4 Alternatives to Wet Blood Collection

Blood sampling for blood analysis is still one of the most important aspects of medicine. A scientist or physician can learn so much from a drop or two of blood!

The methods for collecting blood samples are changing, however. Traditionally, when a scientist or doctor wanted to explore the underlying cause of a person's symptoms, they sent them to the lab for "blood work." This involved a venipuncture blood draw performed by a trained technician, who would insert a needle into a person's vein to draw wet blood into glass tubes. The tubes of wet blood would be tested in the lab.

Today there are several alternative methods to the traditional wet blood collection method, and they provide several advantages.

Here we list four new blood collection methods that may soon make the traditional blood draw and wet blood collection obsolete.

1. Dried Blood Spot (DBS)

Obtained by pricking a finger-tip or heel with a lancet and placing a few drops of blood onto a dried blood spot (DBS) card, DBS sampling provides a simple, user-friendly method of sampling that does not require a controlled environment or a trained phlebotomist.

DBS can be used in most self-sampling scenarios, including outside the clinic. With the traditional DBS card method, a method that has been in use for about 50 years, the blood samples are collected and stored on cards made of a special filter paper.

However, DBS is not suitable for analyzing volatile and air-sensitive analytes. Another drawback of traditional DBS from an analytical point of view is an uneven distribution of the analytes within the spot, caused by analyte nature, DBS card substrate, spotting conditions and, mainly, blood hematocrit.

With traditional DBS cards, there is also a risk of carryover contamination, associated with the sample preparation (punching a pre-sized, partial sample from the DBS disc).

A newer microsampling device called the hemaPEN^®, offers a new more precise way to collect DBS samples onto 4 pre-punched DBS filter papers inside the device.

Once the hemaPEN arrives in the lab for sample processing, the technicians can skip the punching step. Otherwise, the DBS workflow in the lab is much the same.

2. Pre-Cut Dried Blood Spot (PCDBS)

Pre-cut dried blood spot (PCDBS) is a variation of DBS, where the entire spot is analyzed, to reduce or eliminate the impact that hematocrit has on spot formation and subsequent sample quality. The method retains almost all advantages of other microsampling techniques while overcoming the biggest challenge of traditional DBS, hematocrit impact.

However, as with traditional DBS, it requires a precise and accurate volume of blood, making it less suitable for self-sampling scenarios by non-trained individuals.

In these scenarios, the hemaPEN device may be more suitable.

3. Dried Plasma Spot (DPS)

Using dried plasma spots (DPS) instead of DBS represents another approach for avoiding the impact of hematocrit, while still retaining all the advantages over wet blood collection, including ease of collecting, processing, transporting, and storage of samples.

In a self-sampling setting, the patient applies a finger-prick blood drop to a multi-layer collection card and peels off the top layer (separation membrane) after a few minutes. Plasma spot is formed on a lower layer (collection membrane). This technique, however, cannot be used when whole blood samples are required for analysis.

4. Volumetric Absorptive Microsampling

Volumetric absorptive microsampling represents a novel approach that allows for fixed-volume collection of blood with Mitra^® microsampling technology, independent of the hematocrit levels, ambient conditions such as temperature and humidity, finger-prick blood drop size, and the time spent collecting the sample.

As such, the Mitra^® device based on VAMS^® technology provides all of the benefits of DBS, without any of the drawbacks. VAMS can be performed in all self-sampling scenarios, while still being usable for semi-quantitative and quantitative analysis.

VAMS also has advantages in preclinical animal studies for drug development and toxicology, where low sample volumes mean fewer test animals are used. The VAMS microsampling approach provides preclinical researchers with a significant ethical advantage.

In human medicine, microsampling techniques remove the need for venipuncture blood draws, greatly reducing a person's stress and discomfort. Microsampling techniques require only a quick finger-stick or arm-prick. They also reduce sample handling and contamination risks, while increasing sample stability and reducing storage and transportation costs.

Image Credits: Trajan, Neoteryx, Shutterstock, iStock