Blood & Lymphoreticular

Transfusion medicine: blood product selection and indications

Clinical Overview and When to Suspect Transfusion Need

— Packed RBCs (pRBCs): symptomatic anemia or active hemorrhage; each unit raises Hgb ~1 g/dL or Hct ~3%

— Platelets: thrombocytopenia with bleeding or prophylaxis below threshold; each apheresis unit raises count ~30–50k

— Fresh frozen plasma (FFP): multifactor coagulopathy with bleeding, warfarin reversal when 4F-PCC unavailable, TTP plasma exchange replacement, massive transfusion

— Cryoprecipitate: fibrinogen <150–200 mg/dL with bleeding, DIC, dysfibrinogenemia, vWD/hemophilia A when factor concentrate unavailable

— Factor concentrates / 4F-PCC: targeted reversal (warfarin, factor Xa inhibitors with andexanet unavailable), hemophilia

— Albumin / IVIG: volume/oncotic and immune indications (not "blood" but on the same exam axis)

— Acute blood loss with hemodynamic instability regardless of initial Hgb (early labs lag)

— Hgb <7 g/dL in stable hospitalized adult (restrictive strategy)

— Hgb <8 g/dL in cardiovascular disease, postop orthopedic, oncology

— Platelets <10k prophylactic; <20k with fever/sepsis; <50k pre-procedure; <100k for neurosurgery/intracranial bleed

— INR >1.5 with bleeding or before invasive procedure on warfarin (use PCC preferentially)

— Fibrinogen <150 in obstetric hemorrhage, <100 in non-OB bleeding

Transfusion medicine on Step 3 centers on three decisions: which product, what threshold, and how fast—plus recognition and management of reactions

Available products and their core indications:

When to suspect a patient needs transfusion:

Board pearl: Restrictive (Hgb 7) beats liberal (Hgb 9–10) in nearly every adult cohort studied—including septic, ICU, and GI bleed patients—except acute coronary syndrome, where evidence (MINT trial) favors a more liberal Hgb 10 target

Step 3 management: Always ask "Is the patient bleeding or symptomatic?" before transfusing based on a number alone—chronic stable anemia at Hgb 6.8 in an outpatient with iron deficiency gets iron, not blood

Presentation Patterns and Key History

— Dyspnea on minimal exertion, chest pain, lightheadedness, syncope, altered mentation, persistent tachycardia

— Demand ischemia: troponin elevation with anemia in CAD patient

— Site, duration, volume; melena vs hematemesis; trauma mechanism

— Anticoagulant/antiplatelet use—specifically warfarin (give vitamin K + 4F-PCC), DOACs (andexanet for apixaban/rivaroxaban; idarucizumab for dabigatran), heparin (protamine)

— Prior bleeding disorders, family history, easy bruising, menorrhagia

— Prior reactions (febrile, allergic, hemolytic, TRALI, TACO)

— Number of prior transfusions (alloimmunization risk; difficult crossmatch)

— Pregnancy history in Rh-negative women (anti-D sensitization)

— Religious objection (Jehovah's Witness)—document specifically which products are declined; some accept albumin, fractionated factors, or cell saver

— Hematologic malignancy on chemo → irradiated, leukoreduced, often CMV-safe products

— Stem cell transplant candidates/recipients → irradiated to prevent TA-GVHD

— IgA deficiency with anti-IgA antibodies → washed RBCs or IgA-deficient donors

— Chronic transfusion (sickle cell, thalassemia) → phenotypically matched, leukoreduced; monitor for iron overload

Anemia symptoms that justify pRBCs regardless of threshold:

Bleeding history to elicit before any transfusion plan:

Transfusion history is the highest-yield question you can ask:

Underlying disease context drives product choice:

Key distinction: Leukoreduction (standard in US) reduces febrile non-hemolytic reactions, CMV transmission, and HLA alloimmunization; irradiation prevents transfusion-associated graft-versus-host disease in immunocompromised hosts—these are NOT interchangeable

Board pearl: A patient with recurrent anaphylaxis to blood products and no other allergies → check IgA level and anti-IgA antibodies; transfuse washed cellular products or use IgA-deficient donor plasma

Physical Exam Findings and Hemodynamic Assessment

— Vital signs: temperature, HR, BP, RR, SpO₂ (compare q15 min during transfusion)

— Skin: pallor, jaundice, petechiae, purpura, ecchymoses, prior IV sites

— Cardiopulmonary: JVP, lung crackles, S3 gallop, peripheral edema (volume status before TACO risk)

— Mental status baseline (hemolytic reactions and severe anemia both alter cognition)

— Class I (<15% loss): minimal changes, anxiety

— Class II (15–30%): tachycardia, narrowed pulse pressure, orthostasis

— Class III (30–40%): hypotension, tachypnea, decreased urine output, confusion

— Class IV (>40%): profound shock, lethargy, anuria—activate massive transfusion protocol

— Predicted need for ≥10 units pRBCs in 24h, or ≥4 units in 1h with ongoing bleeding

— ABC score ≥2 (penetrating mechanism, SBP ≤90, HR ≥120, positive FAST)

