We report a case of neonatal urinary ascites in a newborn, presenting with a large communicating hydrocele. Initial diagnostic evaluation revealed high-grade ureteropelvic junction obstruction in a solitary functioning kidney with a nonobstructive megaureter. After pyeloplasty and with changing transitional nephrology, the megaureter became obstructive requiring tailoring and reimplantation. The unifying concept of ureteral valves explaining this case is presented.