Phlebotomy - Order of Draw Stories — Part 2 - “The Serum Tubes”

Characters

• Kayla — phlebotomy student

• Mr. Bennett — patient getting routine bloodwork

Kayla:
Good afternoon. My name is Kayla, and I’ll be drawing your blood today.

Mr. Bennett:
Afternoon. You look familiar.

Kayla:
You might have seen me here last week. I’m still training in phlebotomy.

Mr. Bennett:
Still learning all the tube colors?

Kayla:
Unfortunately… yes.

Mr. Bennett:
How many are there?

Kayla:
Too many.

(Both laugh.)

(Kayla prepares the supplies.)

Mr. Bennett:
So what are you studying today?

Kayla:
Today we’re focusing on the red tube and the gold tube, also called the SST tube.

Mr. Bennett:
What does SST mean?

Kayla:
Serum Separator Tube.

Mr. Bennett:
What exactly is serum?

Kayla:
Serum is the liquid part of blood after the blood has clotted.

Mr. Bennett:
So blood changes after it clots?

Kayla:
Yes. Blood contains:

• red blood cells,

• white blood cells,

• platelets,

• and liquid called plasma.

But when blood clots, some clotting proteins are removed, and the remaining liquid is called serum.

Mr. Bennett:
Why do laboratories want serum instead of whole blood?

Kayla:
Many chemistry tests work best using serum because it gives clearer laboratory results.

Mr. Bennett:
What kinds of chemistry tests?

Kayla:
Things like:

• cholesterol,

• liver function tests,

• kidney function,

• hormones,

• electrolytes,

• and metabolic panels.

Mr. Bennett:
So these tubes are used a lot?

Kayla:
Very often. Routine checkups commonly use serum tubes.

(Kayla places the tourniquet.)

Kayla:
This will feel a little tight.

Mr. Bennett:
No problem.

Kayla:
Can you make a fist for me?

(Mr. Bennett makes a fist.)

(Kayla palpates the vein.)

Mr. Bennett:
You seem more confident than last time.

Kayla:
I’m trying to understand the science instead of only memorizing colors.

Mr. Bennett:
That probably helps.

Kayla:
It does. When I understand why a tube is used, the order makes more sense.

(Kayla cleans the site.)

Kayla:
This alcohol will feel cold.

Mr. Bennett:
Always cold.

(Kayla performs the venipuncture.)

Kayla:
Small pinch.

(Blood begins flowing into the red tube.)

Mr. Bennett:
So what’s inside the red tube?

Kayla:
Some red tubes contain no additive at all. Others contain something called a clot activator.

Mr. Bennett:
What does a clot activator do?

Kayla:
It helps the blood clot faster.

Mr. Bennett:
Wait… earlier you said the light blue tube prevents clotting.

Kayla:
Exactly.

Mr. Bennett:
And now this tube helps blood clot?

Kayla:
Right. Different tests require blood in different conditions.

Mr. Bennett:
Healthcare really is chemistry.

Kayla:
And biology. And communication. And sometimes controlled panic.

(Mr. Bennett laughs.)

(Kayla switches to the gold SST tube.)

Mr. Bennett:
What’s different about the gold tube?

Kayla:
The SST tube contains:

• a clot activator,

• and a special separator gel.

Mr. Bennett:
Separator gel?

Kayla:
After the blood clots, the tube is spun in a centrifuge.

Mr. Bennett:
A centrifuge… that spinning machine?

Kayla:
Exactly. The spinning separates the blood components.

Mr. Bennett:
And the gel helps separate them?

Kayla:
Yes. The gel forms a barrier between the serum and the blood cells.

Mr. Bennett:
Why is that useful?

Kayla:
Because laboratories often need clean serum without blood cells mixing into it later.

Mr. Bennett:
So the gel keeps everything separated after spinning?

Kayla:
Exactly.

(Kayla gently inverts the SST tube.)

Mr. Bennett:
You’re flipping the tube again.

Kayla:
Right. The additives must mix properly with the blood.

Mr. Bennett:
But not too hard?

Kayla:
Correct. Shaking can damage blood cells and affect results.

Mr. Bennett:
I honestly never realized how much thought goes into a simple blood draw.

Kayla:
A lot of mistakes in laboratory medicine can happen before the sample even reaches the lab.

Mr. Bennett:
So phlebotomy affects the whole testing process.

Kayla:
Very much.

(Kayla finishes the final tube.)

Kayla:
Alright, I’m releasing the tourniquet.

(She removes the needle and places gauze on the arm.)

Kayla:
Please hold pressure here.

Mr. Bennett:
Got it.

(Kayla activates the safety device and disposes of the needle.)

Mr. Bennett:
So today’s lesson was:

• serum,

• clot activators,

• separator gel,

• and SST tubes?

Kayla:
Exactly.

Mr. Bennett:
And next comes more colors?

Kayla:
Green, lavender, and gray.

Mr. Bennett:
Sounds complicated.

Kayla:
It is. But it’s starting to make sense now.

Mr. Bennett:
That’s probably when real learning begins.

(Kayla smiles.)

Kayla:
I think you’re right.