Haemoglobinometry of the 1st and 2nd blood drops by WHO haemoglobin colour scale and its comparison with automated blood cell counter

Background and objectivesAfter many blood donors being rejected cause of anaemia detected by WHO haemoglobin colour scale, we thought that the first blood drops may have been mixed with the extra cellular fluid leading to the lower range of Hb concentration. Then, we decided to assess the 2nd blood drops so as to compare the results of both 1st and 2nd drops with those of the automated blood cell counter. Materials and Methods A descriptive study was conducted. WHO haemoglobin colour scale and automated blood cell counter were used to test 100 blood donor samples. In this study, we considered 12.5g/dl as the cut off point. ResultsThe study indicated that there are 26% false readings in the assessment of the 1st drop by WHO haemoglobin colour scale; this figure includes 26% false rejection and 0% false acceptance. Test sensitivity and its specificity are 100 and 72.9% respectively. In the assessment of the 2nd drop, we faced 8% false reading including 5% false rejection and 3% false acceptance. Its sensitivity and specificity were 25 and 94.7% respectively. ConclusionsOur research has shown that cause of 26% false rejection in the 1st drop and the low test sensitivity of 25% in the 2nd drop, none of the 1st and 2nd drops are the favorite scale test for screening anaemia among blood donors.