Congenital obstructive megaureter is a urinary malformation affecting the ureterovesical junction and causing obstruction to the flow of urine. It is the second most common cause of hydronephrosis. This malformation affects four times more boys than girls and is bilateral in 25% of cases. It is also associated with contralateral renal dysplasia in 15% of cases. The obstruction is linked to aperistalsis and hypertrophy of the circular muscle bundles and increased collagen 1 level. This malformation is accessible to antenatal screening from the second trimester. It falls within the scope of CAKUT and requires regular monitoring. Indeed, this uropathy can cause repeated pyelonephritis, kidney scarring and affected kidney function.

Inclusion Criteria:

• Minor patient (from 1 to 17 years old)
• Patient treated between January 2010 and December 2017 in one of the participating centers for an obstructive congenital mega-ureter
• Subject (and/or his parental authority) not having expressed, after information, his opposition to the reuse of his data for the purposes of this research

Exclusion Criteria:

• Subject (and/or his parental authority) having expressed, after information, his opposition to the reuse of his data for the purposes of this research

Minor patient (from 1 to 17 years old) treated between January 2010 and December 2017 for an obstructive congenital mega-ureter