There is a duplicated proximal left ureter, however, a single distal ureter is seen inserting into the bladder. Incomplete duplication of the left ureter. Duplication of a single distal ureter with normal insertion into the bladder is the most common of the renal anomalies associated with ureteral bud division. The first division of the elongating ureteral buds occurs earlier than normal, and the two branches continue to elongate before beginning the series of branches that leads to formation of the pelvocalyceal system. Early first branching causes duplication of the distal ureter.
Late duplication is seen as a bifid pelvis.
The most cephalic branch of a duplicated ureter drains only the upper pole, whereas the remainder is drained by the larger inferior collecting system. Duplication of a ureter is a precursor of abnormal placement of renal lobes or lobar dysmorphism.