Management of the Bladder and Calyceal Diverticulum

Bladder and calyceal diverticula are rare clinical entities in the pediatric population. Most of these diverticula are asymptomatic, incidentally detected, and may not require surgical intervention. However, if surgery is indicated, there are minimally invasive treatment options available that have success rates comparable with those of traditional open surgery. In addition, they offer several advantages including reduced morbidity, decreased hospital length of stay, improved cosmesis, and reduced pain medication requirements. In this review, the minimally invasive surgical techniques in the management of bladder and calyceal diverticula are discussed.

Key points

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Bladder diverticulum is a protrusion of the urothelial mucosa at a weak site of the muscular layers of the bladder.
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A calyceal diverticulum is a cavity within the renal parenchyma caused by narrowing of the forniceal or infundibular neck.
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Most of these entities are asymptomatic and may not require surgical intervention.
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If surgery is indicated, various minimally invasive treatment options including laparoscopy, robotic surgery, ureteroendoscopy, and percutaneous procedures have success rates at least equivalent to those of traditional open surgery in the pediatric population.
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Reduced morbidity, decreased hospital length of stay, improved cosmesis, and reduced pain medication requirements are potential advantages of the minimally invasive treatment modalities.

Introduction

Bladder and calyceal diverticula are rare clinical entities in children. Bladder diverticulum is defined as protrusion of the urothelial mucosa at a weak site of the muscular layers of the bladder, whereas calyceal diverticulum is a cavity within the renal parenchyma caused by narrowing of the forniceal or infundibular neck. The true incidence of both situations remains unclear because most of them are asymptomatic and may not require intervention. The estimated percentage of bladder diverticula is approximately 1.7% of symptomatic children. On the other hand, the incidence of calyceal diverticula was reported to be between 0.21% and 0.6% of in children who underwent intravenous urography. In this review, these 2 different entities are discussed separately.

Introduction

Bladder diverticulum

There are 2 types of bladder diverticula in children: congenital (primary) and acquired (secondary). Although several theories for the congenital diverticula exist, the exact etiology still remains uncertain. One theory was proposed by Stephens in 1979, who indicated that the diverticula occur because of “failure of muscle layer.” In that circumstance, either the complete absence or hypoplasia of detrusor muscle led to mucosal protrusion regardless of the normal voiding pressures. Garat and colleagues examined the histologic appearance of the bladder diverticula in 7 children after surgical excision, and concluded that detrusor muscle fibers were present in all cases. Although the muscle fibers were histologically thin, these findings support the hypoplasia theory rather than the complete absence of the detrusor layer.

It has been reported that approximately 90% of congenital bladder diverticula are located adjacent to ureteral orifices. These diverticula were first described by Hutch in 1952 after his finding of a diverticula located superolaterally to the ureteral orifice. He also demonstrated the association of vesicoureteral reflux (VUR) and the diverticula in the same study. At present, diverticula in close proximity to the ureteral orifices are commonly referred to as Hutch diverticula in accord with this first description. The appearance of a Hutch diverticula is shown in Fig. 1 . Previous reports have associated Hutch diverticula with VUR and varying degrees of renal dysplasia. In addition, 10% of bladder diverticula can be located on the posterolateral wall of the bladder and are not associated with the ureteral orifices. These diverticula tend to be large and symptomatic, whereby children with posterolateral diverticula usually present with urinary stasis, retention, recurrent infections, and stone formation.

Secondary or acquired diverticula arise secondarily to high intravesical pressures of the bladder, which may be secondary to neurogenic diseases in children such as spina bifida. In addition, nonneurogenic diseases such as bladder outlet obstruction associated with posterior urethral valves (PUV) and urethral strictures can also lead to diverticula formation. Other causes may be iatrogenic as a result of previous bladder surgery.

Genetic predisposition and syndromic association of bladder diverticula have been described in the literature. Ehler-Danlos syndrome, Williams elfin facies, and Menkes kinky hair syndrome are some of the syndromes that may lead to higher risk for bladder diverticula in children.

