Here are concise viva answers for each question:

Q. What is forward and reverse grouping? Forward grouping detects ABO antigens on red cells using known anti-A and anti-B sera. Reverse grouping detects ABO antibodies in the patient's serum using known A and B cells. Both results must match to confirm the blood group.

Q. How are blood and its components stored? Whole blood and packed red cells are stored at 2-6°C for up to 35-42 days. Platelets are stored at 20-24°C with continuous agitation for up to 5-7 days. Fresh frozen plasma is stored at -25 to -40°C for 1 year, and cryoprecipitate also at -25 to -40°C for 1 year.

Q. What is Bombay blood group? Why is it called Bombay blood group? Bombay blood group (Oh) lacks the H antigen on red cells and has anti-H, anti-A, and anti-B antibodies in serum. It was first discovered in Bombay (Mumbai) in 1952 by Dr. Bhende, hence the name. These individuals can only receive blood from other Bombay group donors.

Q. What are the advantages of gel card method for blood grouping? The gel card method requires no washing steps, gives clear and reproducible results, allows long-term storage of results (cards can be read later), reduces human error, and can be standardized easily. It uses less sample volume and is suitable for automation.

Q. What are the different blood group systems? There are over 30 blood group systems recognized by ISBT. The most clinically important are ABO, Rh (most complex), Kell, Duffy, Kidd, MNS, and Lewis systems. ABO and Rh are most significant in transfusion medicine and obstetrics.

Q. Mention the types of Coombs test and their indications. The Direct Coombs Test (DCT) detects antibodies already bound to red cells - used in autoimmune hemolytic anemia, hemolytic disease of the newborn (HDN), and transfusion reactions. The Indirect Coombs Test (ICT) detects free antibodies in serum - used in antibody screening, crossmatching, and antenatal testing (Rh incompatibility workup).

Q. What tests are done for cross-match before blood transfusion? Major crossmatch (donor cells + recipient serum) detects recipient antibodies against donor cells - most important. Minor crossmatch (recipient cells + donor serum) detects donor antibodies against recipient cells. Tests include immediate spin, 37°C incubation, and indirect Coombs (antiglobulin) phase to detect all clinically significant antibodies.

Q. What is apheresis? Apheresis is a procedure where blood is drawn from a donor, a specific component (platelets, plasma, RBCs, WBCs, or stem cells) is separated and collected, and the remainder is returned to the donor. Types include plateletpheresis, plasmapheresis, leukapheresis, and erythrocytapheresis.

Q. What are donor selection criteria? A donor must be 18-65 years old, weigh >45 kg, have hemoglobin >12.5 g/dL, pulse 60-100 bpm, BP normal, and no history of transfusion-transmissible infections (HIV, HBV, HCV, syphilis, malaria). Donors should not have donated in the last 3 months and must be free of fever, recent surgery, or pregnancy.

Q. Which method is used for hemoglobin estimation in blood bank? The CuSO4 (copper sulfate) specific gravity method is used as a quick screening test - a drop of blood is added to CuSO4 solution (specific gravity 1.053); if it sinks, Hb is adequate (>12.5 g/dL). For accurate estimation, the cyanmethemoglobin (Drabkin's) method is used as the gold standard.

Here is the clinical significance of the major blood group systems:

The most important system in transfusion medicine. Naturally occurring anti-A and anti-B antibodies (IgM) are always present in serum opposite to the antigen. ABO-incompatible transfusion causes acute intravascular hemolytic reaction, which can be fatal. Also critical in organ transplantation.

Second most important system. Anti-D is the most clinically significant antibody. Key significance:

Highly immunogenic after Rh. Anti-K can cause severe HDN and hemolytic transfusion reactions. K antigen suppresses erythropoiesis in the fetus, making HDN worse than expected from antibody titers alone.

Fy(a) and Fy(b) antigens. Clinically causes delayed hemolytic transfusion reactions. Notably, Duffy-null individuals (Fy a-b-) are resistant to Plasmodium vivax malaria, as the Duffy antigen is the receptor for P. vivax invasion.

Anti-Jk antibodies are notorious for being evanescent (disappear rapidly from serum), making them difficult to detect. They cause severe delayed hemolytic transfusion reactions and can cause acute reactions on re-exposure. Also implicated in HDN.

Mainly of blood bank significance. Anti-M and anti-N are usually cold, clinically insignificant IgM antibodies. However, anti-S, anti-s, and anti-U are IgG and can cause hemolytic transfusion reactions and HDN.

Lewis antigens (Le^a, Le^b) are primarily plasma antigens absorbed onto red cells, not intrinsic to the membrane. Anti-Le^a and anti-Le^b are usually IgM, clinically insignificant. Rarely, IgG forms can cause transfusion reactions. Lewis antigens disappear during pregnancy.

Anti-P1 is a common, usually cold, clinically insignificant antibody. However, anti-P (Donath-Landsteiner antibody) is associated with Paroxysmal Cold Hemoglobinuria (PCH) - a rare autoimmune hemolytic anemia.

Anti-I is associated with Mycoplasma pneumoniae infection causing cold agglutinin disease. Anti-i is associated with infectious mononucleosis (EBV). These cause cold autoimmune hemolytic anemia.