The figures illustrate retroaortic anomalies of the renal veins. The overall incidence of these (type I, type II, type III, type IV) may be as high as 16%.
- Type I – Retroaortic left renal vein; normal level of drainage into the IVC (prevalence 0.3 to 1.9%).
- Type II – Retroaortic left renal vein, caudal level of drainage into the IVC (L4/L5) (prevalence 0.4 to 0.9%).
- Type III – Circumaortic left renal veins (venous collar), normal level of drainage into the IVC (prevalence 1.5 to 8.7%).
- Type IV – Retroaortic left renal vein, caudal level of drainage into the left iliac vein (prevalence 0.16%).
- Other (nonclassified) – Supernumerary renal veins, which can involve either kidney.
Modified from: Nam JK, Park SW, Lee SD, Chung MK. The clinical significance of a retroaortic left renal vein. Korean J Urol 2010; 51:276.
