We present a case of incomplete bladder duplication in a male child with no other associated anomalies and review the literature pertaining to this rare anomaly.
Authors: Dushi, Gezim; Ramseyer, Pascal; Osterheld, Maria-Chiara; Meyrat, Blaise; Frey, Peter. CHUV, Lausanne, Switzerland.
Corresponding Author: Peter Frey, MD, BSc, CHUV, Pediatric Urology, Lausanne, Switzerland. Email: [email protected]
Incomplete bladder duplication is an extremely rare condition. Since Cattirri reported the first case in 1670  only 7 further cases have been reported in the literature [1-3]. Incomplete bladder duplication is often associated with other genitourinary anomalies [2,3] and can even be associated with bladder exstrophy . We present a case of incomplete bladder duplication in a male child with no other associated anomalies and review the literature pertaining to this rare anomaly.
This case resembled closely that of a patient we attended not too long ago. He had bladder complications that seemed to have developed from not going to the bathroom as often as he needed. He was as frequent visitor of the casino SBOBET that is nearby to our medical center. We helped him with his condition and of course gave him multiple instructions to follow so that this would not happen again.
A 9 year-old-boy presented at the out-patient clinic after two episodes of asymptomatic lower urinary tract infections. However, he was suffering from voiding difficulties, characterized by urge incontinence, poor urinary stream and the necessity to raise the abdominal pressure in order to initiate voiding. Physical examination was uneventful. A single urethral meatus was observed. Ultrasound, showed two hypoechogenic structures in the pelvis, communicating with each other. The kidneys appeared of normal size and morphology. Voiding cysto-urethrography confirmed the presence of these two communicating structures, lying adjacent to each other in the coronal plane; the left structure was slightly postero-lateral to the structure on the right, which was supposed to be the main bladder, the latter in communication with a single urethra (Figure 1 A).
Figure 1. A. Preoperative VCUG showing the two bladder structures in a latero-lateral position, the right-sided structure being in communication with a single urethra. B. VCUG, showing the reconstructed main bladder after excision of the left-sided structure and re-implantation of the left ureter in a coronal and C. in a sagittal view.
No vesicoureteral reflux was seen. During this procedure the boy could not void despite a filling volume of 600 ml and the entire urethra, therefore, could not be imaged. To further delineate the nature of the left structure we performed magnetic resonance imaging (MRI) (Figure 2 A and B).
Figure 2. MRI: A.Coronal, B.Saggital T2-weighted view of the latero-lateral incomplete bladder duplication.
This structure measured 11 cm in the cranio-caudal axis, 11,2 cm in the antero-posterior and 6 cm in the transverse axis. The communication between the two structures was located on the left infero-lateral side of the supposed main bladder and measured 1,5 cm in diameter. Implantation site of the ureters could not be distinguished.
Cystoscopy was performed. The presence of a single urethra was confirmed and no posterior urethra valves could be detected. The ureteral meatus could not be identified on either side.
On surgery the two structures were identified, each containing a separate ureteric orifice meatus. The right ureteric orifice, draining into the main bladder, lay in a normal position. The left ureteric orifice was identified to be lying in a postero-superior part of the left structure (Figure 3 and 4).
Figure 3. Intraoperative view of the latero-lateral bladder structure and its ureter
Figure 4. Schematic presentation of incomplete bladder duplication
The left ureter was completely mobilized and thereafter re-implanted into the right bladder, applying a modified Cohen procedure. The left structure was excised and the isthmus closed with two layers of running sutures. The excised specimen was fixed in formalin for histologic evaluation. Histology showed the presence of urothelial, smooth muscle and serosal layers. Immunohistochemically the smooth muscle layer stained positive with anti-a-smooth muscle actin (Figure 5).
Figure 5. Immunohistology of the excised left bladder structure, applying monoclonal anti-smooth muscle a-actin antibodies – peroxidase reaction to demonstrate the presence of smooth muscle. (X100)
Three months after surgery, voiding cystourethrography was repeated. It showed the absence of vesicoureteral reflux and a bladder capacity of approximately 250 ml. The presence of a slightly ectatic prostatic urethra was noted and voiding was complete (Figure 1B and C). The patient showed normal urinary continence and no further urinary tract infection was detected.
Discussion and literature review
In 1961, Abrahamson  classified bladder duplication as complete or incomplete. With complete duplication, two bladders are present with separated walls of mucosal and muscular layers, and each one empties through its own urethra. The final diagnosis is made by simultaneous retrograde urethrocystograms . In incomplete bladder duplication, two bladders communicate with each other and drain into a common urethra. Duplication of the bladder may occur in a sagittal or coronal plane given the axis of the septum. The sagittal variant appears to be predominant compared to the coronal one, with a ratio of 2.5:1. According to published literature, the male to female ratio of this anomaly is described to be equal [1, 5-8]. Females are more likely to present the sagittal type of duplication and in males there is no predominance.
The aetiology of bladder duplication, despite the hypotheses proposed by Abrahamson , remains obscure. More recently Voigt  raised the question of whether the aetiology can be explained by the existence of a human homologue of the mouse mutant disorganization gene first described by Hummel in 1959. 
Complete bladder duplication is, in the majority of cases, associated with other anomalies. 40 cases of complete bladder duplication were reviewed by Kossow and Morales in 1973 . They found associated duplication of the lower gastrointestinal tract in 42%, external genitalia in 90% and spina bifida, meningocele or myelomengocele in 15% of cases. Similar findings, except a lower percentage of associated duplication of the external genitalia (30%), were reported by Berrocal et al . Associated urogenital or non-urogenital anomalies seem to depend on the axis of the septum. Non-urogenital anomalies seem to be predominantly present in complete bladder duplication with a saggital septum, while urogenital anomalies are more common in complete duplication with a coronal septum [6, 11-13]. After literature review, only six cases of complete bladder duplication without any associated anomalies were reported .
Of the previously reported 8 cases of incomplete bladder duplication, five presented with other anomalies and three were anomaly-free. In our patient, the ninth reported case, no any additional anomalies were present either. The histology of the excised left structure from our patient showed the typical findings of the bladder wall, comprising urothelial, smooth muscle and serosal layers. In particular the existence of bladder smooth muscles, could be proven by positive specific anti-a-smooth muscle-actin immunohistochemistry findings. Furthermore primary urothelial and smooth muscle cell cultures could be established in-vitro with the excised tissue, thus also proving the existence of bladder duplication.
The treatment of bladder duplication cannot be standardized, due to the great variations in presentation. We agree with statements in the literature, that treatment should aim at optimization of bladder function, addressing urinary continence and minimising the risk of infections [1, 2, 7, 8], which was the initial presentation in our case.
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7. Coker AM, Allshouse MJ, Koyle MA. Complete duplication of bladder and urethra in a sagittal plane in a male infant: case report and literature review. J Pediatr Urol. 2008 4: 255-259.
8. Voigt HR, Wentzel SW. Complete duplication of the bladder, urethra and external genitalia in a male neonate with an imperforate anus. Int J Urol. 2005 12: 702-704.
9. Hummel KP. The inheritance and expression of disorganization, an unusual mutation in the mouse. J Exp Zool. 1958 137: 389–423.
Date added to bjui.org: 14/04/2011