Blood Groups and Antibodies

Blood Groups and Antibodies

Synonym/acronym: ABO group and Rh typing, blood group antibodies, type and screen, type and crossmatch.

Common use

To identify ABO blood group and Rh type, typically for transfusion purposes.


Serum (2 mL) collected in a red-top tube or whole blood (2 mL) collected in a lavender-top (EDTA) tube.

Normal findings

(Method: FDA-approved reagents with glass slides, glass tubes, gel, or automated systems) Compatibility (no clumping or hemolysis).


Blood typing is a series of tests that include the ABO and Rh blood-group system performed to detect surface antigens on red blood cells (RBCs) by an agglutination test and compatibility tests to determine antibodies against these antigens. The major antigens in the ABO system are A and B, although AB and O are also common phenotypes. The patient with A antigens has group A blood; the patient with B antigens has group B blood. The patient with both A and B antigens has group AB blood (universal recipient); the patient with neither A nor B antigens has group O blood (universal donor). Blood group and type is genetically determined. After 6 mo of age, individuals develop serum antibodies that react with A or B antigen absent from their own RBCs. These are called anti-A and anti-B antibodies.

In ABO blood typing, the patient’s RBCs mix with anti-A and anti-B sera, a process known as forward grouping. The process then reverses, and the patient’s serum mixes with type A and B cells in reverse grouping.

Generally, only blood with the same ABO group and Rh type as the recipient is transfused because the anti-A and anti-B antibodies are strong agglutinins that cause a rapid, complement-mediated destruction of incompatible cells. However, blood donations have decreased nationwide, creating shortages in the available supply. Safe substitutions with blood of a different group and/or Rh type may occur depending on the inventory of available units. Many laboratories require consultation with the requesting health-care provider (HCP) prior to issuing Rh-positive units to an Rh-negative individual.

ABO and Rh testing is also performed as a prenatal screen in pregnant women to identify the risk of hemolytic disease of the newborn. Although most of the anti-A and anti-B activity resides in the immunoglobulin M (IgM) class of immunoglobulins, some activity rests with immunoglobulin G (IgG). Anti-A and anti-B antibodies of the IgG class coat the RBCs without immediately affecting their viability and can readily cross the placenta, resulting in hemolytic disease of the newborn. Individuals with type O blood frequently have more IgG anti-A and anti-B than other people; thus, ABO hemolytic disease of the newborn will affect infants of type O mothers almost exclusively (unless the newborn is also type O).

Major antigens of the Rh system are D (or Rho), C, E, c, and e. Individuals whose RBCs possess D antigen are called Rh-positive; those who lack D antigen are called Rh-negative, no matter what other Rh antigens are present. Individuals who are Rh-negative produce anti-D antibodies when exposed to Rh-positive cells by either transfusions or pregnancy. These anti-D antibodies cross the placenta to the fetus and can cause hemolytic disease of the newborn or transfusion reactions if Rh-positive blood is administered.

The type and screen (T&S) procedure is performed to determine the ABO/Rh and identify any antibodies that may react with transfused blood products. The T&S may take from 30 to 45 min or longer to complete depending on whether unexpected or unusual antibodies are detected. Every unit of product must be crossmatched against the intended recipient’s serum and red blood cells for compatibility before transfusion. Knowing the ABO/Rh and antibody status saves time when the patient’s sample is crossmatched against units of donated blood products. There are three crossmatch procedures. If no antibodies are identified in the T&S, it is permissible to use either an immediate spin crossmatch or an electronic crossmatch, either of which may take 5 to 10 min to complete. If antibodies are detected, the antiglobulin crossmatch procedure is performed, along with antibody identification testing, or the process is repeated, beginning with the selection of other units for compatibility testing. Typically, specimens for T&S can be held for 72 hr from the time of collection for use in future crossmatch procedures. This time frame may be extended for up to 14 days for patients with a reliably known history of no prior transfusions or pregnancy within the previous 3 months. Donated blood products are tested for ABO type, Rh factor, blood group antibodies, and transmissible infectious diseases to include hepatitis B surface antigen, hepatitis B core antibody, hepatitis C antibody (by the nucleic acid test [NAT]), ALT, HTLV I and II antibody, HIV 1 and 2 antibody, syphilis, West Nile virus (by the nucleic acid test [NAT]), and Trypanosoma cruzi.

