Ureteropelvic junction obstruction in children: two variants of the same congenital anomaly?

To compare the characteristics of prenatally and postnatally diagnosed ureteropelvic junction obstruction (UPJO) in children.

We reviewed the records of 74 children who underwent pyeloplasty or nephrectomy for UPJO between 1995 and 2000. The patients were divided into 2 groups: prenatally and postnatally diagnosed UPJO. In each group, we compared age at surgery, gender, affected side, anteroposterior diameter (APD) of the renal pelvis, surgical findings, and renal function as determined by creatinine clearance.

Of the 74 children, 44 (59.4%) had a prenatal diagnosis of UPJO and 30 (40.6%) had a postnatal diagnosis despite the fact that all had had a fetal ultrasonography. Median age at the time of surgery was 6.3 years (4 months to 16 years) for children with postnatal UPJO and 3.6 months (1 month to 4 years) for the prenatal group. Forty-three percent of the children in the postnatal group and 25% in the prenatal group were females. Clinical manifestations in children with postnatal UPJO included abdominal pain in 13 (43%) patients, pyelonephritis in 7 (23%), urinary tract infection in 5 (16.6%), and occasional findings upon ultrasound in 5 (16.6%). Excretory urography suggested obstruction in most children. The surgical findings included ureteral kinks due to adhesions in 93.3% of postnatally diagnosed UPJO cases and in 27.3% of prenatal cases (p < 0.01). A reduction in mean creatinine clearance of hydronephrotic kidneys was observed for both groups when compared to reference values for the respective ages, but this difference was not statistically significant.

Postnatally diagnosed UPJO may be considered, at least in part, an entity different from prenatally detected obstruction due to its peculiar characteristics, i.e., postnatal UPJO more frequently affects females, manifests later in life with urinary infection or abdominal pain, and is frequently associated with ureteral kinking.