Screening for lung AVMs is dependent on the age of the individual, and to a lesser degree their symptoms. During childhood, oxygen saturation should be checked every one to two years by finger oximetry done in both lying and sitting positions. Any subnormal result should be followed up with appropriate diagnostic testing. At 10-12 years of age, more sensitive screening should be done to rule out lung AVM(s). Currently in North America, a contrast echocardiogram (echo bubble) is usually recommended every 5 years to screen for lung AVMs in adults. It is a very sensitive test (meaning it will miss very few lung AVMs), but everyone with a ‘positive’ or ‘abnormal’ echo bubble test does not necessarily have a lung AVM large enough to require treatment.