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Segmental Septation of the Inferior Vena Cava

National Cancer Institute Fondazione Pascale Naples, Italy

There are several well-known congenital abnormalities of inferior vena cava, usually recognized incidentally [1-3]. The most frequent abnormalities include the absence of the inferior vena cava, left-sided vena cava, double vena cava (duplication), absence of the hepatic segment of the inferior vena cava with azygos continuation, absence of the infrarenal segment of the inferior vena cava with preservation of the suprarenal segment, circumaortic left renal veins, and retroaortic left renal vein. These anomalies are well explained on the basis of the complex embryogenesis of the inferior vena cava [1-3].

We observed a case of a different kind of vena cava anomaly that, to our knowledge, has not yet been reported in the radiologic literature.

A 54-year-old white man with advanced melanoma underwent whole-body CT examination to rule out visceral involvement. Contrast-enhanced single-detector helical CT was performed using 8-mm thickness, 8 mm/sec table feed, 1-sec revolution time, 5-mm reconstruction interval, and 110 mL of contrast medium injected at a rate of 2 mL/sec. A first acquisition, including the chest and upper abdomen, was obtained 35 sec after beginning contrast medium injection, and a second acquisition, including the upper and lower abdomen, was obtained 65 sec after contrast injection. CT study did not depict any metastatic localization. Nevertheless, an unusual appearance of inferior vena cava was found on the second CT acquisition (Fig. 1A). There was a normal confluence of common iliac veins into a single vena cava but, 2 cm cephalad, the vein turned into two adjacent vessels with interposition of a thin septum running all the way across the lumen.

View larger version (105K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1A —54-year-old man who underwent CT to rule out melanoma metastases. Axial CT scan shows double-channel appearance (arrow) of infrarenal segment of inferior vena cava.

View larger version (137K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1B —54-year-old man who underwent CT to rule out melanoma metastases. Sagittal reformatted image of inferior vena cava clearly shows thin adipose septum (arrow) within infrarenal segment of inferior vena cava.

These veins were noted to run parallel— one anteriorly and the other posteriorly—for 5 cm. Subsequently, the two vessels rejoined together, receiving a single renal vein from each side. The other inferior vena cava segments and the azygos-hemiazygos system had a normal appearance. Sagittal reformation (Fig. 1B) allowed a more comprehensive display of this venous abnormality.

The patient had no history of previous inferior vena cava thrombosis and no history of previous venous instrumentation, such as filter or catheter placement.

The inferior vena cava is composed of four segments: hepatic, suprarenal, renal, and infrarenal. In our observation, the infrarenal segment was involved. Embryologically, this segment is believed to derive from the right supracardinal vein [1-3]. Normally, the left supracardinal vein atrophies or, more probably, is incorporated into the right one by coalescence of multiple anastomoses existing between the two supracardinal veins [1]. Inferior vena cava duplication arises from persistence of the left supracardinal vein [1-3]. Possibly, the anomaly we observed may result from incomplete fusion between the right and left supracardinal veins.

References

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1. Bass JE, Redwine MD, Kramer LA, Huynh PT, Harris JH Jr. Spectrum of congenital anomalies of the inferior vena cava: cross-sectional findings. RadioGraphics 2000;20 : 639-652[Abstract/Free Full Text]
2. Chuang VP, Mena CE, Hoskins PA. Congenital anomalies of the inferior vena cava: review of the embryogenesis and presentation of a simplified classification. Br J Radiol1974; 47:206 -213[Medline]
3. Mayo J, Gray R, St. Louis E, Grosman H, McLoughlin M, Wise D. Anomalies of the inferior vena cava. AJR1983; 140:339 -346[Free Full Text]

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This Article Figures Only Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by De Rosa, V. Articles by Siani, A. Search for Related Content PubMed PubMed Citation Articles by De Rosa, V. Articles by Siani, A. Social Bookmarking                      What's this?