4 alternatives to wet blood collection
While blood analysis is still one of the most important aspects of medicine, the methods for obtaining blood samples are shifting. Compared to wet blood collection methods, these newer techniques provide a range of advantages.
Here are some new specimen collection methods that may make wet blood collection obsolete.
Dried Blood Spot (DBS)
Obtained by application of a finger-prick blood drop, DBS sampling provides a simple, patient-friendly means of sampling that does not require a controlled environment or a trained phlebotomist. It 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 samples are 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. There is also a risk of carryover contamination, associated with the sample preparation (punching a pre-sized, partial sample from the DBS disc).
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, just as all whole-spot approaches, it requires a precise and accurate volume of blood, making it less suitable for self-sampling scenarios by non-trained individuals.
Dried Plasma Spot (DPS)
Using dried plasma spots (DPS) instead of DBS technique 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.
Volumetric Absorptive MicroSampling (VAMS)
Volumetric absorptive microsampling (VAMS™) represents a novel approach that allows volumetric 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 unique VAMS microsampling technique provides all of the benefits associated with 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.
In drug development and toxicology studies, low sample volumes mean fewer test animals used, providing a significant ethical advantage. In human medicine, microsampling techniques remove the need for venipuncture, greatly reducing patient's discomfort. Microsampling techniques also reduce sample handling and contamination risks, while increasing sample stability and reducing storage and transportation costs.