Variations in internal iliac veins detected using multidetector computed tomography

Background: Anatomical variations of the internal iliac veins (IIV), which have the potential to cause problems during related surgery, are not uncommon and are not fully appreciated. Purpose: To determine the types and prevalence rates of anatomical variations of the IIV using multidetector computed tomography (MDCT). Material and Methods: IIV variations in 63 patients who underwent contrast-enhanced MDCT were interpreted and classified by two radiologists retrospectively. The prevalence rates (with 95% confidence intervals [CIs]) were calculated. Results: IIV variations were classified into six types: normal (n=45, 69.8%; 95% CI 59-81%); left IIV connecting with the left external iliac veins centrally (n=5, 7.9%; 95% CI 1-15%); separated trunk of the left IIV draining into the central left common iliac veins (CIV; n=3, 4.8%; 95% CI 0-10%); right IIV draining into the central left CIV (n=7, 11.1%; 95% CI 3 -19%);right IIV draining into the central right CIV (n=1, 1.6%; 95% CI 0-5%); and the bilateral IIVs connecting with each other before draining into the central left CIV (n=3, 4.8%; 95% CI 0-10%). Conclusion: MDCT demonstrates six types of IIV variations; the prevalence rate of IIV anomalies is not low.