Blood & Lymphoreticular

Transfusion reactions: types and management

Clinical Overview and When to Suspect Transfusion Reactions

— Acute (<24 h): acute hemolytic (AHTR), febrile non-hemolytic (FNHTR), allergic/anaphylactic, TRALI, TACO, septic, hypotensive

— Delayed (>24 h to weeks): delayed hemolytic (DHTR), transfusion-associated GVHD (ta-GVHD), post-transfusion purpura (PTP), iron overload, alloimmunization, viral transmission

— STOP the transfusion immediately

— Maintain IV access with normal saline through a new tubing set

— Recheck patient identifiers and unit label (clerical check is the #1 source of AHTR)

— Send remaining product + post-transfusion blood + urine to blood bank

— Notify blood bank and transfusion medicine

CCS pearl: On a CCS case, the first order after any suspicious transfusion symptom is "Stop transfusion" followed by "Normal saline IV" and "Notify blood bank — send unit and patient sample for workup" — these three orders capture nearly every grading point regardless of the underlying reaction type. Do not order acetaminophen or diphenhydramine before stopping the transfusion; that sequencing is a common Step 3 trap.

Board pearl: Mortality is dominated by TRALI (leading cause of transfusion-related death in the US), followed by TACO and AHTR — all three present with respiratory distress or hemodynamic collapse and must be distinguished within minutes.

Definition: Any adverse event temporally related to transfusion of blood components (RBCs, platelets, plasma, cryoprecipitate). Incidence ~1% of all transfusions; severe/fatal reactions are rare but time-critical.

Core categories to memorize:

When to suspect during a transfusion: any new fever, chills, dyspnea, hypotension or hypertension, flank/back pain, dark urine, urticaria, wheeze, or oozing from IV sites within minutes to hours of starting a unit.

Universal first move (any reaction):

Risk substrate: chronically transfused patients (sickle cell, thalassemia, MDS) — alloimmunization, iron overload, DHTR; immunocompromised/neonates — ta-GVHD risk; IgA-deficient patients — anaphylaxis risk.

Presentation Patterns and Key History

— Suggests FNHTR (cytokines from donor leukocytes); diagnosis of exclusion after AHTR/sepsis ruled out

— Classic acute hemolytic (ABO incompatibility, usually clerical error)

— Mild allergic reaction (donor plasma proteins)

— Anaphylactic — strongly consider IgA deficiency with anti-IgA antibodies, especially if recurrent

— TRALI — donor anti-HLA/anti-neutrophil antibodies; often multiparous female donor plasma

— TACO — risk: elderly, CHF, renal failure, rapid/large-volume transfusion

— Septic transfusion, most often platelets (room-temp storage); Yersinia enterocolitica with RBCs

— DHTR — anamnestic response to minor antigen (Kidd/Jka classic)

— ta-GVHD — nearly 100% fatal; prevent with irradiation

— PTP — anti-HPA-1a antibodies

Key distinction: TRALI vs TACO — both cause acute pulmonary edema within 6 h. TRALI is normotensive or hypotensive with normal BNP and normal LV function; TACO is hypertensive with elevated BNP, JVD, and responds to diuresis. This is among the highest-yield Step 3 distinctions on this topic.

Fever + chills only, mild (rise ≥1 °C), within 1–6 h:

Fever + back/flank pain + dark urine + hypotension during infusion:

Urticaria/pruritus alone within minutes:

Urticaria + wheeze + hypotension + angioedema:

Dyspnea + bilateral infiltrates + hypoxia within 6 h, NO volume overload signs:

Dyspnea + hypertension + JVD + S3 + bilateral crackles within 6 h:

High fever + rigors + hypotension + shock during/just after infusion:

Falling Hb 2–14 days post-transfusion, mild jaundice, positive DAT:

Fever + rash + diarrhea + pancytopenia 1–6 weeks post-transfusion:

Thrombocytopenia <10 K at 5–10 days post-transfusion in multiparous woman:

Key history questions: prior transfusions, prior reactions, pregnancy history (alloimmunization), known IgA deficiency, hematologic diagnosis, immunosuppression, cardiac/renal disease, baseline weight and Hb.

Physical Exam Findings (and Hemodynamic Assessment when relevant)

— Fever pattern: low-grade <1 °C rise → FNHTR; high fever + rigors → sepsis or AHTR

— BP: hypotension → AHTR, anaphylaxis, sepsis, TRALI; hypertension → TACO

— RR/SpO₂: hypoxia + tachypnea → TRALI vs TACO vs anaphylaxis

— HR: tachycardia nonspecific but universal in significant reactions

— Diffuse urticaria, flushing → allergic

— Angioedema of lips/tongue, stridor → anaphylaxis

— Petechiae/purpura days later → PTP

— Maculopapular rash + desquamation weeks later → ta-GVHD

— Bilateral crackles + wheeze possible in both TRALI and TACO

— JVD, S3 gallop, peripheral edema point to TACO

— Pink frothy sputum can occur in either but more typical of TACO

— AHTR: warm, hypotensive, tachycardic (distributive picture from complement activation, DIC)

— Septic: warm shock, often profound hypotension within 30 min of infusion start

— Anaphylactic: hypotension + bronchospasm + skin findings

— Flank pain + bladder fullness (oliguria) → AHTR with hemoglobinuric AKI

— Anxiety, "sense of impending doom" early in AHTR or anaphylaxis

— Oozing/bleeding suggests DIC from AHTR — check fibrinogen, platelets, D-dimer urgently

— Visual inspection of post-transfusion plasma sample: pink/red plasma = free hemoglobin = hemolysis

— Urine dipstick positive for blood without RBCs on micro = hemoglobinuria

Step 3 management: At bedside before any labs return, decide between four reaction "buckets" — hemolytic, allergic, volume/lung, septic — using BP direction + skin + lung exam. This drives the next 5 minutes of orders (epinephrine vs diuretic vs antibiotics vs supportive). A reflex "give Tylenol and Benadryl and restart" is incorrect until AHTR, TRALI, and sepsis are excluded.

