Fetal ascites as clinical presentation of inferior vena cava agenesis

Inferior Vena Cava (IVC) is composed of three segments from different embryological origin. Its lack of fusion originates a wide spectrum of anomalies of the IVC. These malformations are present in 0.07-8.7% of the population. It is generally diagnosed as an incidental finding in adult life. It represents between 5 and 9.5% of idiopathic deep vein thrombosis in patients younger than 30 years old without associated risk factors. We present a case of a term newborn with prenatal diagnosis of ascites during the 20th week of gestation. IVC Agenesis was diagnosed with the use of abdominal angiotomography. The treatment of patients with IVC Agenesis is based on the management of its complications. Due to the increased thrombotic risk of these patients, we should consider lifelong anticoagulation. We suggest initiating it during puberty.