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Ob-Gyns Recommend Chromosomal Microarray Analysis for Genetic Evaluation of Fetal Anomalies

November 21, 2013

Washington, DC -- Chromosomal microarray analysis (CMA) is now recommended as the first-line genetic test in pregnancies showing fetal abnormalities on an ultrasound screen, according to the American College of Obstetricians and Gynecologists (The College) and the Society for Maternal-Fetal Medicine (SMFM). CMA is also the preferred genetic test to help identify the cause of death in stillbirths.

CMA is a DNA-based method of prenatal genetic testing. Like the conventional prenatal genetic test known as karyotype, CMA can identify major chromosomal defects such as Down syndrome. But CMA can also find many other genetic defects that are too small to be detected by karyotyping. Both CMA and karyotyping require testing of fetal tissue obtained with chorionic villus sampling or amniocentesis. 

“We’re recommending CMA as the first-line test when an ultrasound reveals one or more major fetal abnormalities,” said Nancy C. Rose, MD, chair of The College’s Committee on Genetics. “The primary advantage of CMA over the conventional karyotype is that it provides more genetic information.”

MutationIn a Committee Opinion issued jointly today by The College and SMFM, another benefit of CMA is that it is considered more objective than karyotyping because it uses computerized analyses. Karyotyping uses microscope analysis which is prone to human error. CMA test results are usually available sooner than karyotype results.

Historically, CMA has been used as the first-tier test in genetic evaluation of infants and children with unexplained intellectual disability, birth defects, or autism disorders. The test detects genetic problems in as many as 15% of children that have a seemingly normal karyotype, according to the opinion released by The College and SMFM.

Pre- and post-test counseling is essential for patients who undergo CMA. The test may identify genetic conditions that are unexpected. Before undergoing prenatal genetic screening, patients should be informed that:

  • CMA does not identify all genetic diseases.
  • Identified diseases may vary in range from mild to severe, and it may not be possible to predict their outcomes.
  • The test may reveal non-paternity or that a fetus is a result of closely related parents.
  • Genetic changes may be identified that may or may not cause disease. 

CMA also is preferred over karyotyping for stillbirth cases because it can identify more clinically significant genetic abnormalities, said Dr. Rose. However, at this time the data do not support using CMA for women with recurrent miscarriage.

Committee Opinion #581 “The Use of Chromosomal Microarray Analysis in Prenatal Diagnosis” is published in the December issue of Obstetrics & Gynecology.

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Other recommendations issued in this month’s Obstetrics & Gynecology:

Committee Opinion #580 “Von Willebrand Disease in Women” (Revised)

ABSTRACT: Von Willebrand disease, the most common inherited bleeding disorder among American women, is a common cause of heavy menstrual bleeding and other bleeding problems in women and adolescent girls. Von Willebrand disease and other inherited and acquired disorders of coagulation and hemostasis should be considered in the differential diagnosis of all patients being evaluated for heavy menstrual bleeding, regardless of age. There are many treatment options available for patients with von Willebrand disease and heavy menstrual bleeding, including hormonal and nonhormonal therapies. A multidisciplinary approach to management, which involves obstetrician gynecologists and hematologists, results in optimal treatment outcomes. Many resources exist for patients and health care providers through the National Heart, Lung, and Blood Institute; National Hemophilia Foundation; and the American Society of Hematology.

Committee Opinion #582 “Addressing Health Risks of Noncoital Sexual Activity” (Revised)

ABSTRACT: Noncoital sexual behavior is a common expression of human sexuality, which commonly cooccurs with coital behavior. Sexually transmitted infections, including human immunodeficiency virus (HIV), herpes simplex virus, human papillomavirus, hepatitis virus (types A, B, and C), syphilis, gonorrhea, and chlamydial infection, can be transmitted through noncoital sexual activity. When engaging in oral and anal sex, most individuals, including adolescents, are unlikely to use barrier protection for a variety of reasons, including a greater perceived safety of noncoital sexual activity compared with vaginal sex. Clinicians should assess patient sexually transmitted infection risk and provide risk reduction counseling accordingly. Clinicians should encourage and counsel patients regarding the correct and consistent use of condoms, barrier protection during oral sex, and cleaning of sex toys. Patients who engage in noncoital sexual activity also commonly have vaginal sex and may require contraceptive counseling.

Practice Bulletin #140 “Management of Abnormal Cervical Cancer Screening Test Results and Cervical Cancer Precursors”

ABSTRACT: Knowledge of the natural history, epidemiology, and basic science of human papillomavirus (HPV) and precancerous lesions of the cervix is rapidly evolving. Guidelines have been revised several times over the past decade to incorporate new evidence and technologies (1, 2). The American Society for Colposcopy and Cervical Pathology (ASCCP) clinical management guidelines were revised again in 2012 (3), and this Practice Bulletin is adapted with permission from the ASCCP publication 2012 Updated Consensus Guidelines for the Management of Abnormal Cervical Cancer Screening Tests and Cancer Precursors. Important changes to these guidelines include the following:

  • Defining when to return to routine screening after treatment or resolution of abnormalities given the longer screening intervals recommended by the updated American Cancer Society screening guidelines (4)
  • Improving incorporation of HPV testing
  • Applying guidelines previously developed for adolescents to individuals aged 21–24 years
  • Integrating new data on risk of high-grade precursor lesions and cancer

The ASCCP–College of American Pathologists Lower Anogenital Squamous Terminology Standardization (LAST) Project recommended standardizing histopathologic terminology for HPV-associated squamous intraepithelial lesions and superficially invasive squamous carcinoma across all lower anogenital tract sites (5). The purpose of this document is to present the most recent revisions to guidelines for managing abnormal cervical cancer screening test results and cervical cancer precursors, describe the LAST Project terminology, and provide guidance on applying the new management guidelines with this terminology.

The American College of Obstetricians and Gynecologists (The College), a 501(c)(3) organization, is the nation’s leading group of physicians providing health care for women. As a private, voluntary, nonprofit membership organization of approximately 57,000 members, The College strongly advocates for quality health care for women, maintains the highest standards of clinical practice and continuing education of its members, promotes patient education, and increases awareness among its members and the public of the changing issues facing women’s health care. The American Congress of Obstetricians and Gynecologists (ACOG), a 501(c)(6) organization, is its companion organization. www.acog.org

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The Society for Maternal-Fetal Medicine (est. 1977) is a non-profit membership group for obstetricians/gynecologists who have additional formal education and training in maternal-fetal medicine. The society is devoted to reducing high-risk pregnancy complications by providing continuing education to its 2,000 members on the latest pregnancy assessment and treatment methods. It also serves as an advocate for improving public policy, and expanding research funding and opportunities for maternal-fetal medicine. The group hosts an annual scientific meeting in which new ideas and research in the area of maternal-fetal medicine are unveiled and discussed. For more information, visit www.smfm.org or www.facebook.com/SocietyforMaternalFetalMedicine.