Vital signs are the cornerstone — recheck every 15 min during reaction:

Skin/mucosa:

Pulmonary:

Cardiovascular hemodynamics:

Abdomen/back:

Neuro:

IV site:

Bedside tools:

Diagnostic Workup — Initial Labs / Imaging / ECG / Biomarkers

— Repeat type & crossmatch on new patient sample

— Direct antiglobulin test (DAT/Coombs) on post-transfusion sample

— Visual inspection of plasma for pink discoloration (free Hgb)

— CBC with smear (schistocytes in microangiopathy, spherocytes in immune hemolysis)

— LDH, indirect bilirubin, haptoglobin — hemolysis panel

— Plasma free hemoglobin if available

— BMP — K⁺ (hyperkalemia from cell lysis), creatinine (AKI)

— Coagulation panel: PT/PTT, fibrinogen, D-dimer — DIC screen

— Urinalysis for hemoglobinuria (heme+, no RBCs)

— Blood cultures from patient AND culture of the residual unit if fever/sepsis suspected

— Return the bag, tubing, and labels to blood bank

— TRALI/TACO: CXR (bilateral infiltrates in both), BNP (elevated in TACO, near-baseline in TRALI), troponin, echo if needed

— Anaphylaxis: tryptase within 1–2 h (elevated); send IgA level and anti-IgA antibody in recurrent or severe cases

— Septic: Gram stain and culture of unit (Yersinia in RBCs; Staph/Strep in platelets)

— DHTR: repeat DAT (often newly positive), antibody screen (new alloantibody, especially Kidd — Jka, Jkb)

— CXR ratio of upper-to-lower zone redistribution + cardiomegaly → TACO

— Bilateral patchy infiltrates with normal heart size → TRALI

Board pearl: The triad ↑LDH + ↑indirect bilirubin + ↓haptoglobin + hemoglobinuria within minutes-to-hours of transfusion is AHTR until proven otherwise. Haptoglobin <25 mg/dL is highly sensitive but slow to drop; plasma color and DAT are the fastest bedside confirmatory tests.

Mandatory immediate orders after stopping transfusion (any moderate/severe reaction):

Reaction-specific add-ons:

ECG: check for peaked T waves, widened QRS if hyperkalemia suspected (massive transfusion, AHTR with cell lysis); also useful if hypotension/chest pain.

Imaging:

Diagnostic Workup — Advanced or Confirmatory Studies

— Post-transfusion DAT positive (IgG and/or C3) — donor cells coated by recipient antibody

— Repeat ABO typing on pre- and post-transfusion samples; clerical error in 90% of fatal cases

— Antibody identification panel — anti-A, anti-B most catastrophic; anti-Kell, Duffy, Kidd more often delayed

— Eluate testing of patient RBCs to identify the offending antibody

— Originally negative antibody screen becomes positive 2–14 days later

— Most common culprits: Kidd (Jka, Jkb), Duffy (Fya), Kell, MNS — Kidd antibodies notorious for evanescing and re-emerging (anamnestic)

— HLA class I/II antibody testing and anti-HNA (human neutrophil antigen) testing of donor — confirms implicated donor and triggers donor deferral

— Echo and BNP to exclude TACO (BNP typically <200 in TRALI, ratio post/pre <1.5)

— BNP > 1.5× baseline post-transfusion, echo showing volume overload/diastolic dysfunction, response to diuresis

— Quantitative IgA (<7 mg/dL = severe deficiency) and anti-IgA antibodies

— Haptoglobin phenotyping if anti-haptoglobin suspected (rare)

— Concordant organism in patient blood culture AND residual unit culture is diagnostic

— Notify blood supplier — mandatory; recall of co-components from same donor

— Skin biopsy (vacuolar interface dermatitis with apoptotic keratinocytes)

— HLA chimerism on patient blood — donor lymphocytes engrafted

— Bone marrow biopsy: aplasia

— Anti-HPA-1a (PlA1) antibodies in a HPA-1a-negative recipient

Key distinction: A newly positive DAT post-transfusion can reflect either AHTR (immediate) or DHTR (delayed). Timing + hemodynamics separate them — DHTR is typically a stable patient with unexplained Hb drop 5–10 days later, often missed if outpatient follow-up labs aren't ordered.

