Excess Tap Water

I used to worked at this hospital where the nurses draw blood from their ICU patients.

One day, we received a blood sample collected in a blue top tube. The test was for a PT/INR. I promptly spun down the sample and ran it.

It took a while to run and finally an error came up saying “coagulation time exceeded” I reran the sample and came up with the same result. Finally, I proceeded to check for clots. Lo and behold! There was a massive clot in the tube.

I promptly called and talked to the ICU nurse who drew the blood. She said she did everything right. She even counted the number of times she inverted the sample right after she poured out the excess tap water in the blue tube.

“What excess tap water?” I asked, and obviously very confused.

She said there was some excess tap water in the tube after it has been washed by the lab. So she poured it off so it won’t dilute the specimen.

“Umm no. That’s the anticoagulant that will stop the blood from clotting.” I said. ” This is the very reason why you need to mix the tube after drawing.”

There was silence on the other line, and she later apologized. I’m glad she learned something that day. 😀

Submitted by:
Ronald Smith
Medical Technologist
Alabama, USA