There is a paucity of studies on the magnitude of reduction of vasovagal reaction by reduced collection volume. This study was thus conducted to determine the difference in reaction rates between two collection volumes among the young first-time donors who are at particular risk of reaction.

Study Design and Methods

This retrospective study analyzed 38,436 whole blood donations made by young (aged 16 to 18 years) first-time donors. The effect of collection volume on vasovagal reaction was compared among different weight subgroups for both sexes by chi-square test.


For females in all weight subgroups and two of the male lower-weight subgroups, the reduction percentages ranged from 35% to 58% (p < 0.05). It was also noted that, among the females, a higher weight was associated with a higher percent reduction in the reaction rate.


With reduced collection volume, this study detected large and significant reduction in reaction rates among all females, as well as lower-weight males.