A 24-year-old primigravid woman at 26 weeks gestation is evaluated during a routine prenatal visit. She has no fatigue, dyspnea, or palpitations. Her pregnancy has been uncomplicated. She takes a daily prenatal multivitamin. Blood pressure is 112/70 mm Hg and pulse is 78/min. Physical examination shows a gravid uterus consistent with gestational age and no peripheral edema.
Laboratory results are as follows:
| Test | Result |
|---|---|
| Hemoglobin | 10.9 g/dL |
| Hematocrit | 32% |
| Mean corpuscular volume | 88 fL |
| White blood cell count | 8,500/mm³ |
| Platelet count | 240,000/mm³ |
| Serum ferritin | 55 ng/mL |
Which of the following is the most appropriate next step in the management of this patient's hematologic findings?
- Reassurance and routine prenatal careAnswer
- BInitiation of high-dose oral ferrous sulfate
- CMeasurement of serum methylmalonic acid
- DPeripheral blood smear evaluation
- EHemoglobin electrophoresis
Answer
Reassurance and routine prenatal care
The correct answer is reassurance and routine prenatal care because this patient's hematologic findings represent the normal physiologic changes of pregnancy. During pregnancy, plasma volume expands by approximately 40-50%, while red blood cell mass increases by only 20-30%. This disproportionate increase leads to a hemodilution effect, lowering the hemoglobin and hematocrit concentrations. In the first and third trimesters, the lower limit of normal for hemoglobin is 11.0 g/dL, while in the second trimester, it drops to 10.5 g/dL. Since this patient is at 26 weeks gestation (second trimester) with a hemoglobin of 10.9 g/dL, normal mean corpuscular volume (MCV), and normal ferritin, she does not have true iron deficiency anemia and requires no further intervention.
Step-by-Step Solution
Key Concept
Physiologic dilutional anemia of pregnancy occurs due to a greater expansion of plasma volume compared to red blood cell mass, resulting in an expected hemoglobin drop (minimum > 10.5 g/dL in the second trimester) without true iron deficiency.