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.
A Holter monitor is a small, battery-powered medical device that measures your heartâs activity, such as rate and rhythm. Your doctor may ask you to use one if they need more information about how your heart functions than a routine electrocardiogram (EKG) can give them. Twenty-four hour Holter monitoring is a continuous test to record your heartâs rate and rhythm for 24 hours.