in more than 95% of patients, serologic crossmatch is used ... · aabb 1992 standards for blood...

Pretransfusion testing Pretransfusion testing : XM vs Type and : XM vs Type and screenscreen

Objective :

Ensure patient safetyIncreasing laboratory efficiency Reducing costs

Automation-computerization

In more than 95% of patients, serologic crossmatch is used to confirm ABO compatibility

Pretransfusion testingPretransfusion testing : XM vs Type and: XM vs Type and screenscreen

Nomenclature

• Test de compatibilité par flacon B 200

• Recherche d’anticorps B 300

Recherche pré-transfusionnelle à l’aide de GR phénotypés avec un minimum de 18 antigènes en cas de commande de sang, y compris une épreuve de compatibilité ABO sur l’ensemble des flacons composant la même commande de sang

Pretransfusion testing

Blood sample

Ab screen

Serologic XM POS NEG NEG

NEG POS IS-XM EXM

Ab identificationAg neg blood

Label and Release Label and releasecompatible blood compatible blood

Pretransfusion testing : XM vs Type and screen

Critical points :

• ABO compatibility

IS-XM (immediat spin XM) vs Electronic XM

• Irregular antibodiesSerologic XM (AHG) vs Antibody screen


• IS-XM limits

– False negative : weak anti A, anti BA2, A2B ... RBCProzone effect, strong Ab

– False positive : rouleaux, cold agglutininsanti A1

Specificity : 99 %Sensitivity : 98 %Praticability !!!!!!


IS-XM mandatory ??

Alternative : • ABO Rh typing patient 2 x

2 different persons 1x automate2 different technics

• ABO Rh typing bag (tubulure)• Electronic XM (EXM)


Electronic XM

ABO incompatibilities

• Mislabeled(1/165) and miscollected patient samples (1/2000)

• Laboratory errors : • Misused patient sample • Technical and clerical errors XM, Type and screen• Mislabed donnor blood bag

• Mistransfusion Right unit to the right patient for the right reason

AABB 1992 Standards for Blood Banks and Transfusion Services

• “If a computer system has been validated on site to prevent therelease of ABO-incompatible blood and blood components, then it may be used prior to transfusion to detect ABO incompatibility instead of a serologic cross-match.”

• To guard against erroneous ABO grouping results two determinations of the recipient’s ABO group are required “of whichone has been made on a current sample and the other made by one of the following methods :– by testing of the same sample– by testing of a second current sample – by comparaison with previous records”

• The system must also contain the confirmed ABO group and Rh type of the of the donor unit, and logic to alert the user to any ABOincompatibility between the recipient and the donor unit selected.

Requirements for the electronic crossmatch EXMRequirements for the electronic crossmatch EXMW J Judd, Vox Sang 74 (suppl 2): 409-417, 1998AABB, BCSH (British Commitee for Standardization in haematology)

•The computer contains logic to prevent assignnemnt and release of ABO incompatible blood (BCSH)•No clinical significant antibodies are detected in the recipient’serum and there is no record of previous detection of such antibodies ( AABB, BSCH)•There are concordant results of at lease two determinations of the recipient’s ABO on record, one of which is from a current sample(AABB, BSCH)•Critical elements of the system have been validated on-site (AABB, BCSH)•There are mechanisms to verify the correct entry of data prior to release of blood (AABB, BCSH)

W J Judd, Vox Sang 74 (suppl 2): 409-417, 1998AABB, BCSH (British Commitee for Standardization in haematology)

•The computer contains logic to prevent assignnemnt and release of ABO incompatible blood (BCSH)•No clinical significant antibodies are detected in the recipient’serum and there is no record of previous detection of such antibodies ( AABB, BSCH)•There are concordant results of at lease two determinations of the recipient’s ABO on record, one of which is from a current sample(AABB, BSCH)•Critical elements of the system have been validated on-site (AABB, BCSH)•There are mechanisms to verify the correct entry of data prior to release of blood (AABB, BCSH)

Requirements for the electronic crossmatch EXMRequirements for the electronic crossmatch EXMW J Judd, Vox Sang 74 (suppl 2): 409-417, 1998AABB, BCSH (British Commitee for Standardization in haematology)

