Background: This chapter will discuss some of the more common bladder anomalies, such as bladder diverticula, and some of the uncommon bladder anomalies, such as bladder ears, congenital hypoplasia of the bladder, megacystis, bladder agenesis, duplication anomalies of the bladder, and finally, bladder septa. A discussion of urachal anomalies (urachal sinus, urachal cyst, urachal diverticulum, patent urachus) also will be included.

Pathophysiology: While the timing of altered embryogenesis leading to these conditions has been a matter of speculation, the embryologic cause of these lesions is unknown. Bladder development occurs during the fifth to seventh week of gestational development. Development depends upon many factors, such as proper mesenchymal differentiation, mesenchymal growth, urine production that stimulates bladder expansion, and detrusor contraction. Bladder cycling, the process of sequential expansion and contraction, is important in the anatomic and physiologic development of the normal bladder. Bladder ears are considered a normal variation, not a congenital anomaly.

Frequency:
 

• In the US: Bladder diverticula are uncommon, but not rare. In a series of over 5,000 children studied, the approximate incidence was 1.7%. All of the other entities are uncommon or rare.

Mortality/Morbidity: Most of these conditions have low mortality and little morbidity.

• Bladder diverticula and vesicourachal diverticulum often are asymptomatic but, when symptomatic, most often present with urinary tract infection. Rarely, they may cause bladder outlet obstruction. Death from peritonitis due to a ruptured infected urachal cyst has been reported in a few cases, but most bladder anomalies are incidental findings and are asymptomatic.

• Patent urachal anomalies usually do not cause significant morbidity or mortality. However, adenocarcinoma has been reported in adults in urachal remnants, presumably from chronic inflammation and infection.

• Bladder agenesis generally is incompatible with life.
  
   
• Megacystitis, bladder duplication, and bladder septation are rare. Morbidity of these conditions generally is related to associated abnormalities (when present) such as high-grade vesicoureteral reflux or renal dysplasia.
  
   
• Only 50 reported cases of bladder duplication exist.
  
   
• Bladder septations are equally rare.

Sex: All of these anomalies are infrequent or rare, and each condition occurs in both males and females. Data are insufficient to give reasonably accurate frequency differences in the sexes.

Age: Bladder anomalies generally are diagnosed in infancy or childhood. With the advent of prenatal ultrasonography, such abnormalities are fully evaluated after birth. When not detected by antenatal screening, most are discovered in the evaluation of a urinary tract infection or, in the case of urachal anomalies, periumbilical drainage or redness.

History:

• Bladder diverticula are herniations of the bladder mucosa through bladder wall musculature (detrusor muscle). Diverticular size can vary greatly, with some attaining a size equal to or greater than the volume of the bladder. Diverticula can be wide or narrow mouthed, as dictated by the size of the musculature (detrusor) defect. Size of diverticular openings has functional implications, since narrow-mouthed diverticula often will empty poorly. Stasis of urine within diverticula can also lead to stone formation or epithelial dysplasia.

• Depending on the size and location, bladder diverticula may cause ureteral obstruction, bladder outlet obstruction, or vesicoureteral reflux. Ureteral obstruction is unusual, occurring in approximately 5% of children with bladder diverticulum. Bladder outlet obstruction is rare. However, vesicoureteral reflux is more common, ranging from 8-13% of patients.

• Bladder diverticula most commonly occur lateral and superior to the ureteral orifices. They also may occur at the dome of the bladder, particularly in such disorders as bladder outlet obstruction (ie, posterior urethral valves) or Eagle Barrett Syndrome (Prune Belly Syndrome).

• Bladder diverticula may be congenital or acquired. In the pediatric population, the majority are congenital. Congenital deficiency or weakness in the Waldeyer fascial sheath has been implicated as a cause. Congenital diverticula tend to be solitary and are located at the junction of the bladder trigone and detrusor. This anatomic location, close to the insertion of the ureter to the bladder, is important, since large diverticula can impinge upon or distort the ureteral orifices. Therefore, undertake surgical excision of these diverticula with care to avoid injuring the ureter.

• Acquired diverticula are the result of obstruction, infections or iatrogenic causes. They tend to be multiple and occur in trabeculated bladders. Examples of loci of obstruction include posterior urethral valves, anterior urethral valves, urethral strictures, neuropathic bladder, and external sphincter dyssynergy. An example of iatrogenic diverticula is herniation of the bladder mucosa through the ureteral hiatus after antireflux surgery, due to inadequate closure of the ureteral hiatus. Many diverticula that are related to obstruction spontaneously resolve after relief or correction of the obstruction. In some cases, the diverticula that occur in response to obstruction serve a beneficial function by acting as pressure pop-off mechanism, protecting the kidney and ureters from high pressures.

• It has been observed that some children with diverticula have voiding dysfunction on urodynamic testing. Whether the voiding dysfunction leads to the formation of diverticula, or the presence of diverticula leads to voiding dysfunction, is unclear.

• A urachal sinus derives from a persistently patent urachus. The sinus drains to the umbilicus, and this drainage often is the result of episodic infections of the sinus, resulting in the appearance of purulent drainage at the umbilicus. Children may present with periumbilical tenderness, a wet umbilicus, or granulation tissue at the level of the umbilicus. In many instances, these children have undergone multiple sliver nitrate cauterizations under the mistaken notion that this is simply granulation tissue after severance of the remnant umbilical cord.

