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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 per RBC Unit 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 iwCLL Response Criteria (2018)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

Thrombophilia Screening Eligibility Algorithm

Choosing Wisely: Thrombophilia testing is high-cost and prone to interference. It should only be performed if it will change clinical management (e.g., stopping prophylaxis).

1. Indications for Workup

2. Contraindications / Exclusions

Screening Eligibility Status

SCREENING NOT INDICATED

Rationale

No high-yield indications for a hereditary thrombophilia workup.

Guidelines & Evidence

Clinical Details

Section 1

When to Use

When to Screen

First unprovoked Venous Thromboembolism (VTE) at a young age (typically < 45-50 years).

Strong family history of VTE (at least one first-degree relative with unprovoked VTE before age 50).

Recurrent unprovoked VTE.

VTE in unusual vascular beds (e.g., cerebral venous sinus, mesenteric, portal veins).

Skin necrosis induced by vitamin K antagonists (suggestive of Protein C deficiency).

The 'Golden Rule' of Timing

Do NOT screen during the acute phase of a VTE or while the patient is on therapeutic anticoagulation (Warfarin, Heparin, or DOACs). Factors like Protein S and Antithrombin are consumed in the acute clot, leading to false positives.

Section 2

Formula & Logic

Exclusion Criteria (Do NOT test if present)

Provoked VTE (e.g., after major surgery, trauma, or prolonged immobilization).

Currently on Warfarin (interferes with Protein C/S results).

Currently on DOACs (Apixaban, Rivaroxaban, etc., interfere with Lupus Anticoagulant and functional assays).

Patient with unprovoked VTE who is already committed to lifelong anticoagulation.

Section 3

Pearls/Pitfalls

Will it Change Management?

This is the fundamental question. Since most patients with unprovoked VTE require long-term anticoagulation anyway, knowing a thrombophilic factor exists rarely changes the treatment plan. The main indication is for counseling family members (especially females about OCP/pregnancy risk).

Wait Time

Standard practice is to wait at least 2 weeks after stopping all anticoagulation (and at least 3-6 months after the acute event) before performing a formal thrombophilia screen.

Section 4

Evidence Appraisal

Primary Strategy

Guidance for the evaluation and treatment of hereditary and acquired thrombophilia.

Stevens SM et al. • Journal of Thrombosis and Thrombolysis. 2016;41(1):154-164.

View Source

Inherited thrombophilia: a double-edged sword.

Middeldorp S. • Hematology Am Soc Hematol Educ Program. 2016;2016(1):1-9.

View Source

Section 5

Literature

Consensus

Reflects the ASH (American Society of Hematology) Choosing Wisely recommendations to avoid unnecessary and misleading testing.

Last Comprehensive Review: 2026

Guidelines & Evidence

Clinical Details

Section 1

When to Use

When to Screen

First unprovoked Venous Thromboembolism (VTE) at a young age (typically < 45-50 years).

Strong family history of VTE (at least one first-degree relative with unprovoked VTE before age 50).

Recurrent unprovoked VTE.

VTE in unusual vascular beds (e.g., cerebral venous sinus, mesenteric, portal veins).

Skin necrosis induced by vitamin K antagonists (suggestive of Protein C deficiency).

The 'Golden Rule' of Timing

Section 2

Formula & Logic

Exclusion Criteria (Do NOT test if present)

Provoked VTE (e.g., after major surgery, trauma, or prolonged immobilization).

Currently on Warfarin (interferes with Protein C/S results).

Currently on DOACs (Apixaban, Rivaroxaban, etc., interfere with Lupus Anticoagulant and functional assays).

Patient with unprovoked VTE who is already committed to lifelong anticoagulation.

Section 3

Pearls/Pitfalls

Will it Change Management?

Wait Time

Standard practice is to wait at least 2 weeks after stopping all anticoagulation (and at least 3-6 months after the acute event) before performing a formal thrombophilia screen.

Section 4

Evidence Appraisal

Primary Strategy

Guidance for the evaluation and treatment of hereditary and acquired thrombophilia.

