Naturally occurring antibodies to the ABO blood type system (Anti-A and Anti-B) are the only red cell antibodies commonly found in human plasma. All other antibodies are called “unexpected red cell antibodies” that may or may not be clinically significant for pretransfusion testing. The antibody screening procedure for Blood Bank is performed to detect unexpected alloantibodies in the plasma of transfusion candidates and to identify obstetrical patients with alloantibodies which might cause hemolytic disease of the newborn. This test is typically performed in conjunction with a blood type (Type and Screen).
Useful For
To detect unexpected antibodies in pretransfusion candidates and to identify obstetrical patients with alloantibodies that may cause hemolytic disease of the newborn. When an individual produces an antibody to an antigen they lack, the antibody is called an alloantibody. When an individual produced antibody to an antigen they posses, this is called an autoantibody. Immunization to red cell antigens may result from exposure to red cells for example, from pregnancy or previous transfusion. The antibody screen is a blood bank test used to detect whether or not a patient has any unexpected antibodies. An additional test, called antibody identification, is then performed after a positive antibody screen to determine the degree of clinical significance of the positive antibody screen. A clinically significant antibody is defined as an antibody that is associated with hemolytic disease of the fetus and newborn (HDFN), hemolytic transfusion reactions, or a notable decrease in transfused red cell survival.
A positive antibody screen in a patient may cause a delay in blood product availability as the positive antibody screen is investigated and evaluated for its clinical significance.
Method Name
Hemagglutination (Tube and Gel Methods)
- Primary method is Gel
Important Note
A patient who is receiving a transfusion or inpatient obstetrical patients must have a new Type and Screen specimen drawn and tested every 72 hours as they may develop clinically significant antibodies within that timeframe.
Reagent red cells used to screen for antibodies are licensed by the US Food and Drug Administration (FDA) and must contain red cell samples that collectively express the following antigens:
D, C, E, c, e, M, N, S, S, P1, Lea, Leb, K, k, Fya, Fyb, Jka, Jkb
Aliases
Antibody Screen; Indirect Coombs; Indirect Antibody Screen, Antibody Screen, Antibody, Screen
Specimen Type
Whole Blood
Specimen Required
Large lavender-top (EDTA) tube, approximately 7 mL
- If the antibody screen is positive, additional samples may be required.
After the patient is positively identified, the sample is drawn and fully labeled with the following information either electronically or handwritten:
- Patient’s full First and Last Name
- Date of Birth or Medical Record Number (MRN#)
- Date and Time specimen was drawn
- Blood Bank Armband Number (BBID) (see below for more information)
- Identify of the person who collected the specimen (Ex: Cerner ID or personnel initials)
All inpatients, or patients potentially receiving a transfusion, must have a blood bank armband (BBID) applied to their wrist and the Blood Bank ID (BBID) number written on the tube. This blood bank armband is a secondary patient identifier that helps ensure a safe and accurate transfusion. Specimens received without a blood bank armband will be rejected. See special instructions for more information.
Specimen Minimum Volume
1.0 – 4.0 mL
NOTE: If the antibody screen is positive, additional samples may be required.
Specimen Stability Information
Stable at room temperature for 24 hours.
Rejected Due To
- If the patient’s full first and last name and date of birth are not clear, accurate, and/or readable the specimen must be rejected.
- If the Blood Bank Armband Number (BBID) from the Blood Bank Armband is missing, inaccurate, illegible and/or can not be confirmed on all inpatient and outpatient potential transfusion specimens, the specimen must be rejected and sample redrawn.
- Specimens may be rejected for insufficient quantity and/or quality reasons (Ex: Hemolysis, dilution, etc).
- If there is any doubt as to the identity of the sample, a new sample must be obtained.
- If a specimen is rejected on a trauma, OR, or other critical patient when blood is needed urgently/immediately, have the specimen redrawn in accordance with this policy and follow the policy “Issue of Blood in Urgent Situations”. Uncrossmatched blood can still be given in an emergent situation.
- In the case of a positive antibody screen or history of an antibody, the Provider must evaluate the necessity of blood urgently as the uncrossmatched blood released may be incompatible and may cause a hemolytic transfusion reaction.
Special Instructions
The person drawing the blood sample must confirm the patient’s identity by checking at least two independent identifiers before collected a specimen such as: first name, last name, date of birth, and medical record number. If possible, patient identification should be obtained verbally directly from the patient. The phlebotomist must not rely on a bed tag or on charts or records placed nearby. After positively identifying the patient, the sample is drawn and fully labeled with the following information either electronically or handwritten: Patient’s full first and last name, date of birth or medical record number (MRN#), date and time specimen was drawn, Blood Bank Armband Number (see below for more information), and identify of the person who collected the specimen (Ex: Cerner ID or personnel initials).
All inpatients, or patients potentially receiving a transfusion, must have a Blood Bank Armband applied to their wrist and the Blood Bank Armband Number (BBID) number written on the tube. Please write the number clearly and do not use a gel pen (anything written in gel pen smears as the specimen is transported in a bag to the lab). This blood bank armband is a secondary patient identifier that helps ensure a safe and accurate transfusion. Specimens received without a blood bank armband ID will be rejected.
Performing Laboratory
Glens Falls Hospital Laboratory
Reference Values
Negative: No clinically significant antibodies present
Positive: Potentially clinically significant antibodies present
- A clinically significant antibody is defined as an antibody that is associated with hemolytic disease of the fetus and newborn (HDFN), hemolytic transfusion reactions, or a notable decrease in transfused red cell survival.
Day(s) and Time(s) Performed
24 hours 7 days a week
Analytical Time
STAT turn around time approximately 30 minutes.
Routine inpatient samples around time is approximately 1- 4 hours.
Routine outpatient samples to 1-2 days.
If a positive antibody screen is identified it may take additional time as the positive antibody screen is investigated and evaluated for its clinical significance.
Specimen Retention Time
Antibody Screen specimens are held for 10 days
Reflex Tests
- When a patient’s antibody screen is positive, potentially clinically significant antibodies may be present. An Antibody Identification test (AB ID) will reflex to investigate and determine what is causing the patient’s positive antibody screen.
- If an antibody identification test can not be completed at the hospital, for example due to a complicated work up and limited resources, the sample may be sent to a reference lab for further workup to determine what is causing the patient’s positive antibody screen. This is essential to determine whether or not there are clinically significant antibodies.
Analytical Time
STAT turn around time approximately 30 minutes.
Routine inpatient samples around time is approximately 1- 4 hours.
Routine outpatient samples to 1-2 days.
If a positive antibody screen is identified it may take additional time as the positive antibody screen is investigated and evaluated for its clinical significance.