A 27-year-old woman, gravida 1 para 0, at 9 weeks gestation comes to the clinic for an initial prenatal visit. The patient has mild nausea but is otherwise feeling well. She recently completed law school and is studying for the bar examination. The patient has no known medical conditions and has had no surgeries. Her mother and sister have anemia. The patient eats fish but otherwise usually follows a vegetarian diet. Prior to this pregnancy, menses occurred monthly with 5-6 days of bleeding that was heaviest the first 2 days. She does not use tobacco, alcohol, or illicit drugs. Temperature is 36.7 C (98 F), blood pressure is 110/80 mm Hg, pulse is 76/min, and respirations are 16/min. Examination shows no abnormalities. Laboratory results are as follows: Transvaginal ultrasound shows a 9-week intrauterine gestation with normal cardiac activity. Which of the following is the best next step in management of this patient?

Question

A 27-year-old woman, gravida 1 para 0, at 9 weeks gestation comes to the clinic for an initial prenatal visit.  The patient has mild nausea but is otherwise feeling well.  She recently completed law school and is studying for the bar examination.  The patient has no known medical conditions and has had no surgeries.  Her mother and sister have anemia.  The patient eats fish but otherwise usually follows a vegetarian diet.  Prior to this pregnancy, menses occurred monthly with 5-6 days of bleeding that was heaviest the first 2 days.  She does not use tobacco, alcohol, or illicit drugs.  Temperature is 36.7 C (98 F), blood pressure is 110/80 mm Hg, pulse is 76/min, and respirations are 16/min.  Examination shows no abnormalities.  Laboratory results are as follows:  Transvaginal ultrasound shows a 9-week intrauterine gestation with normal cardiac activity.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

This patient's microcytic anemia (mean corpuscular volume [MCV] <80 µm³) in the setting of normal iron studies is likely due to a hemoglobinopathy, which causes anemia either through abnormal globin production (eg, alpha- or beta-thalassemia) or hemoglobin structure (eg, Hgb S, C, or E). These traits are inherited in an autosomal recessive manner; therefore, preconception and prenatal screening are performed to identify those patients at risk of an affected offspring. Patients with anemia require additional testing to determine its etiology and potential impact on the patient and fetus (Choice D). Hemoglobin electrophoresis helps distinguish between alpha or beta-thalassemia, sickle cell, and hemoglobin C or E carriers. If the patient is identified as a hemoglobinopathy carrier, the father should be screened. If both parents are carriers, genetic counseling, hematology, and reproductive counseling are performed to discuss the risks of an affected fetus (eg, hydrops fetalis due to alpha-thalassemia major). Preimplantation and prenatal fetal diagnosis are available (eg, chorionic villi sampling, amniocentesis), although new, noninvasive techniques (eg, free fetal cell DNA) are being developed. (Choice A) Pregnant patients require increased folate for red blood cell expansion and prevention of fetal neural tube defects, with inadequate intake or absorption causing anemia. However, folate deficiency causes macrocytosis (MCV >100 µm³). (Choice C) Lead toxicity causes anemia by inhibiting heme biosynthesis, with an elevated risk in pregnancy as the fetus is more vulnerable to lead's adverse effects. Microcytic anemia is commonly seen; however, iron and total iron binding capacity levels are typically low. In addition, lead poisoning is more common in children and those with occupational risk factors (eg, exposure to lead paint, battery manufacturing). (Choice E) Hypothyroidism typically causes anemia by decreased red blood cell mass with a normocytic MCV (80-100 µm³) or in association with pernicious anemia (ie, macrocytic). In addition, TSH screening is not recommended for asymptomatic pregnant patients. (Choice F) Vitamin B₁₂ deficiency may be seen in patients with poor gastrointestinal absorption (eg, gastritis) or inadequate dietary intake of B₁₂-rich animal products (eg, vegan diet). However, anemia due to vitamin B₁₂ deficiency causes macrocytic, not microcytic, anemia. Educational objective: Preconception counseling and testing identifies couples at risk for autosomal recessive hemoglobinopathies that might affect their offspring. Patients with microcytic anemia and normal iron studies require further testing with hemoglobin electrophoresis. Based on these results, patients may be offered genetic counseling, hematology consultation, and fetal diagnostic testing. References: Prenatal and preimplantation diagnosis of hemoglobinopathies. (http://www.ncbi.nlm.nih.gov/pubmed/29741247) Molecular diagnosis of thalassemias and hemoglobinopathies: an ACLPS critical review. (http://www.ncbi.nlm.nih.gov/pubmed/28605432)

A 27-Year-Old Woman, Gravida 1 Para 0, at 9 Weeks