This article discusses some of the more common pediatric bladder anomalies, such as bladder diverticula, as well as some of the uncommon 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 (ie, urachal sinus, urachal cyst, urachal diverticulum, patent urachus) is also included. [1, 2]
The timing of altered embryogenesis leading to bladder anomalies has been a matter of speculation, and 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.
Bladder diverticula are uncommon but not rare. In a series of over 5000 children studied, the approximate incidence was 1.7%. All of the other entities are uncommon or rare. In particular, megacystis, bladder duplication, and bladder septation are quite rare. For example, only 50 reported cases of bladder duplication exist. [3, 4]
Bladder anomalies are generally diagnosed in infancy or childhood. With the advent of prenatal ultrasonography, such abnormalities are fully evaluated after birth. When they are not detected by antenatal screening, they are most commonly discovered in the evaluation of a urinary tract infection or, in the case of urachal anomalies, periumbilical drainage or redness. All of these anomalies occur in both males and females. The data are insufficient to establish any reasonably accurate frequency differences between the sexes.
The prognoses for the various pediatric bladder anomalies are as follows:
Bladder diverticula - Excellent
Urachal sinus - Excellent
Urachal cyst - Excellent
Patent urachus - Excellent
Vesicourachal diverticulum - Excellent
Bladder ears - Excellent
Bladder agenesis - Guarded
Megacystis - Good
Bladder duplication - Good to excellent
Bladder septation - Variable, ranging from guarded to good, depending on the anatomy and the degree of renal dysfunction
Most of these pediatric bladder anomalies have a low mortality and are associated with little morbidity.
Bladder diverticula and vesicourachal diverticula often cause no symptoms, but in symptomatic cases, patients most often present with urinary tract infection. Rarely, bladder diverticula and vesicourachal diverticula 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 patients are asymptomatic.
Patent urachal anomalies do not usually cause significant morbidity or mortality. However, adenocarcinoma has been reported in adults in urachal remnants, presumably from chronic inflammation and infection. The risk of later adenocarcinoma appears to be low in children with asymptomatic lesions. 
Bladder agenesis generally is incompatible with life.
The morbidity of megacystis, bladder duplication, and bladder septation is generally related to associated abnormalities (when present), such as high-grade vesicoureteral reflux (VUR) or renal dysplasia.
In all of these conditions, an element of voiding dysfunction may exist. Parents should be educated regarding frequent and complete bladder emptying after the toilet training period to guard against infrequent and dysfunctional voiding patterns. In general, children should void approximately 5-6 times per day, which equates to voiding every 3 hours. Infrequent and dysfunctional voiding in the presence of an anatomic abnormality may place the child at increased risk for febrile urinary tract infections and renal damage.
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