a paramedian or transverse cystotomy should be considered since these incisions create bladder flaps that facilitate the creation of a long submucosal tunnel for the appendix or ileal tube. Regardless of the bladder incision created, it must be sufficiently long to open the bladder widely. If the cystotomy is too short, the augmented segment may behave as a diverticulum, thus facilitating urinary stasis and stone formation. Once the bladder has been prepared, the midline incision is carried above the umbilicus and the peritoneum is entered. Retraction at this point is provided by a Bookwalter retractor.

Should one encounter an augmented bladder in which the intestinal segment has formed a pseudodiverticulum the following technique has been helpful. Create a cystotomy incision that transects the anterior lip of the opening into the intestinal segment. Through this cystotomy, incise
the posterior lip of the opening with electrocautery until it is seen to spring open. This incision is not full-thickness. This defect should be closed transversely with continuous 3-0 polyglycolic acid (PGA), thus completing a Heineke-Mikulicz-like repair. The anterior cystotomy should then be closed transversely as well. (Author’s personal observation of W. H. Hendren)








TABLE 107.3 COMPARISON OF GASTROINTESTINAL SEGMENTS IN PEDIATRIC AUGMENTATION CYSTOPLASTY








































































Advantages


Disadvantages


Ileum


Most compliant


Diarrhea



Less mucus


Vitamin B12 deficiency


Short mesentery


Hyperchloremic acidosis


Poor muscle backing


Sigmoid


Readily mobilized


Unit contractions



Easily implanted


Lower compliance



Good muscle backing


Mucus




Hyperchloremic acidosis




Perforation risk


Ileocecal


Valve as antireflux/continence mechanism


Diarrhea



Good capacity reservoir


Not always available



Constant blood supply


Contractile


Stomach


Short gut/radiation


Hypochloremic alkalosis



Chloride pump


Rhythmic contractions



Minimal mucus


Hematuria/dysuria



Fewer infections




Ease of implantation




Good muscle backing








FIGURE 107.1 A: Preparation of the bladder for clam augmentation cystoplasty. B: Sagittal incision is made to create two bladder flaps.


Ileocystoplasty

Ileum is by far the most popular segment used for bladder augmentation. The segment, 20 to 25 cm long, is based on a pedicle that is supplied by branches of the superior mesenteric artery and that is sufficiently mobile to be brought into the pelvis (Fig. 107.2). On occasion, an abnormally thick, fatty, or short mesentery can limit mobility of the vascular pedicle, thus necessitating extensive division of the mesentery posteriorly. The terminal 15 to 20 cm of ileum, as measured from the ileocecal valve proximally, is spared in order to retain bile salt absorption, thus preventing steatorrhea and vitamin B12 deficiency (Fig. 107.3). The portion of ileum to be used is measured, and 5-0 silk sutures used to mark the proximal and distal limits of resection. Prior to dividing the mesentery, the vascular supply to the isolated segment should be observed by transillumination and the proposed incisions in the mesentery marked. Beginning at the mesenteric border of the bowel, the mesentery is divided between pairs of fine hemostats, and the vascular arcades are ligated with 5-0 silk suture ties. The bowel is then divided between atraumatic bowel clamps that have been applied at the proximal and distal limits of resection. Once the ileal segment reaches into the pelvis without tension on the vascular pedicle, no further mesenteric division is needed. An ileoileal anastomosis is performed cephalad to the isolated ileal segment and the mesenteric trap is closed. The bowel clamps are removed and a thorough lavage of the ileal segment is performed with sterile saline. It is the preference of the authors to configure the ileal segment into a U configuration (Fig. 107.4). The antimesenteric border of the ileal segment can then be opened using scissors or the cutting current with little concern for bleeding that usually ceases spontaneously. The segment is folded 180-degrees and the adjoining edges are sutured as full-thickness using continuous locking 4-0 PGA. Once the ileal cap has been formed, it is anastomosed to the opened bladder beginning at the most posterior portion of the bladder incision (Fig. 107.5). Hemostatic clamps may be left on the short ends of the tied sutures in order to identify
the most posterior limit of the anastomotic line, thus facilitating placement of the second, reinforcing suture layer between the serosal surfaces of the bladder and ileum. A suprapubic catheter is placed through the bladder wall prior to completion of the first anastomotic closure (Fig. 107.6).






FIGURE 107.2 Blood supply to the jejunum, ileum, and ascending and transverse colon. (Reprinted with permission from Hinman F Jr, ed. Gastrointestinal tract. In: Hinman’s Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)






FIGURE 107.3 Ileocystoplasty. A: 20- to 40-cm segment of ileum at least 15 cm from the ileocecal valve is removed and opened on its antimesenteric border. Ileoileostomy reconstitutes the bowel. B: The opened ileal segment is reconfigured. This can be done in a U, S, or W configuration. It can be further folded as a cup patch. C: The reconfigured ileal segment is anastomosed widely to the native bladder. (Reprinted with permission from Adams MC, Joseph DB. Urinary reconstruction in children. In: Wein AJ, Kavoussi LR, Novick AC, et al, eds. Campbell’s Urology, 9th ed. Philadelphia: WB Saunders, 2007.)

Only gold members can continue reading. Log In or Register to continue

Apr 24, 2020 | Posted by in UROLOGY | Comments Off on Augmentation Cystoplasty in Children
Premium Wordpress Themes by UFO Themes