PURLS / PEER REVIEWED

A New Protocol for RhD-negative Pregnant Women?

Clinician Reviews. 2018 June;28(6):e5-e7

References

1. de Haas M, Thurik FF, van der Ploeg CP, et al. Sensitivity of fetal RHD screening for safe guidance of targeted anti-D immunoglobulin prophylaxis: prospective cohort study of a nationwide programme in the Netherlands. BMJ. 2016;355:i5789.
2. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 75: Management of alloimmunization during pregnancy. Obstet Gynecol. 2006; 108:457-464. 
3. Urbaniak SJ, Greiss MA. RhD haemolytic disease of the fetus and the newborn. Blood Rev. 2000;14(1):44-61.
4. Mayne S, Parker JH, Harden TA, et al. Rate of RhD sensitisation before and after implementation of a community based antenatal prophylaxis programme. BMJ. 1997;315(7122):1588.
5. MacKenzie IZ, Bowell P, Gregory H, et al. Routine antenatal Rhesus D immunoglobulin prophylaxis: the results of a prospective 10 year study. Br J Obstet Gynecol. 1999;106:492-497.
6. Zolotor AJ, Carlough MC. Update on prenatal care. Am Fam Physician. 2014;89(3):199-208.
7. Mackie FL, Hemming K, Allen S, et al. The accuracy of cell-free fetal DNA-based non-invasive prenatal testing in singleton pregnancies: a systematic review and bivariate meta-analysis. BJOG. 2017;124(1):32-46.
8. American College of Obstetricians and Gynecologists Committee on Practice Bulletins-Obstetrics. Practice Bulletin No. 181: Prevention of Rh D Alloimmunization. Obstet Gynecol. 2017;130:e57-e70.
9. National Institute for Health and Care Excellence. High-throughput non-invasive prenatal testing for fetal RHD genotype 1: Recommendations. www.nice.org.uk/guidance/dg25/chapter/1-Recommendations. Accessed May 7, 2018. 
10. Hawk AF, Chang EY, Shields SM, Simpson KN. Costs and clinical outcomes of noninvasive fetal RhD typing for targeted prophylaxis. Obstet Gynecol. 2013;122(3):579-585.

WHAT’S NEW

Accurate test, potential to reduce unnecessary Tx

Fetal RhD testing at 27 weeks’ gestation appears to be highly accurate and could reduce the unnecessary use of anti-D immunoglobulin when the fetal RhD is negative.

CAVEATS

Different results by ethnicity?

Dutch participants are not necessarily reflective of the US population. Known variation in the rate of fetal RhD positivity among RhD-negative pregnant women by race and ethnicity could mean that the number of women able to forego anti-D immunoglobulin prophylaxis would be different in the United States than in other countries.

Also, in this study, polymerase chain reaction for two RhD sequences was run in triplicate, and a computer-based algorithm was used to automatically score samples to provide results. For safe implementation, the cell-free fetal RhD DNA testing process would need to follow similar methods.

CHALLENGES TO IMPLEMENTATION

Cost and availability are big unknowns

Cost and availability of the test may be barriers, but there is currently too little information on either subject in the United States to make a determination. A 2013 study indicated that the use of cell-free DNA testing to determine fetal RhD status was then approximately $682.¹⁰

ACKNOWLEDGEMENT

The PURLs Surveillance System was supported in part by Grant Number UL1RR024999 from the National Center for Research Resources, a Clinical Translational Science Award to the University of Chicago. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Center for Research Resources or the National Institutes of Health.

Reprinted with permission from the Family Physicians Inquiries Network and The Journal of Family Practice (2018;67[5]: 306, 308, 319).