- Email: [email protected]
BLADDER DIVERTICULA, URACHAL ANOMALIES, AND OTHER UNCOMMON ANOMALIES OF THE BLADDER
CHAPTER
31
BLADDER DIVERTICULA, URACHAL ANOMALIES, AND OTHER UNCOMMON ANOMALIES OF THE BLADDER
Hiep T. Nguyen and Bartley G. Cilento Jr.
BLADDER DIVERTICULA
Presentation
Definition and Etiology
Although in some children bladder diverticula have no functional consequences, in others they produce bladder outlet obstruction, vesicoureteral reflux (VUR), or ureteral obstruction or predispose to urinary tract infections. Bladder diverticula may enlarge to the extent that they compress the bladder neck or proximal urethra (Fig. 31-3).18,19 A vicious cycle may develop in which increased outlet resistance promotes further filling of the diverticulum, resulting in increasing enlargement of the diverticulum and, consequently, increasing obstruction.18,20 The bladder diverticula may become so large that they herniate through the femoral or inguinal canal.21 Alternatively, bladder diverticula, especially those near the ureteral orifice, may incorporate the ureteral tunnel, resulting in VUR (Fig. 31-4).22 However, it remains unclear whether paraureteral diverticula cause reflux or are merely associated with it. In the literature, the incidence of VUR in association with paraureteral diverticula ranges from 5% to 100%, whereas the incidence of primary reflux associated with paraureteral diverticula ranges from 8% to 13%.3,7,23 In the past, the presence of reflux with a paraureteral diverticulum dictated excision of the diverticulum and ureteral reimplantation. Subsequently, it was observed that reflux in association with a paraureteral diverticulum may regress spontaneously. Amar22 noted that, in girls, especially those with small diverticula, the associated reflux resolves spontaneously as the bladder matures; in boys, the diverticula tended to be larger, and the associated reflux was less likely to disappear. More recently, Afshar and colleauges24 retrospectively evaluated the resolution of VUR in children with and without congenital paraureteral diverticula. They observed that Kaplan-Meier analysis and the log rank test did not demonstrate any difference in resolution rate between the two groups; multivariate analysis demonstrated grade as the only variable affecting the outcome. Currently, it is generally accepted that the extent to which bladder diverticula cause VUR depends on the dynamic interaction between the ureteral orifice and the diverticulum. The ureteral orifice that becomes incorporated into the diverticulum on filling is likely to reflux, owing to the displacement of the ureteral orifice from the trigone and the shortening of its submucosal tunnel. Bladder diverticula may also cause ureteral obstruction.25-27 In a large study of children with bladder diverticula, Barrett and associates7 noted that approximately 5% of the patients had radiologic evidence of ureteral obstruction. In association with ureteral obstruction, bladder diverticula may result in ipsilateral renal dysplasia and may also obstruct the contralateral ureteral orifice. It is likely that the obstruction is caused by direct ureteral compression by the diverticulum; inflammation or infection leading to peridiverticular and ureteral fibrosis; or intrinsic hypomuscularity of the distal ureters and ureterovesical junction resulting in a functional obstruction of the ureterovesical junction.27
Bladder diverticula are herniations of bladder mucosa between fibers of the detrusor muscle. Depending on the size of the muscular defect, the diverticula have either a narrow or a wide neck. Although muscle is abundant around the neck and less so in the side walls, there are only sparse detrusor muscle fibers at the dome of the diverticulum.1 In children, the most common location for bladder diverticula is lateral and cephalad to the ureteral orifice.2 However, in association with outlet obstruction or prune-belly syndrome, they can also occur at the dome of the bladder. Bladder diverticula are uncommon but not rare. In their pediatric genitourinary database of 5084 children, Blane and colleagues3 found a 1.7% incidence of bladder diverticulum. Bladder diverticula may be acquired or congenital. Acquired diverticula are usually multiple and associated with bladder trabeculation. They are the result of bladder outlet obstruction or infection or have iatrogenic causes. Bladder neck or urethral obstruction from posterior urethral valves (PUV), anterior urethral diverticulum, urethral stricture, neuropathic bladder dysfunction, or external sphincter dyssynergia increases bladder voiding pressures, forcing the bladder mucosa through the gap in the muscle of the bladder wall. These diverticula usually resolve after correction of the outlet obstruction. In children with PUV, acquired bladder diverticula can serve as a pressure pop-off mechanism to protect kidney4,5 and bladder function.6 Some have speculated that acquired diverticula may also develop after severe urinary infection7; the inflammation weakens the bladder muscle and leads to diverticula formation in the absence of outlet obstruction. Rarely, bladder diverticula are acquired iatrogenically, such as after antireflux surgery in which defects in the bladder muscular wall were not appropriately reapproximated.8 In the past, it was thought that all diverticula are acquired. However, it is now well recognized that the majority of bladder diverticula in children are congenital.7,9 Congenital bladder diverticula most often are solitary, occur in a smooth wall bladder, and are more common in males. They are usually located in the lateral cornu of the trigone and the ureteral hiatus and can impinge on, engulf, or be separate from ureteral orifices (Fig. 31-1). The cause is believed to be an inherent weakness in the detrusor musculature, in particular deficiencies of the Waldeyer fascial sheath.10 Congenital bladder diverticula have also been associated with Menkes syndrome, a neurodegenerative and connective tissue disorder with characteristic increases in tissue copper and metallothionein content11-13; Ehlers-Danlos syndrome, a collagen biogenesis disorder14-17; cutis laxa, a syndrome of decreased or absent elastic tissue (Fig. 31-2); Williams’ syndrome, a disorder characterized by growth and mental retardation, facial anomalies, and aortic stenosis3; and prune-belly syndrome. 416
chapter
31: Bladder Diverticula, Urachal Anomalies, and Other Uncommon Anomalies of the Bladder
417
A
Figure 31-2 Voiding cystourethrogram demonstrates multiple bladder diverticula in a patient with cutis laxa. c hemotherapy, or both (depending on the type, grade, and stage of the tumor) is often required.
Radiographic Evaluation B
C Figure 31-1 A, Common location for congenital bladder diverticulum. The ureters may insert near (B) or into (C) the diverticulum.
