Congenital anomalies of the kidney and urinary tract exhibit a wide anatomic spectrum. These anomalies include renal anomalies and ureteropelvic anomalies, duplex collecting systems, and anomalies of the bladder and urethra. The ureteral anomalies can be of termination, structure, number or position. Duplex renal systems are commoner in females (65% of cases) and occur bilaterally in 20% of cases. Incomplete duplication is three times more common than complete duplication, which is reported to occur in about one of every 500 people.
Case presentation
In the routine educational dissection in the academic year 2017–2018 in our department of anatomy, in a male cadaver of about 50 years on the right side, two ureters were observed-first ureter(U1) from the hilum and the second ureter(U2) 2 cms below the first ureter (Fig. 1). The U1 was medial to the U2 in its upper course and then crossed two times the U2 from behind and again reached medial to the U2. The two ureters joined and formed a common channel before piercing the ureter. When the right kidney was opened, two separate pelvicalyceal systems were observed. The single ureter was observed on left side.
Fig. 1
Uniteral duplex collecting system of the right kidney with incomplete duplication of ureter.
Uniteral duplex collecting system of the right kidney with incomplete duplication of ureter.
Discussion
Embryologically, a single ureteric bud may divide before fusion with the mesenchyme to form a bifid ureter and a duplex kidney. Complete ureteral duplication will occur if two ureteral buds arise close together at the normal position on the mesonephric duct. The embryology of incomplete duplication is not well understood, but this anomaly may develop when a single ureteral bud branches before it reaches the metanephnic blastema. Ureteroureteral reflux, also known as yo-yo,saddle, or seesaw reflux, is a common but transitory phenomenon observed in incomplete duplication of ureters. Duplex systems are occasionally found incidentally on abdominal examination or during surgery. On an average 3% excretory urograms show ureteral duplication on routine examination. Diagnosis is usually made in childhood or antenatally, although it can be found in adulthood. Imaging modalities used include ultrasound, nuclear medicine, excretory urogram and computerized tomography. In adults, computerized tomography often demonstrates hydronephrosis, with a greater prevalence in the upper pole moiety. Bilateral duplicated collecting systems complicated with right ectopic ureteral orifice has been reported by Min Tang et al.
Conclusion
When symptomatic the recommended treatment for a duplex system is by ureterectomy or upper-pole heminephrectomy. Surgical approaches can be either open or laparoscopic, with laparoscopic gaining more favour except in complicated cases such as in our patient. Radiologists and surgeons should be aware that duplex systems may not always be visible on urography and sonography.
Fig. 1