Urinary Tract Pathology
Ureteral Duplication (bifid ureters) is a congenital malformation of the urinary tract, quite common in women, affecting about 1 % of the general population.
Ureteral development begins around the 4th week of embryonic life, when the ureteral bud arises from the mesonephric ducts and gives rise to the ureter as well as other parts of collective system. In ureteral duplication the ureteral bud is splitting or arises twice before metanephric blastema formation, causing multiple forms of abnormalities of the ureters or of the renal pelvis (duplication of ureters is often associated with duplication of the renal pelvis).
Ureteral Duplication - Classification :
- unilateral : affects only one kidney
- bilateral : both kidneys are affected
- partial ("Y" shape or incomplete) : ureter shows duplication only in the upper / proximal segment, which merge before opening into the bladder
- complete (total) : the two ureters are separated, one drains from the upper pole, the other from the lower pole of the kidney. The two ureters can merge very close to the opening point in the bladder, or one of them can drain into an ectopic point, most commonly, into the vagina or the urethra.
Clinical manifestations range from asymptomatic (in most cases) to signs of urinary tract infection (because of a vesicoureteral reflux), urinary incontinence, especially in females, in cases of ectopic ureter reaching the vagina or the urethra.
Complete and bilateral ureteral duplication
The ureters had a normal length about 25 - 30 cm and an outer diameter of about 5 - 9 mm. They emerge separately from the renal pelvis, one draining from the upper pole, the other from the lower pole of the kidney, with separate courses.
The two ureters merge at a point above the junction with the urinary bladder.
Both kidney and urinary bladder have normal size without macroscopically visible pathological changes.