— Empiric 1:1:1 ratio pRBC:FFP:platelets approximates whole blood reconstitution

— Fever ≥1°C rise, rigors, back/flank pain, dark urine → suspect acute hemolytic reaction

— Hypoxia + bilateral infiltrates within 6h → TRALI

— Hypoxia + hypertension + JVD + crackles → TACO

— Urticaria + wheeze + hypotension → anaphylaxis

Pre-transfusion exam—mandatory baseline so you can detect reactions:

Hemodynamic signs of acute blood loss:

Massive transfusion protocol (MTP) triggers:

Signs during transfusion that should stop the infusion immediately:

CCS pearl: Before any transfusion order in CCS, document type and crossmatch sent, two-patient-identifier verification, consent obtained, and baseline vitals; reassess vitals at 15 min, 1 hour, and post-transfusion—failure to monitor is a deductable safety omission

Board pearl: Hypotension during transfusion in a patient on an ACE inhibitor receiving products through a bedside leukoreduction filter suggests bradykinin-mediated hypotensive reaction—stop the transfusion

Diagnostic Workup — Initial Labs and Pre-Transfusion Testing

— Type and screen: ABO/Rh + antibody screen against panel of common antigens; valid 3 days if recent pregnancy/transfusion, longer if not; appropriate when transfusion probability is low

— Type and crossmatch: physically mixes donor RBCs with recipient serum; reserve specific units; required before actual transfusion

— Emergency release (uncrossmatched): O-negative for women of childbearing age, O-positive acceptable for males and post-menopausal females; switch to type-specific as soon as available

— CBC with differential (Hgb, Hct, MCV, platelets, WBC)

— Reticulocyte count if anemia workup ongoing—don't transfuse over the diagnosis in stable patients

— Iron studies, B12, folate if MCV abnormal and clinically stable

— PT/INR, aPTT, fibrinogen for coagulopathy assessment

— Type and screen on every potentially transfused patient at admission

— Hemolysis labs: LDH ↑, haptoglobin ↓, indirect bilirubin ↑, peripheral smear, DAT (Coombs)

— GI source: rectal exam, FOBT, endoscopy planning

— Menstrual/GU losses, occult chronic disease

— Alloantibodies detected → extended typing, may take hours to days to find compatible units—communicate with blood bank early

— Sickle cell patients → C, E, K antigen matching minimum to reduce alloimmunization

Type and screen vs type and crossmatch:

Baseline labs before transfusion:

Workup for the cause of anemia—don't skip this:

Cross-match special situations:

Board pearl: A positive direct antiglobulin test (DAT/direct Coombs) in a post-transfusion patient with falling Hgb and rising bilirubin 2–14 days after transfusion = delayed hemolytic transfusion reaction from anamnestic antibody response, classically anti-Kidd (Jk^a)

Step 3 management: Never transfuse to a specific Hgb number in a hemodynamically stable patient with iron deficiency—oral or IV iron corrects anemia without transfusion risk and allows ongoing source workup

Diagnostic Workup — Advanced and Reaction Investigation

— Send remaining product + tubing to blood bank

— Post-transfusion blood: repeat type and crossmatch, DAT, plasma free Hgb, haptoglobin, LDH, bilirubin

— Urine: hemoglobinuria (red urine, dipstick + for blood but no RBCs on micro)

— Clerical check for ABO mismatch (most common cause of fatal acute hemolytic reaction—a system error, not biology)

— TRALI: normal-low BP, no JVD, normal BNP, no diuretic response; mechanism = donor anti-HLA/anti-neutrophil antibodies → pulmonary edema; supportive care, ventilation

— TACO: hypertension, JVD, elevated BNP, responds to diuresis; risk = elderly, CHF, renal failure, rapid/large-volume transfusion

— Diagnosis of exclusion after ruling out hemolysis and bacterial contamination

— Cytokines from residual donor leukocytes; prevented by leukoreduction (standard in US)

— Highest risk with platelets (room temperature storage)

— High fever, rigors, hypotension during/shortly after transfusion → blood cultures from patient and unit, broad-spectrum antibiotics

— Delayed hemolytic (2–14 days): falling Hgb, +DAT, new alloantibody

— Post-transfusion purpura (~1 week): severe thrombocytopenia, anti-HPA-1a in HPA-1a-negative recipient; treat with IVIG

— TA-GVHD (1–6 weeks): fever, rash, diarrhea, pancytopenia, hepatitis—nearly always fatal; prevent with irradiation

Workup of suspected transfusion reaction (stop transfusion, maintain IV access with saline, recheck identifiers):

TRALI vs TACO differentiation (both present with hypoxia + infiltrates within 6h):

Febrile non-hemolytic reaction workup:

Bacterial contamination:

Anaphylactic reaction: check IgA level and anti-IgA antibodies in patient

Delayed reactions:

Key distinction: TRALI improves with supportive care; TACO improves with diuretics—giving Lasix in TRALI is harmful (already volume-deplete intravascularly)

Board pearl: Hyperkalemia, hypocalcemia (citrate toxicity), and metabolic alkalosis are classic massive transfusion electrolyte derangements—monitor and replace calcium especially

Risk Stratification and Transfusion Threshold Logic

— Hgb <7 g/dL: general hospitalized adults including ICU, sepsis, GI bleed (after initial resuscitation in stable patients)

— Hgb <8 g/dL: preexisting cardiovascular disease, postoperative orthopedic/cardiac surgery, symptomatic

— Hgb <8 g/dL: hematology/oncology patients on therapy (some institutions use 7)

— Hgb <10 g/dL (liberal): acute coronary syndrome (MINT trial favors liberal); some neurocritical care protocols

— Active hemorrhage: transfuse based on clinical picture and rate of loss, not a number

— <10 × 10⁹/L: prophylactic in stable patient (AABB)

— <20 × 10⁹/L: fever, sepsis, minor procedures (central line in some protocols)

— <50 × 10⁹/L: most surgeries, lumbar puncture, active bleeding

— <100 × 10⁹/L: neurosurgery, intracranial hemorrhage, ophthalmologic surgery

— Do NOT transfuse platelets in: TTP, HIT, ITP (unless life-threatening bleeding)—can worsen thrombosis

— INR >1.5–2 with active bleeding or pre-procedure when PCC unavailable

— Massive transfusion in 1:1:1 ratio

— TTP (plasma exchange)

— Multiple factor deficiency from liver disease + bleeding

— Dose: 10–15 mL/kg (typically 2–4 units)

— Fibrinogen <150 mg/dL with obstetric hemorrhage or <100 with other bleeding

— Dose: 1 unit/10 kg raises fibrinogen ~50–75 mg/dL

Restrictive vs liberal RBC transfusion thresholds (current evidence-based):

Platelet thresholds:

Plasma (FFP) indications:

Cryoprecipitate:

Board pearl: Platelets in TTP can be lethal—triggers further microvascular thrombosis; prioritize plasma exchange; platelets only for life-threatening bleeding

Step 3 management: Don't transfuse FFP for an asymptomatic mildly elevated INR (e.g., 1.6) before a low-risk procedure like paracentesis or thoracentesis—evidence shows no benefit and substantial harm risk

Pharmacotherapy and Adjuncts — Reversal Agents and Alternatives

— Warfarin + major bleeding or emergent surgery: 4-factor PCC (Kcentra) 25–50 units/kg IV + vitamin K 10 mg IV; FFP only if PCC unavailable

— Warfarin + INR 4.5–10, no bleeding: hold warfarin ± oral vitamin K 1–2.5 mg

— Dabigatran + life-threatening bleed: idarucizumab 5 g IV

— Apixaban/rivaroxaban + life-threatening bleed: andexanet alfa; alternative 4F-PCC 50 units/kg

— Heparin: protamine 1 mg per 100 units heparin given in last 2–3 hours

— LMWH: protamine partially reverses (~60%)

— tPA-related hemorrhage: cryoprecipitate (target fibrinogen >150) + platelets + consider TXA

— Tranexamic acid (TXA): trauma (CRASH-2: within 3h of injury), postpartum hemorrhage (WOMAN trial), menorrhagia, dental procedures in hemophilia

— Dose: 1 g IV over 10 min, then 1 g over 8h in trauma

— Oral ferrous sulfate 325 mg every other day (better absorption than daily)

— IV iron (sucrose, ferumoxytol, ferric carboxymaltose) for malabsorption, intolerance, CKD, ongoing losses, pre-op anemia optimization

Anticoagulation reversal (often replaces or complements transfusion):

Antifibrinolytics:

Erythropoiesis-stimulating agents (ESAs): chronic kidney disease anemia (target Hgb 10–11, not >11.5), chemotherapy-induced anemia (with cautions—shortened survival in some cancers)

Iron:

Desmopressin (DDAVP): mild hemophilia A, type 1 vWD, uremic platelet dysfunction

Recombinant factor concentrates: hemophilia A (factor VIII), hemophilia B (factor IX); preferred over cryo/FFP

Board pearl: Pre-operative anemia should be diagnosed and treated weeks before elective surgery (iron, ESA if indicated)—not corrected on day of surgery with transfusion, which increases morbidity and mortality

Step 3 management: A patient on apixaban with severe GI bleed → hold apixaban, supportive resuscitation, consider andexanet (cost and availability limit use), or 4F-PCC 50 units/kg as practical alternative

Procedures and Special Product Modifications

— Leukoreduced: standard in US; reduces FNHTR, CMV transmission, HLA alloimmunization

— Irradiated: prevents TA-GVHD; required for stem cell transplant recipients/candidates, hematologic malignancies on intensive chemo, congenital immunodeficiency (SCID, DiGeorge), intrauterine and neonatal transfusions, directed donations from blood relatives, HLA-matched platelets

— CMV-seronegative or leukoreduced (functionally equivalent): CMV-seronegative pregnant women, CMV-seronegative transplant recipients, low-birth-weight neonates, HIV with low CD4

— Washed: IgA deficiency with anti-IgA, recurrent severe allergic reactions, neonatal alloimmune thrombocytopenia

— Volume-reduced: pediatric, severe CHF

— All blood products through standard 170–260 μm filter

— Only normal saline compatible at the line (LR may clot with citrate; D5W causes RBC hemolysis)

— One unit pRBCs over ~2 hours (max 4 hours from removal from refrigerator)

— Platelets and FFP infuse faster (~30 min per unit)

