4Ts Score (HIT)aaIPI (Age-adjusted IPI)ABC Score (Massive Transfusion)Absolute Neutrophil Count Age-adjusted D-dimer Threshold aGvHD Grading (Glucksberg/MAGIC)AL Amyloidosis Staging (Mayo)Anti-Xa Monitoring Interpreter Antiphospholipid Syndrome Classification Binet / Rai Staging (CML)Blood Volume Calculator Caprini VTE Risk Score CISNE Score CLL-IPI Coombs-Negative Haemolysis Checklist Corrected Reticulocyte Count CRS Grading (ASTCT 2019)DAT Interpretation Algorithm Deauville Score Interpreter DIC Score (ISTH)DIPSS (MF)DIPSS-Plus (MF)DOAC Dose Selector DOAC Renal Dose Adjustment DRI (Disease Risk Index)Durie-Salmon Staging (historical)EBMT Risk Score ELN 2022 AML Risk Classification ELTS Score (CML)England & Fraser Index EUTOS Score (CML)Expected Hb Rise Calculator (Post-Transfusion)Factor Inhibitor Bethesda Titre Interpreter Febrile Neutropaenia Risk (MASCC)Fibrinogen Replacement FLIPI (Follicular Lymphoma IPI)FLIPI-2 French TTP Score GAPSS (Global APS Score)Haemophilia Severity Classification HbS Percentage Target Calculator HCT-CI (Comorbidity Index)HEP Score Heparin Nomogram (Weight-based)Hepatic Iron Index HERDOO2 Rule HFE Haemochromatosis Risk Estimator ICANS Grading (ASTCT 2019)IMWG Response Criteria (Myeloma)IPI (International Prognostic Index)IPSID / Lugano Classification IPSS-M (Molecular IPSS)IPSS-R (Revised IPSS for MDS)Iron Deficit Calculator (Ganzoni Formula)ISS (Myeloma)ISTH Bleeding Assessment Tool (BAT)ISTH Non-Overt DIC Score ITP Bleeding Score IWG ITP Response Criteria JAK2V617F Allele Burden Interpreter Karnofsky Performance Scale Leucostasis Risk Threshold Lupus Anticoagulant (LAC) Reporting Framework MAGIC aGvHD Biomarker Score MCV-based Anaemia Algorithm Mentzer Index MIPI (MCL IPI)MIPSS70+ v2.0 (MF)Mixing Study Interpretation MRD Assessment Threshold Interpreter mSMART 3.0 (Myeloma)MTP Activation Criteria NCCN-IPI NIH Chronic GvHD Scoring NTDT Iron Burden Estimator Padua RAM PBT (Paediatric BAT)PCNSL MSKCC Score PERC Rule Perioperative Anticoagulation Bridging PESI Score (PE Mortality)PLASMIC Score Platelet Increment Calculator (CCI)PNH Clone Size Interpreter R-IPI (Revised IPI)R-ISS (Revised ISS)Reticulocyte Index (RPI)Revised Geneva Score (PE)Revised Response Criteria (NHL)Revised Zubrod / ECOG Performance Shine & Lal Index Sickle Cell Disease Risk (TCD)SLiM-CRAB Criteria SOKAL Score (CML)Sokal/EUTOS/ELTS Comparison sPESI (Simplified PESI)TACO Risk Score Thalassaemia Transfusion Threshold Thrombocytopaenia Differential Thrombophilia Screening Eligibility Algorithm Time in Therapeutic Range (TTR)TLS Risk Classification Transferrin Saturation Calculator Vienna Prediction Model von Willebrand Factor Activity Interpreter Warfarin Dose Calculator Wells Score (DVT)Wells Score (PE)WHO 2022 AML Classification Mapper WHO Bleeding Scale YEARS Algorithm

DAT Interpretation Algorithm

DAT Interpretation: The pattern of IgG and Complement (C3) reactivity on the direct antiglobulin test (Coombs) defines the class of immune haemolysis.

Guidelines & Evidence

Verified

Last Review: 2026-07-17

When to Use

When to Use

Differentiating the types of Autoimmune Haemolytic Anaemia (AIHA).

Investigating suspected Haemolytic Disease of the Fetus and Newborn (HDFN).

Workup for suspected acute or delayed haemolytic transfusion reactions.

Evaluating drug-induced immune haemolytic anaemia (DIIHA).

Patient Population

Any patient with biochemical features of haemolysis and a positive direct Coombs test. The pattern of reactivity (IgG vs. C3) is the primary diagnostic classifier.

When Not to Rely on This Score Alone

DAT negative AIHA — a negative DAT does not 100% exclude immune haemolysis (requires specialized assays).

Asymptomatic positive DAT — many healthy individuals or those with hyperglobulinemia have a positive DAT without haemolysis.

To monitor response to therapy — clinical and biochemical markers (Hb, LDH, Retics) are superior for monitoring treatment response.

How it Works

Patterns of Reactivity

Pattern	IgG	C3d	Possible Diagnoses
Warm AIHA	+	±	Idiopathic, SLE, CLL, Drugs
Cold Agglutinin (CAD)	-	+	Idiopathic, Mycoplasma, EBV, Lymphoma
Mixed AIHA	+	+	Idiopathic, SLE
PCH	-	+	Syphilis (classic), Viral (children)
Drug-Induced	+	±	Penicillins, Cephalosporins, NSAIDs

Last Comprehensive Review: 2026-07-17