Anomalous Communication Between Right Internal Iliac Vein And Left Common Iliac Vein - A Case Report

Introduction :

The internal iliac vein (hypogastric vein) begins near the upper part of the greater sciatic foramen, passes upward behind and slightly medial to the Internal iliac artery and, at the brim of the pelvis, joins with the external iliac vein to form the common iliac vein.

The common iliac veins are formed by the union of external and internal iliac veins. The left and right common iliac veins come together in the abdomen at the level of the fifth lumbar vertebra, forming the inferior vena cava. They drain blood from the pelvis and lower limbs.

The inferior vena cava (IVC) is the large vein that carries deoxygenated blood from the lower half of the body into the right atrium of the heart. It is formed by the union of the common iliac veins anterior to the body of the fifth lumbar vertebra, a little to its right side. It is posterior to the abdominal cavity and runs along the right side of the vertebral column (i.e. it is a retroperitoneal structure). It enters the right atrium at

the lower right, back side of the heart.

Case Presentation :

During routine educational dissection for medical undergraduates, we have come across a case of an anomalous communication between right internal iliac vein and left common iliac vein in a 55-year-old male cadaver. Formation of the IVC is also contributed by this anomalous communication between right internal iliac vein and left common iliac vein. Due to its complex embryogenesis and relationship with other abdominal and thoracic structures, IVC may develop abnormally.

Discussion :

Anatomical variation of the inferior vena cava occurs in 0.4-4% of the population¹.

Anomalies of the inferior vena cava and renal veins occur infrequently but if unidentified can lead to significant morbidity during surgical exploration². Embryogenesis of the IVC is a complicated process involving development, regression, anastomosis and replacement of three pairs of venous channels: posterior cardinal, subcardinal and supracardinal veins³.

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Superior view of the male pelvis

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IVC – inferior vena cava, RCIV – right common iliac vein, LCIV – left common iliac vein. RIIV – right internal iliac vein, AC - anomalous communication between right internal iliac vein and left common iliac vein.

The normal IVC converts to unilateral right sided system consisting of four segments, namely of hepatic, prerenal, renal and post renal segments. The hepatic IVC develops by coalescence of hepatic sinusoids, which are derived from the vitelline vein. The right sub cardinal vein develops into the suprarenal segment of IVC thus forming an anastomosis with the hepatic segment. The renal segment develops from anastomoses between the sub cardinal and supra cardinal veins. The post renal IVC is formed by confluence of the common iliac veins, the caudal extremity of the right post cardinal vein, the right post cardinal- supra cardinal anastomosis, a part of the right supracardinal vein, and the right supra cardinal- sub cardinal anastomosis⁴.The aberrant development of these venous systems, for unknown reasons, causes anomalies of the IVC system³.

Most of these variations are found via radiology or during post-mortem, dissection of cadavers in university anatomy classes, their identification is important in the clinical realm because it may reduce misdiagnoses⁵. It has been reported that these variants can be confused with lymphadenopathy, aortic aneurysm, and retroperitoneal cysts, which often leads to unnecessary interventions^{, 6}.

Conclusion :

A high index of suspicion on the part of the surgeon is required to prevent inadvertent injury to these anomalous veins and to avoid significant hemorrhage during retroperitoneal surgery. Preoperative assessment and intra operative awareness are important to prevent unexpected venous injuries⁷.Anomalous communication between right internal iliac vein and left common iliac vein is not been reported in the literature.