Acute hemolytic transfusion reaction confirmation:

Delayed hemolytic reaction:

TRALI workup (largely clinical, but supportive testing):

TACO confirmation:

Anaphylaxis workup:

Septic transfusion:

ta-GVHD:

PTP:

Risk Stratification or First-Line Management Logic

— Step 1: ABCs and vitals — any hypoxia, hypotension, or stridor → resuscitation pathway

— Step 2: Clerical recheck — patient ID vs unit label vs lab slip

— Step 3: Pattern recognition to assign to one of six pathways:

1. Mild allergic (urticaria only, stable): antihistamine, may cautiously resume transfusion slowly — the only reaction where resumption is permissible

2. FNHTR (isolated fever, stable, AHTR excluded): antipyretic, do not resume the same unit

3. AHTR: aggressive IVF, maintain UOP >100 mL/h, monitor K⁺, treat DIC, ICU

4. Anaphylaxis: IM epinephrine 0.3–0.5 mg, airway, IVF, antihistamines, steroids

5. TRALI: supportive O₂/ventilation (lung-protective), avoid diuretics, ICU

6. TACO: upright positioning, IV furosemide, O₂, slow/stop infusion; if must transfuse again, give small aliquots over 4 h with diuretic cover

7. Sepsis: broad-spectrum antibiotics within 1 h, IVF, vasopressors, ICU

Step 3 management: The only reaction where you may restart the same unit is a mild urticarial allergic reaction that fully resolves with antihistamine. Every other reaction — fever, hypotension, dyspnea, hemolysis signs — mandates permanent discontinuation of that unit and full workup. This is a recurring Step 3 vignette: "After giving diphenhydramine, the hives resolve — what next?" Answer: resume the transfusion slowly under monitoring, not discard.

Board pearl: For future transfusions in a confirmed reaction, premedication and component modification are reaction-specific (see chunk 15) — generic "Tylenol + Benadryl for everyone" is not evidence-based and is a wrong answer on Step 3.

Triage algorithm after stopping transfusion:

Severity flags requiring rapid escalation: SpO₂ <90%, SBP <90, oliguria, altered mental status, DIC labs, peaked T waves.

Pharmacotherapy — First-Line Drug Regimen

— Diphenhydramine 25–50 mg IV (or cetirizine PO if mild)

— If pruritus only, can resume same unit slowly after resolution

— Epinephrine 0.3–0.5 mg IM (1:1000) into anterolateral thigh — first-line, do not delay for IV access

— Repeat q5–15 min PRN; IV infusion 0.1 mcg/kg/min if refractory

— Adjuncts: H1 blocker (diphenhydramine 50 mg IV), H2 blocker (famotidine 20 mg IV), methylprednisolone 125 mg IV, albuterol nebulizer for bronchospasm

— Aggressive IV crystalloid (1–2 L bolus)

— Acetaminophen 650 mg PO/PR — meperidine 25 mg IV only for severe rigors (avoid in elderly/renal)

— Normal saline wide open — target UOP >100 mL/h (or 1 mL/kg/h)

— Furosemide only if volume-loaded with oliguria after adequate hydration

— Treat hyperkalemia (calcium gluconate, insulin/dextrose, kayexalate/dialysis)

— DIC: replace with FFP, cryo (fibrinogen <100), platelets as needed

— Vasopressors (norepinephrine) for refractory hypotension

— Supportive O₂ ± mechanical ventilation with low tidal volume (6 mL/kg)

— Avoid diuretics and aggressive fluids — pulmonary edema is permeability-type, not hydrostatic

— Steroids not routinely recommended (no clear benefit)

— IV furosemide 20–40 mg (or higher in CKD)

— O₂, upright positioning, slow or halt remaining transfusion

— Consider noninvasive ventilation (BiPAP) if severe

— Broad-spectrum antibiotics covering Gram-negatives (Yersinia, Pseudomonas) and Gram-positives — e.g., piperacillin-tazobactam + vancomycin

— IVF, vasopressors, source control (discontinue and return unit)

CCS pearl: In a TRALI case, ordering "furosemide IV" loses points because the mechanism is increased pulmonary capillary permeability, not volume overload. Order "oxygen, intubation if indicated, ICU transfer, mechanical ventilation low tidal volume" and not diuretics.

Allergic (urticarial):

Anaphylaxis:

FNHTR:

AHTR:

TRALI:

TACO:

Septic transfusion:

Procedures / Revascularization / Invasive Management

— Anaphylaxis with angioedema/stridor: early intubation — airway closes fast; cricothyrotomy kit at bedside

— TRALI with PaO₂/FiO₂ <300 and worsening: intubate with ARDSnet low tidal volume (6 mL/kg ideal body weight), plateau pressure <30

— TACO refractory to diuretics: noninvasive positive pressure ventilation (BiPAP) often avoids intubation

— Central line for vasopressors in shock (AHTR, sepsis, refractory anaphylaxis)

— Arterial line for continuous BP monitoring in ICU

— Norepinephrine first-line vasopressor; epinephrine infusion for refractory anaphylaxis

— Indicated in AHTR with anuric AKI, refractory hyperkalemia, severe acidosis, or volume overload unresponsive to diuretics

— CRRT preferred if hemodynamically unstable

— Rare; considered in severe DHTR in sickle cell disease (hyperhemolysis syndrome) or massive AHTR with ongoing hemolysis

— Plasmapheresis is sometimes used in PTP alongside IVIG

— PTP: IVIG 1 g/kg/day × 2 days is first-line; platelet transfusion usually ineffective and only for life-threatening bleeding (use HPA-1a–negative platelets if available)

— ta-GVHD: no effective treatment once established — mortality >90%; prevention by irradiating cellular products is the only effective strategy

— Iron overload from chronic transfusion: deferasirox (oral) or deferoxamine (parenteral) when ferritin >1000 ng/mL or after ~20 units RBC

— Leukoreduction — prevents FNHTR, CMV transmission, HLA alloimmunization

— Irradiation — prevents ta-GVHD (mandatory for immunocompromised, neonates, intrauterine, directed donations from relatives, Hodgkin lymphoma, BMT recipients, congenital T-cell defects)

— Washing — removes plasma; for IgA-deficient patients with anti-IgA or recurrent severe allergic reactions

— CMV-seronegative units — for CMV-negative pregnant patients, neonates, transplant recipients

Board pearl: Irradiation prevents ta-GVHD, not CMV; leukoreduction reduces CMV transmission and FNHTR, not GVHD. Mixing these up is a top-tier Step 3 trap.