In association with bladder outlet obstruction, VUR, or ureteral obstruction, bladder diverticula may predispose to urinary tract infections. However, urinary infection can occur in children independent of obstruction or reflux. Because of a lack of musculature, large bladder diverticula do not empty on voiding, allowing stasis of urine (Fig. 31-5).28-30 Furthermore, some children with bladder diverticula have an abnormal voiding pattern on urodynamic evaluation, including detrusor-sphincter dyssynergia, hyperreflexia, or hypotonia.31 It remains to be determined whether bladder diverticula cause these abnormal urodynamic findings or whether such abnormalities in bladder function lead to diverticular changes. Nevertheless, these findings, in addition to urinary stasis, may predispose children with bladder diverticula to recurrent urinary tract infection. Recent small reports32 in the literature have suggested that surgical excision of primary bladder diverticula can eliminate infections and is associated with improvement of voiding dysfunction. Other, albeit rare, presentations of bladder diverticula have also been reported. Spontaneous perforation of a congenital bladder diverticulum may occur, resulting in abdominal pain and sepsis.33 Although this is an uncommon cause for these symptoms, it must be considered if the etiology is not clear. Delay in diagnosis of a bladder rupture can result in morbid outcomes. Tumors may also develop in the bladder diverticula. These tumors could be urothelial in origin34 or they could be intradiverticular sarcomas or carcinosarcomas.35 Patients with diverticular tumors often present with gross or microscopic hematuria. The tumors tend to be more aggressive than their bladder counterparts, with a high incidence of intra-abdominal recurrences. Treatment with surgery, or
Bladder diverticula may be diagnosed by various radiologic methods. Because of their dynamic nature, they can be elusive on uroradiologic studies. The voiding cystourethrogram is the best modality for identifying bladder diverticula.36 Diverticula can be detected by bladder ultrasonography, especially if it is performed with an empty and then a full bladder. Intravenous pyelograms are not sensitive in detecting bladder diverticula because they are easily overshadowed by the bladder’s filling with contrast material.
Management The management of bladder diverticula depends on the symptoms, such as infection, obstruction, or reflux. In their absence, intervention is often not necessary. However, surgical intervention may be required if there is recurrent infection, bladder outlet obstruction, persistent VUR, or functionally significant ureteral obstruction. In the presence of bladder outlet obstruction, diverticulectomy is often necessary to relieve the obstruction of the bladder neck or proximal urethra, using open surgical, endoscopic,37 or laparoscopic methods.38 For patients who have persistent reflux, diverticulectomy with ureteral reimplantation is recommended. Traditionally, this is performed intravesically, with careful attention to reinforcing the hiatus to prevent postoperative diverticula formation. However, extravesical detrusorrhaphy for the refluxing ureters associated with paraureteral diverticula can be performed with minimal postoperative morbidity and as effectively as the intravesical method.39 In the presence of ureteral obstruction, management depends on upper tract function of the affected renal unit, requiring either diverticulectomy with reimplantation or nephrectomy.
ANOMALIES OF THE URACHUS Definition and Etiology The urachus lies between the transversalis fascia and the peritoneum, adjacent to umbilical ligaments, the remnants of the umbilical arteries. The urachus is 3 to 10 cm long and 8 to 10 mm
418
part
A
IV: Bladder
C
B
Figure 31-3 Voiding cystourethrogram demonstrates progressive filling of the bladder diverticulum (D) during voiding (A and B) with resultant obstruction of the outlet of the bladder (B) by the large diverticulum (C).
A
B
Figure 31-4 Voiding cystourethrogram demonstrates vesicoureteral reflux in a ureter that inserted into a diverticulum (arrow) (A), which allows contrast material to reflux into the upper collecting system (B). in diameter. It is surrounded by the umbilicovesical fascial sheath, which extends laterally to each umbilical artery and inferiorly over the bladder dome to the hypogastric arteries posteriorly and the pelvic diaphragm anteriorly, forming a self-contained space that is capable of limiting the spread of infection or neoplasm. The urachus is composed of three histologic layers: an inner cuboidal or transition layer, a submucosal tissue layer, and an outer smooth muscle layer. The central lumen is irregular and beaded and is filled with desquamated epithelial debris.40 In the sheep experimental model, premature closure of the urachus results in hydronephrosis,41 suggesting that, during fetal life, the urachus provides a lowresistance outlet for drainage of the bladder while the urinary sphincter matures. Embryologically, the majority of the urachus is derived from the bladder, and the proximal portion is formed from the allantoic duct.42 As the bladder descends into the pelvis, it retains its attachment to the umbilicus by the urachus. As the urachus develops, it loses its attachment to the umbilicus. Based on the differential growth rates of the urachus, anterior abdominal wall, and bladder descent, four anatomic
ariants of urachal termination result (Fig. 31-6).43,44 In type I, v the urachus fails to atrophy, retaining its attachment to the dome of the bladder, separate from each umbilical artery. A type II variant results when the urachus fuses with one of the umbilical arteries and continues as a single fibrous cord to the umbilicus. In type III, the urachus fuses with both the umbilical arteries and continues as a single structure to the umbilicus. Finally, a type IV variant occurs when the urachus forms an atrophied tube that terminates before fusing with the umbilical arteries, ending within the fascia or blending into a plexus of fibrous tissue (the plexus of Luschka) formed by the urachus and the umbilical arteries.42 Between the 4th and 5th month of gestation, the potential communication between the apex of the bladder and the urachal canal is segmentally obstructed by desquamated epithelium.40
Presentation and Radiographic Examination Congenital anomalies of the urachus, including urachal sinus, urachal cyst, patent urachus, and vesicourachal diverticulum (Fig. 31-7), represent an arrest of the normal involutionary
chapter
31: Bladder Diverticula, Urachal Anomalies, and Other Uncommon Anomalies of the Bladder
A
419
B
Figure 31-5 Voiding cystourethrogram demonstrates filling of the diverticulum (D) during bladder (B) filling (A) and during voiding (B). The bladder diverticulum may fill during voiding and, because of its lack of musculature, cannot empty.
Umbilicus
Umbilicus Umbilical artery
Umbilical artery Urachus Umbilical artery
Bladder
A
Umbilical artery
eriumbilical pain (22%), and dysuria (2%).45 Urachal anomp alies usually occur as isolated defects and are not associated with other syndromes, with the exception of prune-belly syndrome or bladder outlet obstruction in association with a patent urachus. Of the urachal anomalies, urachal sinus and urachal cyst are more common (43% to 59% and 29% to 43%, respectively) than patent urachus and vesicourachal diverticulum (10% to 15% and 4% to 6%, respectively).45-47 The diagnosis of urachal anomalies can often be made with a thorough physical examination and the appropriate radiographic test. In a child with periumbilical drainage, a sinogram should be obtained to evaluate for a urachal sinus or patent urachus. In a child with a periumbilical mass, ultrasonography should be performed and should be diagnostic for a urachal cyst.45
Urachus
Urachal Sinus Umbilicus Urachus Umbilical artery
Bladder
B
Umbilicus Umbilical artery
Plexus of Luschka
Umbilical artery
Bladder
C
Umbilical artery
Bladder
D
Urachus
Figure 31-6 Four types of variant in urachal termination: A, type I:
A urachal sinus arises from a type I urachal termination variant when the urachus remains patent through part of its length (Fig. 31-8). An alternating sinus may be formed if a small urachal cyst becomes chronically infected and drains into the umbilicus or the bladder.48 Children with urachal sinus may present with intermittent or persistent umbilical drainage, with periumbilical pain and tenderness, or with just a wet umbilicus and surrounding granulation tissue. Gastrointestinal symptoms may result if other umbilical remnants become involved in the inflammatory process. In the presence of a sinus at the umbilicus, a sinogram with radiopaque material is diagnostic.45 Treatment of urachal sinus is directed toward controlling the associated infection, after which complete excision of the sinus tract along with resection of the omphalomesenteric duct remnants should be performed.44 At the time of resection, care should be taken to avoid damaging intraperitoneal structures that may be densely adherent to the inflammatory mass.
