Obstetricians and their patients are faced with an increasingly complex array of prenatal screening and diagnostic testing options. With the benefit of more options comes the challenge of providing patients with the information they need to make an informed choice about testing that is consistent with their clinical situation and personal values. In a busy clinical setting, it’s often unrealistic to review the recommended content of pretest counseling as described by professional societies. In some cases, it’s prudent to refer a patient to a genetic counselor for discussion of testing options (Table 1); the National Society of Genetic Counselors and the American College of Medical Genetics and Genomics both provide information that can be helpful in locating genetic counseling services.1,2 However, it’s neither practical nor realistic to send every prenatal patient for formal genetic counseling. Therefore, obstetricians need to have a strategy to provide basic pretest education and counseling to their pregnant patients. This article discusses the important elements of pretest counseling that should be provided to every prenatal patient, and some suggestions on how to do such counseling in a manner that is adequate and yet realistic.
Current recommendations for testing
The American College of Obstetricians and Gynecologists (ACOG) makes several recommendations regarding patient counseling about testing for aneuploidy, as well as for carrier screening. According to ACOG, “[a]neuploidy screening or diagnostic testing should be discussed and offered to all women early in pregnancy…”.3 ACOG also recommends that all women be offered carrier screening that includes, at a minimum, cystic fibrosis (CF) and spinal muscular atrophy (SMA); additional tests may also be recommended depending on the patient’s race and ethnicity.4 Genetic testing should be an informed patient choice, with an underlying foundation of shared decision making that fits the patient’s clinical circumstances, values, interests, and goals. Clearly, complying with these recommendations is challenging in the context of an initial prenatal visit that must also address other important aspects of prenatal care.
Elements of routine pretest counseling
Review of family history
While most genetic disorders occur in patients with no relevant family history or risk factors, patients who have a family history of concern often benefit from genetic counseling. ACOG recommends that all women have a family history evaluation for inherited risk.4,5 Genetic counselors typically assess family history by creating a three-generation pedigree, but there are also tools available to collect family history information (Tables 2,3).6 In a busy obstetrical practice, use of this type of family history questionnaire or checklist is usually the most practical. Asking patients to complete the questionnaire prior to the clinic visit can ensure that patients have time to contact family members as needed to collect more accurate information. Any positive responses should be followed up to obtain more detail, including the relationship of the affected family member(s) to the patient, exact diagnosis, age at onset, and severity of disease. Concern is generally greatest when there is an affected first-degree relative (parent or sibling) and less commonly when a more distant relative (aunt, uncle, grandparent, or cousin) has a genetic disorder. An exception is with X-linked disorders, in which case a genetic variant can be passed through unaffected female relatives. Concerns in first-degree relatives, or for X-linked disorders related through female relatives, should prompt consideration of referral for formal genetic counseling.1
Importantly, simply ordering expanded carrier screening is not adequate to assess risk for a familial genetic disorder. While expanded carrier screening may include testing for a gene or genes that cause a particular disorder, such panels may not include all variants in a given gene. Therefore, the detection rate of expanded carrier panels is usually lower than targeted testing. Ideally, the specific variant in the family should be identified in order to provide accurate genetic counseling and prenatal testing.
The authors report no potential conflicts of interest with regard to this article.
- National Society of Genetic Counselors home page. Available at https://www.nsgc.org/ Accessed January 8, 2019.
- American College of Medical Genetics and Genomics home page. Available at https://www.acmg.net Accessed January 8, 2019.
- American College of Obstetricians and Gynecologists Committee on Practice Bulletins—Obstetrics, Committee on Genetics, and the Society for Maternal-Fetal Medicine. Practice Bulletin No. 163: Screening for Fetal Aneuploidy. Obstet Gynecol. 2016 May;127(5):e123-37.
- American College of Obstetricians and Gynecologists Committee on Genetics. Committee Opinion No. 690: Carrier Screening in the Age of Genomic Medicine. Obstet Gynecol. 2017 Mar;129(3):e35-e40.
- Committee Opinion No. 478: Family history as a risk assessment tool. American College of Obstetricians and Gynecologists Committee on Genetics. Obstet Gynecol. 2011 Mar;117(3):747-50
- Raby BA, Kohlman W, Venne V. (2018) Genetic counseling: Family history interpretation and risk assessment. Tirnauer JS, ed. UpToDate. Waltham, MA: UpToDate Inc. https://www.uptodate.com.