BLADDER DUPLICATION AND SEPTATION
Bladder duplication and septation are very rare congenital abnormalities, with only a small number of cases reported in the scientiﬁc literature. In either duplication or septation, division of the bladder may be complete or incomplete, and it may occur in the coronal or sagittal plane.
In duplication, each half of the divided bladder receives its own ureter and possesses its own full thickness wall. In incomplete duplication, the two halves typically unite above the level of the bladder neck and then drain together into a single urethra. In complete duplication, the two halves remain separate to the level of the bladder neck and can even drain into two independent urethras, each with its own external meatus. In some cases, however, one of the bladder halves lacks a urethral component, resulting in outlet obstruction and ipsilateral renal abnormalities.
In septation, a ﬁbromuscular wall divides the bladder into separate compartments. In contrast to duplication, septation produces two compartments that share a common wall. Like duplication, septation can be incomplete or complete, depending on how far the wall extends toward the bladder neck. Septation, however, is not associated with duplication of the urethra, and thus both compartments must be in open communication with the urethra. In some cases, however, fusion of the septum with the bladder neck causes one compartment to lose access to the urethra, resulting in obstruction.
Bladder duplication and septation are frequently associated with other anomalies, especially in the genitourinary system. For example, vesicoureteral reﬂux may be seen on one or both sides, resulting in hydronephrosis if severe. Likewise, one or both of the bladder components may lack a normal continence mechanism. If there is complete duplication of the bladder, concurrent duplication of the external genitalia may be seen as well. Less often, duplication may also occur in the lower gastrointestinal tract or spine.
The embryologic basis for these various anomalies is unknown. It is possible that complete duplication of the bladder and adjacent organ systems reﬂects partial twinning of the embryonic tail early in gestation. In contrast, isolated defects of the bladder may reﬂect abnormalities during cloacal septation (see Plate 2-4).
Presentation And Diagnosis
The timing of diagnosis depends on the nature and extent of the malformation. If there is external evidence of duplication such as in the genitals or spine the patient is likely to undergo comprehensive evaluation early in life, during which the bladder abnormality will be discovered. In contrast, if there is no external evidence of duplication, an evaluation may not be performed unless recurrent febrile urinary tract infections occur (secondary to urine stasis and or vesicoureteral reﬂux) or persistent incontinence is noted. In such cases, the bladder anomaly should be noted during imaging with ultrasound, CT, or voiding cystourethrography. Once the diagnosis has been established, further evaluation should include a renal scan to assess kidney function, as well as video-urodynamic studies to examine voiding from each bladder compartment and to determine if vesicoureteral reﬂux is present.
The need for surgical intervention depends on the nature and extent of the malformation. If an obstruction is present, it should be excised as soon as possible so as to reduce the risk of further infection and preserve renal function. If incontinence, vesicoureteral reﬂux, external duplication, and or other anomalies are present, a more complex intervention will be required, the speciﬁcs of which must be tailored to each individual patient.