Screening for Hemoglobinopathies in Pregnancy – The ACOG Approach
Hemoglobinopathies describe multiple disorders that affect the structure and function of hemoglobin. They are single gene disorders that have variable expressivity ranging from mild to severe. Identification of carriers allows patients to make informed reproductive planning decisions.
Test all patients for CBC and RBC indices as part of antepartum care
Add Hgb electrophoresis if
Increased risk based on ethnicity: African, Middle Eastern, Southeast Asian, West Indian and Mediterranean ancestry
MCV is low (<80 fL)
Indicates risk for one of the thalassemia traits
Serum ferritin levels recommended to check for possible iron deficiency anemia
If Hgb electrophoresis is normal, follow up is still required to rule out alpha-thalassemia
Abnormal Hgb electrophoresis identifies a carrier
Offer testing to partners of carriers to assess whether the fetus is at risk
Refer to genetic counseling if both members of a couple are carriers
Hemoglobinopathies, such as sickle cell disease, can affect the structure of hemoglobin, while mutations causing thalassemias result in reduced production of hemoglobin chains. These conditions are autosomal recessive so carriers will not necessarily be identified without screening. If a patient’s partner is also a hemoglobinopathy carrier, there is a significant risk of the offspring being affected and referral is advised. Hemoglobinopathy screening should be offered to high risk groups, which include those of African, Middle Eastern, Southeast Asian, West Indian and Mediterranean ancestry. Low risk individuals are those from Northern European, Japanese, Native American, Inuit and Korean background.
Hgb electrophoresis is the appropriate test to identify abnormal hemoglobins
Abnormal Hgb electrophoresis will identify abnormal hemoglobin, such as Hb AS, AC, SS, SC, A2
Beta-thalassemia is associated with elevated HbF and elevated HbA2
Hgb electrophoresis can be normal in alpha-thalassemia; therefore, further genetic testing will be required if patients of Southeast Asian descent have decreased MCV but normal Hgb electrophoresis
If both partners are carriers, prenatal diagnosis is available through either CVS or amniocentesis
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