Inferior vena cava agenesis: a rare cause of deep vein thrombosis.

The development of deep vein thrombosis (DVT) is influenced by a myriad of risk factors which are seen across a wide spectrum of healthcare settings. We present a previously fit and well male in his early 40s with extensive bilateral lower limb DVT associated with total inferior vena cava (IVC) agenesis. The diagnosis was made with contrast-enhanced CT imaging of the abdomen and pelvis. With no demonstrable subhepatic IVC, the majority of the venous drainage was via large azygous veins and distended collateral vessels. Lifelong anticoagulation was advised by both haematology and vascular surgery teams. IVC agenesis represents a very rare and largely unknown clinical entity within the medical community with currently no firmly established pathogenesis, guideline for future VTE prophylaxis or standardised follow-up strategy.