Mayo Clinic needs blood. But what happens when you donate?

ROCHESTER — “I’m afraid of needles,” I said.

Jennifer Hoffman, a donor services tech — or phlebotomist — at the Mayo Clinic Blood Donor Center, admitted she’s not a big fan of needles either.

I raised an eyebrow. Needles are this woman’s job. “When they’re coming at me,” she added.

On Monday, Mayo Clinic sent out a notice asking for blood donors, specifically those with type O-positive, which is me. Seeing a need and a possible story, I set up an appointment and a behind-the-scenes look at what happens to blood donations. Here’s what I learned about donating blood.

Step one involves very little blood. What it does involve is a lot of questions.

Have you traveled outside the U.S. or Canada within the last few months? Lots of questions about exposure to HIV and hepatitis. Have you shared any needles recently?

Some of the questions might seem odd or even intrusive — did you take an aspirin within a certain number of hours? — but there’s a good reason behind them. The blood donated will likely be used to help someone who is trying to get healthy. Blood that carries pathogens or some amount of a prescription drug someone else has taken that is a barrier to the receiver’s health is not helpful.

A “Yes” to some of these questions doesn’t automatically preclude you from donating, said Dr. Justin Juskewitch, associate medical director of the Mayo Clinic Blood Donor Program. But it might lead to further questioning to ensure the blood donation can do some good.

The questions aren’t Mayo’s. The Food and Drug Administration formulated the questions, and they are asked wherever you donate.

After answering questions at a computer screen, you’re taken back to an exam room where your finger is pricked and a small blood test is done. The donor’s arms are examined, mainly for signs of needle usage and any sores or other skin ailments that might indicate a skin infection at the needle site.

For those who may be scared of needles, the doctor will probably give you a quick warning just before sticking you with a needle.

Hoffman and her fellow phlebotomists are highly skilled at their jobs. The only thing that gives Hoffman problems, she said, is “super small veins.” If she can’t find a vein, which is exceedingly rare, she might call one of her colleagues.

“Just feel for a little bounce,” she said as she tapped the inside of my elbow joint. “And if you need it, you can always have somebody else come over. Maybe they can have a better feeling.”

The process takes less than 15 minutes, Hoffman said. A sample collection is taken first and divided up into testing vials. Once that is taken, the machine switches over and collects the 450 milliliters — about a pint — of whole blood.

Donors are required to wait 12 weeks after giving a pint of whole blood before they’re able to donate again.

Why the call out? Juskewitch said Mayo Clinic is currently using about 20% more O-type blood than usual. Hence the shortage and the need.

About 38% of the population is O-positive, according to the American Red Cross. Juskewitch said O-positive and O-negative blood types represent about 45% of blood donors. O-negative is the universal donor type, but only about 7% of blood donors have O-negative blood. O-positive is about 39% of donors, and can be accepted by 85% of those in need.

When Mayo One air ambulance lifts off from the helipad it has six units of O-negative, Juskewitch said. The emergency department at Mayo Clinic Hospital-Saint Marys has some O-negative on hand. But what gets used the most is O-positive.

Before the blood can be used, it undergoes testing and processing. If no problems are identified, Mayo Clinic Blood Donor Center can release the blood for clinical use shortly after.

In the meantime, the blood is immediately filtered to remove the white blood cells, which can cause fevers in patients if not removed. From there, there are three usable parts of the blood: red blood cells, platelets and plasma. Platelets are generally collected separately and are good for only five days, and one of those days is for testing.

A technician will put the donated bag of blood in a centrifuge, which separates the plasma from the red blood cells. Those components are then put into separate units for storage.

A person can donate two platelet units a week up to 24 times a year. That’s a different process where the plasma and red blood cells are returned to the donor during the donation. So is donating “double red” where a person only donates red blood cells, but that cannot be done as often as donating whole blood.

While waiting for the testing and processing to wrap up, whole blood is separated into red blood cells and plasma. The red cells are refrigerated at temperatures between 1 and 5 degrees Celsius. Plasma is frozen and lasts up to a year. Red blood cells can sit on the shelf for 42 days, Juskewitch said.

With the current shortage, O-type blood won’t sit that long.

“It’s about a 50-50 split between the ORs, surgery, and our medical patients, mostly our cancer patients,” Juskewitch said.

Mayo Clinic uses about 50,000 units of blood a year, and needs to collect about 100 units a day — whole blood can be separated into multiple uses, so those 100 a day might be more uses than 100. Most is collected through the Blood Donor Program, which includes the donor center at the Hilton Building, 200 First St. SW; a new donor center at the 4115 Building, 4115 W. Frontage Road; and at Saint Marys, Joseph Building, 1216 Second St. SW. There’s also the Mayo Clinic Bloodmobile.

“We always aim to have a 12-day blood supply on the shelves for our red cells,” Juskewitch said. “So we will preemptively, as we are looking at our inventory each day, be calling donors based off of what we already have scheduled.”