The left lumbar cystic structure is suggestive of an accessory kidney with obstructed pelvicalyceal system as the left kidney. This could be associated with ureteric anomalies as ectopic ureteric opening and fusion anomalies as causes of obstruction. Ureteric strictures and pelviureteric junction obstruction also can result from recurrent urinary tract infections that associate ureteric anomalies. 

The certain cause of obstruction is not known as the delayed excretory phase is not available.