B, type II; C, type III; D, type IV. See text for descriptions.
Urachal Cyst rocess of the urachus. They rarely manifest in childhood p and may not be symptomatic until adulthood. In symptomatic patients, these anomalies are seen equally in males and females. Common presenting symptoms include periumbilical discharge (42%), an umbilical mass (33%), abdominal or
A urachal cyst develops most commonly in the distal third of the urachus but can occur in the proximal third, depending on the type of urachal termination variant. In a type II or III variant in which the umbilical end of the urachus is obliterated, a cyst filled with desquamated epithelium can develop
420
part
IV: Bladder
Bladder Bladder
A
Urethra
B
Urethra
Figure 31-8 Contrast material fills in the bladder (B) and in the
Bladder Bladder
C
Urethra
D
urachal sinus (arrow).
Urethra
Figure 31-7 Four types of urachal anomalies: A, urachal sinus; B, urachal cyst; C, patent urachus; D, vesicourachal diverticulum.
in the bladder end (distal third of the urachus). Alternatively, in a type IV variant, degeneration of one of the plexuses of Luschka results in a cyst in the proximal third of the urachus.48 In autopsy series, the incidence of urachal cyst is 1 in 5000.49 Urachal cysts rarely manifest in the newborn period but may become symptomatic during late childhood or in early adult life. The presenting symptoms of children with urachal cyst include an asymptomatic suprapubic mass, fever with suprapubic pain, or irritative voiding symptoms with a palpable suprapubic mass. Not uncommonly, the urachal cyst may become infected, with Staphylococcus aureus the most common bacterium cultured.50 Because of the anatomy and location of the urachal cyst, infection is usually limited to the space of Retzius, but occasionally, an infected cyst ruptures into the peritoneum with resultant bowel fistula formation.51 The diagnosis of urachal cyst is most often made by ultrasonography, delineating the location of the cyst relative to the bladder and peritoneum and the limit of extension (Fig. 31-9).45 Computed tomography may be occasionally useful in further defining the extent of the cyst and the involvement of adjacent
Figure 31-9 Ultrasound study shows a urachal cyst (arrow) located anterior to the bladder.
chapter
A
31: Bladder Diverticula, Urachal Anomalies, and Other Uncommon Anomalies of the Bladder
B
421
C
Figure 31-10 Voiding cystourethrogram demonstrates a catheter in the patent urachus (A), with subsequent filling of the bladder with contrast material through the patent urachus (B) and voiding through the urethra (C).
structures such as bowel. Intravenous pyelography, voiding cystourethrography, or cystoscopy can be done to evaluate the degree of involvement of the bladder wall.48 Treatment for urachal cyst depends on the presenting symptoms. For children in whom the urachal cyst presents as an asymptomatic mass, observation may be appropriate for small cysts. With an infected urachal cyst, the initial treatment may include incision and drainage, marsupialization, or percutaneous catheter drainage. Definitive treatment with surgical excision should be performed after the inflammation subsides. This staged approach to treating infected urachal cysts helps to limit the amount of bladder wall resected and reduces the risk of injury to adjacent intraperitoneal structures.
Patent Urachus A patent urachus—a communication between the umbilicus and the bladder—results from the failure of a type I urachal termination variant to obliterate by desquamation of its epithelial mucosa. In autopsy series, the incidence of a patent urachus is 1 in 761.49 A patent urachus may be seen in patients with prune-belly syndrome but is uncommon in those with PUV.52 Patent urachus may manifest as an incidental finding on newborn ultrasonography; as a wet umbilicus with surrounding granulation tissue; as intermittent or continuous urinary drainage that is accentuated in the prone position or with crying, straining, or voiding; or as a periumbilical swelling or mass secondary to an associated umbilical hernia or engorgement of the urachal vasculature.48 The diagnosis of a patent urachus in patients with these symptoms should be differentiated from that of omphalitis, granulation of a healing umbilical stump, patent vitelline or omphalomesenteric duct, infected umbilical vessel, and external urachal sinus. Analysis of periumbilical fluid for creatinine or urea is useful in differentiating a patent urachus from these other conditions, and a fistulogram with radiopaque material is often diagnostic.45 A voiding cystourethrogram should be obtained to identify the fistula tract (Fig. 31-10) and, more importantly, to rule out the concomitant presence of bladder outlet obstruction or VUR. In the management of a patent urachus, observation may be indicated for young infants without symptoms, because the involution of the urachus is not complete at birth, and spontaneous closure can occur during the first months of life.53 In patients who have a patent urachus in association with bladder outlet obstruction, treatment of only the bladder outlet
Figure 31-11 Voiding cystourethrogram demonstrates a catheter placed into a vesicourachal diverticulum (arrow).
obstruction is often adequate, because spontaneous closure of the patent urachus usually occurs after adequate relief of bladder outlet obstruction. However, if drainage continues for several months, excision of the urachal tract and cuff of bladder through an extraperitoneal approach may be required.54
Vesicourachal Diverticulum Vesicourachal diverticulum develops when the communication between the bladder and the urachus fails to obliterate in a type II or III urachal termination variant, resulting in a fusiform outpouching at the apex of the bladder (Fig. 31-11). The
422
part
IV: Bladder
diverticulum is often nonobstructive, drains well, and therefore does not predispose to stagnation of urine or infection.48 It may be found in association with prune-belly syndrome and other bladder outlet obstructive disorders. However, vesicourachal diverticulum can also occur in the absence of functional or anatomic obstruction. The diverticulum does not usually require treatment. On the rare occasions when it is large, empties poorly because of a narrowed neck, or contracts paradoxically, excision of the vesicourachal diverticulum may be required.
Management Although most of these urachal anomalies are treated surgically, some patients with these anomalies are observed. Urachal carcinoma may develop within these anomalies, but it is rare in children (0.01%55) and accounts for fewer than 0.34% of all bladder cancers.56,57 The most common histologic type is adenocarcinoma, but other types have been reported, including transitional cell carcinoma,57 neuroblastoma,55 rhabdomyosarcoma,58 teratoma,59 yolk sac carcinoma,60 and inflammatory myofibroblastic tumors.61 Patients with urachal carcinoma most often present with hematuria and a palpable mass. The most common finding on radiologic evaluation is a filling defect within the bladder, with stippled calcifications. Patients with adenocarcinoma of the urachus have improved overall and disease-specific mortality risks compared to those with adenocarcinoma of the bladder.62 However, the prognosis of patients with urachal adenocarcinoma often remains poor because of late presentation with local invasion. Close radiologic evaluation is therefore warranted in children with urachal anomalies.