Febrile nonhemolytic reaction and urticarial/allergic reaction are the two most common types of reactions that occur in blood product transfusions. Many institutions have a policy that provides for premedication with acetaminophen and diphenhydramine to avoid initiation of mild transfusion reactions, where appropriate.

This procedure is contraindicated for



  • Determine ABO and Rh compatibility of donor and recipient before transfusion (type and screen or crossmatch).
  • Determine anti-D antibody titer of Rh-negative mothers after sensitization by pregnancy with an Rh-positive fetus.
  • Determine the need for a microdose of immunosuppressive therapy (e.g., with RhoGAM) during the first 12 wk of gestation or a standard dose after 12 wk of gestation for complications such as abortion, miscarriage, vaginal hemorrhage, ectopic pregnancy, or abdominal trauma.
  • Determine Rh blood type and perform antibody screen of prenatal patients on initial visit to determine maternal Rh type and to indicate whether maternal RBCs have been sensitized by any antibodies known to cause hemolytic disease of the newborn, especially anti-D antibody. Rh blood type, antibody screen, and antibody titration (if an antibody has been identified) will be rechecked at 28 wk of gestation and prior to injection of prophylactic standard dose of Rho(D) immune globulin RhoGAM IM or Rhophylac IM or IV for Rh-negative mothers. These tests will also be repeated after delivery of an Rh-positive fetus to an Rh-negative mother and prior to injection of prophylactic standard dose of Rho(D) immune globulin (if maternal Rh-negative blood has not been previously sensitized with Rh-positive cells resulting in a positive anti-D antibody titer). A postpartum blood sample must be evaluated for fetal-maternal bleed on all Rh-negative mothers to determine the need for additional doses of Rh immune globulin. One in 300 cases will demonstrate hemorrhage greater than 15 mL of blood and require additional Rho(D) immune globulin.
  • Identify donor ABO and Rh blood type for stored blood.
  • Identify maternal and infant ABO and Rh blood types to predict risk of hemolytic disease of the newborn.
  • Identify the patient’s ABO and Rh blood type, especially before a procedure in which blood loss is a threat or blood replacement may be needed.
  • Identify any unusual transfusion related antibodies in the patient’s blood, especially before a procedure in which blood replacement may be needed.

Potential diagnosis

Agglutination is graded from 1+ to 4+ in manual testing systems; with 4+ being the strongest degree of agglutination. Automated testing systems are capable of reporting 1+ to 4+ graded results, or providing images of the tested material so laboratory professionals can interpret the results, or providing computer assisted interpretation of the test results as positive or negative findings. ABO system: A, B, AB, or O specific to person Rh system: positive or negative specific to person Crossmatching: compatibility between donor and recipient Incompatibility indicated by clumping (agglutination) of red blood cells
Group and TypeIncidence (%)Alternative Transfusion Group and Type of Packed Cell Units in Order of Preference If Patient’s Own Group and Type Not Available
O positive37.4O negative
O negative6.6O positive*
A positive35.7A negative, O positive, O negative
A negative6.3O negative, A positive,* O positive*
B positive8.5B negative, O positive, O negative
B negative1.5O negative, B positive,* O positive*
AB positive3.4AB negative, A positive, B positive, A negative, B negative, O positive, O negative
AB negative0.6A negative, B negative, O negative, AB positive,* A positive,* B positive,* O positive*
Rh Type
 Rh positive85–90
 Rh negative10–15
*If blood units of exact match to the patient’s group and type are not available, a switch in ABO blood group is preferable to a change in Rh type. However, in extreme circumstances, Rh-positive blood can be issued to an Rh-negative recipient. It is very likely that the recipient will develop antibodies as the result of receiving Rh-positive red blood cells. Rh antibodies are highly immunogenic, and, once the antibodies are developed, the recipient can only receive Rh-negative blood for subsequent red blood cell transfusion.