Stevens SM et al. • Journal of Thrombosis and Thrombolysis. 2016;41(1):154-164.

View Source

Inherited thrombophilia: a double-edged sword.

Middeldorp S. • Hematology Am Soc Hematol Educ Program. 2016;2016(1):1-9.

View Source

Section 5

Literature

Consensus

Reflects the ASH (American Society of Hematology) Choosing Wisely recommendations to avoid unnecessary and misleading testing.

Last Comprehensive Review: 2026

Related Hematology Tools

Mixing Study Interpretation

Age-adjusted D-dimer Threshold

sPESI

HEP Score

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Thrombophilia Screening Eligibility Algorithm

Choosing Wisely: Thrombophilia testing is high-cost and prone to interference. It should only be performed if it will change clinical management (e.g., stopping prophylaxis).

1. Indications for Workup

2. Contraindications / Exclusions

Screening Eligibility Status

SCREENING NOT INDICATED

Rationale

No high-yield indications for a hereditary thrombophilia workup.

Guidelines & Evidence

Clinical Details

Section 1

When to Use

When to Screen

First unprovoked Venous Thromboembolism (VTE) at a young age (typically < 45-50 years).

Strong family history of VTE (at least one first-degree relative with unprovoked VTE before age 50).

Recurrent unprovoked VTE.

VTE in unusual vascular beds (e.g., cerebral venous sinus, mesenteric, portal veins).

Skin necrosis induced by vitamin K antagonists (suggestive of Protein C deficiency).

The 'Golden Rule' of Timing

Section 2

Formula & Logic

Exclusion Criteria (Do NOT test if present)

Provoked VTE (e.g., after major surgery, trauma, or prolonged immobilization).

Currently on Warfarin (interferes with Protein C/S results).

Currently on DOACs (Apixaban, Rivaroxaban, etc., interfere with Lupus Anticoagulant and functional assays).

Patient with unprovoked VTE who is already committed to lifelong anticoagulation.

Section 3

Pearls/Pitfalls

Will it Change Management?

Wait Time

Standard practice is to wait at least 2 weeks after stopping all anticoagulation (and at least 3-6 months after the acute event) before performing a formal thrombophilia screen.

Section 4

Evidence Appraisal

Primary Strategy

Guidance for the evaluation and treatment of hereditary and acquired thrombophilia.

Stevens SM et al. • Journal of Thrombosis and Thrombolysis. 2016;41(1):154-164.

View Source

Inherited thrombophilia: a double-edged sword.

Middeldorp S. • Hematology Am Soc Hematol Educ Program. 2016;2016(1):1-9.

View Source

Section 5

Literature

Consensus

Reflects the ASH (American Society of Hematology) Choosing Wisely recommendations to avoid unnecessary and misleading testing.

Last Comprehensive Review: 2026

Guidelines & Evidence

Clinical Details

Section 1

When to Use

When to Screen

First unprovoked Venous Thromboembolism (VTE) at a young age (typically < 45-50 years).

Strong family history of VTE (at least one first-degree relative with unprovoked VTE before age 50).

Recurrent unprovoked VTE.

VTE in unusual vascular beds (e.g., cerebral venous sinus, mesenteric, portal veins).

Skin necrosis induced by vitamin K antagonists (suggestive of Protein C deficiency).

The 'Golden Rule' of Timing

Section 2

Formula & Logic

Exclusion Criteria (Do NOT test if present)

Provoked VTE (e.g., after major surgery, trauma, or prolonged immobilization).

Currently on Warfarin (interferes with Protein C/S results).

Currently on DOACs (Apixaban, Rivaroxaban, etc., interfere with Lupus Anticoagulant and functional assays).

Patient with unprovoked VTE who is already committed to lifelong anticoagulation.

Section 3

Pearls/Pitfalls

Will it Change Management?

Wait Time

Standard practice is to wait at least 2 weeks after stopping all anticoagulation (and at least 3-6 months after the acute event) before performing a formal thrombophilia screen.

Section 4