OTHER UNCOMMON ANOMALIES OF THE BLADDER Bladder Ears Bladder ears are lateral protrusions of the bladder wall into the internal inguinal ring. They are seen frequently on intravenous pyelography or voiding cystourethrography but usually recede when the bladder is filled to capacity (Fig. 31-12).48 They are caused by the close proximity of the infant bladder to the internal rings and are rarely seen in adults. Treatment is usually not necessary, because most resolve spontaneously with the growth of the bladder. However, on occasion, bladder ears may herniate into the internal ring and be accidentally resected during herniorrhaphy.63,64
Bladder Agenesis Bladder agenesis is a rare anomaly in viable newborns65,66; most with this anomaly do not survive. Fewer than 20 live births of infants with bladder agenesis have been reported in the literature, with the majority being girls.67-69 Although most of these patients are diagnosed during infancy, some patients with bladder agenesis are not diagnosed until a later age.67 In the absence of the bladder and trigone, the ureteral orifices follow the terminations of the mesonephric ducts and enter into the urethra, the vestibule, or Gartner duct in the female or the prostatic urethra in the male; or they may enter the rectum or the patent urachus.69-72 The ureters may remain separate or form a common channel. They are often hydronephrotic with or without associated renal dysplasia. Bladder agenesis is most often associated with neurologic, orthopedic,73 or other urogenital anomalies such as solitary kidney, renal agenesis, renal dysplasia, or an absence of the prostate, vagina, seminal
Figure 31-12 Voiding cystourethrogram demonstrates a bladder ear
(arrow).
vesicles, or penis.68,74,75 Hindgut abnormalities can occur,76 but the hindgut is usually normal. Palmer and Russi70 postulated that bladder agenesis results from failure of the lower portions of the mesonephric ducts to develop into the mesodermal portion of the bladder. More specifically, Krull and associates69 suggested that, in bladder agenesis, there is a failure of incorporation of the mesonephric ducts and ureters into the trigone, which prevents urine from accumulating in the developing bladder. Consequently, the bladder fails to develop due to a lack of distention with urine. In patients with bladder agenesis, initial treatment with urinary diversion is necessary, with complex urinary construction undertaken at a later age when appropriate.
Bladder Hypoplasia and Megacystis In congenital hypoplasia of the bladder and megacystis, it is believed that inadequate or excess filling of urine results in underdevelopment or overdevelopment of the fetal bladder. A hypoplastic bladder with little capacity develops in those disorders in which an inadequate amount of urine is stored in the fetal bladder (severe epispadias with incontinence, urogenital sinus abnormalities in females, bilateral renal agenesis, severe renal dysplasia) or the bladder is bypassed altogether (bilateral ureteral ectopia with distal urethral or vaginal orifices in the female).48 The congenital hypoplastic bladder can improve with refunctionalization but more commonly requires augmentation. In contrast, primary congenital megacystis is associated with massively refluxing megaureters and an excess amount of stored urine during bladder development (Fig. 31-13). Congenital megacystis was previously attributed to congenital bladder neck obstruction.77,78 However, it was subsequently recognized that megacystis most likely results from the constant recycling of urine between massively dilated upper tracts and the bladder.79 In patients with congenital
chapter
A
31: Bladder Diverticula, Urachal Anomalies, and Other Uncommon Anomalies of the Bladder
423
C
B
Figure 31-13 Voiding cystourethrogram demon
D
E
strates an enlarged bladder (A) with bilateral massive vesicoureteral reflux (B). The bladder is emptied after voiding (C); however, a large amount of contrast material remains in the upper collecting systems (D), which then drains into the bladder (E). This constant cycling of urine is thought to be the cause of megacystis.
megacystis, the trigone is wide and poorly developed, with gaping, laterally displaced ureteral orifices. These bladders are able to contract and empty normally, although much of their capacity goes into the upper urinary tracts. The diagnosis can be made prenatally, and the patients should be started on prophylactic antibiotic therapy.80 Congenital megacystis can also be seen in association with microcolon-intestinal hypoperistalsis syndrome81,82 or Ehlers-Danlos syndrome83 or secondary to outlet obstruction such as that caused by PUV, urethral diverticulum, anterior sacral meningomyelocele, sacrococcygeal teratoma, pelvic neuroblastoma, or cystic duplication of the rectum. The treatment of primary congenital megacystis is primarily directed at correcting the massive VUR, and reduction cystoplasty is often not needed.84 However, antireflux surgery in patients with congenital megacystis is often difficult to perform because of the thinness of the bladder wall. In patients with secondary forms of congenital megacystis, treatment of the obstruction is often adequate, and reduction cystoplasty is not routinely recommended.
Bladder Duplication Bladder duplication anomalies can be classified as complete or incomplete. In complete duplication, two bladder halves are present, each with a full-thickness muscular wall and mucosa (Fig. 31-14).85,86 Each bladder half is on one side of the midline, has an ipsilateral ureter, and drains into its complementary urethra. Fewer than 50 cases of complete bladder duplication have been reported in the literature. This duplication anomaly is more common in males. In 90% of cases, there is an associated complete duplication of the penis in the male or of the vagina
Figure 31-14 Voiding cystourethrogram demonstrates contrast ma-
terial filling two separate bladders (B) through two urethras (arrows). There is reflux into the right collecting system. Each bladder has a separate renal unit emptying into it.
424
part
IV: Bladder
A
B
Figure 31-15 Ultrasound study (A) suggests the presence of bladder septation (arrow), which was later confirmed on intravenous pyelog raphy (B).
and uterus in the female.87,88 In 40% to 50% of the cases, the hindgut is also duplicated.87,89 Lumbar vertebral duplication and fistulas between the rectum, vagina, and urethra may also be present. Major reconstructive surgery may be necessary for some of these patients. In incomplete duplication, the bladder is divided by a full-thickness wall, either sagittally or coronally.90,91 The two bladder halves, each with an ipsilateral ureter, communicate and drain into one common urethra. Incomplete bladder duplication is less common than its complete counterpart. In contrast to complete bladder duplication anomalies, genital and anorectal anomalies are not usually associated with the incomplete form. Usually, incomplete bladder duplication does not result in serious sequelae.92
with dysplasia or obstruction of one unit (which in turn can obstruct the contralateral unit).48 In contrast, both compartments in the incomplete septated bladder drain freely. In a multiloculated bladder, the rarest of the septation anomalies, fibromuscular walls compartmentalize the bladder body into unequal chambers. The serosal surface of the multiloculated bladder appears normal. The upper tracts are usually duplicated, with each entering into a separate chamber. The renal units to the blind compartments are dysplastic or obstructed, or both.48 Surgical treatment of these compartmentalization anomalies should be tailored for each patient, taking into account whether the bladder segments are obstructed and the degree of renal dysplasia associated with the obstructed bladder segments.
Compartmentalization Anomalies of the Bladder Compartmentalization anomalies such as septated, multiloculated, or hourglass bladder are often misdiagnosed as ectopic ureteroceles, bladder or urachal diverticulum, or dilated posterior urethra secondary to PUV. In the septated bladder, the bladder body is divided, completely or incompletely, in either the frontal or sagittal plane, by a partition of mucosa alone or with muscularis and mucosa (Fig. 31-15). One ureter enters each compartment, and there is a single bladder neck and urethra. Thus, complete bladder septation is associated
ACKNOWLEDGMENT We thank Dr. Robert Lebowitz for his invaluable assistance with the photographs in this chapter.
