Medical Blood Testing Overview

A blood test is a type of lab test where a sample of blood is drawn from a vein or from a finger prick. There are many different reasons you may need one of these tests including STD testing, pregnancy tests, thyroid checks, allergy testing and to monitor blood sugar levels. A blood draw is the most commonly performed medical test.

How is the test performed?

In most cases the lab test includes blood being drawn from a vein using a needle on the anterior forearm (inside elbow). In other cases, where the patient’s vein is fragile or not easily found or in the case of a small child or elderly person a finger prick may be used to obtain a small amount of blood. The area will be cleaned first with an antiseptic. Next the technician or nurse will tie a small rubber elastic around your upper arm to help apply pressure to the area making the vein swell with blood. They will then insert a needle into the vein and as the blood fills a vial attached to the needle, the elastic band will be removed. Once the sample is collected, the needle is removed and pressure is applied to the puncture site to stop bleeding.

How do I prepare?

Some tests require fasting the night before and morning of the test. Your doctor or lab will instruct you on whether this is required. In most blood test cases no preparation is needed.

When will I get the results and what do they mean?

In most cases, you will get results of the test within a few days to a week. The results you obtain from the physician or lab will include a reference range. The reference range in general is the value that 95% of the healthy population falls into. “Normal” results would mean your sample fell into that range. An “abnormal” result does not necessarily mean there is something wrong with you. There are many factors that can affect results such as diet, medication, stress and the handling of the sample. Any “abnormal” results should be discussed with your doctor.

What is the benefit to using a private lab?

At a private lab you can schedule a test without a doctor’s order. Results are available within one to two days and because insurance is not accepted, in most cases you pay less for the test. All tests are confidential.