Mechanisms to verify the correct data entry “crux” EXM

•Maximal use of bar codes to enter patient and donor unit information•Confirmatory testing of donor unit ABO/Rh; computer interpretation of results; comparison vs.initially entered ABO/Rh with warning of discrepancy•Computer interpretation of patient ABO/Rh test results, verification of manually entered results •Computer comparison of current and historical ABO/Rh types, with warning of discrepancy

W J Judd, Vox Sang 74 (suppl 2): 409-417, 1998AABB, BCSH (British Commitee for Standardization in haematology)

Mechanisms to verify the correct data entry “crux” EXM

•Maximal use of bar codes to enter patient and donor unit information•Confirmatory testing of donor unit ABO/Rh; computer interpretation of results; comparison vs.initially entered ABO/Rh with warning of discrepancy•Computer interpretation of patient ABO/Rh test results, verification of manually entered results •Computer comparison of current and historical ABO/Rh types, with warning of discrepancy


Législation françaiseGroupe sanguin ABOUne détermination : fonction des conditions techniques• Si effectuée par automate + informatique, une détermination=une réalisation• Si non, une détermination repose sur 2 réalisations effectuées par 2

techniciens différents, saisie manuelle des résultats passant par une double saisie par 2 personnes différentes.

Groupe sanguin ABO RhD valide• Réalisé sur 2 prélèvements différents à raison d’une détermination par

prélèvement

Recherche d’anticorps• Au moins 3 hématies, détection des anticorps correspondants aux antigènes :

Rh D, C, E, c, e, K, k, Kpb, Fya, Fyb, Jka, Jkb, M, N, S, s, Lea, Leb, Lub

• Pas de mélange

RAI Spécificités anticorpsAnticorps Hôpital Erasme 1998-2000 RAI Tot

n = 1114 5.2%

Anti D 339 30%Anti E 212 19%Anti K 97 9%Anti c 41 4%Anti C 17 1.5%Anti Cw 15 1.5%Anti Fya 25 2.5%Anti S 5 0.5%Anti Jka, Jkb 11 1%anti Lea, Leb, P1, M, N, ac froids 170 15 %

Divers* 10 1%Mélange 172 15%* : e, k, s, Fyb, Wra, Kpa, Coa, Cob, ac privés, ac publics

Pretransfusion testing Pretransfusion testing : XM vs Type and : XM vs Type and screenscreenG.Garratty, Transfusion, 43, 844-847, july 2003"How concerned should we be about missing antibodies to low incidence antigens. »

Ab of potential clinical significance could be missed for :• Ab LIA (low incidence antigen) not detected• Ab showing dosage (anti Jka...) not detected if

heterozygous RBC • Joint antigen : f, G not on screening RBC but present

on transfused RBC• Weak Ab reacting with “fresh donor RBC” but not

with screening RBC.

Pretransfusion testing : XM vs Type and screenG.Garratty, Transfusion, 43, 844-847, july 2003"How concerned should we be about missing antibodies to low incidence antigens."

Pretransfusion testing : XM vs Type and screenClinical risk of Ab LIA • Blood unit possess the putative antigen• Ab LIA clinically significant? Often IgM

Incompatibility frequency = Ag frequency X Ab frequencyCw : 0.0001,Wra, Jsa : 0.000017Anti Wra : 2% random sera HTR rare ?,Ab LIA often associate to other Ab

Shluman : 2 pts with HTR/1.3 million Ab screen, HTR :1/650.000 Rouger : 30 years :2 HTR 600.000Ab screenSchoneville : 22 years, 1795 pts, 2257 Ab, 94 Ab LIA

Risk comparable XM, Ab screen


• 2 ABO Rh typing patient - 2 technicians, 2 technics- 1 + computer checking

• ABO Rh typing blood pack• « Electronic XM »• Direct Coombs test patient (Transplantation)• Direct Coombs donor??