REFERENCES For complete list of references log onto www.expertconsult.com
31
BLADDER DIVERTICULA, URACHAL ANOMALIES, AND OTHER UNCOMMON ANOMALIES OF THE BLADDER
Hiep T. Nguyen and Bartley G. Cilento Jr.
BLADDER DIVERTICULA
Presentation
Definition and Etiology
Although in some children bladder diverticula have no functional consequences, in others they produce bladder outlet obstruction, vesicoureteral reflux (VUR), or ureteral obstruction or predispose to urinary tract infections. Bladder diverticula may enlarge to the extent that they compress the bladder neck or proximal urethra (Fig. 31-3).18,19 A vicious cycle may develop in which increased outlet resistance promotes further filling of the diverticulum, resulting in increasing enlargement of the diverticulum and, consequently, increasing obstruction.18,20 The bladder diverticula may become so large that they herniate through the femoral or inguinal canal.21 Alternatively, bladder diverticula, especially those near the ureteral orifice, may incorporate the ureteral tunnel, resulting in VUR (Fig. 31-4).22 However, it remains unclear whether paraureteral diverticula cause reflux or are merely associated with it. In the literature, the incidence of VUR in association with paraureteral diverticula ranges from 5% to 100%, whereas the incidence of primary reflux associated with paraureteral diverticula ranges from 8% to 13%.3,7,23 In the past, the presence of reflux with a paraureteral diverticulum dictated excision of the diverticulum and ureteral reimplantation. Subsequently, it was observed that reflux in association with a paraureteral diverticulum may regress spontaneously. Amar22 noted that, in girls, especially those with small diverticula, the associated reflux resolves spontaneously as the bladder matures; in boys, the diverticula tended to be larger, and the associated reflux was less likely to disappear. More recently, Afshar and colleauges24 retrospectively evaluated the resolution of VUR in children with and without congenital paraureteral diverticula. They observed that Kaplan-Meier analysis and the log rank test did not demonstrate any difference in resolution rate between the two groups; multivariate analysis demonstrated grade as the only variable affecting the outcome. Currently, it is generally accepted that the extent to which bladder diverticula cause VUR depends on the dynamic interaction between the ureteral orifice and the diverticulum. The ureteral orifice that becomes incorporated into the diverticulum on filling is likely to reflux, owing to the displacement of the ureteral orifice from the trigone and the shortening of its submucosal tunnel. Bladder diverticula may also cause ureteral obstruction.25-27 In a large study of children with bladder diverticula, Barrett and associates7 noted that approximately 5% of the patients had radiologic evidence of ureteral obstruction. In association with ureteral obstruction, bladder diverticula may result in ipsilateral renal dysplasia and may also obstruct the contralateral ureteral orifice. It is likely that the obstruction is caused by direct ureteral compression by the diverticulum; inflammation or infection leading to peridiverticular and ureteral fibrosis; or intrinsic hypomuscularity of the distal ureters and ureterovesical junction resulting in a functional obstruction of the ureterovesical junction.27
Bladder diverticula are herniations of bladder mucosa between fibers of the detrusor muscle. Depending on the size of the muscular defect, the diverticula have either a narrow or a wide neck. Although muscle is abundant around the neck and less so in the side walls, there are only sparse detrusor muscle fibers at the dome of the diverticulum.1 In children, the most common location for bladder diverticula is lateral and cephalad to the ureteral orifice.2 However, in association with outlet obstruction or prune-belly syndrome, they can also occur at the dome of the bladder. Bladder diverticula are uncommon but not rare. In their pediatric genitourinary database of 5084 children, Blane and colleagues3 found a 1.7% incidence of bladder diverticulum. Bladder diverticula may be acquired or congenital. Acquired diverticula are usually multiple and associated with bladder trabeculation. They are the result of bladder outlet obstruction or infection or have iatrogenic causes. Bladder neck or urethral obstruction from posterior urethral valves (PUV), anterior urethral diverticulum, urethral stricture, neuropathic bladder dysfunction, or external sphincter dyssynergia increases bladder voiding pressures, forcing the bladder mucosa through the gap in the muscle of the bladder wall. These diverticula usually resolve after correction of the outlet obstruction. In children with PUV, acquired bladder diverticula can serve as a pressure pop-off mechanism to protect kidney4,5 and bladder function.6 Some have speculated that acquired diverticula may also develop after severe urinary infection7; the inflammation weakens the bladder muscle and leads to diverticula formation in the absence of outlet obstruction. Rarely, bladder diverticula are acquired iatrogenically, such as after antireflux surgery in which defects in the bladder muscular wall were not appropriately reapproximated.8 In the past, it was thought that all diverticula are acquired. However, it is now well recognized that the majority of bladder diverticula in children are congenital.7,9 Congenital bladder diverticula most often are solitary, occur in a smooth wall bladder, and are more common in males. They are usually located in the lateral cornu of the trigone and the ureteral hiatus and can impinge on, engulf, or be separate from ureteral orifices (Fig. 31-1). The cause is believed to be an inherent weakness in the detrusor musculature, in particular deficiencies of the Waldeyer fascial sheath.10 Congenital bladder diverticula have also been associated with Menkes syndrome, a neurodegenerative and connective tissue disorder with characteristic increases in tissue copper and metallothionein content11-13; Ehlers-Danlos syndrome, a collagen biogenesis disorder14-17; cutis laxa, a syndrome of decreased or absent elastic tissue (Fig. 31-2); Williams’ syndrome, a disorder characterized by growth and mental retardation, facial anomalies, and aortic stenosis3; and prune-belly syndrome. 416
chapter
31: Bladder Diverticula, Urachal Anomalies, and Other Uncommon Anomalies of the Bladder
417
A
Figure 31-2 Voiding cystourethrogram demonstrates multiple bladder diverticula in a patient with cutis laxa. c hemotherapy, or both (depending on the type, grade, and stage of the tumor) is often required.
Radiographic Evaluation B
C Figure 31-1 A, Common location for congenital bladder diverticulum. The ureters may insert near (B) or into (C) the diverticulum.
In association with bladder outlet obstruction, VUR, or ureteral obstruction, bladder diverticula may predispose to urinary tract infections. However, urinary infection can occur in children independent of obstruction or reflux. Because of a lack of musculature, large bladder diverticula do not empty on voiding, allowing stasis of urine (Fig. 31-5).28-30 Furthermore, some children with bladder diverticula have an abnormal voiding pattern on urodynamic evaluation, including detrusor-sphincter dyssynergia, hyperreflexia, or hypotonia.31 It remains to be determined whether bladder diverticula cause these abnormal urodynamic findings or whether such abnormalities in bladder function lead to diverticular changes. Nevertheless, these findings, in addition to urinary stasis, may predispose children with bladder diverticula to recurrent urinary tract infection. Recent small reports32 in the literature have suggested that surgical excision of primary bladder diverticula can eliminate infections and is associated with improvement of voiding dysfunction. Other, albeit rare, presentations of bladder diverticula have also been reported. Spontaneous perforation of a congenital bladder diverticulum may occur, resulting in abdominal pain and sepsis.33 Although this is an uncommon cause for these symptoms, it must be considered if the etiology is not clear. Delay in diagnosis of a bladder rupture can result in morbid outcomes. Tumors may also develop in the bladder diverticula. These tumors could be urothelial in origin34 or they could be intradiverticular sarcomas or carcinosarcomas.35 Patients with diverticular tumors often present with gross or microscopic hematuria. The tumors tend to be more aggressive than their bladder counterparts, with a high incidence of intra-abdominal recurrences. Treatment with surgery, or
Bladder diverticula may be diagnosed by various radiologic methods. Because of their dynamic nature, they can be elusive on uroradiologic studies. The voiding cystourethrogram is the best modality for identifying bladder diverticula.36 Diverticula can be detected by bladder ultrasonography, especially if it is performed with an empty and then a full bladder. Intravenous pyelograms are not sensitive in detecting bladder diverticula because they are easily overshadowed by the bladder’s filling with contrast material.
