Venous malformations may cause pain or swelling of the affected area or extremity. Slowed blood flow in abnormally dilated veins (venous ectasias) may lead to unusual sensations such as heaviness, numbness or tingling of the involved arm or leg.
Abnormal blood flow may also cause skin ulcers, muscle cramping or joint pain when walking. Blood clots (phleboliths) within superficial venous malformations result in inflammation and pain. The malformation may increase the risk of developing blood clots in the deep veins (deep vein thrombosis, DVT), which is a serious medical condition.
If these deep blood clots travel to the blood vessels of the lungs (pulmonary emboli, PE), this can be life-threatening. Venous malformations involving the pelvic area may cause bleeding from the bladder, GI tract/rectum, or genitalia. Individuals with large or multiple venous malformations may have blood abnormalities that increase the risk of bleeding and clotting.