Question

A 31-year-old pregnant female has a sudden onset of cramping pelvic pain with vaginal bleeding at 36 weeks' gestation. Following an emergency delivery of a male infant, her postpartum hematocrit is 18%. A STAT order for two units of RBCs arrives in the transfusion service. As the first unit is nearly finished transfusing, she becomes febrile and hypotensive. Her urine output ceases. The lab receives a posttransfusion sample; a transfusion reaction investigation begins. The plasma appears pink in the posttransfusion sample. The DAT is positive.

1. Based on the info, what type of transfusion reaction is most likely occurring? Defend your answer.

2. Propose a possible explanation for the cause of the transfusion reaction.

3. What strategy do you follow to further investigate this transfusion reaction?

Answer 1

The likely transfusion reaction is an acute hemolytic transfusion reaction (HTR), with symptoms and laboratory findings suggestive of a type II hypersensitivity reaction causing RBC destruction. Investigation into this reaction should include stopping the transfusion, supportive care, and further tests to confirm blood type compatibility.

Step-by-step explanation:

Based on the information provided, the most likely type of transfusion reaction occurring is an acute hemolytic transfusion reaction (HTR). This is indicated by symptoms like fever, hypotension, and the absence of urine output (anuria) post-transfusion, as well as the laboratory finding of a positive direct antiglobulin test (DAT) and pink plasma, suggesting hemoglobinuria. These clinical signs are consistent with a type II hypersensitivity reaction leading to destruction of red blood cells.

The possible explanation for the cause of the transfusion reaction could be an ABO incompatibility or Rh incompatibility, where the transfused red blood cells (RBCs) are recognized as foreign by the recipient's immune system and thus are being lysed. To further investigate this transfusion reaction, the strategy should entail stopping the transfusion immediately, maintaining urine output with diuretics if necessary, and providing supportive care for shock if present. Laboratory tests should include rechecking the blood type of both the donor and recipient, as well as performing crossmatch tests to identify any incompatibility.

The case discussed in the question also touches upon hemolytic disease of the newborn (HDN) in its context. HDN is a condition that arises from Rh factor incompatibility between a Rh-negative mother and a Rh-positive fetus, leading to a type II hypersensitivity hemolytic reaction.