Clinical Opinion
Is Rh immune globulin needed in early first-trimester abortion? A review

https://doi.org/10.1067/mob.2003.208Get rights and content

Abstract

The prophylactic use of Rh immune globulin has been a medical success, protecting women who could be at risk from exposure to the Rh(D) antigen. Thus, it is not surprising that Rh(D) immunoprophylaxis has been extended from women with term pregnancies to all women with miscarriages, abortions, and ectopic pregnancies. In this article we review the existing medical literature to assess the risks of fetomaternal hemorrhage and Rh isoimmunization after complications of a first-trimester pregnancy, induced abortion, or ectopic pregnancy. The evidence to support the use of Rh immune globulin in the first trimester is sparse, but there is theoretic evidence of its necessity. Despite weak evidence to support its use, there is little risk. (Am J Obstet Gynecol 2003;188:623-7.)

Section snippets

Evidence supporting Rh immune globulin in early-trimester abortions

Fetal-maternal transfusion has been demonstrated as early as 5 to 6 weeks of gestation. The mean volume of fetal-maternal transfusion at 8 weeks has been calculated to be 0.33 mL.2 No recent studies have looked at whether those fetal red blood cells (RBC) express the Rh(D) antigen; however, Bergstrom et al12 demonstrated that fetal RBCs can express the Rh(D) antigen as early as 38 days from conception, or 52 days from last menstrual period. The amount of fetal blood needed to cause

Evidence against Rh immune globulin in early-trimester abortions

A weakness of the evidence supporting the use of Rh immune globulin in the first trimester is its reliance on studies that evaluated fetomaternal hemorrhage (positive KB test) and not the actual development of Rh(D) antibodies. Thus, the true incidence of the development of Rh(D) antibodies in an abnormal first-trimester pregnancy or after elective termination is difficult to determine and remains unknown. A second severe limitation is that many of these studies have no control population or

Critique of the data

The data available to make an evidence-based recommendation regarding the utility of Rh immune globulin in the first trimester are extremely limited. Most studies were performed in the early 1970s and were not controlled. In aggregate, these data demonstrate that the number of cases of Rh-negative women who become isoimmunized after pregnancy complications or terminations in the first trimester is very low. The incidence of isoimmunization after a first-trimester abortion ranged from 0% to 3%.

Clinical recommendations

Although the evidence to support the use of Rh immune globulin in the first trimester is sparse, there is theoretic evidence of its necessity. Although calculations of the amount of blood necessary to result in immunosensitization are problematic, they do suggest that fetal-maternal hemorrhage in the first trimester is of sufficient volume to potentially cause immunosensitization. Moreover, there have been cases of immunosensitization reported with first-trimester abortions, although the actual

Cited by (33)

  • “Provoked” feto-maternal hemorrhage may represent insensible cell exchange in pregnancies from 6 to 22 weeks gestational age

    2019, Contraception
    Citation Excerpt :

    Moreover, the characterization of early antigenic expression and thus the immunologic significance of fetal red blood cells has also been limited [11–13]. Regardless, it is common for some small volume of fetal cells to enter the maternal circulation during normal pregnancy [14–16]. Given the uncertainty surrounding risk for sensitization across gestational ages and risk events, the American College of Obstetricians and Gynecologists (ACOG) recommends consideration of treatment for all Rh-negative women with vaginal bleeding, first-trimester miscarriage, amniocentesis, CVS, and ectopic pregnancy at any point in gestation [17].

  • Complications in Early Pregnancy

    2019, Emergency Medicine Clinics of North America
View all citing articles on Scopus

Reprint requests: Kurt T. Barnhart, MD, MSCE, Department of Obstetrics and Gynecology, University of Pennsylvania Medical Center, 3400 Spruce St, Dulles 106, Philadelphia, PA 19104. E-mail: [email protected]

View full text