Airway management:

Hemodynamic support:

Renal replacement therapy:

Exchange transfusion / plasmapheresis:

Therapeutic procedures by reaction:

Blood product modifications (procedural choices for future transfusions):

Special Populations — Elderly and Renal/Hepatic Impairment

— Highest risk for TACO — incidence up to 1–5% with standard transfusion rates

— Strategies: transfuse one unit at a time, infuse over 3–4 h (not the maximum 4-h window pushed to the limit), reassess between units, use restrictive Hb threshold (7 g/dL in stable patients; 8 g/dL in cardiac/orthopedic surgery patients)

— Pre-transfusion furosemide 20–40 mg IV for high-risk patients (CHF, CKD, prior TACO)

— Upright positioning during transfusion

— Reduced fluid tolerance → TACO risk; transfuse during or just before dialysis when feasible

— Hyperkalemia risk amplified in AHTR — older blood (stored >14 days) has higher K⁺

— Consider fresh (<7 days) or washed RBCs for massive transfusion in dialysis patients

— Avoid avoidable transfusions — optimize ESA (erythropoietin) and iron stores

— Baseline coagulopathy complicates DIC assessment in AHTR — track fibrinogen trend rather than absolute value

— Higher risk for TRALI due to underlying immune dysregulation

— Cirrhotics with variceal bleeding: target Hb 7 g/dL — over-transfusion worsens portal pressure and rebleeding

— Use restrictive threshold 8 g/dL for symptomatic CAD; avoid transfusing asymptomatic Hb 8–10

— Pre-transfusion BNP and lung exam; post-transfusion CXR if any new dyspnea

— Beta-blockers may mask tachycardia of early reaction — rely on temperature, BP, SpO₂, mental status

— ACE inhibitors associated with bradykinin-mediated hypotensive reactions, especially with bedside leukoreduction filters — hold ACEi if recurrent hypotensive reactions

Step 3 management: For an 82-year-old with CHF and Hb 7.5 needing transfusion, order one unit PRBC over 4 h with IV furosemide 20 mg midway, head of bed up, reassess vitals and exam before considering a second unit. Don't order "2 units PRBC now" — that's a classic TACO setup.

Elderly (>65, especially with cardiac disease):

Chronic kidney disease / dialysis:

Hepatic impairment / cirrhosis:

Heart failure:

Polypharmacy considerations:

Special Populations — Pregnancy, Pediatrics, and Immunocompromised

— Rh-negative pregnant patients must receive Rh-negative blood to prevent anti-D alloimmunization and future hemolytic disease of the fetus and newborn (HDFN)

— If Rh-positive blood given inadvertently to Rh-negative woman of childbearing age: RhIG (Rho(D) immune globulin) 300 mcg per 15 mL Rh+ RBCs (or per Kleihauer-Betke calculation for large exposures)

— CMV-seronegative or leukoreduced products for CMV-negative pregnant patients (prevent congenital CMV)

— TRALI risk: avoid plasma from multiparous female donors — most US blood centers now use male-predominant plasma sourcing

— Irradiated, CMV-safe, leukoreduced products

— Volume calculated: typically 10–15 mL/kg PRBC over 2–4 h

— Higher risk for hyperkalemia with rapid infusion of stored blood → use fresh (<7 days) for large-volume neonatal transfusions

— Exchange transfusion for severe HDFN

— Goal: phenotypically matched (C, E, K minimum) RBCs to prevent alloimmunization

— Hyperhemolysis syndrome: post-transfusion Hb falls below pre-transfusion level with destruction of both donor and recipient RBCs — treat with IVIG + steroids, avoid further transfusion if possible

— Iron overload monitoring with ferritin and MRI T2*

— Mandatory irradiation of all cellular products to prevent ta-GVHD

— Note: HIV alone is not an indication for irradiation

— Washed RBCs or IgA-deficient donor plasma to prevent anaphylaxis

— Honor refusal of whole blood, RBCs, plasma, platelets; some accept albumin, factor concentrates, cell salvage — document specifics individually

Board pearl: A directed donation from a first-degree relative carries increased ta-GVHD risk because of shared HLA haplotypes (donor lymphocytes recognized as self by recipient but recipient cells appear foreign to donor lymphocytes) — always irradiate related-donor units.

