The effect of holding times of whole blood and its components during processing on in vitro and in vivo quality.

Whole blood is not usually collected close to the processing site, which results in a holding time between collection and processing. In some countries, the holding time is limited to 8 hours, after which the units are cooled, rendering them useless for platelet preparation. Other countries allow a 24-hour (“overnight”) ambient hold to allow platelet preparation. The impact of this holding time on subsequent blood components will be reviewed in this article. In addition, there are various “in-process” holding times that further prolong the time before the final blood component is ready. Particularly, these in-process holding times are not well defined and poorly controlled,but can nevertheless affect the biochemical and functional characteristics of blood components. Furthermore, current, non–evidence-based, guidelines have restricted the length of some of these holding times. This article summarizes the evidence and fills gaps where evidence is lacking.