Venous malformations are another type of vascular malformation; they result from abnormal development of the veins in the affected areas. They typically appear as a bluish discoloration of the skin, lips or inside of the mouth, and tend to increase in size with effort such as crying, pushing or other maneuvers that increase pressure in the venous system. They do not have the increased pulsations or temperature that is seen in AVMs, and they generally do not cause any strain on the heart. The abnormal veins have poorly formed walls due to insufficient smooth muscle, and gradually “stretch” over time. As blood accumulates in the spaces, clots form and may calcify, causing “phleboliths” or vein stones.

Symptoms vary according to the location of the VM. Those involving the tongue or other structures around the airway may cause problems with breathing or speaking, while those in the legs typically cause painful swelling. In the legs and arms, the swelling can often be improved by wearing elastic stockings or sleeves.

Treatment of VMs involves techniques that damage and close the abnormal veins to relieve the swelling. These procedures are usually performed in an angiography suite, with the assistance of ultrasound guidance and “fluoroscopy” or real-time x-ray monitoring.

With sclerotherapy, a substance is injected to produce scarring within the VM. Different substances (sclerosing agents) are used to achieve this goal. Endovenous laser therapy is a technique that aids sclerotherapy of large venous malformations. The combination of endovenous laser therapy and sclerosant injection appears to result in a more rapid response and an easier recovery from the procedures. Extensive VMs often require a series of ablation procedures, and patients may benefit from additional treatment a few years later.