In neonates with low hemoglobin levels, which condition is indicated by a blood smear showing sickle-shaped cells?

The presence of sickle-shaped cells in a blood smear is a hallmark characteristic of sickle cell anemia, which is a genetic blood disorder caused by a mutation in the hemoglobin gene. In sickle cell anemia, red blood cells become rigid and assume a crescent or sickle shape, particularly under conditions of low oxygen. This abnormal shape leads to various complications, including vaso-occlusive crises, hemolytic anemia, and increased risk of infections.

In the context of neonates with low hemoglobin levels, identifying sickle-shaped cells in a blood smear is critical as it points towards a diagnosis of sickle cell anemia. Diagnosis typically involves further testing, but the presence of these distinctive cells is a key indicator.

Other conditions listed do not present with sickle-shaped cells. For example, thalassemia is characterized by microcytic anemia with normal shaped red blood cells and does not show the sickling phenomenon. Iron deficiency anemia generally presents with smaller and paler red blood cells due to low hemoglobin content, but not sickle forms. Leukemia can lead to various abnormal white blood cell morphologies and some anemias, but it does not result in the formation of sickle-shaped red blood cells. Thus, the observation of