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.
High blood pressure. Most of us on occasion can hear our heart beat during the night when things are very quiet. Most of us ignore it during the day, but it's there always. I suggest you see your doctor to check out your ears and possibly do a few other tests should he/she feel the need.