— Activate early based on triggers

— Empiric 1:1:1 ratio pRBC:FFP:platelets

— Add TXA within 3 hours of trauma

— Replace calcium (1 g IV calcium gluconate per ~4 units pRBCs) for citrate toxicity

— Monitor fibrinogen, K, Ca, lactate, base deficit, temperature; warm products and patient

— TTP: replace with FFP (provides ADAMTS13)

— Other indications: myasthenic crisis, Guillain-Barré, anti-GBM disease, hyperviscosity

Product modifications—know which patient gets which:

Administration mechanics:

Massive transfusion protocol execution:

Plasma exchange (TPE):

CCS pearl: When ordering a transfusion in CCS, order "transfuse 1 unit pRBC, then recheck CBC"—single-unit dosing in stable patients reflects best practice; reassess before automatically giving a second unit

Board pearl: Irradiation does NOT prevent CMV; leukoreduction or CMV-seronegative selection does—conflating these is a classic exam trap

Special Populations — Elderly and Renal/Hepatic Impairment

— Higher TACO risk: diastolic dysfunction, reduced renal reserve, polypharmacy

— Transfuse single units slowly (over full 4 hours if tolerated), reassess between units

— Consider pre-transfusion furosemide 20–40 mg IV in patients with known CHF or borderline volume status

— Lower threshold to escalate to ICU monitoring if cardiopulmonary comorbidity

— Treat with ESAs (epoetin alfa, darbepoetin) targeting Hgb 10–11 g/dL—avoid >11.5 (increased CV events, stroke per TREAT, CHOIR)

— Ensure iron repletion before/during ESA therapy (ferritin >100, TSAT >20%)

— Reserve transfusion for symptomatic anemia or acute drops; minimize to avoid alloimmunization in transplant candidates

— Heparin during HD increases bleeding risk

— Uremic platelet dysfunction → DDAVP, cryoprecipitate, conjugated estrogens for bleeding (not platelet transfusion, which is ineffective)

— INR reflects synthetic dysfunction, not necessarily bleeding risk (anti- and procoagulant factors both decreased—"rebalanced hemostasis")

— Do not transfuse FFP to "correct" INR before paracentesis or thoracentesis in stable cirrhotics

— For active bleeding: target fibrinogen >150 with cryoprecipitate, platelets >50, address portal hypertension source

— Vitamin K 10 mg SC/IV daily × 3 if nutritional deficiency suspected

— After ~10–20 units, monitor ferritin and consider chelation (deferasirox, deferoxamine) when ferritin >1000 or liver iron concentration elevated

— Common in thalassemia major, sickle cell disease, MDS

Elderly patients:

Chronic kidney disease and anemia:

Dialysis patients:

Hepatic impairment:

Iron overload in chronically transfused:

Board pearl: Hepcidin is elevated in CKD and inflammation, sequestering iron in macrophages—oral iron absorption is poor; IV iron is preferred in CKD patients on ESAs

Step 3 management: Stable cirrhotic with INR 2.2 needing paracentesis → proceed without FFP; routine correction is not indicated and exposes patient to transfusion risks

Special Populations — Pregnancy, Pediatrics, and Sickle Cell

— Rh-negative women: anti-D immunoglobulin (RhoGAM) 300 μg at 28 weeks, within 72h postpartum if neonate Rh-positive, after any sensitizing event (miscarriage, ectopic, amniocentesis, abdominal trauma)

— Postpartum hemorrhage: TXA within 3 hours, uterotonics, 1:1:1 MTP if massive

— Avoid unnecessary transfusion in childbearing-age women to limit alloimmunization affecting future pregnancies

— Use CMV-seronegative or leukoreduced products in seronegative pregnant patients

— Smaller aliquot volumes; irradiated, CMV-safe, leukoreduced for neonates <4 months

— Fresher units (<7 days) reduce hyperkalemia risk in large-volume neonatal transfusion

— Neonatal alloimmune thrombocytopenia (NAIT): maternal anti-HPA-1a antibodies; transfuse maternal washed platelets or HPA-1a–negative platelets

— Hemolytic disease of the newborn: intrauterine transfusion with O-negative, CMV-safe, irradiated, fresh, leukoreduced pRBC

— Simple transfusion: symptomatic anemia (drop >2 g/dL from baseline), aplastic crisis (parvovirus B19), splenic sequestration

— Exchange transfusion: acute chest syndrome (severe), stroke, multiorgan failure, priapism unresponsive to medical therapy

— Always use phenotypically matched (at minimum C, E, K) and HbS-negative units to reduce alloimmunization and delayed hemolytic reactions

— Avoid transfusing for vaso-occlusive pain crisis alone (no benefit)

Pregnancy:

Neonates and pediatrics:

Sickle cell disease transfusion:

Chronic transfusion (sickle stroke prevention, thalassemia): target HbS <30%, monitor iron overload with ferritin and MRI T2\* (cardiac/hepatic)

Board pearl: Sickle cell patient transfused recently with sudden Hgb drop, jaundice, dark urine, pain crisis → hyperhemolysis syndrome / delayed hemolytic transfusion reaction; further transfusion can worsen hemolysis—give IVIG + steroids, avoid additional units if possible

Key distinction: Anti-D prophylaxis prevents Rh sensitization; it does NOT treat already-formed alloantibodies

Complications and Adverse Outcomes

— ABO incompatibility—almost always clerical error

— Fever, chills, flank/back pain, hemoglobinuria, hypotension, DIC, AKI

— STOP transfusion, IV fluids, maintain UOP >100 mL/h, treat DIC, vasopressors as needed

— Most common reaction; cytokine-mediated

— Fever ≥1°C rise without hemolysis; manage with acetaminophen, slow/stop transfusion to exclude AHTR

— Mild urticaria: pause, give diphenhydramine, may resume

— Anaphylaxis: stop, epinephrine, airway support; evaluate for IgA deficiency

— Leading cause of transfusion-related mortality

— Acute hypoxemia + bilateral infiltrates within 6h, no volume overload

— Supportive (lung-protective ventilation); donor-deferral strategies (male-predominant plasma) reduce incidence

— Hypoxemia + hypertension + JVD + BNP elevation

— Diuresis, slow future transfusions, single-unit dosing

— HIV ~1 in 1.5 million; HCV ~1 in 1.2 million; HBV ~1 in 800k–1 million

— Bacterial contamination of platelets ~1 in 2,500–5,000

— Emerging: babesia, Zika, WNV, Chagas (regional screening)

Acute hemolytic transfusion reaction (AHTR):

Febrile non-hemolytic transfusion reaction (FNHTR):

Allergic / anaphylactic:

TRALI:

TACO:

Bacterial contamination/sepsis: platelets > RBCs; fever, hypotension, rigors within 4h

Delayed hemolytic / serologic reactions: anamnestic alloantibody, +DAT, falling Hgb 2–14 days later

TA-GVHD: 1–6 weeks post, fever/rash/diarrhea/pancytopenia—nearly 100% mortality; prevented by irradiation

Post-transfusion purpura: anti-HPA-1a; treat with IVIG

Iron overload: chronic transfusion → cardiomyopathy, cirrhosis, endocrinopathy

Infectious risk (per unit in US):

Board pearl: TRALI mortality is now reduced via "male-only plasma" donor strategy because multiparous female donors more often carry anti-HLA antibodies from prior pregnancies

Step 3 management: Any reaction → stop transfusion, maintain IV access with NS, recheck identifiers, notify blood bank, send unit + post-transfusion sample for workup—this exact sequence is the testable behavior

When to Escalate — ICU, Consult, Massive Transfusion

— Hemorrhagic shock with ongoing bleeding

— ABC score ≥2 in trauma

— Predicted ≥10 units pRBC in 24h or ≥4 units in 1h

— Obstetric hemorrhage with hemodynamic instability

— Hemodynamic instability requiring vasopressors

— Respiratory failure (TRALI, severe TACO requiring positive pressure)

— Suspected severe hemolytic reaction with AKI/DIC

— Massive transfusion in progress

— Acute coronary syndrome triggered by anemia

— Suspected TTP (schistocytes + thrombocytopenia + neuro/renal/fever)—plasma exchange within hours is lifesaving

— Suspected HIT (4Ts score ≥4)—stop heparin, start non-heparin anticoagulant (argatroban, bivalirudin, fondaparinux)

— Difficult crossmatch / multiple alloantibodies

— Hyperhemolysis in sickle cell

— Post-transfusion purpura

— Persistent bleeding despite resuscitation and reversal

— GI bleed unresponsive to endoscopy → IR embolization or surgery

— Postpartum hemorrhage → uterine artery embolization, B-Lynch, hysterectomy

— Patients with multiple alloantibodies (extended phenotype matching needed)

— Jehovah's Witness with severe anemia (bloodless medicine protocol—EPO, IV iron, cell saver, tolerate lower Hgb)

— Anticipated massive transfusion (cardiac surgery, trauma, OB)

Activate massive transfusion protocol (MTP) when:

ICU admission criteria post-transfusion or during bleeding:

Hematology consultation indicated for:

Surgery/IR consultation:

Transfusion medicine / blood bank early notification:

CCS pearl: In an unstable GI bleed, your order set should include two large-bore IVs, type and crossmatch ×4–6 units, transfuse pRBC, IV PPI, NPO, GI consult for endoscopy, ICU admission, hourly vitals—missing endoscopy consult or PPI is a typical CCS deduction

Board pearl: A platelet count of 8k with no bleeding in stable ITP gets steroids + IVIG, not platelet transfusion—platelets are destroyed too rapidly to be effective except in life-threatening hemorrhage

Key Differentials — Causes of Anemia and Thrombocytopenia

— Acute blood loss: trauma, GI bleed, ruptured ectopic, postpartum hemorrhage—transfuse as indicated

— Iron deficiency: microcytic, low ferritin, high RDW; treat with iron, find source (colonoscopy in any adult >50 or unexplained)

— Anemia of chronic disease/inflammation: normo/microcytic, normal-high ferritin, low TSAT; treat underlying cause

— B12/folate deficiency: macrocytic, hypersegmented neutrophils; replete vitamin, not transfuse unless severe symptoms

— Hemolytic anemias: ↑LDH, ↑indirect bili, ↓haptoglobin, ↑reticulocytes

— Aplastic anemia / MDS: pancytopenia; supportive transfusions + definitive therapy

— ITP: treat with steroids/IVIG/TPO agonists; platelets only for life-threatening bleed

— TTP: ADAMTS13 deficiency; plasma exchange + steroids ± caplacizumab; platelets contraindicated

— HIT: stop heparin, start argatroban/bivalirudin; avoid platelet transfusion (prothrombotic)

— DIC: treat underlying cause; transfuse based on bleeding + labs (platelets, FFP, cryo)

— Drug-induced: stop offending agent (heparin, vancomycin, quinine, linezolid)

— Isolated PT ↑: factor VII deficiency, early vitamin K deficiency, warfarin

— Isolated aPTT ↑: hemophilia A/B, vWD, factor XI deficiency, lupus anticoagulant

— Both ↑: liver disease, DIC, vitamin K deficiency, supratherapeutic warfarin

Anemia by mechanism (determines whether transfusion is even appropriate):

Warm AIHA (+DAT IgG) → steroids

Cold AIHA (+DAT C3) → avoid cold, rituximab

G6PD, hereditary spherocytosis, sickle cell, thalassemia

Thrombocytopenia—platelet transfusion is NOT indicated in several:

Coagulopathy differentials:

Board pearl: Schistocytes + thrombocytopenia + AKI/neuro changes + fever → think TTP first; do not wait for ADAMTS13 result—start plasma exchange empirically

Key distinction: Microangiopathic hemolytic anemia (MAHA) appears in TTP, HUS, DIC, HELLP, malignant hypertension—treatments differ radically; getting the diagnosis right matters more than transfusing

Key Differentials — Bleeding and Transfusion Reaction Mimics

— Dilutional from aggressive crystalloid resuscitation

— Lab error / hemolyzed sample

— Pregnancy physiologic hemodilution (peak ~28–32 weeks)

— Underlying sepsis (cultures, broad antibiotics)

— Bacterial contamination of unit (especially platelets)

— Acute hemolytic reaction (recheck labels, DAT, free Hgb)

— Anaphylaxis (urticaria, wheeze)

— TRALI vs TACO (hypoxia/infiltrates)—differentiate by BP, JVD, BNP

— FNHTR (cytokines—diagnosis of exclusion)

— AHTR (hemolysis labs)

— Bacterial contamination (blood cultures)

— Unrelated infection

— TACO (hypertensive, JVD, BNP↑) → diuretics

— TRALI (normo/hypotensive, no JVD) → supportive ventilation

— Anaphylaxis (urticaria, wheeze, hypotension) → epinephrine

— Acute MI from demand ischemia in CAD

— Unrelated PE

— Acute hemolytic reaction

— Mechanical hemolysis from rapid infusion through small catheter or pressure bag with incompatible fluids

— Delayed hemolytic (days later)

— Underlying PNH, G6PD, sickle cell crisis

— Ongoing bleeding (most common—don't assume reaction)

— Delayed hemolytic transfusion reaction (2–14 days)

— Hemodilution

— Lab variability

Causes of "low Hgb" that aren't true anemia:

Mimics of transfusion reaction—patient with fever and hypotension during transfusion:

Differential of post-transfusion fever:

Differential for post-transfusion dyspnea:

Differential for post-transfusion hemoglobinuria:

Differential of falling Hgb post-transfusion:

Board pearl: A patient transfused for GI bleed whose Hgb keeps dropping despite multiple units is still bleeding—escalate to endoscopy/IR/surgery, do not just keep transfusing

Step 3 management: Hypotension + flushing only (no respiratory or cutaneous symptoms) during transfusion in patient on ACE inhibitor → bradykinin-mediated; stop transfusion, supportive care, document reaction

Secondary Prevention and Long-Term Plan

— Identify and treat the underlying cause of anemia (GI workup, gynecologic evaluation, nutritional repletion)

— Iron repletion: oral ferrous sulfate 325 mg every other day or IV iron if intolerant/malabsorption/CKD

— Vitamin B12 1000 μg IM monthly or 1000–2000 μg PO daily if deficient

— Folate 1 mg daily if deficient

— Address chronic disease drivers (CKD with ESA, IBD control)

— Restart timing balances rebleed vs thromboembolism risk

— GI bleed on warfarin/DOAC for AFib: typically resume within 7–14 days after hemostasis; earlier in high-stroke-risk patients

— Consider switching warfarin → DOAC (lower ICH risk) or PPI co-prescription

— Document shared decision-making

— Hydroxyurea, L-glutamine, voxelotor, crizanlizumab depending on phenotype

— Annual transcranial Doppler in children ages 2–16

— Chronic transfusion + chelation for stroke prevention/recurrence

— Vaccinations: pneumococcal, meningococcal, H. flu, annual influenza

— Monitor ferritin every 3 months; cardiac/hepatic MRI T2\* annually

— Initiate chelation when ferritin >1000 or after ~20 units

— Hepatitis B vaccination; monitor hepatitis serologies

— Screen 4–6 weeks before elective surgery

— IV iron ± ESA to optimize Hgb >12 in women, >13 in men before major surgery

— Reduces transfusion need and improves outcomes

Post-bleeding/post-transfusion outpatient priorities:

