The internal anatomy of the inferior vena cava with specific emphasis on the entrance of the renal, gonadal and lumbar veins.

Major tributaries such as the renal and adrenal veins have been studied extensively; however, tributaries of the infra-renal segment of the inferior vena cava (IVC) have not been given much attention. Accurate knowledge of the anatomy of these veins is necessary for improved efficacy of surgical interventions in the retroperitoneum. The aim of this study therefore was to provide a comprehensive picture of the internal anatomy of the tributaries of the infra-renal segment of the IVC. Dissection of the posterior abdominal wall was performed on 30 formalin-fixed cadavers. Endoscopic study was carried out followed by a midline venotomy on the anterior wall of the isolated IVC, the location and orientation of its tributaries and their ostia were observed and measurements taken. The results showed that while there was great variation in the drainage pattern of the lumbar veins, most lumbar veins had ostia located between L2 and L3 vertebrae irrespective of the location of renal and gonadal tributaries. Valves were found in 81.81 % of gonadal veins, in 56.60 % of all lumbar veins and discrete ostial valves in 14.81 % of renal veins. The location of the tributaries of the IVC was correlated with the vertebral levels. Empirical data regarding their ostio-valvular complexes were established, which put into question widely accepted concept of valveless tributaries. Our results may implicate surgical procedures in and around the retroperitoneal region.