Most bladder diverticula are asymptomatic, small, and diagnosed incidentally during the clinical workup for urinary tract infections. The most common presentation in these children is recurrent urinary tract infections. Large diverticula may be associated with urinary stasis and incomplete emptying of the bladder, which may lead to the urinary tract infections and bladder stones. Bladder diverticula may even present with pyelonephritis, whereby VUR was associated with the diverticula in a case report. Lower urinary tract symptoms such as urinary frequency and nocturnal enuresis are other potential presenting symptoms, in addition to hematuria. Although rarely seen, some children may present with urinary retention requiring clean intermittent catheterization.

Voiding cystoureterography (VCUG) is the gold-standard imaging method in the diagnosis of bladder diverticula. VCUG also provides additional information regarding the presence of VUR and the anatomy of the posterior urethra. Renal and bladder ultrasonography (US), computed tomography (CT), and intravenous pyelography (IVP) are other imaging modalities that may be helpful in diagnosing this rare clinical entity. In patients with affected upper urinary tracts, dimercaptosuccinic acid (DMSA) renal scan elucidates the differential function of the kidney and the presence of renal scarring.

Indications and Contraindications

The absolute indications for surgical management of bladder diverticula are still undetermined. For incidentally diagnosed asymptomatic small diverticula, close observation is an acceptable treatment option. As a general guideline, large diverticula (>3 cm) are often surgically treated because these children are at higher risk for urinary tract infections, voiding difficulties, and stone formation. At the time of the diverticula resection, antireflux surgery is also commonly performed. Bowel and bladder dysfunction should begin to be addressed preoperatively. One should keep in mind that the excision of bladder diverticula in children with hypotonic bladders may not resolve the lower urinary tract symptoms. For children with secondary bladder diverticula, it is essential that the primary cause, such as PUV, urethral strictures, or neurogenic bladders, should be treated concurrently.

Minimally Invasive Management of Bladder Diverticulum

Traditionally, open surgical repair by either intravesical or extravesical approaches have been the treatment of choice for bladder diverticula. In the last 2 decades, with the advancement of the endourologic instruments, conventional laparoscopy, and robotic technology, there has been an increasing volume of reports on the minimally invasive management of bladder diverticula. The main goal of these minimally invasive techniques are to achieve success rates similar to those of open surgery but with the typical benefits of laparoscopic and robotic surgery, such as shorter stays in hospital, improved cosmesis related to smaller incisions, and reduced pain medication. Although no prospective comparative trials for open and minimally invasive treatments have been performed to date for bladder diverticula, one can speculate that the improved cosmesis and shorter stays in hospital associated with minimally invasive approaches are desired if the high success rates associated with open surgery are maintained.

Current options for minimally invasive management of bladder diverticula are endoscopic resection, fulguration, endoscopic injection of bulking agents at the neck of the diverticula, conventional laparoscopy, and robot-assisted laparoscopic surgery.

Technique

As endoscopic approaches (fulguration, injections, and so forth) have been reported elsewhere, this section focuses on laparoscopic and robotic treatment options for minimally invasive surgery for bladder diverticula in children.

The preoperative preparation and patient positioning for laparoscopic/robotic management are similar to those for other pelvic procedures such as ureteral reimplantation, orchiopexy, or bladder neck reconstruction.