• Urachal cyst is a fluid-filled structure occurring in between the two obliterated ends of the urachus: umbilicus and bladder dome. Most occur in the distal third of the urachus. In infancy, such cysts are rarely symptomatic, but they are detected with increasing frequency as an incidental finding during bladder ultrasonography in children undergoing evaluation for other reasons (eg, prenatal hydronephrosis, urinary tract infections). More commonly, the urachal cyst is detected in early childhood or adolescence. Symptoms generally are related to infection and the resultant inflammation and include suprapubic mass, fever, pain, bladder or irritative voiding symptoms. Staphylococcus aureus is the most common bacterial organism. The peritoneum alone separates the cyst from the intraabdominal cavity, so the inflammatory process may involve the adjacent intraabdominal contents, resulting in abdominal pain. Death from intraabdominal rupture has been reported.

• A patent urachus is a communication from the umbilicus to the bladder. Infants present with continuous or intermittent drainage from the umbilicus. Crying, straining, voiding, or the prone position may accentuate intermittent drainage. The tract may become inflamed, resulting in tenderness, periumbilical swelling, and serosanguinous or purulent discharge. The patent urachus also may be associated with bladder outlet obstruction, such as posterior urethral valves. Correction of the obstruction may result in the spontaneous resolution of the patent urachus. However, if the patent urachus persists beyond several months after relief of the obstruction, it should be surgically corrected.

• Vesicourachal diverticulum is an outpouching at the apex of the bladder that results from incomplete closure of the proximal urachus. Most are asymptomatic since they drain well with bladder emptying. Often, vesicourachal diverticula are discovered incidentally during evaluation for other reasons. Rarely, they become large and empty poorly, resulting in recurrent urinary tract infections or stone formation.

• Bladder ears are lateral protrusions of the bladder through the internal inguinal ring and into the inguinal canal. In infants, the bladder assumes a more abdominal position, which places it in close proximity to the internal inguinal ring. With growth, the pelvis becomes more developed, and the bladder assumes a more pelvic position. Therefore, this is rarely seen in adults. Bladder ears often are seen during the voiding cystourethrogram (VCUG) or intravenous pyelogram (IVP), when the bladder is filled to capacity. Knowledge of this entity is important to surgeons during inguinal herniorrhaphy, since occasional reports have been made of partial or near total cystectomy performed under the mistaken notion that this was a large hernia sac.

• Bladder agenesis: This condition is rare (approximately 45 reported cases) and generally incompatible with life. Fewer than 20 cases have been reported in live births, and all have been females, presumably since they have less outlet resistance than males, resulting in some preservation of renal function. Ureters may enter into the urethra, vagina, Gartner duct cyst (female), prostatic urethra, rectum, or the patent urachus. Most often, associated hydroureteronephrosis and renal dysplasia (variable) are present. Other associated anomalies include neurologic, orthopedic, hindgut, and other urogenital anomalies, such as renal agenesis, absence of the prostate, vagina, seminal vesicles, epididymis, or penis.

• Megacystitis often is discovered postnatally when completing the evaluation of prenatal hydronephrosis. Febrile urinary tract infection is the other common presentation. Megacystitis is an enlarged bladder, believed to be secondary to overfilling of the fetal bladder during development. This condition is associated with massive high-grade vesicoureteral reflux, which may also be the etiology of megacystitis. In the presence of massive reflux, a large percentage of the voiding bladder volume is refluxed into the upper tracts. This causes constant recycling of the urine between the bladder and ureters, resulting in progressive dilation of both. Megacystitis can be seen in other conditions, such as posterior urethral valves, Ehlers-Danlos syndrome, urethral diverticulum, microcolon hypoperistalsis syndrome, sacral meningomyelocele, sacrococcygeal teratoma, and pelvic neuroblastoma.

• Bladder duplication: Bladder duplication is rare, with fewer than 50 cases reported. Duplication can be complete or partial, with complete duplication more common than incomplete duplication. The 2 halves of the bladder are on either side of the midline, with the corresponding ipsilateral ureter draining each bladder half. Associated anomalies occur with much greater frequency in complete bladder duplication, including duplication of the penis, vagina, uterus, lumbar vertebrae, and hindgut. In addition, fistulas may be present between the rectum, vagina, and urethra. With complete bladder duplication, 2 urethras will exist. With incomplete bladder duplication, the bladder will join distally into one common urethra.

• Bladder septation: Bladder septation anomalies are rare. Fibromuscular or mucosa septations divide the bladder into equal or unequal portions. Septations may be complete or incomplete. Functioning of the associated renal units depend on adequacy of upper tract drainage.

Physical: For many of the bladder anomalies, no overt physical findings are seen. They are elucidated after radiologic imaging for such things as a history of prenatal hydronephrosis or urinary tract infections. Physical findings relative to each of the anomalies are as follows:

• Bladder diverticula - None

• Urachal sinus - Intermittent drainage from umbilicus (may be serous or serosanguinous)

• Urachal cyst - None (with infected cyst physical findings include infraumbilical or suprapubic mass with tenderness or erythema of overlying skin).

• Patent urachus - Intermittent umbilical drainage (may be serous or urine)

• Vesicourachal diverticulum - None

• Bladder ears - None

• Bladder agenesis - None (Most physical findings pertain to various associated anomalies.)

• Megacystitis - None

• Bladder duplication - None (In complete bladder duplication, it may be possible to identify 2 urethral openings.)