When a person's blood is analyzed under a microscope distinct blood differences are visible. In the early 20th century, an Austrian scientist named Karl Landsteiner classified blood according to those differences. Landsteiner observed two distinct chemical molecules present on the surface of the red blood cells. He labeled one molecule "A" and the other molecule "B".
Blood Type A - If the red blood cell has only "A" molecules on it.
Blood Type B - If the red blood cell has only "B" molecules on it.
Blood Type AB - If the red blood cell has a mixture of both "A" & "B" molecules.
Blood Type O - If the red blood cell has neither "A" or "B" molecule.
RH factor in blood types stands for "Rhesus Factor". Blood tests were performed on Rhesus monkeys and the Rh+ and Rh- factors were isolated. An antigen found in the red blood cells of most people: those who have Rh factor are said to be Rh positive (Rh+), while those who do not are Rh negative (Rh-). What about the meaning of RHD- Rh blood group, D antigen . The rhesus complex is not just one antigen, but several, when someone is told to be Rh+, it usually refers to the D antigen (one of the components of the Rh complex), because it's the most common, and the easiest to identify, however it's not the only one.
What is the Rarest Blood Type
According to the American Red Cross the rarest is AB(-), present in 1% of the Caucasians, in African Americans it is even rarer. B(-) and O(-) are also very rare, each accounting for less than 5% of the world's population. Some people with rare blood types bank their own blood in advance of surgical procedures to ensure that blood is available to them.
DOs and DON'Ts of blood donation
In order to ensure safe and health environment to both donors as well as recipients, we greatly recommend to follow the below rules:
DO donate blood, only if you satisfy all of the following conditions
- You are between age group of 18-60 years.
- Your weight is 45 kgs or more.
- Your hemoglobin is 12.5 gm% minimum.
- Your last blood donation was 3 or more months earlier.
- You are healthy and have not suffered from malaria, typhoid or other transmissible disease in the recent past.
DO NOT donate blood, if you have any of the following conditions
- Cold / fever in the past 1 week.
- Under treatment with antibiotics or any other medication.
- Cardiac problems, hypertension, epilepsy, diabetes (on insulin therapy), history of cancer, chronic kidney or liver disease, bleeding tendencies, venereal disease etc.
- Major surgery in the last 6 months.
- Vaccination in the last 24 hours.
- Had a miscarriage in the last 6 months or have been pregnant / lactating in the last one year.
- Had fainting attacks during last donation.
- Have regularly received treatment with blood products.
- Shared a needle to inject drugs/ have history of drug addiction.
- Had sexual relations with different partners or with a high risk individual.
- Been tested positive for antibodies to HIV.