Management The management of bladder diverticula depends on the symptoms, such as infection, obstruction, or reflux. In their absence, intervention is often not necessary. However, surgical intervention may be required if there is recurrent infection, bladder outlet obstruction, persistent VUR, or functionally significant ureteral obstruction. In the presence of bladder outlet obstruction, diverticulectomy is often necessary to relieve the obstruction of the bladder neck or proximal urethra, using open surgical, endoscopic,37 or laparoscopic methods.38 For patients who have persistent reflux, diverticulectomy with ureteral reimplantation is recommended. Traditionally, this is performed intravesically, with careful attention to reinforcing the hiatus to prevent postoperative diverticula formation. However, extravesical detrusorrhaphy for the refluxing ureters associated with paraureteral diverticula can be performed with minimal postoperative morbidity and as effectively as the intravesical method.39 In the presence of ureteral obstruction, management depends on upper tract function of the affected renal unit, requiring either diverticulectomy with reimplantation or nephrectomy.
ANOMALIES OF THE URACHUS Definition and Etiology The urachus lies between the transversalis fascia and the peritoneum, adjacent to umbilical ligaments, the remnants of the umbilical arteries. The urachus is 3 to 10 cm long and 8 to 10 mm
418
part
A
IV: Bladder
C
B
Figure 31-3 Voiding cystourethrogram demonstrates progressive filling of the bladder diverticulum (D) during voiding (A and B) with resultant obstruction of the outlet of the bladder (B) by the large diverticulum (C).
A
B
Figure 31-4 Voiding cystourethrogram demonstrates vesicoureteral reflux in a ureter that inserted into a diverticulum (arrow) (A), which allows contrast material to reflux into the upper collecting system (B). in diameter. It is surrounded by the umbilicovesical fascial sheath, which extends laterally to each umbilical artery and inferiorly over the bladder dome to the hypogastric arteries posteriorly and the pelvic diaphragm anteriorly, forming a self-contained space that is capable of limiting the spread of infection or neoplasm. The urachus is composed of three histologic layers: an inner cuboidal or transition layer, a submucosal tissue layer, and an outer smooth muscle layer. The central lumen is irregular and beaded and is filled with desquamated epithelial debris.40 In the sheep experimental model, premature closure of the urachus results in hydronephrosis,41 suggesting that, during fetal life, the urachus provides a lowresistance outlet for drainage of the bladder while the urinary sphincter matures. Embryologically, the majority of the urachus is derived from the bladder, and the proximal portion is formed from the allantoic duct.42 As the bladder descends into the pelvis, it retains its attachment to the umbilicus by the urachus. As the urachus develops, it loses its attachment to the umbilicus. Based on the differential growth rates of the urachus, anterior abdominal wall, and bladder descent, four anatomic
ariants of urachal termination result (Fig. 31-6).43,44 In type I, v the urachus fails to atrophy, retaining its attachment to the dome of the bladder, separate from each umbilical artery. A type II variant results when the urachus fuses with one of the umbilical arteries and continues as a single fibrous cord to the umbilicus. In type III, the urachus fuses with both the umbilical arteries and continues as a single structure to the umbilicus. Finally, a type IV variant occurs when the urachus forms an atrophied tube that terminates before fusing with the umbilical arteries, ending within the fascia or blending into a plexus of fibrous tissue (the plexus of Luschka) formed by the urachus and the umbilical arteries.42 Between the 4th and 5th month of gestation, the potential communication between the apex of the bladder and the urachal canal is segmentally obstructed by desquamated epithelium.40
Presentation and Radiographic Examination Congenital anomalies of the urachus, including urachal sinus, urachal cyst, patent urachus, and vesicourachal diverticulum (Fig. 31-7), represent an arrest of the normal involutionary
chapter
31: Bladder Diverticula, Urachal Anomalies, and Other Uncommon Anomalies of the Bladder
A
419
B
Figure 31-5 Voiding cystourethrogram demonstrates filling of the diverticulum (D) during bladder (B) filling (A) and during voiding (B). The bladder diverticulum may fill during voiding and, because of its lack of musculature, cannot empty.
Umbilicus
Umbilicus Umbilical artery
Umbilical artery Urachus Umbilical artery
Bladder
A
Umbilical artery
eriumbilical pain (22%), and dysuria (2%).45 Urachal anomp alies usually occur as isolated defects and are not associated with other syndromes, with the exception of prune-belly syndrome or bladder outlet obstruction in association with a patent urachus. Of the urachal anomalies, urachal sinus and urachal cyst are more common (43% to 59% and 29% to 43%, respectively) than patent urachus and vesicourachal diverticulum (10% to 15% and 4% to 6%, respectively).45-47 The diagnosis of urachal anomalies can often be made with a thorough physical examination and the appropriate radiographic test. In a child with periumbilical drainage, a sinogram should be obtained to evaluate for a urachal sinus or patent urachus. In a child with a periumbilical mass, ultrasonography should be performed and should be diagnostic for a urachal cyst.45
Urachus
Urachal Sinus Umbilicus Urachus Umbilical artery
Bladder
B
Umbilicus Umbilical artery
Plexus of Luschka
Umbilical artery
Bladder
C
Umbilical artery
Bladder
D
Urachus
Figure 31-6 Four types of variant in urachal termination: A, type I:
A urachal sinus arises from a type I urachal termination variant when the urachus remains patent through part of its length (Fig. 31-8). An alternating sinus may be formed if a small urachal cyst becomes chronically infected and drains into the umbilicus or the bladder.48 Children with urachal sinus may present with intermittent or persistent umbilical drainage, with periumbilical pain and tenderness, or with just a wet umbilicus and surrounding granulation tissue. Gastrointestinal symptoms may result if other umbilical remnants become involved in the inflammatory process. In the presence of a sinus at the umbilicus, a sinogram with radiopaque material is diagnostic.45 Treatment of urachal sinus is directed toward controlling the associated infection, after which complete excision of the sinus tract along with resection of the omphalomesenteric duct remnants should be performed.44 At the time of resection, care should be taken to avoid damaging intraperitoneal structures that may be densely adherent to the inflammatory mass.
