Inferior vena cava duplication.

Abstract

Dear Editor, Duplication is an uncommon anomaly of the inferior vena cava and it may occur in up to 3 % of general population. Although it remains asymptomatic, inferior vena cava duplication may play a role as a confounding factor in imaging diagnostic tests and also may represent a hazard for bleeding during retroperitoneal surgery. A 72-year-old woman was referred to the department for a pelvic mass involving the wall of the intraperitoneal rectum. Two years before she had undergone open surgery consisting of hysterectomy and bilateral annessectomy for ovarian cancer. Surgery was followed by chemotherapy courses. In the follow-up, a CT scan of the abdomen revealed, in adjunct to the pelvic lesion, a rounded enhanced structure 11 mm in diameter located near the left side of the infrarenal aorta that was reported as an enlarged lymph node (Fig. 1). Clinical features strongly suggested a pelvic recurrence from ovarian cancer involving the rectum with aortic lymph-nodes metastasis and surgery was planned. At laparotomy, the diagnosis of pelvic recurrence of ovarian cancer extended into the rectal wall was confirmed. After mobilization of the descending colon and the sigmoid, it was discovered that the left common iliac vein did not merge with the right common iliac vein to form the inferior vena cava (IVC) (Fig. 2). The left common iliac vein proceeded cephalad representing a left IVC, to flow into the left renal vein (RV). During its course, the left IVC drained the left gonadic vein. The venous trunk formed by the left IVC and the left RV passed anteriorly to the aorta, and drained into the right IVC to form a single suprarenal IVC (Fig. 3). No enlarged node was found around the aorta. The IVC anomaly did not prevent performing the planned procedure of anterior resection of the rectum that was safely accomplished. Surprisingly, the IVC anomaly had not been mentioned in the report of the hystero-annessectomy operation. The IVC is formed between weeks 6 and 10 of gestation. It has been estimated that duplication occurs in 0.2–3.0 % of the general population [1]. The infrarenal portion of the IVC is formed from two embryonic veins, the supracardinal veins. The right supracardinal vein persists and develops as IVC while the left supracardinal vein regresses. Persistence of both supracardinal veins results in duplication of IVC [2]. Failure to form an adequate anastomosis between the embryonic supracardinal veins has been suggested as an alternative theory to explain the IVC anomaly [3]. Typically, the IVC presents bilaterally and the left renal vein ends into the left IVC, which crosses anterior to the aorta to join the right IVC. Depending on the size of the duplicated IVC and the preaortic trunk, a morphologic classification of this anomaly has been proposed [4]. Type I duplication refers to bilateral and symmetrical IVC having the same caliber of the preaortic trunk; in type II, both the right and left IVC are symmetric but their caliber is smaller compared to the caliber of the preaortic trunk, and in type III duplication the caliber of the left IVC is smaller in comparison to the caliber of the right IVC and the preaortic trunk. In the presented case, the caliber measured by CT scan was 11 mm for the left IVC and 19 mm for the right & Massimo Chiarugi massimo.chiarugi@med.unipi.it