Which term describes the dilution of blood due to increased plasma volume during pregnancy?

Which term describes the dilution of blood due to increased plasma volume during pregnancy?

• A. Polycythemia
• B. Hemoconcentration
• C. Hemodilution
• D. Dehydration

Answer: (C)

During pregnancy, plasma volume expands substantially, while red blood cell mass increases only modestly. This disproportionate rise in plasma volume dilutes the blood, causing lower hemoglobin and hematocrit levels even though the total red cell mass has not decreased. This dilution effect is called hemodilution. It explains the common finding of physiologic anemia of pregnancy. Polycythemia would mean an elevated red cell concentration and higher hematocrit. Hemoconcentration refers to a concentrated blood state from fluid loss or dehydration, which raises hematocrit rather than lowers it. Dehydration similarly lowers plasma volume and increases, not dilutes, hematocrit.

During pregnancy, plasma volume expands substantially, while red blood cell mass increases only modestly. This disproportionate rise in plasma volume dilutes the blood, causing lower hemoglobin and hematocrit levels even though the total red cell mass has not decreased. This dilution effect is called hemodilution. It explains the common finding of physiologic anemia of pregnancy.

Polycythemia would mean an elevated red cell concentration and higher hematocrit. Hemoconcentration refers to a concentrated blood state from fluid loss or dehydration, which raises hematocrit rather than lowers it. Dehydration similarly lowers plasma volume and increases, not dilutes, hematocrit.