The Logistics of Large Plasma Pool Deconstruction

Nucleic acid testing (NAT) of source plasma in large pools is cost efficient for laboratories while increasing the safety of plasma-derived products. Pool configuration reduces the number of tests run when compared to individual testing. Thus, a pool of 96 donations would require one test, while testing 96 donations individually would require 96 tests. Pooling therefore allows for faster release of donations to fractionators.

But pool testing adds a layer of complexity. This process requires additional instrumentation (including the pooler itself) and software (which allows communication between the pooler, the assay instruments and the laboratory information system (LIMS), in order to identify individual donations within each testing pool. Many laboratories test over 3-5,000 samples per shift in pools of 96 and even larger. Each sample tube must be available for retesting until the final results are released, which requires sample storage capacities.

When a plasma pool is reactive for one of the targets (HIV, HBV, HCV, and/or HAV) or exceeding the defined cut-off for Parvo B19, the laboratory must identify the implicated donation or donations using a plasma pool deconstruction algorithm. Each sub pools forming the large pool is tested to identify the reactive one. Individual samples composing that sub-pool are then tested individually. This process can be lengthy, requires expertise, additional time for pool deconstruction and certainly carries over to the following work shift.

Fortunately, laboratories can establish industry-standard procedures that optimize workflow and improve efficiency, without compromising safety. Here are some of the operational considerations of large pool testing, related to technology:

Flexible software

■ Sample management: Using software with the ability to communicate with the LIMS, will ensure that all samples are tracked, pooled, screened, and    released within committed timelines

■ Algorithm for deconstruction: Based on the testing algorithm, the middleware should identify and list the pools to be retested or deconstructed for    testing

Automation

■ Capacity of the pooling instrument: Adapting the number of pooling systems based on throughput and deck capacity

■ Pool homogenization: The addition of a mixing step after pooling donation samples is critical to yielding trustworthy test results

■ Multiplex assays: Ability to detect multiple pathogens in one single test. Capacity to run multiple assays in parallel from the same sample pool

Testing plasma samples using large pools has many advantages; however, it increases workflow complexity. Each laboratory should establish LEAN laboratory processes in order to maximize efficiency.