Lab Questions & Answers

When you visit any lab, we want you to have a comfortable and convenient experience. Learn the answers to several frequently asked questions about laboratory services & blood work.

Effective June 1, Mercy’s outreach lab services transitioned to Quest Diagnostics. Please consult your provider for a referral to another lab service site, as the decisions on testing facilities are always made by providers and patients together.

Orders for lab testing are good for one calendar year, but be sure to follow your doctor’s instructions regarding the preferred timing for your tests.

There’s a good chance your lab tests won’t require you to prepare at all, but follow your doctor’s instructions for fasting or other preparation. Fasting means not eating or drinking for a specified time period before your test to ensure your results are accurate.

It depends on the tests your doctor orders. For blood work, don’t eat anything or drink liquids other than water for eight hours prior to arriving at Mercy Lab. For a lipid panel, a 12-hour fast is required. Don’t drink coffee or juice, chew gum, use tobacco or eat while you’re fasting. It’s OK to drink water and take your medications as directed by your provider before testing.

A phlebotomist – a technician who specializes in drawing blood – will call you into a private area, where your blood will be drawn or other samples will be taken, depending on the test you’re having. We’ll explain the process before performing the test.


A phlebotomist uses a small needle for blood samples. The procedure is quick and relatively painless – usually, patients feel a pinch. It’s not unusual to experience slight bruising at the site. The phlebotomist will keep pressure on the site and then apply gauze or a band-aid. If you’re using blood thinners, pressure may be kept on the site a little longer.

Most tests are performed in our own facilities and shared electronically via MyMercy. More complex tests may be sent to special labs, and you'll need to check with your doctor’s office to get your test results.

Results for routine lab tests performed at Mercy are usually available the next morning. Complex tests sent to special labs will take longer and may vary based on type; confirm the timing of these tests with your doctor's office.

A toxicology test (“tox screen”) would need to be performed to show the presence of drugs or other chemicals in your blood. A tox screen can be used to check for one specific drug or up to 30 drugs at once. These may include prescription medicines, vitamins, supplements, alcohol and illegal drugs such as cocaine and heroin. Testing is often done on urine or saliva instead of blood. Many drugs will show in urine or saliva samples, and these tests are easier to perform than blood tests.

Imaging & Lab Services

At Mercy, we offer comprehensive lab & imaging services to diagnose conditions and injuries, including: