PA21.1-6 | Blood Groups & Transfusion Medicine — Case Study

CLINICAL SCENARIO

A clinical case-study assignment in which you evaluate a patient who develops an adverse reaction mid-transfusion, work through the investigation algorithm used in transfusion medicine, explain the immunohaematological basis of the reaction, and propose evidence-based prevention strategies. The case integrates PA21.1–PA21.6 (ABO/Rh blood group systems, blood component preparation, compatibility testing, transfusion reactions, haemovigilance).

Section 1 — Reaction Identification and Immediate Management

Identify the type of acute transfusion reaction Mr Rajan is experiencing. List the four immediate steps you must take at the bedside the moment you suspect an acute haemolytic transfusion reaction (AHTR). Justify why each step is time-critical.

Guidance: Name the reaction type precisely (acute haemolytic transfusion reaction — ABO-incompatible). The four STOP steps are: (1) STOP the transfusion immediately; (2) maintain IV access with normal saline; (3) check identity of patient vs. unit (clerical recheck); (4) notify blood bank and return the incriminating unit. Explain the physiological rationale for each — e.g., stopping prevents further antigen load; saline supports BP and protects renal tubules; return of the unit allows the blood bank to confirm the error and perform repeat grouping. Aim for ~200 words.

Section 2 — Investigation Algorithm

Outline the step-by-step investigation algorithm for a suspected AHTR. For each investigation, state: (a) what you are testing, (b) expected finding in this case, and (c) why it confirms or excludes a haemolytic event.

Guidance: Investigations should cover at minimum: (1) repeat ABO/Rh grouping on a new patient sample and on the bag label; (2) direct antiglobulin test (DAT/Coombs) on the post-transfusion patient sample; (3) plasma haemoglobin / pink-tinged plasma visual check (free Hb); (4) urine haemoglobin (haemoglobinuria, as seen in this case); (5) LDH, indirect bilirubin, haptoglobin (haemolysis markers); (6) full blood count (dropping Hb, rising WBC), coagulation screen for DIC. Tabulate if you wish. Link each finding to the underlying mechanism (intravascular vs. extravascular haemolysis). Aim for ~250 words.

Section 3 — Immunohaematological Basis

Explain the immunohaematological mechanism by which ABO-incompatible blood causes acute intravascular haemolysis. Your explanation must cover: (a) the ABO antibody type present in Mr Rajan's plasma, (b) the complement pathway activated, and (c) why the reaction is clinically more severe than Rh-incompatible reactions.

Guidance: Key points: Group A patients have naturally occurring anti-B IgM antibodies (isohaemagglutnins). IgM efficiently activates the classical complement pathway from C1q through to the membrane attack complex (C5b-9), resulting in direct intravascular lysis — haemoglobin/haem spill into plasma. Contrast with Rh sensitisation (IgG, extravascular haemolysis in the spleen, usually subacute). Discuss haemoglobinuria → renal tubular injury → acute kidney injury — particularly dangerous in Mr Rajan's pre-existing CKD. Mention cytokine storm (IL-1, IL-6, TNF-α) as the mechanism for hypotension and rigors. Aim for ~250 words.

Section 4 — Differential Diagnosis

Two other acute transfusion reactions can present with hypotension and respiratory distress: Transfusion-Related Acute Lung Injury (TRALI) and Transfusion-Associated Circulatory Overload (TACO). Construct a comparison table distinguishing AHTR, TRALI, and TACO across: onset, mechanism, key clinical signs, key investigation finding, and specific management step that differs from generic supportive care.

Guidance: TRALI: within 6 h, donor anti-HLA/anti-neutrophil antibodies activate pulmonary endothelium → non-cardiogenic pulmonary oedema; hypoxia dominant, no haemolysis markers, CXR bilateral infiltrates, no elevated BNP; management = stop + supportive O2, NO diuretics. TACO: circulatory overload, elevated BNP, bilateral effusions, responds to diuretics. AHTR: haemolysis markers, DAT positive, haemoglobinuria distinguishes it. Students should present a clearly formatted 3-column table. Aim for ~200 words.

Section 5 — Prevention and Haemovigilance

Identify the single error that led to this reaction and describe the two-stage safe-transfusion bedside check protocol that should have prevented it. Then, outline Mr Rajan's ongoing monitoring plan for the next 24 hours and the component of choice if he still requires red-cell support after the reaction has resolved.

Guidance: The error: failure to perform patient-to-unit identity verification at the bedside. The protocol: (1) independent positive patient identification (name + DOB + hospital ID against wristband); (2) unit label verification (blood group, unique unit number, expiry, cross-match report). Both steps must be independently confirmed before spiking. Monitoring: hourly urine output (target >1 mL/kg/hr), serial Hb/LDH/bilirubin/haptoglobin at 4 h and 12 h, renal function (urea, creatinine), coagulation screen for DIC. Component choice after resolution: a freshly cross-matched, group A Positive PRBC unit with a full electronic cross-match confirmed by the blood bank. Mention leuco-depleted components if CMV risk is relevant. Aim for ~200 words.

Section 6 — Reflective Summary

In 150–200 words, reflect on what this case illustrates about the relationship between a systems-level process failure (the missed bedside check) and a patient-level biological catastrophe (ABO-incompatible AHTR). What would you personally ensure before your next transfusion prescription?

Guidance: Encourage integration of patient safety culture with immunohaematology. Look for students who connect the 'never event' framing (ABO-incompatible transfusion is a WHO Never Event) with the specific biology they described in Sections 1–3. Strong answers will also mention that Mr Rajan's CKD amplified his risk of acute kidney injury and that the intern's time pressure is a system latent error, not just individual negligence. Penalise vague generic statements ('I will be more careful') — credit specific protocol-linked commitments.

PEER REVIEW

You will review one classmate's submission using the rubric above. For each criterion:
1. Award a score from the five rating levels provided.
2. Write 2–3 sentences of specific, evidence-based feedback — quote or paraphrase what your peer wrote and explain why it meets or falls short of the criterion.
3. Avoid generic praise ('good job') — all feedback must be actionable.
4. Complete the overall comment box (minimum 50 words) with the most important strength and one concrete suggestion for improvement.

Your peer-review grade will be assessed on the quality of feedback (specificity, accuracy, constructiveness), not on whether your scores match the instructor's.