B, type II; C, type III; D, type IV. See text for descriptions.
Urachal Cyst rocess of the urachus. They rarely manifest in childhood p and may not be symptomatic until adulthood. In symptomatic patients, these anomalies are seen equally in males and females. Common presenting symptoms include periumbilical discharge (42%), an umbilical mass (33%), abdominal or
A urachal cyst develops most commonly in the distal third of the urachus but can occur in the proximal third, depending on the type of urachal termination variant. In a type II or III variant in which the umbilical end of the urachus is obliterated, a cyst filled with desquamated epithelium can develop
420
part
IV: Bladder
Bladder Bladder
A
Urethra
B
Urethra
Figure 31-8 Contrast material fills in the bladder (B) and in the
Bladder Bladder
C
Urethra
D
urachal sinus (arrow).
Urethra
Figure 31-7 Four types of urachal anomalies: A, urachal sinus; B, urachal cyst; C, patent urachus; D, vesicourachal diverticulum.
in the bladder end (distal third of the urachus). Alternatively, in a type IV variant, degeneration of one of the plexuses of Luschka results in a cyst in the proximal third of the urachus.48 In autopsy series, the incidence of urachal cyst is 1 in 5000.49 Urachal cysts rarely manifest in the newborn period but may become symptomatic during late childhood or in early adult life. The presenting symptoms of children with urachal cyst include an asymptomatic suprapubic mass, fever with suprapubic pain, or irritative voiding symptoms with a palpable suprapubic mass. Not uncommonly, the urachal cyst may become infected, with Staphylococcus aureus the most common bacterium cultured.50 Because of the anatomy and location of the urachal cyst, infection is usually limited to the space of Retzius, but occasionally, an infected cyst ruptures into the peritoneum with resultant bowel fistula formation.51 The diagnosis of urachal cyst is most often made by ultrasonography, delineating the location of the cyst relative to the bladder and peritoneum and the limit of extension (Fig. 31-9).45 Computed tomography may be occasionally useful in further defining the extent of the cyst and the involvement of adjacent
Figure 31-9 Ultrasound study shows a urachal cyst (arrow) located anterior to the bladder.
chapter
A
31: Bladder Diverticula, Urachal Anomalies, and Other Uncommon Anomalies of the Bladder
B
421
C
Figure 31-10 Voiding cystourethrogram demonstrates a catheter in the patent urachus (A), with subsequent filling of the bladder with contrast material through the patent urachus (B) and voiding through the urethra (C).
structures such as bowel. Intravenous pyelography, voiding cystourethrography, or cystoscopy can be done to evaluate the degree of involvement of the bladder wall.48 Treatment for urachal cyst depends on the presenting symptoms. For children in whom the urachal cyst presents as an asymptomatic mass, observation may be appropriate for small cysts. With an infected urachal cyst, the initial treatment may include incision and drainage, marsupialization, or percutaneous catheter drainage. Definitive treatment with surgical excision should be performed after the inflammation subsides. This staged approach to treating infected urachal cysts helps to limit the amount of bladder wall resected and reduces the risk of injury to adjacent intraperitoneal structures.
Patent Urachus A patent urachus—a communication between the umbilicus and the bladder—results from the failure of a type I urachal termination variant to obliterate by desquamation of its epithelial mucosa. In autopsy series, the incidence of a patent urachus is 1 in 761.49 A patent urachus may be seen in patients with prune-belly syndrome but is uncommon in those with PUV.52 Patent urachus may manifest as an incidental finding on newborn ultrasonography; as a wet umbilicus with surrounding granulation tissue; as intermittent or continuous urinary drainage that is accentuated in the prone position or with crying, straining, or voiding; or as a periumbilical swelling or mass secondary to an associated umbilical hernia or engorgement of the urachal vasculature.48 The diagnosis of a patent urachus in patients with these symptoms should be differentiated from that of omphalitis, granulation of a healing umbilical stump, patent vitelline or omphalomesenteric duct, infected umbilical vessel, and external urachal sinus. Analysis of periumbilical fluid for creatinine or urea is useful in differentiating a patent urachus from these other conditions, and a fistulogram with radiopaque material is often diagnostic.45 A voiding cystourethrogram should be obtained to identify the fistula tract (Fig. 31-10) and, more importantly, to rule out the concomitant presence of bladder outlet obstruction or VUR. In the management of a patent urachus, observation may be indicated for young infants without symptoms, because the involution of the urachus is not complete at birth, and spontaneous closure can occur during the first months of life.53 In patients who have a patent urachus in association with bladder outlet obstruction, treatment of only the bladder outlet
Figure 31-11 Voiding cystourethrogram demonstrates a catheter placed into a vesicourachal diverticulum (arrow).
obstruction is often adequate, because spontaneous closure of the patent urachus usually occurs after adequate relief of bladder outlet obstruction. However, if drainage continues for several months, excision of the urachal tract and cuff of bladder through an extraperitoneal approach may be required.54
Vesicourachal Diverticulum Vesicourachal diverticulum develops when the communication between the bladder and the urachus fails to obliterate in a type II or III urachal termination variant, resulting in a fusiform outpouching at the apex of the bladder (Fig. 31-11). The
422
part
IV: Bladder
diverticulum is often nonobstructive, drains well, and therefore does not predispose to stagnation of urine or infection.48 It may be found in association with prune-belly syndrome and other bladder outlet obstructive disorders. However, vesicourachal diverticulum can also occur in the absence of functional or anatomic obstruction. The diverticulum does not usually require treatment. On the rare occasions when it is large, empties poorly because of a narrowed neck, or contracts paradoxically, excision of the vesicourachal diverticulum may be required.
Management Although most of these urachal anomalies are treated surgically, some patients with these anomalies are observed. Urachal carcinoma may develop within these anomalies, but it is rare in children (0.01%55) and accounts for fewer than 0.34% of all bladder cancers.56,57 The most common histologic type is adenocarcinoma, but other types have been reported, including transitional cell carcinoma,57 neuroblastoma,55 rhabdomyosarcoma,58 teratoma,59 yolk sac carcinoma,60 and inflammatory myofibroblastic tumors.61 Patients with urachal carcinoma most often present with hematuria and a palpable mass. The most common finding on radiologic evaluation is a filling defect within the bladder, with stippled calcifications. Patients with adenocarcinoma of the urachus have improved overall and disease-specific mortality risks compared to those with adenocarcinoma of the bladder.62 However, the prognosis of patients with urachal adenocarcinoma often remains poor because of late presentation with local invasion. Close radiologic evaluation is therefore warranted in children with urachal anomalies.
