An unexplained fall in hemoglobin and mild jaundice in a patient transfused with Red Blood Cells one week ago most likely indicates what condition?

The situation described—an unexplained fall in hemoglobin and mild jaundice occurring one week after a red blood cell transfusion—strongly suggests a delayed hemolytic transfusion reaction. This type of reaction typically arises when the recipient has developed antibodies against the transfused red blood cells due to a previous sensitization, which may have occurred through a prior transfusion or pregnancy.

In a delayed hemolytic reaction, the patient’s body slowly begins to destroy the transfused red blood cells, leading to a drop in hemoglobin levels and the release of bilirubin from the breakdown of hemoglobin, which causes jaundice. This process often does not become evident until days or even weeks after the transfusion, aligning perfectly with the timeline observed in this scenario.

Other options do not fit the clinical context as well. For instance, paroxysmal nocturnal hemoglobinuria is a rare acquired hemolytic anemia caused by a defect in the blood cell membrane, which would not typically present immediately after a transfusion and involves specific symptoms and laboratory findings beyond just mild jaundice. Similarly, posttransfusion hepatitis is related to viral infections and would present with more systemic signs of liver dysfunction rather than isolated drops in hemoglobin and mild jaundice. The