Pregnancy:

Neonates and infants:

Sickle cell disease:

Immunocompromised (HSCT, congenital T-cell defects, Hodgkin, fludarabine/cladribine/alemtuzumab recipients, intrauterine transfusion, directed donation from blood relatives):

IgA-deficient patients:

Jehovah's Witnesses:

Complications and Adverse Outcomes

— AHTR → pigment nephropathy from free hemoglobin → ATN

— Prevention: aggressive isotonic fluids, target UOP >100 mL/h, treat DIC

— May require RRT; usually recovers if hemodynamics restored

— Activated by complement and tissue factor release during AHTR

— Manifests as oozing, prolonged PT/PTT, low fibrinogen, elevated D-dimer, schistocytes

— Replace with FFP, cryoprecipitate (target fibrinogen >150), platelets >50K if bleeding

— TRALI may evolve into ARDS — most recover within 72–96 h, but mortality 5–25%

— Lung-protective ventilation, conservative fluid strategy

— ~250 mg iron per unit RBC; clinical overload after ~20 units

— Causes cardiomyopathy (leading cause of death in thalassemia), cirrhosis, endocrinopathies (diabetes, hypogonadism)

— Monitor with ferritin and cardiac/hepatic MRI T2*; chelate with deferasirox/deferoxamine/deferiprone

— Antibodies to RBC, HLA, or HPA antigens → harder crossmatch, platelet refractoriness, future DHTR

— Prevention: leukoreduction, phenotypic matching in chronically transfused patients

— Post-transfusion platelet increment <5 K/μL × 2 transfusions

— Causes: immune (anti-HLA) and non-immune (fever, sepsis, DIC, splenomegaly)

— Management: leukoreduced + HLA-matched platelets

— HIV ~1 in 1.5 million, HCV ~1 in 1.2 million, HBV ~1 in 800,000 — Yersinia (RBC) and bacterial contamination of platelets remain most common acute infections

— Emerging: Babesia, West Nile, Zika, Chagas, vCJD (deferral-based prevention)

Key distinction: Platelet refractoriness (failure to bump count) is not a transfusion reaction per se; it's an outcome of alloimmunization. Confirm with 1-hour post-transfusion platelet count — immune cause if <5K increment at 1 h; non-immune if increment initially good then drops by 24 h.

Acute kidney injury:

Disseminated intravascular coagulation:

ARDS:

Iron overload (chronic transfusion):

Alloimmunization:

Platelet refractoriness:

Transfusion-transmitted infection (rare in US):

Post-transfusion purpura: profound thrombocytopenia at 5–10 days; bleeding risk

ta-GVHD: pancytopenia and marrow aplasia; >90% fatal

When to Escalate Care — ICU, Consult, or Inpatient Triage

— Anaphylaxis requiring epinephrine + airway support

— AHTR with hypotension, AKI, DIC, or hyperkalemia

— TRALI requiring high FiO₂ or mechanical ventilation

— TACO requiring BiPAP or refractory to diuretics

— Septic transfusion with hemodynamic instability

— Any reaction with vasopressor requirement, SpO₂ <90% on supplemental O₂, GCS drop

— Transfusion medicine / blood bank — mandatory for every reaction beyond mild urticaria/FNHTR; they direct workup, donor traceback, regulatory reporting

— Hematology — for DHTR, hyperhemolysis, PTP, ta-GVHD, refractoriness, chronic transfusion planning

— Critical care — early for respiratory or hemodynamic instability

— Nephrology — for AHTR with AKI requiring RRT

— Pulmonology — for evolving ARDS in TRALI

— Allergy/immunology — for recurrent allergic reactions or suspected IgA deficiency

— Any reaction more severe than isolated mild urticaria or simple FNHTR → admit for monitoring at least 24 h

— Suspected TRALI/TACO → telemetry + continuous SpO₂

— AHTR/sepsis → ICU

— Fatal transfusion reactions must be reported to the FDA Center for Biologics Evaluation and Research (CBER) within 24 h by phone/email and a written report within 7 days — required by federal law

— Non-fatal serious reactions reported per state and institutional rules

— Septic reactions trigger product recall and donor deferral through AABB/blood supplier

— Order "transfer to ICU," "consult transfusion medicine," "consult hematology" for the appropriate reaction

— Order "continuous pulse oximetry" and "telemetry" for TRALI/TACO

CCS pearl: In a fatal AHTR case, the simulation expects orders for clerical investigation, FDA notification, and root cause analysis (institutional patient safety report) — Step 3 increasingly tests systems-level responses, not just bedside care.

Immediate ICU transfer indicated for:

Consultations:

Inpatient triage minimums:

Regulatory reporting:

CCS-specific escalation cues:

Key Differentials — Same-Category Causes

— TRALI: normo-/hypotensive, normal BNP, normal LV, no JVD, no edema, normal heart size, does not respond to diuretics, pathophysiology = capillary leak

— TACO: hypertensive, ↑BNP, ↑JVD, S3, cardiomegaly, responds to diuretics, pathophysiology = hydrostatic overload

— AHTR: <24 h, often minutes, intravascular hemolysis, fever/back pain/hypotension, ABO mismatch most common, severe

— DHTR: 2–14 days, extravascular hemolysis, often subtle Hb drop + jaundice, anamnestic response to Kidd/Duffy/Kell, mild

— FNHTR: temperature rise ≥1 °C, otherwise stable, no hemodynamic changes, no hemolysis labs, negative DAT, no plasma discoloration

— AHTR: fever + at least one of (hypotension, back pain, hemoglobinuria, positive DAT, pink plasma)

— Always work up AHTR before declaring FNHTR

— Allergic: hives ± pruritus only, normotensive, no airway/respiratory involvement

— Anaphylactic: hypotension + bronchospasm or angioedema ± hives; consider IgA deficiency

— Septic: very high fever, rigors, often with platelet transfusions (room-temp storage); positive cultures from unit and patient

— AHTR: hemoglobinuria, hemolysis labs, positive DAT, clerical mismatch

— Both can cause DIC; cultures and hemolysis panel differentiate

— ta-GVHD: pancytopenia is hallmark (marrow aplasia from donor T cells), 1–6 wk post-transfusion in at-risk host

— DRESS/viral: eosinophilia, less likely pancytopenic, different temporal links

Board pearl: "Bilateral infiltrates within 6 h of transfusion" → if the question gives you a BNP value, use it: BNP near baseline → TRALI; BNP markedly elevated → TACO. If BNP isn't given, look for hypertension + JVD (TACO) vs hypotension + clear cardiac exam (TRALI).

