January 6, 2009 Leave a comment
A bladder diverticulum is the protrusion of mucosa through the detrusor muscle fibers as a result of a structural defect (congenital or primary diverticulum) or of chronic dysfunction of bladder voiding (diverticulum secondary to obstructive pathology of the lower urinary tract). The diverticulum wall is composed of the following layers from inside out: mucosa, subepithelial connective tissue or lamina propria, isolated and thin muscle fibers, and adventitial tissue. The most frequent causes provoking an increase in bladder voiding pressure and the eventual formation of diverticulum are benign prostatic hyperplasia, urethral strictures, contracture or sclerosis of the bladder neck, urethral valves, and vesicosphincteric dyssynergy. The diverticula are located in the weakest points of the bladder, such as the ureteral hiatus (paraureteral or Hutch diverticulum) and both posterolateral walls.
Diverticula are most commonly found on ultrasonography performed for the study of a prostatic syndrome in men or repeated urinary infections in women. Echography is highly useful for assessing whether a diverticulum is inhabited by lithiasis or tumor, although endoscopic examination should be performed if intradiverticular pathology is suspected or hematuria is present. Cystograms obtained by excretory urography or by retrograde instillation of contrast medium may provide the same information as ultrasonography with regard to the number, location, size, and urinary retention volume of the diverticulum. However, a voiding cystourethrogram with lateral and oblique projections will be indispensable when a urethral obstructive cause is suspected or in congenital cases to rule out possible vesicoureteral reflux.
Differential diagnosis should be established with the “pseudodiverticular” images observed in cystograms: bladder ears, hourglass bladder, and vesical hernias. On ultrasound, they should be differentiated from urachal cysts, prostatic utricle cysts, or Müllerian duct cysts and blind-ending bifid ureters. Other less-frequent congenital anomalies should also be considered, such as vesicourachal diverticulum, incomplete bladder duplication, and septation of the bladder, which may be mistaken in both examinations.
INDICATIONS FOR SURGERY
The presence of intradiverticular disease (tumor or lithiasis), spontaneous diverticular rupture, or complications related to the size (³4 cm diameter) or location of the diverticulum are absolute indications for open surgery. A large diverticulum may be the cause of deficient voiding and chronic urinary infection or obstruction of the ureter and even of the posterior urethra in children, whereas paraureteral or hiatal diverticulum are usually associated with different degrees of reflux.
With the aim of improving vesical voiding, we recommend the simultaneous resection of all bladder diverticula, even those of small size (1 to 3 cm diameter) if the patient must undergo open prostatectomy, cystolithotomy, ureteroneocystostomy, or Y-V plasty of the bladder neck. Similarly, a vesical diverticulum should never be operated on without previously or simultaneously correcting the cause of obstruction, whether anatomic or functional (neurogenic bladder), that provoked it.
A “wait-and-see” approach may be adopted in children with asymptomatic small-sized (rare) congenital or paraureteral diverticula and with low-grade associated reflux. Saccules and small diverticula may be treated successfully by electrocoagulation of their mucosa with the ball electrode when the primary obstructive disease is endoscopically resolved. However, we do not consider the laparoscopic approach to a diverticulum to be indicated because it will not solve the cause and will prolong surgery.
The bladder is approached via an infraumbilical midline extraperitoneal laparotomy incision. The dissection is carried into the space of Retzius with a sponge stick, and anterior bladder wall and vesical neck are identified. After reflecting the peritoneum from the bladder dome, we normally perform transverse cystotomy at this level, as it provides better exposure of bladder contents and facilitates placement of a small self-retaining retractor and additional stay sutures. The trigone, both ureteral meati, the bladder neck, and all possible diverticular orifices are clearly visualized from the bladder dome opening.
In cases of intradiverticular tumor, we instill 30 mg of mitomycin by urethral catheter before the surgery and carefully protect the surgical field with moist sterile cloths to avoid possible tumor contamination during diverticulectomy. The bladder mucosa should also be thoroughly inspected to rule out papillary tumors that may have gone unnoticed on the previous endoscopic examination.
