W10TL5+6 - Pre-Transfusion Testing

Question 1

Steps Involved in Pre-transfusion Testing

Answer 1

Sample collection
- request form
- collection
- appropriate sample
ABO and Rh(D) grouping
Antibody Screen
Selection of appropriate donor
Cross-match
Transfusion

Question 2

Request Form

Answer 2

A request must be received from the lab before testing or issue of blood
Requests that don’t comply with lab are rejected
Requests may be written, verbal, electronic or any combination of these
The request must clearly identify the patient with 3 unique identifiers (Full name, DOB and/or MRN/NHI)

Question 3

Verbal Requests

Answer 3

Patient must have a valid group and screen
May be made face to face or by telephone
Must be documented by the person receiving the request
The person making the request must be recorded along with the information required
- 3 unique identifiers
- product required
- number of doses required etc.

Question 4

Specimen Collection

Answer 4

EDTA (plasma) or clotted (serum) specimens are both suitable for testing
- although which is used will depend on the test, method or platform
Specimen must clearly have patient details (2 unique identifiers)
- labelling performed immediately after collection and in the presence of the patient

Question 5

Sample Acceptance and Validity

Answer 5

Specimens must be checked on receipt to ensure that they are labelled correctly
Gross haemolysed specimens should not normally be accepted for testing
- haemolysis may be caused by inappropriate collection, storage or transport, or by patients underlying condition
Blood group and antibody screen should be completed within 48 hours of the specimen being collected
- unless it is stored refrigerated

Question 6

Appropriately Stored Specimens

Answer 6

72 hours from collection - if patient has been pregnant or transfused in the last 3 months
7 days from collection - if the patient has not been pregnant or transfused in previous 3 months
(Up to) 3 months from collection - for specimen taken in advance of surgery
- must be checked at collection as well as admission to patient 3 months later

Question 7

Specimen Storage

Answer 7

Whole blood (EDTA)
- 18-25 °C for up to 48 hours
- 2-8 °C for up to 7 days
Separated plasma
- 18-25 °C for up to 48 hours
- 2-8 °C for up to 7 days
- -20 °C for up to 3 months

Question 8

ABO and Rh(D) Grouping

Answer 8

A full ABO group, Rh(D) type and antibody screen must be performed on all specimens
- reverse ABO group not required for newborn infant samples
New patients must have a second confirmatory ABO/Rh(D) type performed on either a new aliquot from original sample with same or different reagents or a new specimen
- if manual, should be performed by a different person

Question 9

ABO and Rh(D) Grouping Controls

Answer 9

Anti-A
- pos control: A cells
- neg control: B cells
Anti-B
- pos control: B cells
- neg control: A cells
Anti-D
- pos control: RhD pos
- neg control: RhD neg

Question 10

Controls for Antibody Screening

Answer 10

A weak positive antibody control, such as anti-D concentration of at least 0.1 UI/mL should be run at least once per day or on each day that the lab undergoes testing

Question 11

Selection of Appropriate Donor - Clinically Significant Antibody

Answer 11

If the patient has a clinically significant antibody, red cells negative for the corresponding antigen should be selected
If the patient has a history of a clinically significant antibody but one is not currently detectable by IAT, antigen negative red cells are required

Question 12

Selection of Appropriate Donor - Non Clinically Significant Antibody

Answer 12

If patient has an antibody that is not considered clinically significant but which is reactive at 37 °C, IAT crossmatch compatible cells should be selected
- these cells don’t need to be antigen negative

Question 13

Selection of Plasma Products

Answer 13

Plasma products should be preferably the same ABO blood group as the patient
Where this isn’t possible, products that are ABO compatible with patient’s red cells should be selected
Group AB plasma products typically used when the patients group is unknown
Plasma products don’t need to have same Rh(D) group

Question 14

Selection of Extended Life Plasma

Answer 14

ELP is a separate but complementary product of thawed FFP but which in contrast has an extended shelf life of up to 5 days after thawing when stored at 2-6 °C

Question 15

Selection of Platelet Products

Answer 15

Should be preferably same ABO/Rh(D) type as patient
If not available, use ABO nonidentical platelets
Matching of platelets for Rh(D) type is desirable but may be considered less important than ABO matching

Question 16

Reasons for a Positive Cross-Match

Answer 16

Negative aby screen, incompatible immediate spin X-match
- recipient and donor are ABO incompatible
- recipient producing aby’s that react at RT (“cold” antibodies)
- ABO subgroup (i.e. A2 producing anti-A1 antibody)
Negative aby screen, incompatible IAT X-match
- donor has a positive DAT
- recipient has aby to low incidence antigen

Question 17

Transfusion Steps

Answer 17

Inspect unit for:
- haemolysis
- expiry date
Donor RBC unit is labelled with recipient ID’s, compatibility testing results
Unit released
Patient ID verified
Patient transfused
Keep pre-transfusion samples for 7 days post-transfusion

Question 18

MSBOS

Answer 18

Maximum surgical blood order schedule

Question 19

Pre-Transfusion Testing in Emergencies

Answer 19

Pre-transfusion specimen should be obtained ASAP
Still must be labelled correctly
Pre-transfusion testing must be completed ASAP regardless of the fate of the patient

Question 20

Blood Products Given in an Emergency

Answer 20

Red cells must be group O
- ABO/Rh(D) compatible cells may be issued once patient has a confirmed ABO/Rh(D) type
Red cells must not be issued on basis of historical blood group
ABO non-identical platelets may be given
Plasma products should be group AB if possible
- group A may also be used