Arterial Blood Gases. Test Overview. An arterial blood gas (ABG) test measures the acidity (pH) and the levels of oxygen and carbon dioxide in the blood from an artery. This test is used to check how well your lungs are able to move oxygen into the blood and remove carbon dioxide from the blood.
How Often the Test Is Done During Your Pregnancy. Your doctor may use the Doppler often to listen to your baby's heartbeat during routine checkups, starting at about 8 to 10 weeks. Handheld Dopplers will not work quite this early.
You know the one: lub-dub, lub-dub, lub-dub. Most of us think it's the sound of our heart beating or contracting, but it's not. What we're hearing is the sound of two pairs of valves closing inside the chambers of our heart. Like turnstiles, these valves allow blood to move in one direction through the heart and keep it from backing up down a one-way street.