Why was my dried blood spot sample rejected?

When dried blood spot (DBS) samples are rejected, it is common to wonder why the sample was rejected and how the error causing the rejection occurred.

Sample rejections can be caused by a number of factors. Below we outline the different types of sample rejections that can occur with Dried Blood Spot Card collections.

A properly collected specimen clearly fills out the full dotted-line circle of the dried blood spot collection card and saturates through the card to both sides.

Properly Collected Specimen

Note that the circles are fully filled, with blood saturating all the way through to the back of the card.

Rejected Specimens

Not Fully Saturated:

This specimen (front is on top, back on bottom) is not properly saturated. Note how the blood does not extend to the dotted line, nor does it soak through to the back of the paper. This indicates that there was not a strong enough flow of blood to the hands before performing the fingerstick. Washing your hands under warm water prior to collection may improve this result.

Too small of a sample:

Here we can see that the drops of blood do not fully fill the circle, providing too small a quantity of blood to perform needed tests. They also do not saturate well to the back of the card. This is due to low blood flow. If you are noticing low blood flow, try washing your hands under warm water and sticking a different finger.

Double Dropping

We call this "double dropping" even though there's more like ten to twelve drops on each circle. That's when there is so little blood coming out that it takes many drops to fill each circle and usually does not saturate through to the other side of the paper. If you are noticing low blood flow, try washing your hands under warm water and sticking a different finger.