Scimitar syndrome, also known as pulmonary venolobar syndrome or hypogenetic lung syndrome, is characterized by a hypoplastic lung that is drained by an anomalous vein into the systemic venous system. It is a type of partial anomalous pulmonary venous return.

It is essentially a combination of pulmonary hypoplasia and partial anomalous pulmonary venous return (PAPVR). It almost exclusively occurs on the right side.

Haemodynamically, there is an acyanotic left to right shunt. The anomalous vein usually drains into: 

• inferior vena cava: most common 
• right atrium 
• portal vein