A patient was transfused 4 units of blood 2 hours ago, and now she complains of chest discomfort. X-ray shows bilateral fissural thickening. Which of the following is the most probable cause?

Explanation

## Correct Answer: A. Fluid overload The clinical presentation of chest discomfort with bilateral fissural thickening on chest X-ray occurring 2 hours post-transfusion is pathognomonic for **transfusion-related circulatory overload (TRCO)**, a form of fluid overload. The key discriminator is the timing (early, within hours) and the radiological finding of bilateral fissural thickening, which represents pulmonary edema from acute volume expansion. In Indian blood banking practice, TRCO is one of the most common transfusion complications, particularly in patients with pre-existing cardiac or renal compromise. The mechanism involves rapid infusion of 4 units of blood (approximately 1000–1200 mL) overwhelming the patient's circulatory capacity, leading to increased hydrostatic pressure in pulmonary capillaries and interstitial edema. Bilateral fissural thickening (Kerley B lines) is the classic radiological sign of pulmonary edema from cardiogenic causes or volume overload. Management includes diuretics, oxygen therapy, and fluid restriction—standard protocols in Indian tertiary care settings. The absence of fever, hemoglobinuria, or jaundice rules out immune-mediated transfusion reactions. ## Why the other options are wrong **B. Hypocalcemia** — Hypocalcemia from citrate toxicity occurs during massive transfusion (>10 units in <24 hours) and presents with paresthesias, tetany, or cardiac arrhythmias—not chest discomfort with pulmonary edema. Bilateral fissural thickening is not a feature of hypocalcemia. This is a distractor for students who recall citrate as a transfusion complication but miss the timing and radiological clue. **C. Graft-versus-host disease** — Transfusion-associated GVHD (TA-GVHD) typically occurs 3–30 days post-transfusion, not within 2 hours. It presents with fever, rash, diarrhea, and hepatosplenomegaly—not acute chest discomfort. Bilateral fissural thickening is not characteristic. TA-GVHD requires transfusion of viable T lymphocytes, usually in immunocompromised recipients, making it rare in routine transfusions. **D. ABO incompatibility reactions** — ABO incompatibility causes acute hemolytic transfusion reaction with fever, chills, hemoglobinuria, jaundice, and flank pain within minutes to 1 hour. Chest discomfort may occur, but bilateral fissural thickening indicates pulmonary edema, not hemolysis. The absence of hemoglobinuria and the specific radiological finding of fissural thickening point away from immune hemolysis. ## High-Yield Facts - **Bilateral fissural thickening (Kerley B lines)** = classic radiological sign of pulmonary edema from volume overload or cardiogenic causes. - **TRCO (transfusion-related circulatory overload)** occurs within 1–6 hours of transfusion; presents with dyspnea, chest discomfort, and pulmonary edema. - **4 units of blood** = ~1000–1200 mL; rapid infusion can overwhelm cardiac output, especially in elderly or cardiac-compromised patients. - **Citrate toxicity** requires massive transfusion (>10 units in <24 hours); not seen with 4 units. - **TA-GVHD** onset is 3–30 days post-transfusion; ABO incompatibility presents within minutes with hemoglobinuria and jaundice. ## Mnemonics **TRCO vs. AHTR (Acute Hemolytic Transfusion Reaction)** **TRCO**: Timing 1–6 hrs, Bilateral fissural thickening, NO hemoglobinuria. **AHTR**: Timing minutes–1 hr, Fever + chills + hemoglobinuria + jaundice. Use this to distinguish volume overload from immune hemolysis. **Pulmonary Edema Signs on CXR** **Kerley B lines** (fissural thickening) = hydrostatic edema (cardiogenic or volume overload). **Bat's wing** (perihilar opacities) = severe pulmonary edema. Both point to TRCO in acute transfusion setting. ## NBE Trap NBE pairs transfusion complications with immune-mediated reactions (AHTR, GVHD) to distract from the simpler diagnosis of volume overload. The specific radiological clue (bilateral fissural thickening) is the discriminator that forces recognition of pulmonary edema, not hemolysis or delayed immune phenomena. ## Clinical Pearl In Indian blood banks, TRCO is the most common serious transfusion complication after febrile non-hemolytic reactions. Elderly patients and those with pre-existing left ventricular dysfunction are at highest risk. Slow transfusion (1 unit over 2–3 hours) with concurrent diuretic cover is standard practice in high-risk patients in Indian tertiary centers. _Reference: Robbins Ch. 4 (Hemodynamic Disorders); Harrison Ch. 135 (Transfusion Medicine); KD Tripathi Ch. 18 (Blood and Blood Products)_