OTHER UNCOMMON ANOMALIES OF THE BLADDER Bladder Ears Bladder ears are lateral protrusions of the bladder wall into the internal inguinal ring. They are seen frequently on intravenous pyelography or voiding cystourethrography but usually recede when the bladder is filled to capacity (Fig. 31-12).48 They are caused by the close proximity of the infant bladder to the internal rings and are rarely seen in adults. Treatment is usually not necessary, because most resolve spontaneously with the growth of the bladder. However, on occasion, bladder ears may herniate into the internal ring and be accidentally resected during herniorrhaphy.63,64
Bladder Agenesis Bladder agenesis is a rare anomaly in viable newborns65,66; most with this anomaly do not survive. Fewer than 20 live births of infants with bladder agenesis have been reported in the literature, with the majority being girls.67-69 Although most of these patients are diagnosed during infancy, some patients with bladder agenesis are not diagnosed until a later age.67 In the absence of the bladder and trigone, the ureteral orifices follow the terminations of the mesonephric ducts and enter into the urethra, the vestibule, or Gartner duct in the female or the prostatic urethra in the male; or they may enter the rectum or the patent urachus.69-72 The ureters may remain separate or form a common channel. They are often hydronephrotic with or without associated renal dysplasia. Bladder agenesis is most often associated with neurologic, orthopedic,73 or other urogenital anomalies such as solitary kidney, renal agenesis, renal dysplasia, or an absence of the prostate, vagina, seminal
Figure 31-12 Voiding cystourethrogram demonstrates a bladder ear
(arrow).
vesicles, or penis.68,74,75 Hindgut abnormalities can occur,76 but the hindgut is usually normal. Palmer and Russi70 postulated that bladder agenesis results from failure of the lower portions of the mesonephric ducts to develop into the mesodermal portion of the bladder. More specifically, Krull and associates69 suggested that, in bladder agenesis, there is a failure of incorporation of the mesonephric ducts and ureters into the trigone, which prevents urine from accumulating in the developing bladder. Consequently, the bladder fails to develop due to a lack of distention with urine. In patients with bladder agenesis, initial treatment with urinary diversion is necessary, with complex urinary construction undertaken at a later age when appropriate.
Bladder Hypoplasia and Megacystis In congenital hypoplasia of the bladder and megacystis, it is believed that inadequate or excess filling of urine results in underdevelopment or overdevelopment of the fetal bladder. A hypoplastic bladder with little capacity develops in those disorders in which an inadequate amount of urine is stored in the fetal bladder (severe epispadias with incontinence, urogenital sinus abnormalities in females, bilateral renal agenesis, severe renal dysplasia) or the bladder is bypassed altogether (bilateral ureteral ectopia with distal urethral or vaginal orifices in the female).48 The congenital hypoplastic bladder can improve with refunctionalization but more commonly requires augmentation. In contrast, primary congenital megacystis is associated with massively refluxing megaureters and an excess amount of stored urine during bladder development (Fig. 31-13). Congenital megacystis was previously attributed to congenital bladder neck obstruction.77,78 However, it was subsequently recognized that megacystis most likely results from the constant recycling of urine between massively dilated upper tracts and the bladder.79 In patients with congenital
chapter
A
31: Bladder Diverticula, Urachal Anomalies, and Other Uncommon Anomalies of the Bladder
423
C
B
Figure 31-13 Voiding cystourethrogram demon
D
E
strates an enlarged bladder (A) with bilateral massive vesicoureteral reflux (B). The bladder is emptied after voiding (C); however, a large amount of contrast material remains in the upper collecting systems (D), which then drains into the bladder (E). This constant cycling of urine is thought to be the cause of megacystis.
megacystis, the trigone is wide and poorly developed, with gaping, laterally displaced ureteral orifices. These bladders are able to contract and empty normally, although much of their capacity goes into the upper urinary tracts. The diagnosis can be made prenatally, and the patients should be started on prophylactic antibiotic therapy.80 Congenital megacystis can also be seen in association with microcolon-intestinal hypoperistalsis syndrome81,82 or Ehlers-Danlos syndrome83 or secondary to outlet obstruction such as that caused by PUV, urethral diverticulum, anterior sacral meningomyelocele, sacrococcygeal teratoma, pelvic neuroblastoma, or cystic duplication of the rectum. The treatment of primary congenital megacystis is primarily directed at correcting the massive VUR, and reduction cystoplasty is often not needed.84 However, antireflux surgery in patients with congenital megacystis is often difficult to perform because of the thinness of the bladder wall. In patients with secondary forms of congenital megacystis, treatment of the obstruction is often adequate, and reduction cystoplasty is not routinely recommended.
Bladder Duplication Bladder duplication anomalies can be classified as complete or incomplete. In complete duplication, two bladder halves are present, each with a full-thickness muscular wall and mucosa (Fig. 31-14).85,86 Each bladder half is on one side of the midline, has an ipsilateral ureter, and drains into its complementary urethra. Fewer than 50 cases of complete bladder duplication have been reported in the literature. This duplication anomaly is more common in males. In 90% of cases, there is an associated complete duplication of the penis in the male or of the vagina
Figure 31-14 Voiding cystourethrogram demonstrates contrast ma-
terial filling two separate bladders (B) through two urethras (arrows). There is reflux into the right collecting system. Each bladder has a separate renal unit emptying into it.
424
part
IV: Bladder
A
B
Figure 31-15 Ultrasound study (A) suggests the presence of bladder septation (arrow), which was later confirmed on intravenous pyelog raphy (B).
and uterus in the female.87,88 In 40% to 50% of the cases, the hindgut is also duplicated.87,89 Lumbar vertebral duplication and fistulas between the rectum, vagina, and urethra may also be present. Major reconstructive surgery may be necessary for some of these patients. In incomplete duplication, the bladder is divided by a full-thickness wall, either sagittally or coronally.90,91 The two bladder halves, each with an ipsilateral ureter, communicate and drain into one common urethra. Incomplete bladder duplication is less common than its complete counterpart. In contrast to complete bladder duplication anomalies, genital and anorectal anomalies are not usually associated with the incomplete form. Usually, incomplete bladder duplication does not result in serious sequelae.92
with dysplasia or obstruction of one unit (which in turn can obstruct the contralateral unit).48 In contrast, both compartments in the incomplete septated bladder drain freely. In a multiloculated bladder, the rarest of the septation anomalies, fibromuscular walls compartmentalize the bladder body into unequal chambers. The serosal surface of the multiloculated bladder appears normal. The upper tracts are usually duplicated, with each entering into a separate chamber. The renal units to the blind compartments are dysplastic or obstructed, or both.48 Surgical treatment of these compartmentalization anomalies should be tailored for each patient, taking into account whether the bladder segments are obstructed and the degree of renal dysplasia associated with the obstructed bladder segments.
Compartmentalization Anomalies of the Bladder Compartmentalization anomalies such as septated, multiloculated, or hourglass bladder are often misdiagnosed as ectopic ureteroceles, bladder or urachal diverticulum, or dilated posterior urethra secondary to PUV. In the septated bladder, the bladder body is divided, completely or incompletely, in either the frontal or sagittal plane, by a partition of mucosa alone or with muscularis and mucosa (Fig. 31-15). One ureter enters each compartment, and there is a single bladder neck and urethra. Thus, complete bladder septation is associated
ACKNOWLEDGMENT We thank Dr. Robert Lebowitz for his invaluable assistance with the photographs in this chapter.
REFERENCES For complete list of references log onto www.expertconsult.com