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1. A young male smoker [smoking 1 to 2 cigarettes / day since last one year] donated blood for the first time. Bright cherry red color of packed red blood cells (RBCs) was observed in the component laboratory.

2. Important differentials for cherry red colored units include hemolysis, accidental collection of arterial blood, donations with a lower hematocrit, and rarely, carbon monoxide poisoning [1].

3. The supernatant of the unit was clear after centrifugation showing no evidence of hemolysis. The presence of arterial blood collection was ruled out as the concerned phlebotomist was questioned who denied pulsatile and rapid blood collection during the donation process. Variable shades of red may be seen in blood units that reflect a difference in the hematocrit of the donor (i.e. higher the hematocrit, darker the color) [2].

4. Additionally, a complete hemogram along with a peripheral blood smear (PBS) examination was done. Donor’s pre donation hemoglobin, hematocrit and RBC count were 12.5 g/dL; 37.1% and 3.8 million/mm3 respectively. All red cell indices were normal and PBS revealed normocytic normochromic RBCs.

5. Carbon monoxide poisoning is a rare cause for cherry red discoloration [3]. However, in our case this was unlikely as there was history of intake of only 1 to 2 cigarettes / day.

6. Most probable cause for the cherry red discoloration was therefore the lower hematocrit. Since the hemoglobin level was well within the permissible level for donation, transfusing such unit would not be detrimental and was eventually issued to the patient.

Reference:

1. Sood T, Bedi RK, Mittal K. Discolored blood and blood components: A dilemma for transfusion specialists. Transfus Apher Sci. 2014 Apr; 50(2):255-9

2. Visual Assessment Guide, Canadian blood Services, 2009. Available from: https://professionaleducation.blood.ca/sites/msi/files/VAG_en.pdf. [Last accessed on 2019 Mar 03].

3. Carbon monoxide poisoning Wikipedia, the free encyclopedia. Available from: https://en.wikipedia.org/wiki/Carbon_monoxide_poisoning. [Last accessed on 2019 Mar 03]