Critical findings

  • Note and immediately report to the HCP any signs and symptoms associated with a blood transfusion reaction.

  • It is essential that critical findings be communicated immediately to the requesting HCP. A listing of these findings varies among facilities.

  • Timely notification of a critical finding for lab or diagnostic studies is a role expectation of the professional nurse. The notification processes will vary among facilities. Upon receipt of the critical finding the information should be read back to the caller to verify accuracy. Most policies require immediate notification of the primary HCP, hospitalist, or on-call HCP. Reported information includes the patient’s name, unique identifiers, critical finding, name of the person giving the report, and name of the person receiving the report. Documentation of notification should be made in the medical record with the name of the HCP notified, time and date of notification, and any orders received. Any delay in a timely report of a critical finding may require completion of a notification form with review by Risk Management.

  • Signs and symptoms of blood transfusion reaction range from mildly febrile to anaphylactic and may include chills, dyspnea, fever, headache, nausea, vomiting, palpitations and tachycardia, chest or back pain, apprehension, flushing, hives, angioedema, diarrhea, hypotension, oliguria, hemoglobinuria, renal failure, sepsis, shock, and jaundice. Complications from disseminated intravascular coagulation (DIC) may also occur.

  • Possible interventions in mildly febrile reactions include slowing the rate of infusion, then verifying and comparing patient identification, transfusion requisition, and blood bag label. The patient should be monitored closely for further development of signs and symptoms. Administration of epinephrine may be ordered.

  • Possible interventions in a more severe transfusion reaction may include immediate cessation of infusion, notification of the HCP, keeping the IV line open with saline or lactated Ringer’s solution, collection of red- and lavender-top tubes for posttransfusion work-up, collection of urine, monitoring vital signs every 5 min, ordering additional testing if DIC is suspected, maintaining patent airway and blood pressure, and administering mannitol. See Effects of Natural Products on Laboratory Values online at DavisPlus for a more detailed description of transfusion reactions and potential nursing interventions.

Interfering factors

  • Drugs, including levodopa, methyldopa, methyldopate hydrochloride, and cephalexin, may cause a false-positive result in Rh typing and in antibody screens.
  • Recent administration of blood, blood products, dextran, or IV contrast medium causes cellular aggregation resembling agglutination in ABO typing.
  • Contrast material such as iodine, barium, and gadolinium may interfere with testing.
  • Abnormal proteins, cold agglutinins, and bacteremia may interfere with testing.
  • Testing does not detect every antibody and may miss the presence of a weak antibody.
  • History of bone marrow transplant, cancer, or leukemia may cause discrepancy in ABO typing.