Within "transfusion reaction" itself, the highest-yield differentiating pairs:

TRALI vs TACO (acute dyspnea + bilateral infiltrates within 6 h):

AHTR vs DHTR (hemolysis post-transfusion):

FNHTR vs early AHTR (fever during infusion):

Allergic (urticarial) vs anaphylactic:

Septic vs AHTR (fever + hypotension):

ta-GVHD vs viral exanthem / drug reaction (delayed rash + fever + cytopenias):

Key Differentials — Other-Category Causes

— Coincidental bacteremia, line infection, urosepsis can mimic septic transfusion reaction. Distinguish via culture concordance (organism from unit AND patient = transfusion source) and timing relative to transfusion.

— Fever + rash 2–6 wk after new drug; eosinophilia, transaminitis, LAD; consider in patients on new antibiotics during admission

— Acute dyspnea + hypoxia post-transfusion; clear lungs and unilateral CXR favor PE over TRALI/TACO; CT-PA if suspicion

— Elderly with chest discomfort and pulmonary edema after transfusion may have demand ischemia precipitating LV failure; ECG and troponin distinguish

— Often unilateral or dependent; segmental rather than bilateral diffuse

— Timing >6 h post-transfusion or clear preceding infection favors primary pulmonary process

— Penicillins, cephalosporins, NSAIDs — positive DAT, but no transfusion timing relationship

— In patients with known AIHA, post-transfusion Hb drop may reflect underlying disease, not DHTR — antibody screen patterns differ

— Day 5–10 platelet drop in hospitalized patient — can mimic PTP; HIT has thrombosis, PTP has bleeding and recent transfusion

— Schistocytes, thrombocytopenia, AKI, neuro changes, fever — but DAT is negative in TTP (non-immune microangiopathy); positive in AHTR/DHTR

— Antibiotic, contrast, or premedication given concurrently — review timeline carefully

— Crush injury, tumor lysis, missed dialysis — peaked T waves not always transfusion-related

Key distinction: DAT-negative hemolysis with schistocytes + thrombocytopenia + AKI + fever + neuro changes is TTP, not a transfusion reaction — treat with plasma exchange, not just supportive care. Mistaking TTP for DHTR delays life-saving plasmapheresis.

Sepsis from non-transfusion source:

Drug reaction / DRESS:

Pulmonary embolism:

Acute coronary syndrome / flash pulmonary edema:

Aspiration pneumonia:

Pneumonia / community-acquired ARDS:

Drug-induced hemolytic anemia:

Autoimmune hemolytic anemia flare:

Heparin-induced thrombocytopenia:

TTP/HUS:

Anaphylaxis to medication given simultaneously:

Hyperkalemia from other source:

Secondary Prevention / Discharge Medications / Long-Term Plan

— FNHTR: leukoreduced products (now universal in US); pre-medicate with acetaminophen 650 mg only if recurrent despite leukoreduction

— Allergic (urticarial), recurrent: pre-medicate with diphenhydramine 25–50 mg; for severe/recurrent → washed RBCs/platelets

— IgA deficiency with anti-IgA: IgA-deficient donor plasma/platelets, washed cellular products

— AHTR: rigorous identification protocols, electronic patient ID matching; antibody screen + crossmatch with extended phenotype

— DHTR: record the antibody in a transfusion passport / wallet card; future units must be antigen-negative for that specificity (Kidd, Duffy, Kell, etc.)

— TRALI: notify blood center to defer implicated donor; subsequent transfusions standard

— TACO: single-unit transfusions, slow infusion (4 h max per unit), pre-transfusion diuretic, restrictive Hb threshold

— ta-GVHD survivors (rare): lifelong irradiated cellular products; flag in chart

— PTP: future cellular products from HPA-1a–negative donors; document antibody

— Sickle cell with hyperhemolysis: avoid transfusion when possible; if essential, IVIG + steroids prophylaxis and phenotypically matched units

— Hb 7 g/dL for stable hospitalized adults including ICU and GI bleed

— Hb 8 g/dL for cardiac surgery, orthopedic surgery, pre-existing CVD

— Symptomatic anemia trumps numeric threshold

— Initiate after ~20 units RBC or ferritin >1000 in chronic transfusion patients

— Deferasirox PO daily; monitor renal, hepatic function

Step 3 management: A patient who had FNHTR last admission does not need premedication for the next transfusion — leukoreduction is already universal in the US and is the evidence-based prevention. Reflex pre-medication is a low-value, wrong-answer choice on Step 3.

Document the reaction in the EHR and the blood bank record — future transfusions will trigger protocol modifications automatically.

