The Genome

CMECNE

Microcephaly – Beyond the Zika Virus

Learning Objectives and CME/Disclosure Information

This activity is intended for healthcare providers delivering care to women and their families.

After completing this activity, the participant should be better able to:

1. Define microcephaly in the fetus and the newborn
2. Discuss the conditions that are associated with microcephaly

Estimated time to complete activity: 0.25 hours

Faculty:

Susan J. Gross, MD, FRCSC, FACOG, FACMG
President and CEO, The ObG Project

Disclosure of Conflicts of Interest

Postgraduate Institute for Medicine (PIM) requires instructors, planners, managers and other individuals who are in a position to control the content of this activity to disclose any real or apparent conflict of interest (COI) they may have as related to the content of this activity. All identified COI are thoroughly vetted and resolved according to PIM policy. PIM is committed to providing its learners with high quality CME activities and related materials that promote improvements or quality in healthcare and not a specific proprietary business interest of a commercial interest.

Faculty: Susan J. Gross, MD, receives consulting fees from Cradle Genomics, and has financial interest in The ObG Project, Inc.

Planners and Managers: The PIM planners and managers, Trace Hutchison, PharmD, Samantha Mattiucci, PharmD, CHCP, Judi Smelker-Mitchek, MBA, MSN, RN, and Jan Schultz, MSN, RN, CHCP have nothing to disclose.

Method of Participation and Request for Credit

Fees for participating and receiving CME credit for this activity are as posted on The ObG Project website. During the period from Dec 31 2017 through Dec 31 2021, participants must read the learning objectives and faculty disclosures and study the educational activity.

If you wish to receive acknowledgment for completing this activity, please complete the post-test and evaluation. Upon registering and successfully completing the post-test with a score of 100% and the activity evaluation, your certificate will be made available immediately.

For Pharmacists: Upon successfully completing the post-test with a score of 100% and the activity evaluation form, transcript information will be sent to the NABP CPE Monitor Service within 4 weeks.

Joint Accreditation Statement

In support of improving patient care, this activity has been planned and implemented by the Postgraduate Institute for Medicine and The ObG Project. Postgraduate Institute for Medicine is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.

Physician Continuing Medical Education

Postgraduate Institute for Medicine designates this enduring material for a maximum of 0.25 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Continuing Nursing Education

The maximum number of hours awarded for this Continuing Nursing Education activity is 0.2 contact hours.

Read Disclaimer & Fine Print

WHAT IS IT?

Microcephaly means “small head”, and can be used interchangeably in some instances with microencephaly, “small brain”
- Consider abnormal development (primary microcephaly) if detected prior to 32 weeks gestation, as opposed to a degenerative condition in which normal head size becomes smaller (secondary microcephaly)

SYNOPSIS:

Microcephaly has an incidence of 2-12 in 10,000 births in the USA, and can be diagnosed prenatally via ultrasound (in second or early third trimester) or postnatally via measurement of head circumference (HC). Microcephaly has been linked to developmental delay, seizures, as well as feeding, vision and hearing problems. Prognosis depends on the severity of the microcephaly and whether it is associated with other anomalies.

KEY POINTS:

Definitions

SMFM – Fetal Microcephaly

HC ≥ 3 SD below the mean for gestational age is the recommended definition
HC ≥ 5 SD below the mean is a certain diagnosis

CDC – Postnatal Congenital Microcephaly

Definite Congenital Microcephaly
- HC at birth < 3rd percentile for gestational age and sex
- If HC not available at birth, HC < 3rd percentile for age and sex within the first 2 weeks of life
- For Stillbirths and elective terminations, CDC definition based on HC at delivery < 3rd percentile for gestational age and sex
Possible Congenital Microcephaly
- For Live Births: If earlier HC is not available, HC < 3rd percentile for age and sex beyond 6 weeks of life
- For All Pregnancy Outcomes: Microcephaly diagnosed or suspected on prenatal ultrasound in the absence of available postnatal HC measurements

Management

If fetal HC by ultrasound is > 2 SD below the mean for gestational age, a careful evaluation of the fetal intracranial anatomy is indicated
- If the intracranial anatomy is normal, consider follow-up in 3-4 weeks
When evaluating the finding of fetal microcephaly, assess for the following
- Infectious exposures including
  - Zika virus
  - Maternal syphilis, herpes, HIV, rubella, toxoplasmosis, cytomegalovirus
- Alcohol consumption, exposure to certain medications and/or smoking during pregnancy
- Genetic conditions, including aneuploidy or single gene disorders
Many ultrasound packages report HC percentiles and not standard deviations (SD) and often the lowest reported HC measurement is <5th percentile
- In such cases, SMFM suggests using head circumference (in millimeters) to determine SD below the mean
- SMFM provides a table (see ‘Learn More – Primary Sources’ below) to determine the number of SD below the mean as a function of gestational age
Role of MRI: The SOGC Guideline states (III-A evidence)

Once fetal microcephaly is identified by ultrasound, fetal magnetic resonance imaging, when available and if potential findings are likely to alter pregnancy management, may be considered.

Fetal magnetic resonance imaging images should be reviewed by a radiologist with expertise in fetal magnetic resonance imaging.

Consider referral to a Fetal Maternal Medicine Specialist
Consider referral to Genetic Counseling, especially if microcephaly is associated with other findings
Consider referral to Pediatric Neurologist for review of short and long term potential outcomes for the newborn and child with microcephaly

Image credit: Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities

Learn More – Primary Sources:

Microcephaly: An Epidemiologic Analysis

SMFM Statement- Ultrasound Screening for Fetal Microcephaly Following Zika virus Exposure

SOGC Guideline 380: Investigation and Management of Prenatally Identified Microcephaly

CDC: Zika Virus For Healthcare Providers

CDC: Areas with Risk of Zika in the US

Serial Head and Brain Imaging of 17 Fetuses With Confirmed Zika Virus Infection in Colombia, South America

US Zika Pregnancy Registry Collaboration: Birth Defects Among Fetuses and Infants of US Women With Evidence of Possible Zika Virus Infection During Pregnancy

ACOG Committee Opinion 784: Management of Patients in the Context of Zika Virus

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:

Maternal-Fetal Medicine Specialist Locator-SMFM

Take a post-test and get CME credits

TAKE THE POST TEST

2nd Trimester Ultrasound Reference Library, Now Available on Your Phone with ObGFirst

Learn More  »

< Previous

All The Genome Posts

Next >

Microcephaly – Beyond the Zika Virus