The absence of crossing vessels in association with ureteropelvic junction obstruction detected by prenatal ultrasonography

Purpose: The widespread use of prenatal ultrasonography has led to a marked increase in the incidence of ureteropelvic junction obstruction presenting in infancy. Which of these prenatally detected lesions requires repair has yet to be fully determined. Attempts to characterize prenatally detected ureteropelvic junction obstruction in regard to symptomatic obstruction detected later in life may provide useful insights into the management of these incidentally discovered lesions. We evaluated the presence of crossing vessels in ureteropelvic junction obstruction identified by prenatal ultrasonography. Materials and Methods: We reviewed the records of patients who underwent dismembered pyeloplasty for primary ureteropelvic junction obstruction with specific attention to the mode of presentation and presence of crossing vessels associated with obstruction. Results: In 30 patients with a mean age of 6 months ureteropelvic junction obstruction detected prenatally was not associated with a crossing vessel. Ureteropelvic junction obstruction was identified postnatally in 125 patients who underwent open pyeloplasty. It was detected incidentally in 8, of whom crossing vessels were present in 1 (12%). There were signs or symptoms related to ureteropelvic junction obstruction in 117 patients. In contrast to the group with prenatally detected ureteropelvic junction obstruction in which crossing vessels were never noted, crossing vessels were associated with 36 (30%) of the 120 kidneys operated on in this postnatally discovered group. Conclusions: No crossing vessels were present in patients with prenatally detected ureteropelvic junction obstruction compared with 30% in symptomatic patients. This finding may reflect the natural history of the disorder, or it may suggest that prenatally identified ureteropelvic junction obstruction is an entity largely different from obstruction presenting later in life.