Figure 3.

Major considerations in the management of upper tract and lower tract obstruction. For upper tract obstruction, most commonly unilateral ureteropelvic junction (UPJ) obstruction, the severity of functional obstruction is a major determinant for timing and selection of candidates for pyeloplasty. For lower tract obstruction, most commonly due to posterior urethral valves, surgical intervention is generally in the immediate postnatal period, although fetal intervention may be attempted in specialized centers. Long-term prognosis will be dependent on the degree of nephron maldevelopment and on the severity of bladder as well as kidney dysfunction.