Detection of crossing vessels as the cause of ureteropelvic junction obstruction: The role of antegrade pyelography prior to endopyelotomy

PURPOSE: To review the utility of antegrade pyelography in detecting crossing vessels as the cause of uretero-pelvic junction (UPJ) obstruction prior to planned endopyelotomy. MATERIALS AND METHODS: A retrospective review of the medical records, surgical reports, and medical images was performed in 109 consecutive adult patients in our practice who underwent antegrade pyelography just prior to planned endopyelotomy for symptomatic UPJ obstruction between January 1996 and December 2002. RESULTS: Fourteen patients were identified in whom a specific antegrade pyelographic appearance was detected in the diagnosis UPJ obstruction caused by crossing vessels. Surgical plans were changed in all 14 patients from antegrade endopyelotomy to open surgical pyeloplasty, during which the anterior (ventral) crossing vessels causing obstruction were confirmed. An additional three patients in the reviewed endopyelotomy group clinically failed their initial endopyelotomy procedure and were shown at the time of subsequent open or laparoscopic reconstructive surgery to have UPJ obstruction caused by anterior crossing vessels, but that diagnosis was missed at the time of the initial antegrade pyelogram. CONCLUSION: A specific antegrade pyelographic appearance was identified to diagnose UPJ obstruction caused by anterior crossing vessels with a sensitivity of 82.4% and a specificity of 100%. The direct obstructing effect of the vessels on the ureter is defined with pyelography as an acute posteriorly angulated ureteral deformity just below a patent UPJ. Recognition of this specific antegrade pyelographic appearance permits use of an appropriate surgical technique for UPJ obstruction repair.