Reaction-specific prevention for future transfusions:

Restrictive transfusion thresholds (evidence-based) — universal secondary prevention:

Iron chelation:

Follow-Up, Monitoring Parameters, and Rehab/Counseling

— Vitals at baseline, 15 min after start, hourly, and at completion

— Direct visualization of patient for first 15 min (highest reaction risk window)

— Stop at any new symptom; document

— AHTR: UOP, K⁺, creatinine, hemolysis labs, coag panel q6h until stable; ICU monitoring

— TRALI: continuous SpO₂, daily CXR until resolution (typically 48–96 h)

— TACO: daily weights, I/O, repeat BNP, CXR; cardiology if persistent dysfunction

— Allergic: observe 4 h post-resolution for biphasic reaction in anaphylaxis

— DHTR: trend Hb, retic, LDH, bilirubin daily until stable

— PTP: daily CBC; monitor for bleeding

— ta-GVHD: weekly CBC, LFTs; usually fatal despite monitoring

— Hematology clinic at 2–4 weeks for any patient with newly identified alloantibody, DHTR, PTP, hyperhemolysis, or planned chronic transfusion

— Repeat antibody screen at 3 and 6 months after DHTR (antibodies may evanesce, then re-emerge)

— Primary care follow-up within 1–2 weeks for medication reconciliation and counseling

— Provide a wallet card documenting reaction type and required product modifications (irradiation, washing, antigen-negative, IgA-deficient, CMV-negative)

— Educate on symptoms to report immediately at future transfusions: chills, back pain, dyspnea, rash, dark urine

— Discuss alloimmunization implications for future pregnancies in women of childbearing age

— Quarterly ferritin, annual hepatic/cardiac MRI T2* if applicable

— Annual antibody screen with extended phenotyping

— Hepatitis B vaccination if not immune

— Reassess transfusion need vs alternatives (ESAs, hydroxyurea in SCD, luspatercept in MDS/thalassemia)

Board pearl: A transfusion reaction wallet card is the patient-safety equivalent of a drug allergy bracelet — Step 3 may test whether you provide and document it before discharge. Failure to communicate special transfusion requirements during transitions of care is a recurring sentinel-event scenario.

During transfusion (every transfusion, not just post-reaction):

Post-reaction monitoring (varies by reaction):

Outpatient follow-up:

Patient counseling:

Chronic transfusion patients:

Ethical, Legal, and Patient Safety Considerations

— Required for elective transfusion; must include risks (infection, reaction, alloimmunization), benefits, alternatives (iron, ESAs, cell salvage, observation), and right to refuse

— Emergency transfusion in unconscious patient: implied consent doctrine permits life-saving transfusion absent advance directive to the contrary

— Honor refusal even if life-threatening when patient is a competent adult with clear advance directive

— Minors: courts may override parental refusal if life-threatening — pediatric ethics consult and legal team

— Document specific products refused; some accept albumin, factor concentrates, IV iron, EPO, intraoperative cell salvage

— Two unique identifiers (name + DOB or MRN) must be verified at the bedside by two qualified staff before transfusion — single most effective AHTR prevention

— Wristband checks, barcode scanning (electronic verification) reduce mismatch rates

— Fatal transfusion reactions → FDA CBER within 24 h (phone/email) + written report within 7 days (21 CFR 606.170)

— Septic reactions and TRALI also reported to blood supplier for donor traceback

— Institutional patient safety event reporting and root cause analysis

— Special transfusion requirements (irradiation, washing, antigen-negative, CMV-negative) must be communicated in transfer summaries — failure is a top sentinel event

— Hand-off should include reaction history, antibodies, product modifications

— Sickle cell patients face higher alloimmunization rates partly due to donor-recipient antigen mismatch (predominantly White donor pool, predominantly Black recipient pool) — recruiting diverse donors is an evolving health-equity priority

— Directed donations are not safer than volunteer-donor pool blood; relatives' donations carry higher ta-GVHD risk — counsel patients accordingly

Step 3 management: A 16-year-old Jehovah's Witness with life-threatening anemia whose parents refuse transfusion → emergency court order or hospital ethics/legal pathway to authorize transfusion; you cannot let a minor die based on parental refusal alone. Document the process meticulously.

Informed consent for transfusion:

Jehovah's Witnesses:

Clerical errors and patient identification:

Mandatory reporting:

Transitions of care:

Equity and access:

Conflict of interest in directed donations:

High-Yield Associations and Rapid-Fire Clinical Facts

— Yersinia enterocolitica in stored RBCs (cold-tolerant Gram-negative)

— Staphylococcus epidermidis, S. aureus, Streptococcus in platelets (stored at room temp — biggest infectious risk in modern era)

Board pearl: "Multiparous female donor + bilateral pulmonary infiltrates + hypotension within 6 h" → TRALI, prevent with male-predominant plasma sourcing.

#1 cause of transfusion-related death in the US: TRALI (then TACO, then AHTR/sepsis depending on year)

Most common acute reaction overall: FNHTR (incidence reduced sharply since universal leukoreduction)

Most common cause of fatal AHTR: clerical error with ABO mismatch

Most common bacterial contamination organism:

Most common antibodies causing DHTR: Kidd (Jka), Duffy, Kell, MNS — Kidd antibodies are famously evanescent, dropping below detection threshold, then re-appearing on rechallenge ("the Kidd antibody disappears at exactly the worst time")

TRALI donor profile: multiparous female donor plasma containing anti-HLA/anti-HNA antibodies

ta-GVHD high-risk recipients: intrauterine transfusion, neonates, congenital T-cell defects (SCID, DiGeorge), Hodgkin lymphoma, fludarabine/cladribine/alemtuzumab/bendamustine recipients, allogeneic HSCT, directed donation from blood relatives, granulocyte transfusions