ABCD testAntibody screenBlood group checkCompatibilityDelivery control

Elective surgery preadmission blood sampleNo transfusion, no pregnancy 3 m 1 month, 15 days, 1 week??Transfusion or pregnancy 3 m : 3 days

Our approach to pretransfusion testingReceive sampleTransfusion request form

ComputerNo discrepancySample properly labeled

ABO Rh typing Ab screenAUTOMATE AUTOMATE

Computer

NEG POS

Select ABO Rhidentical blood

Identify AbElectronic XM Ag neg blood

Serologic XM

Label andrelease blood


CUB Hôpital Erasme 1er mars 1997

• Groupes sanguins sur automate informatique centraleC10, Rosys Immucor : groupes complets des patients (ABO,RhK)Rosys : groupes contrôle des tubulures des poches (ABD)

• Recherche d’anticorps Cassettes gel OrthoMitisPerformances : 45-50 RAI /h 3 GR 2 milieux 35 mintube de serum codebar directement utilisétraçabilité : résultats, contrôles, lots de réactifs…

Autovue 07/2002 bi directionnel informatique


Patients non connus 10-15 % patients

Jour semaine• 1 groupe complet Rosys ordinateur• 1 RAI + groupe ABD CD Autovue ordinateur• Compatibilité électronique

Garde (nuit, WE) • 1 groupe complet Autovue• 1 RAI + groupe ABD CD Autovue ordinateur• Compatibilité électronique


Patient connu contrôle ordinateur • RAI+ groupe ABD CD• Compatibilité électronique

Panne informatique et ou de l ’Autovue• 2 groupes réalisés par le même technicien en manuel • Compatibilité électronique non réalisable • Compatibilité ABO (IS-XM) sauf sur les poches O

Urgence vitale (1-2/an)• Délivrance de 2 U GR ORhD-, ORh D+ + Plasma AB• RAI + Groupes sur Autovue (30 min) + EXM• Préparation GR groupe patient


1er mars 1997- 31 Décembre 2002

Poches de sang41.035 patients ==> 110.039 poches préparées

54.453 poches transfusées

Coombs direct patients (01 03 99 - 31 12 99)13.607 patients ==> 541 positifs 3.9% 529 IgG, 12 C'Eluat positif : 9 3 anti E, 8 aspécifiques

Coombs direct donneurs12 mois : 7/4.581 nouveaux donneurs 0.15%

Pretransfusion testing : XM vs type and screen

1er mars 1997- 31 Décembre 2002

Erreurs détectées : Groupe donneur ==> 2 1 ABO, 1 RhD (1997-1998)Compatibilité informatique ==> 36 1/mois

Hémovigilance : 01/01/2003 31/09/200319 réactions transfusionnelles 0.3 %

– 18 frissons, hyperthermie 3 anti HLA, 15 cause??– 1 rash

6 erreurs détectées : ± 6000 pts 1/1.000 pts, 0.5/1000 poches– 3 erreurs patient prélèvement– 2 erreurs étiquettes– 1 erreur labo (tube) urgence, manuel

XM

RAI +

ISXM ABO

RAI+

ABCD test

RAI+

ABCD test+ contrôle inform lit

Incompatibilité ABO

++++ +++ +++ ? ++++

Ac irréguliers

+++

++++

++++

++++

Ac privés

++++

- ou +

- ou +

- ou +

CD patient

+++

si auto GR

-

-

-

CD donneur

+++

-

-

-

Si RAI positive

XM OBLIGATOIRE

XM RAI +ISXM ABO

RAI+ABCD test

RAI+ABCD test+

contrôle inform lit

Automatisation +“sur mesure”

+++personnalisé

+++?personnaliséinformatisé

++++personnaliséinformatisé

“sur mesure”

Délai délivrancedes poches

+ ++ +++ +++

Gestion banquede sang

+ ++ ++++ ++++

Coût : réactifs personnel

+++++

+++++

+++++

+++++++


CostKuryan et al, Vox sanguinis,78,113, 2000 (500 bed hospital)• No XM : � 40 % 33.000 $/y• IS-XM : � 30 %

Erasme Hospital• � 1 person/3• � stress, � safety ( night, WE…technician alone)


Processus transfusionnel Sécurisation« Try to remove the human element from entire pretransfusion

testing process »

• Identification du patient Bracelet bar code, contrôle par ordinateur au lit

• Etiquetage échantillons Bar code au lit , généré à partir du bar code du patient

• Etiquetage des pochesUniformisation ISBT code 128Bar code pour chaque composants, n° poche, ABO/Rh, type composant, date péremption

• Utilisation de l ’informatique + automatisation

in more than 95% of patients, serologic crossmatch is used ... · aabb 1992 standards for blood...

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