Which change is NOT typically seen in erythroblastosis fetalis?

In erythroblastosis fetalis, the primary issue is the destruction of fetal red blood cells (RBCs) due to maternal antibodies attacking the fetal cells, typically seen in Rh incompatibility situations. As a result, one of the hallmark findings is an increased number of erythroblasts, which are immature red blood cells, in the fetal circulation as the body attempts to compensate for the anemia caused by the hemolysis.

When analyzing the answer choice indicating decreased fetal red blood cells, it is essential to recognize that while the overall number of mature, circulating red blood cells may be decreased due to destruction, the body responds by increasing erythropoiesis leading to an elevation of erythroblasts in the circulation. Therefore, decreased fetal red blood cells does not accurately depict the characteristic compensatory response observed in erythroblastosis fetalis.

In contrast, the other options reflect the typical changes occurring in this condition. A large placenta can occur due to increased blood flow and compensatory hyperplasia of the villous tissue caused by fetal anemia. Increased villous stromal edema is also noted due to the pathological changes in the placental structure as it tries to accommodate the increased blood volume and metabolic demands of the fetus. Lastly, the presence