Irradiation indication ≠ HIV — HIV patients do not routinely need irradiated blood

CMV-safe products: leukoreduced or CMV-seronegative — both acceptable in most settings (granulocytes are exception — require seronegative)

Washed products indication: IgA deficiency with anti-IgA, recurrent severe allergic reactions, neonatal cardiac surgery (to reduce K⁺)

Restrictive Hb threshold: 7 g/dL (general), 8 g/dL (CVD, orthopedic/cardiac surgery)

One-unit-at-a-time rule: transfuse one unit, reassess clinically before ordering the next — reduces TACO and over-transfusion

Massive transfusion protocol ratio: 1:1:1 (PRBC:FFP:platelets) for trauma resuscitation

Platelet refractoriness diagnostic: 1-hour post-transfusion platelet increment <5 K/μL = immune (HLA alloimmunization)

Hyperkalemia risk: stored blood >14 days, especially in neonates, renal failure, rapid large-volume transfusion

Board Question Stem Patterns

— "5 minutes into transfusion, patient develops fever, back pain, hypotension. Urine becomes dark. Plasma sample appears pink." → Stop transfusion, IVF, send DAT and clerical check. Most likely cause: ABO mismatch from clerical error.

— "Within 4 h of transfusion, patient develops hypoxia and bilateral pulmonary infiltrates. BP 90/60. BNP normal. Donor was a multiparous woman." → TRALI. Treat with lung-protective ventilation; avoid diuretics.

— "Elderly woman with CHF, received 2 units PRBC over 2 h. Now dyspneic, JVD, BP 180/95, bilateral crackles, BNP elevated." → TACO. Treat with furosemide, O₂, sit upright.

— "Within 5 min of plasma transfusion, patient develops hypotension, wheezing, angioedema. History of recurrent transfusion-related allergic reactions." → IgA deficiency with anti-IgA. Treat with IM epinephrine. Future products: washed or IgA-deficient.

— "1 °C temperature rise during transfusion. BP, HR stable. No other symptoms." → FNHTR. Stop transfusion, exclude AHTR with DAT and plasma inspection, then acetaminophen.

— "Sickle cell patient received transfusion 7 days ago. Hb dropped from 9 to 6 with jaundice, new positive DAT, new anti-Jka." → DHTR (Kidd). Antigen-negative units for future transfusions; document antibody.

— "30 min into platelet transfusion, patient develops 40 °C fever, rigors, BP 70/40. Gram stain of unit shows GPCs in clusters." → Septic transfusion (Staph). Broad-spectrum antibiotics, IVF, vasopressors.

— "Hodgkin lymphoma patient receives RBCs from sister. 3 weeks later: fever, rash, diarrhea, pancytopenia." → ta-GVHD from non-irradiated related-donor blood. Mortality >90%; prevent with irradiation.

— "Multiparous woman, platelet count 5K eight days after transfusion, with petechiae." → PTP from anti-HPA-1a. Treat with IVIG.

Step 3 management: When stem gives a temporal clue (minutes, hours, days, weeks), use it as the primary discriminator — it usually narrows to one reaction before you even read the labs.

Stem 1 — Acute hemolytic transfusion reaction:

Stem 2 — TRALI:

Stem 3 — TACO:

Stem 4 — Anaphylaxis with IgA deficiency:

Stem 5 — FNHTR:

Stem 6 — DHTR:

Stem 7 — Septic transfusion from platelets:

Stem 8 — ta-GVHD:

Stem 9 — PTP:

One-Line Recap

Recognize the reaction by timing and pattern, stop the transfusion immediately, run a hemolysis and clerical workup on every significant reaction, and tailor product modifications (leukoreduction, irradiation, washing, antigen-matching) to prevent recurrence.

Board pearl: Master the TRALI vs TACO distinction (BNP, BP, JVD), the AHTR clerical-error pathway, and the irradiation vs leukoreduction product-modification logic — these three concepts account for the majority of Step 3 transfusion-reaction questions.

Acute, within 24 h: AHTR (hypotension + hemolysis + back pain), FNHTR (isolated fever), allergic/anaphylaxis (urticaria ± hypotension/bronchospasm), TRALI (hypoxia, normal BNP, hypotensive), TACO (hypoxia, ↑BNP, hypertensive, JVD), septic (high fever + shock, often platelets), hypotensive (ACEi + bedside leukoreduction filter).

Delayed, >24 h: DHTR (Kidd/Duffy/Kell, 2–14 d), ta-GVHD (fever/rash/pancytopenia 1–6 wk, fatal — prevent with irradiation), PTP (anti-HPA-1a, severe thrombocytopenia at d5–10, treat with IVIG), iron overload (chronic — chelate), alloimmunization.

Universal first orders (CCS): Stop transfusion → NS IV → notify blood bank → send unit + post-transfusion sample + urine → DAT + plasma color + CBC + hemolysis panel + coags + cultures.

Step 3 prevention pearls: restrictive Hb thresholds (7 or 8), one-unit-at-a-time with reassessment, leukoreduce universally, irradiate for immunocompromised/related donors/neonates/Hodgkin/intrauterine, wash for IgA deficiency, antigen-match in chronic transfusion (especially sickle cell), document reaction with wallet card and communicate at every transition of care, and report fatal reactions to FDA CBER within 24 hours.