Diverticulum excision has been described in three different approaches: extravesical (V. V. Czerny, 1896), intravesical (H. H. Young, 1906), and the intravesical and extravesical combination (G. Marion, 1913). The most commonly used procedures and the points of technique that we use are the following.
If the diverticulum is small (£5 cm diameter), we perform intravesicalization and eversion of its wall, grasping and tractioning its bottom gently with an Allis or Pean-type clamp inserted through its neck. If this maneuver is performed carefully, and fibrosis secondary to infection is absent, the majority of these diverticula are rapidly and easily removed. The mucosa of the everted diverticular neck is divided using electrocautery, and the defect of the bladder wall is sutured with 3-0 chromic catgut using separate submucosal and muscular sutures. In case of a saccule, a fine ligature of the neck and resection of its everted mucosa will suffice.
If this maneuver is not feasible because of peridiverticular adhesions, we proceed to sharply split the mucosa around the diverticular orifice and dissect with scissors as far as the periadventitial space. In this way, the diverticular neck remains separated from the bladder wall and is pulled toward the vesical cavity with Allis-type clamps. At the same time, the adventitial adhesions that fix the diverticular sac are freed gently with a small moist gauze, and the sac is drawn into the bladder. The bladder wall is then closed as mentioned previously.
Combined Intravesical and Extravesical Diverticulectomy
In a large diverticulum complicated with peridiverticulitis or in a paraureteral location, it is obligatory to place a 7- or 8-Ch ureteral catheter in the corresponding side before dissection. This will avoid an inadvertent lesion of the ureter or at least facilitate its immediate repair. These diverticula must be excised by a combined intra- and extravesical approach, first identifying and dissecting the diverticular neck. For this, the maneuver of inserting the surgeon’s index finger into the diverticulum and gently tractioning the upper face of its neck toward the surface is very useful. We also recommend completely filling the diverticular sac with a moist gauze to unfold its wall and delimit its margins as accurately as possible. Dissection must begin at the diverticular neck, which is sectioned extravesically with electrocautery and separated from the bladder wall, whose orifice is sutured with 3-0 chromic catgut using extramucosal separate stitches.
Tractioning the edges of the diverticular mouth toward the surface with Allis-type clamps allows the sac wall to be dissected from neighboring tissue with scissors and a small moist swab. It should always be borne in mind that the ureteral course may have been modified by the great diverticular volume, and the ureter may be closely adhered to its wall if repeated infectious processes have occurred. This dissection will be very difficult if great peridiverticulitis is present, and it is more advisable simply to denude it of its mucosal lining with fine scissors or with the cutting current and the ball electrode from inside the diverticular cavity and then place a suction drain within it (first described by Pousson in 1901 and Geraghty in 1922). The bladder wall is closed with absorbable 3-0 interrupted sutures. We leave an aspirating drain in the Retzius space and a urethral 18-Fr Foley catheter, which may both be removed after 5 or 6 days.
The most serious specific complication of excision of a bladder diverticulum is an injury to the juxtavesical or pelvic ureter during dissection of large diverticulum. With prior placement of an ipsilateral ureteral catheter, this lesion will not go unnoticed by the surgeon and can be easily sutured with absorbable 5-0 or 6-0 separate stitches if it is a partial or incomplete section. If the ureter has been severely damaged, or its section is complete and near the vesical hiatus, the distal ureter must be abandoned, and it is preferable to carry out ureteral reimplantation following the technique of Leadbetter–Politano with or without vesical lateralization to the psoas muscle (“psoas hitch”). End-to-end suture of ureteral edges must never be performed in precarious conditions because it is highly likely that it will be complicated by urinary fistula or ureteral stenosis, which will further aggravate the situation. If the ureteral lesion is more extensive and located higher, and the bladder in turn is reduced in size and of limited mobility, we prefer to perform transureteroureterostomy and ureteral suture with the aid of the surgical microscope.
Less serious complications include vesical urine leakage, which may cease spontaneously if the Foley catheter is maintained for some more days, providing the obstructive pathology has been resolved. If a urinary fistula is established, we advise closing it with a flap from the bladder wall itself.
The excision of the diverticulum is generally curative for that particular lesion, although correction of the underlying cause (e.g., outlet obstruction) is required to prevent formation of additional diverticulum.