Anticoagulation re-initiation after bleeding:

Sickle cell disease longitudinal care:

Chronic transfusion patients (thalassemia, MDS, SCD):

Pre-operative anemia management:

Board pearl: Postoperative orthopedic patients tolerate Hgb 8 thresholds (FOCUS trial)—do not reflexively transfuse asymptomatic patients with Hgb 8.5 just because they had a hip replacement

Step 3 management: Iron deficiency anemia in an adult >50 mandates colonoscopy regardless of GI symptoms—missing this workup is a recurrent exam and real-world miss

Follow-Up, Monitoring, and Counseling

— Vital signs every 15 min × first hour, then per protocol

— Reassess symptoms during and 1h after completion

— Repeat CBC 15 min to several hours post to assess response (immediate post for active bleeding; delayed if stable)

— Each unit pRBC expected ↑Hgb 1 g/dL—failure to rise suggests ongoing loss or hemolysis

— Repeat CBC in 1–2 weeks (sooner if symptomatic or chronic loss)

— Reticulocyte response if treating with iron/B12/folate

— Ferritin and TSAT 4–6 weeks after iron repletion course

— Document any reactions in medical record and patient-held card

— Risks: infection (very low), reactions (febrile most common), TRALI/TACO, alloimmunization, iron overload in chronic transfusion

— Benefits: oxygen-carrying capacity, hemostasis support

— Alternatives: iron, ESAs, autologous donation (limited utility), cell salvage in surgery, tolerating lower Hgb if asymptomatic

— Document informed consent—Step 3 testable

— Document specifically which products and fractions are acceptable to the individual

— Some accept albumin, immune globulin, factor concentrates, cell saver with continuous circuit

— Coordinate with bloodless medicine program; use EPO, IV iron, TXA, minimize phlebotomy

— Ferritin every 3 months; cardiac and hepatic MRI T2\* yearly

— Alloantibody screen before each transfusion

— Vaccination updates, hepatitis screening

Post-transfusion monitoring:

Outpatient follow-up after transfusion episode:

Counseling patients pre-transfusion:

Jehovah's Witness counseling:

Chronic transfusion monitoring:

Board pearl: Donor blood is screened for HIV, HBV, HCV, HTLV, syphilis, WNV, Chagas, Zika (regional), babesia (regional)—residual risk is real but very low; counsel honestly without alarming

CCS pearl: After transfusing, always order a follow-up CBC—failure to verify response is a documentation gap; in active bleeding, repeat in 1–2 hours

Ethical, Legal, and Patient Safety Considerations

— Discuss risks, benefits, alternatives (iron, ESAs, watchful waiting, cell saver)

— Document patient understanding; obtain written consent when feasible

— In emergencies threatening life, implied consent applies; document urgency

— Adults with capacity may refuse blood—their decision is legally and ethically binding even if it leads to death

— Document specific products refused; confirm decision privately (away from family pressure) when possible

— Children of Jehovah's Witnesses: parents cannot refuse life-saving transfusion for a minor; seek emergency court order if elective, transfuse under emergency exception if life-threatening

— Offer blood-conservation strategies (EPO, IV iron, TXA, cell salvage, acceptance of low Hgb)

— Two-patient-identifier verification at bedside by two qualified staff

— Pre-transfusion checklist mandatory

— Bar-code scanning where available

— Report all errors to hospital quality and blood bank; mandatory reporting of transfusion-associated fatalities to FDA within 24 hours, written report within 7 days

— Document transfusion reactions in discharge summary so future providers know

— Communicate alloantibody status across systems—patient-held wallet card

— Discharge medication reconciliation must include iron/B12/folate started during admission

— If wrong unit transfused with no harm, still disclose to patient (transparency standard)

— Root cause analysis to prevent recurrence

— Use professional medical interpreters (not family) for consent discussions

Informed consent for transfusion:

Jehovah's Witnesses:

Clerical/identification errors (single biggest cause of fatal AHTR):

Transition of care risks:

Disclosure of errors:

Religious, cultural, and language barriers:

Board pearl: A Jehovah's Witness adult bleeding from a duodenal ulcer with Hgb 4 who refuses transfusion: respect the refusal, maximize non-blood therapies (IV iron, EPO, TXA, endoscopic hemostasis, surgery if needed)—forced transfusion is battery

Step 3 management: A 6-year-old child of a Jehovah's Witness needs emergent transfusion for trauma—transfuse under emergency doctrine, then notify hospital ethics/legal; parental refusal does not extend to life-threatening pediatric care

High-Yield Associations and Rapid-Fire Facts

— 1 unit pRBC → Hgb +1 g/dL (Hct +3%)

— 1 unit apheresis platelets → +30–50k

— 1 unit FFP → ~3–5% factor increase; dose 10–15 mL/kg

— 1 unit cryo per 10 kg → fibrinogen +50–75 mg/dL

— 1 unit pRBC must complete within 4h of leaving fridge

— Universal RBC donor: O-negative

— Universal RBC recipient: AB-positive

— Universal plasma donor: AB plasma

— Universal platelet donor: typically O (low-titer for non-O recipients)

