A pseudoaneurysm is a blood filled cavity in direct communication with a artery or vein. Unlike a true aneurysm which an actual dilatation of the blood vessel a pseudoaneurysm is not formed by the vessel walls. These result when the vessel wall is injured during trauma or any medical procedure and blood continues to flow out of the vessel into this cavity which forms a wall from the surrounding tissue.
A pseudoaneurysm can be seen over sites where previous surgery has happened or at places where blood vessels have been accessed for any procedure like angiogram ( eg. Wrist / groin ). A pseudoaneurysm can also be associated with AV fistula puncture sites. These can get infected with damage to skin and can rupture leading to heavy bleeding and have to be diagnosed and treated adequately at the earliest.
A vascular surgeon will be able to determine which is the best option depending on specific patient parameters.