右尿管走行異常および大動脈前腸骨静脈合流を伴う右重複下大静脈のまれな1例—CT所見および発生学的1考察

A rare case of the right double inferior vena cava（RDIVC）associated with circumcaval right ureter and preaortic iliac confluence：CT findings and embryological briefing

下大静脈の先天奇形は無症状であることがほとんどで，多くは画像診断にて偶然発見され，下大静脈後尿管，左下大静脈，腹部大動脈の左右に認められる重複下大静脈〔bilateral duplication of the inferior vena cava（IVC）〕，下大静脈奇静脈連結などが知られている。なかでも重複下大静脈は，比較的頻度が高く，0.3〜2.8％と報告されている^1）。

Recently, congenital anomalies of the inferior vena cava（IVC）and its tributaries have become more commonly detected in asymptomatic patients by CT. The most common are circumcaval ureter, bilateral duplication of IVC, left IVC, and azygos continuation of IVC. To our knowledge, one of IVC anomalies, the ipsilateral or right double IVC（RDIVC）excluding fenestration of IVC is so rare that 13 cases have been reported following the first report by Doyle et al in 1992. It is reported one case of RDIVC is associated with circumcaval ureter and preaortic iliac confluence. In this report, we describe the 2^nd case incidentally detected by CT, and its embryological and clinical implications.