Nursing Implications and Procedure

Potential nursing problems

ProblemSigns & SymptomsInterventions
Injury risk (Related to possible transfusion reaction secondary to protein hypersensitivity; WBC febrile reaction; hemolytic incompatibility)Fever, chills, rash, itching, decreased blood flow to organs, renal failureTake vital signs prior to transfusion; take vital signs within 15 min after the transfusion has started and assess for fever and chills; monitor for fever, chills, itching, and rash during transfusion; administer ordered premedication to prevent fever and itching; consider the use of a leukocyte filter; follow standard hospital procedure to ensure a correct match prior to transfusion; immediately stop transfusion if reaction is noted; follow institutional process for assessing for transfusion reaction; collect urine and blood sample for analysis per institutional policy
Gas exchange (Related to insufficient oxygen supply secondary to blood loss)Decreased activity tolerance; increased shortness of breath with activity; weakness; orthopnea; cyanosis; cough; increased heart rate; weight gain; edema in the lower extremities; weakness; increased respiratory rate; use of respiratory accessory muscles Auscultate and trend breath sounds; perform pulse oximetry to monitor oxygenation; administer oxygen as ordered; collaborate with physician to consider intubation and/or mechanical ventilation; place the head of the bed in high Fowler’s position; administer diuretics, vasodilators as ordered; administer ordered blood or blood products; monitor HGB/HCT
Cardiac output (Related to inadequate circulating blood supply secondary to blood loss) Decreased peripheral pulses; decreased urinary output; cool, clammy skin; tachypnea; dyspnea; edema; altered level of consciousness; abnormal heart sounds; crackles in lungs; decreased activity tolerance; weight gain; fatigue; hypoxia Assess peripheral pulses and capillary refill; monitor blood pressure and check for orthostatic changes; assess respiratory rate, breath sounds, and orthopnea; assess skin color and temperature; assess level of consciousness; monitor urinary output; use pulse oximetry to monitor oxygenation; monitor sodium and potassium levels; monitor HGB/HCT; administer ordered oxygen
Fluid volume (Related to increased circulatory volume secondary to blood transfusion and normal saline IV fluids) Excess: edema, shortness of breath, increased weight, ascites, rales, rhonchi, and diluted laboratory values Monitor transfusion rate, transfuse according to standards of care; monitor respiratory status with establishment of baseline assessment data; administer ordered diuretic


  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this test can assist in identification of blood type.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s immune and hematopoietic systems, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Note any recent or past procedures, especially blood or blood product transfusion or bone marrow transplantation, that could complicate or interfere with test results.
  • Obtain a list of the patient’s current medications including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.
  • Make sure a written and informed consent has been signed prior to any transfusion blood products.


  • Potential complications:
  • A transfusion reaction may occur in some patients. A transfusion reaction is also a critical finding. Signs, symptoms, and possible interventions are described in the Critical Findings section.

  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
  • Although correct patient identification is important for test specimens, it is crucial when blood is collected for type and crossmatch because clerical error is the most frequent cause of life-threatening ABO incompatibility. Therefore, additional requirements are necessary, including the verification of two unique identifiers that could include any two unique patient demographics such as name, date of birth, Social Security number, hospital number, date, or blood bank number on requisition and specimen labels; completing and applying a wristband on the arm with the same information; and placing labels with the same information and blood bank number on blood sample tubes.
  • Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
  • Promptly transport the specimen to the laboratory for processing and analysis.


  • Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.
  • Patient Education

    • Inform the patient of ABO blood and Rh type, and advise him or her to record the information on a card or other document routinely carried.
    • Inform women who are Rh-negative to inform the HCP of their Rh-negative status if they become pregnant or need a transfusion.
    • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP.
    • Answer any questions or address any concerns voiced by the patient or family.
  • Expected Patient Outcomes

    • Knowledge
    • Verbalizes understanding regarding the risks and benefits of blood transfusion
    • Discusses possible transfusion alternatives other than donor blood
    • Skills
    • Identifies transfusion reaction symptoms that should be immediately reported
    • States understanding that the purpose of the transfusion is to replace lost circulating blood stores
    • Attitude
    • Discusses and resolves anxiety related to blood transfusion
    • Voices any religious or cultural objections to the ordered transfusion

Related Monographs

  • Related tests include Coomb’s antiglobulin, bilirubin, CBC, CBC hematocrit, CBC hemoglobin, CBC platelet count, CBC RBC count, cold agglutinin, FDP, fecal analysis, GI blood loss scan, haptoglobin, IgA, iron, Kleihauer-Betke, laparoscopy abdominal, Meckel’s diverticulum scan, and UA.
  • Refer to Effects of Natural Products on Laboratory Values online at DavisPlus for further information regarding laboratory studies used in the investigation of transfusion reactions, findings, and potential nursing interventions associated with types of transfusion reactions.
  • Refer to the Immune and Hematopoietic systems tables at the end of the book for related tests by body system.
Handbook of Laboratory and Diagnostic Tests, © 2013 Farlex and Partners