A 27-year-old female who is 5 months pregnant has come to her ob-gyn due to a fear that something wrong with her baby. Following her previous routine visit she noted that her baby was moving frequently but in the past 2 days she has not felt any movements. Her physician performs a routine physical exam and notes that the fetal heart rate is tachycardic. The physician orders an ultrasound and during this exam notes a significant pleural and pericardial effusion. A diagnosis of potential hydrops fetalis is made with additional diagnostic tests ordered. Which of the following is most closely associated with non-immune (Rh)-mediated hydrops fetalis?

Question

Quizplus · Accepted Answer

Hemoglobin Barts is associated with non-immune hydrops fetalis, often due to alpha-thalassemia major where there is a deletion of all four alpha-globin genes, leading to severe anemia and heart failure in the fetus.  Hydrops fetalis is the result of the loss of expression of all four copies of the a-globin gene. This leads to a loss of any functional embryonic or fetal hemoglobin tetramers being synthesized. Instead, the fetus expresses only the gamma (g) globin gene which forms homotetramers that are referred to as hemoglobin Barts. This hemoglobin has very high affinity for oxygen resulting in poor oxygen release and thus, oxygen starvation in the fetal tissues. Heart failure results as the heart tries to pump more oxygenated blood to oxygen starved tissues leading to marked edema evidence as pleural and pericardial effusions by ultrasound.

A 27-Year-Old Female Who Is 5 Months Pregnant Has Come