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CMECNE

When to Administer Anti-D Immune Globulin to Prevent Rh D Alloimmunization

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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. Recall what pregnancy events warrant administration of anti-D immune globulin if an unsensitized pregnant women is Rh D-negative and the fetus is Rh D-positive
2. Explain why additional anti-D immune globulin may be required if an unsensitized pregnant women who is Rh D-negative is exposed to >30 mL of Rh D-positive fetal whole blood

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 April 8 2018 through April 8 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.

Designated for 0.1 contact hours of pharmacotherapy credit for Advance Practice Registered Nurses.

Read Disclaimer & Fine Print

CLINICAL ACTIONS:

Rh D alloimmunization can be prevented with the administration of anti-D immune globulin.  ACOG recommends administration of anti-D immune globulin to unsensitized Rh D-negative women as follows

Level A Recommendation (good and consistent science)

  • 28 weeks (reduces risk from 2% to 0.2%)
  • Within 72 hours of birth, if infant is Rh D positive and patient is not sensitized

Level B Recommendation (limited or inconsistent science)

  • All invasive diagnostic procedures such as CVS and amniocentesis if fetus may be Rh D positive

Level C Recommendation (consensus/expert opinion)

ACOG language in (” “)

  • External cephalic version, regardless of success (“indicated”)
  • Evacuation of suspected molar pregnancy (“reasonable to administer”)
  • First trimester miscarriage
    • Spontaneous (1.5-2% risk – “should be considered”)
    • Instrumentation (4-5% risk – “should be given”)
  • Termination of pregnancy, either medical or surgical (“should be given”)
  • Ectopic pregnancy (“recommended”)
  • Antenatal hemorrhage >20 weeks gestation (“recommended”)
  • Abdominal trauma (“should be administered”)
  • Fetal death in the 2nd or 3rd trimester (“should be administered”)

SYNOPSIS:

All pregnant women are currently tested at the time of the first prenatal visit for ABO blood group and Rh D type and screening for red cell antibodies. The potential volume of fetal–maternal hemorrhage that can cause Rh D alloimmunization is extremely variable and ranges from 0.1 mL to 30 mL.  Data is limited when it comes to many of the potential sensitizing events and therefore some of the recommendations are based on consensus and expert opinion.

KEY POINTS:

  • Multiple consensus guidelines worldwide recommend
    • Patients should undergo repeat Rh D antibody screening before receiving anti-D immune globulin at 28 weeks and postpartum
  • Providers should be alert to any other events in pregnancy that may increase risk for fetal-maternal hemorrhage
  • ACOG advises that for weak D (previously known as Du)

Clinicians are advised to administer Rh D immune globulin to patients with weak D blood type in appropriate clinical situations, by the same rationale as that for Rh D typing blood donors, until further scientific and economic studies are available.

  • Anti-D immune globulin is purified and tested for viral infections, and therefore risk of viral infection is exceedingly low
    • Manufactured without mercury-containing thimerosal since 2001
  • Failures may still occur due to
    • Not administering in 3rd trimester
    • Insufficient dosage or not administering within 72 hours after a known sensitizing pregnancy event or following birth
    • Unrecognized fetal–maternal hemorrhage
  • Note: There is discussion in the CDC recommendations that receipt of antibody-containing blood products such as intravenous immune globulin may interfere with rubella (and MMR) vaccine and seroconversion. However, the CDC states

Previous administration of human anti-Rho(D) immune globulin (RhoGam) does not generally interfere with an immune response to rubella vaccine and is not a contraindication to postpartum vaccination. However, women who have received anti-Rho immune globulin should be serologically tested 6–8 weeks after vaccination to ensure that seroconversion has occurred.

Assessing Fetal-Maternal Hemorrhage Volume

  • Screening
    • Rosette fetal red blood cell assay to detect greater than 2 mL of fetal whole blood in maternal circulation
  • Quantification tests are appropriate if rosette test is positive
    • Kleihauer-Betke (inexpensive, but lacks standardization and precision)
      • Volume of fetal bleed: % fetal cells x maternal blood volume
      • Maternal blood volume: 70 mL/kg x weight (kg) (assume 5,000 mL if maternal information is unknown)
    • Flow cytometry (more accurate, but limited by cost and availability)

Dosing (ACOG)

  • Screen all Rh D-negative women with Rh D-positive infants for fetal-maternal hemorrhage volume
  • Standard 300-microgram dose of anti-D immune globulin covers 30 mL of Rh D-positive fetal whole blood (or 15 mL of fetal red blood cells)
  • Exposures to <30 mL of Rh D-positive fetal whole blood
    • 28 weeks: 300 micrograms
    • After birth (within 72 hours): 300 micrograms
  • Exposures to >30 mL of Rh D-positive fetal whole blood
    • Assess volume of fetal-maternal hemorrhage to guide dosing
    • Can use up to eight full vials at one time
    • IM: Separate sites every 12 hours until the desired dosage has been reached
    • IV: Rh immune globulin is also available

LEARN MORE – PRIMARY SOURCES:

ACOG Practice Bulletin 181: Prevention of Rh D Alloimmunization

ACOG Practice Bulletin 192: Management of Alloimmunization During Pregnancy

CDC: Epidemiology and Prevention of Vaccine-Preventable Diseases – Rubella

Locate a Maternal Fetal Medicine Specialist

Maternal Fetal Medicine Specialist Locator-SMFM

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Related ObG Topics:

Practical obstetrics info for your women's healthcare practice
Alloimmunization and Red Cell Antibodies – Time to be Concerned?

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Computer System Requirements

OBG Project CME requires a modern web browser (Internet Explorer 10+, Mozilla Firefox, Apple Safari, Google Chrome, Microsoft Edge). Certain educational activities may require additional software to view multimedia, presentation, or printable versions of their content. These activities will be marked as such and will provide links to the required software. That software may be: Adobe Flash, Apple QuickTime, Adobe Acrobat, Microsoft PowerPoint, Windows Media Player, or Real Networks Real One Player.

Disclosure of Unlabeled Use

This educational activity may contain discussion of published and/or investigational uses of agents that are not indicated by the FDA. The planners of this activity do not recommend the use of any agent outside of the labeled indications.

The opinions expressed in the educational activity are those of the faculty and do not necessarily represent the views of the planners. Please refer to the official prescribing information for each product for discussion of approved indications, contraindications, and warnings.

Disclaimer

Participants have an implied responsibility to use the newly acquired information to enhance patient outcomes and their own professional development. The information
presented in this activity is not meant to serve as a guideline for patient management. Any procedures, medications, or other courses of diagnosis or treatment discussed or suggested in this activity should not be used by clinicians without evaluation of their patient’s conditions and possible contraindications and/or dangers in use, review of any applicable manufacturer’s product information, and comparison with recommendations of other authorities.

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