Cystoscopy is strongly recommended to reveal enhanced anatomic information about the configuration of the orifices, location of the diverticula, and their associations. In addition, placing a ureteral catheter on the ipsilateral side may help to identify the ureter and the diverticulum during transperitoneal dissection for laparoscopy/robotic surgery. For the child with an extremely large posterior diverticulum, both ureters can be intubated to aid with identification. A urethral catheter is placed after prepping for bladder filling and emptying during the procedure. The patient is then positioned supine and secured to the table with tape in the Trendelenburg position to allow the intestinal contents to fall away from the pelvis. The robotic camera trocar is placed through an umbilical incision either via an open Hasson technique or with the aid of a Veress needle to create the pneumoperitoneum. The size of the camera trocar can be either 8.5 mm or 12 mm for robotic surgery, depending on the body mass index of the patient or surgeon preference. A 5- or 10-mm camera trocar can be used for conventional laparoscopy cases. Next, 2 robotic instrument ports (5 mm or 8 mm) are inserted along the axillary line at the same level of the umbilicus on each side. If a fourth accessory port is preferred by the surgeon, it can be inserted in the contralateral upper quadrant, where it can be used by the bedside assistant because it will be below the level of the robotic arms when the patient is in the Trendelenburg position. The configuration of the port placements is illustrated in Fig. 2 . Following the completion of the port placements, the surgical robot (Intuitive Surgical, Sunnyvale, CA, USA) is docked from the foot position. For tall patients, the robot can be docked from the side of the legs to allow the patient to stay in the supine position and avoid the dorsal lithotomy position and its risk for positioning injuries.

Once the camera, instrument, and assistant ports are placed, the bladder is filled with saline to visualize the bulge of the diverticulum. Afterward, a peritoneal window is created and the diverticulum is mobilized down to the diverticular neck. If the diverticulum is away from the ureter, the diverticulum is resected circumferentially using electrocautery or sharp dissection. The mucosal edges are closed using 4-0 absorbable sutures, and the muscle layers are approximated over the mucosal closure using 4-0 absorbable sutures. Alternatively, circumferential suturing can be performed at the neck of the diverticulum for the mucosal layer before resection of the diverticulum, similarly to an appendectomy.

If the ureter is in close proximity to the diverticulum, it is recommended to identify the ureter to prevent possible ureteral injury. If associated VUR on the ipsilateral side is present, extravesical ureteroneocystostomy can be carried out concurrently after diverticulum excision. The need for ureteroneocystostomy should be decided individually according to the grade of the reflux, proximity of the diverticulum to the ureteral orifice, presence of kidney scarring, and the symptoms of the patient.

Finally the watertight anastomosis is checked by filling the bladder with saline, and the specimen is removed with the use of a laparoscopic pouch. A Foley catheter should stay in the bladder postoperatively for at least 24 hours, and placement of a Jackson-Pratt drain near the operational field is optional. The surgical steps of extravesical robotic-assisted laparoscopic bladder diverticulum excision are illustrated in Fig. 3 .

Macejko and colleagues previously reported that combination of flexible cystoscopy with robotic surgery for the illumination of the diverticulum may be helpful for diverticular identification and dissection during the extravesical approach. These investigators used this technique for 2 of their patients successfully, and concluded that this combination facilitates the surgical steps. Other investigators suggested the use of 1% intravesical methylene blue during transperitoneal robotic excision of diverticulum. Similar to the illumination technique, this offers assistance in the identification of the diverticular neck. Further studies are needed to establish its utility in children.

Alternatively, an intravesical pneumovesicoscopic approach with either laparoscopic or robotic-assisted diverticula excision can be performed in children. During this approach, after pneumovesicum is achieved, the diverticulum is retracted by grasping the mucosa of the diverticular wall intravesically. It is then dissected from the bladder completely, and the defect in the bladder wall is closed with 2 layers of sutures. Reimplantation of the ureter may also be necessary. The major limitation of this approach is the need for large enough bladder capacity of approximately 250 mL, which may not available in younger children.

Complications and management

Besides the general complications of laparoscopic surgery, one of the most common complications that may occur after laparoscopic/robotic bladder diverticula excision is urinary leakage, which may be secondary to incomplete closure of the bladder defect. A Foley catheter or suprapubic drainage may be helpful for spontaneous closure of the opening. Postoperative abscess formation can be seen, and should be treated with appropriate antibiotics or drainage if necessary. Ureteral injury, urinary obstruction, and hydronephrosis are other possible complications. If the diverticulum is close to the ureter, preoperative ipsilateral ureteral catheterization may help to avoid these injuries. Many of the ureteral complications may be conservatively treated by ureteral stent placement. Injury to other pelvic structures such as the vas deferens and rectum can be seen, especially in the small pelvic space of children.

