Circumaortic left renal vein with an accessory retroaortic branch in a cadaver: A rare combination of type I and III variants

Congenital anomalies in renal venous anatomy are of clinical significance due to their implications in diagnostic imaging, surgical interventions, and renal transplantation. Among these, retroaortic and circumaortic left renal veins (RLRVs) are rare and often discovered incidentally during imaging or dissection. This case report aims to document and describe multiple rare congenital variations in renal venous anatomy observed during routine cadaveric dissection, with a focus on their classification and potential clinical relevance. Routine anatomical dissection was performed on the cadaver of an 84-year-old female donor in a medical anatomy laboratory setting. Detailed observation and documentation of the renal venous drainage patterns were conducted, with findings compared to existing anatomical classifications of RLRVs. Dissection revealed a circumaortic left renal vein composed of an anterior branch and an accessory retroaortic branch. Additionally, two distinct right renal veins were identified, draining independently into the inferior vena cava. These findings represent an unusual combination of Type I and Type III RLRV anomalies, along with bilateral supernumerary renal veins. This case highlights a rare and complex variation in bilateral renal venous anatomy, emphasizing the importance of a thorough understanding of venous developmental embryology. Such knowledge is crucial for clinicians involved in surgical planning, abdominal imaging, and renal transplant procedures to minimize the risk of iatrogenic injury and improve patient outcomes. • Documents rare combination of Type I and III retroaortic renal vein anatomy • Identifies bilateral supernumerary renal veins during cadaveric dissection • Reports on incidence of circumaortic and retroaortic renal vein anamolies • Emphasizes clinical relevance for imaging, surgery, and renal transplantation • Contributes to anatomical literature on renal venous developmental variations