— Most common reaction: FNHTR

— Most fatal: AHTR (ABO incompatibility, clerical error) and TRALI

— Most likely bacterial contamination: platelets

— Most common cause of delayed hemolytic: anti-Kidd (Jk^a)—antibodies disappear then anamnestic response

— Irradiated: stem cell transplant, intensive chemo, congenital immunodeficiency, intrauterine/neonatal, directed donation from relatives

— CMV-safe (seronegative or leukoreduced): seronegative pregnant women, seronegative transplant, low-birth-weight neonates

— Washed: IgA deficiency with anti-IgA, recurrent severe allergic, NAIT

— Sickle cell: phenotypically matched (C, E, K), HbS-negative

— TTP: plasma exchange, NOT platelets

— HIT: no platelets, no heparin, use argatroban/bivalirudin

— DIC: treat cause + platelets/FFP/cryo as needed

— vWD: DDAVP (type 1), vWF-containing concentrate (type 2/3)

— Hemophilia A: factor VIII concentrate (recombinant)

— Hemophilia B: factor IX concentrate

One-liners:

Compatibility:

Reaction recall:

Product modifications—who needs what:

Disease-specific:

Massive transfusion electrolyte derangements: hypocalcemia (citrate), hyperkalemia, metabolic alkalosis, hypothermia

Board pearl: Patient with hemoglobinuria + back pain + fever during transfusion = ABO mismatch from clerical error until proven otherwise—stop infusion immediately

Board Question Stem Patterns

"During the second unit of pRBCs, patient develops fever 39°C, back pain, dark red urine..." → Acute hemolytic transfusion reaction (ABO mismatch); STOP transfusion, IV fluids, send unit + post-sample, check DAT/free Hgb

"30 minutes into transfusion, sudden dyspnea, BP 80/50, bilateral infiltrates, BNP normal..." → TRALI; supportive lung-protective ventilation, NOT diuretics

"Elderly CHF patient 1h into second unit, dyspneic, BP 180/100, JVD, crackles, BNP elevated..." → TACO; diurese, slow future transfusions to single units

"Patient with IgA deficiency develops urticaria, wheezing, hypotension 10 min into transfusion..." → Anaphylaxis; epinephrine; future transfusions need washed RBCs or IgA-deficient donor plasma

"5 days post-transfusion, Hgb dropping, mild jaundice, +DAT, new anti-Jk^a..." → Delayed hemolytic transfusion reaction

"3 weeks post-transfusion in immunocompromised patient, fever, rash, diarrhea, pancytopenia..." → TA-GVHD; prevention is irradiation

"Thrombocytopenia, schistocytes, fever, AKI, confusion..." → TTP; plasma exchange, NOT platelets

"Hgb 8.5 in stable post-op orthopedic patient asymptomatic..." → Do NOT transfuse (threshold 8 with symptoms)

"Cirrhotic with INR 2 needs paracentesis, stable..." → Proceed without FFP

"Warfarin-treated patient with INR 8, intracranial hemorrhage..." → 4F-PCC + vitamin K 10 mg IV

"Sickle cell patient post-transfusion with worsening anemia, jaundice, pain..." → Hyperhemolysis; IVIG + steroids, avoid further transfusion if possible

"Trauma patient receiving 8 units pRBC, now hypocalcemic with prolonged QT..." → Citrate toxicity; IV calcium gluconate

"Jehovah's Witness adult refuses transfusion with Hgb 5..." → Respect refusal; IV iron, EPO, TXA, cell saver, surgery if needed

Board pearl: Step 3 stems reward the diagnostic + management combo answer—"stop transfusion AND send samples AND notify blood bank" beats any single action; pick the most comprehensive correct option

One-Line Recap

Transfusion medicine on Step 3 = matching the right product to the right indication at the right threshold, recognizing reactions immediately, and choosing modifications (irradiated, CMV-safe, washed, phenotypically matched) for the right hosts.

Thresholds: Restrictive (Hgb <7) for most; Hgb <8 in CV disease/post-op ortho; Hgb <10 in ACS; platelets <10 prophylactic, <50 procedure, <100 neurosurgery; FFP for bleeding + INR >1.5 or massive transfusion; cryo for fibrinogen <150 (OB) / <100 (other)

Reactions: AHTR (clerical, hemoglobinuria, AKI) and TRALI (hypoxia, no volume overload) are the deadliest; FNHTR is most common; bacterial contamination most likely with platelets; TACO responds to diuresis, TRALI does not; TA-GVHD prevented by irradiation; anaphylaxis in IgA deficiency needs washed products

Don't transfuse: platelets in TTP/HIT, FFP for asymptomatic mild INR elevation in cirrhotics pre-paracentesis, blood for asymptomatic chronic iron deficiency (give iron); always treat the underlying cause

Special hosts: sickle cell → phenotypically matched + HbS-negative; immunocompromised/transplant → irradiated; seronegative pregnant/transplant → CMV-safe; IgA deficient → washed; Rh-negative women → anti-D prophylaxis to prevent future HDFN

Step 3 management: Always verify two identifiers, document consent, monitor vitals q15 min, stop transfusion at first sign of reaction, send unit + sample to blood bank, report transfusion fatalities to FDA within 24 hours, and treat the underlying cause of anemia/bleeding rather than reflexively transfusing to a number