Approach To Anemia In Pregnancy Definitions

Anemia: Hemoglobin level less than 10.5 g/dL in the pregnant woman. Iron deficiency anemia: Fall in hemoglobin level due to insufficient iron to meet the increased iron requirements during pregnancy.

Hemolytic anemia: Abnormally low hemoglobin level, due to red blood cell destruction, which may be divided into congenital causes and acquired causes.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency: X-linked condition whereby the red blood cell may have a decreased capacity for anaerobic glucose metabolism. Certain oxidizing agents, such as nitrofurantoin, can lead to hemolysis.

Clinical Approach

Anemia is a common complication in the pregnant woman. It most often is due to iron deficiency, partially because of decreased iron stores prior to pregnancy, and increased demands for iron (due to fetus' need and expanded maternal blood volume). A hemoglobin level below 10.5 g/dL usually is considered a sign of anemia in the pregnant woman, with mild anemia between 8 to 10 g/dL and severe less than 7g/dL. A gravid woman who presents with mild anemia and no risk factors for hemoglobinopathies (African-American, Southeast Asian, or Mediterranean descent) can be treated with supplemental iron and the hemoglobin level reassessed in 3 to 4 weeks. Persistent anemia necessitates an evaluation for iron stores, such as ferritin level (low with iron deficiency) and hemoglobin electrophoresis.

The size of the red blood cell may give a clue about the etiology. Microcytic anemia is most commonly due to iron deficiency, although thalassemia also may be causative. Macrocytic anemias may be due to vitamin B12 and folate deficiency. Because vitamin B,, stores last for many years, megaloblastic anemias in pregnancy are much more likely to be caused by folate deficiency.

Less commonly, a woman with G6PD deficiency may develop hemolytic anemia triggered by various medications such as sulfonamides, nitrofurantoin, and antimalarial agents. Nitrofurantoin is one of the most common medications used for uncomplicated urinary tract infections. Affected women usually have dark-colored urine due to the bilirubinuria and jaundice, and fatigue due to the anemia. G6PD deficiency is more commonly seen in the African-American population.

In the pregnant woman with anemia, jaundice, and thrombocytopenia, the examiner must also consider other hemolytic processes, such as HELLP syndrome, which is a life-threatening condition best treated by delivery. In evaluating anemia, if other hematologic cell lines, such as the white blood cell count or platelet count, also are decreased, a bone marrow process, such as leukemia or tuberculosis infection of the marrow, should be considered. Bone marrow biopsy may be indicated in these circumstances.

Comprehension Questions

[31.1] A 30-year-old woman G1 PO complains of nausea and vomiting for the first 3 months of her pregnancy. She is noted to have a hemoglobin level of 9.0 g/dL. and the mean corpuscular volume was increased above normal. Which of the following is the most likely etiology of the anemia?

A. Iron deficiency

B. Folate deficiency

C. Vitamin B,, deficiency

D. Physiologic anemia of pregnancy

[31.2] Which of the following is found with hemolysis?

A. Decreased serum haptoglobin level

B. Decreased serum bilirubin level

C. Decreased reticulocyte count

D. Decreased serum lactate dehydrogenase level

[31.3] A 33-year-old African-American woman G1 PO at 16 weeks'gestation is diagnosed with sickle cell trait. Her husband also is a carrier for the sickle cell gene. Which of the following best describes the likelihood that their unborn baby will have sickle cell disease?

[31.4] A 36-year-old G2 PI at 24 weeks' gestation has fatigue of 4 weeks' duration. Her hemoglobin level is 8.0 g/dL, leukocyte count 2.0 cells/mm3, and platelet count 20.000/nim\ Which of the following is the most likely diagnosis?

A. Iron deficiency anemia

B. HELLP syndrome

C. Severe preeclampsia

D. Acute leukemia

Answers

[31.1] B. Of the macrocytic causes of anemia, folate deficiency is more commonly seen than vitamin Bp deficiency.

[31.2] A. Haptoglobin levels are decreased with hemolysis due to hemoglobin binding to this protein.

[31.3] D. With autosomal recessive disorders, when both parents are heterozygous for the gene (gene carriers), then there is a 1:4 chance that the offspring will be affected by the disease or will be homozygous for the gene.

[31,4J D. Pancytopenia suggests a bone marrow process.

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