Reporting, Follow-Up, and Clinical Implications

There is no standardized follow-up protocol after the minimally invasive treatment of bladder diverticula excision. In previously reported series, serial renal US and a postoperative VCUG at the 3- to 4-month mark are the most common imaging methods. It is important to address bowel and bladder dysfunction both preoperatively and postoperatively, as this may lead to urinary tract symptoms after surgery and may affect the surgical success rate. In addition, if clinical symptoms such as urinary urgency, frequency, and incontinence arise, anticholinergic therapy and urodynamic studies may be helpful in this setting.

Outcomes

Although the minimally invasive techniques for the treatment of bladder diverticula are increasingly becoming popular, publications regarding the pediatric population are limited to a few case reports. The initial reports for laparoscopic bladder diverticulectomy were published in1992 and included adult cases. The first report of laparoscopic bladder diverticulectomy was published in 1994 in a 6-year-old boy who underwent simultaneous nephroureterectomy and diverticulectomy. More recently, a pneumovesicoscopic approach was described by 2 different investigators. Badawy and colleagues reported 3 children with bladder diverticula who underwent pneumovesicoscopic diverticulectomy. The mean operative time was 133 minutes, and the patients were discharged home on the second day. Postoperative imaging confirmed the success of their procedures in all 3 cases. Other investigators reported 6 children with a mean age of 5.6 years. The mean operative time was 110 minutes and no complications were encountered. Postoperative VCUG at 3 to 6 months after surgery confirmed the success of these procedures.

The first report of robotic-assisted bladder diverticulectomy in children was in 2009 by Meeks and colleagues, who performed this procedure in a 12-year-old boy with a 12-cm diverticulum. More recently, Christmann and Casale presented their experience with robotic diverticulectomy in 14 children. The mean patient age was 7.9 years and all children underwent a transperitoneal extravesical approach. The mean operative time including cystoscopy was 132 minutes, and most of the patients were discharged 1 day after surgery. All children were catheterized for 1 day. Postoperative urinoma or retention was not noted in any of the patients. The symptoms of the 6 patients who had diurnal enuresis preoperatively were all resolved within 3 months.

Current Controversies and Future Considerations

One of the controversies of bladder diverticula is the presence of VUR and its management. In earlier publications, it has been proposed that the presence of bladder diverticula decreases the spontaneous resolution of VUR in children. Therefore it has been recommended that ureteroneocystostomy should be carried out if surgery is planned for periureteral diverticula. Reports with a different viewpoint have been published more recently. Afshar and colleagues reported on 141 children with periureteral diverticula associated with various degrees of VUR, whereby they assessed the spontaneous resolution rates of these children in comparison with a control group consisting of 95 patients with primary VUR during a median follow-up of 47 months. In both groups the resolution, persistence, and the necessity of VUR correction rates were noted to be similar (diverticula patients: 43%, 27%, 30%, respectively; control patients: 44%, 31%, 25%, respectively). The investigators concluded that the natural history of VUR is similar in children with accompanying bladder diverticula, and therefore the treatment strategy for VUR patients with or without diverticula should remain the same.

Another controversy concerns the use of minimally invasive surgical approaches. The cumulative data in the literature reveals similar operative times and success rates for both intravesical and extravesical approaches. Therefore, laparoscopic or robotic-assisted laparoscopic approaches remain as viable options for the treatment of bladder diverticula, and are subject to patient and surgeon preferences as well as the availability of the equipment. The advantages of robotic technology such as improved ergonomics for the surgeon, tremor cancellation, 3-dimensional visualization, and wrist-like movement do offer advantages over laparoscopy, and are especially helpful for reconstructive procedures of the bladder and ureter when suturing is used.

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