Screening for Hemoglobinopathies in Pregnancy – The ACOG Approach

CLINICAL ACTIONS:

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

SYNOPSIS:

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.

KEY POINTS:

• 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

Learn More – Primary Sources:

ACOG Committee Opinion 691: Carrier Screening for Genetic Conditions

ACOG Committee Opinion 690: Carrier Screening in the Age of Genomic Medicine

Locate a genetic counselor or genetics services:

Genetic Services Locator-ACMG

Genetic Services Locator-NSGC

Genetic Services Locator-CAGC

Locate a Maternal Fetal Medicine Specialist: SMFM