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- Title
Induced Abortion and the Risk of Rh Sensitization.
- Authors
Horvath, Sarah; Huang, Zhen-Yu; Koelper, Nathanael C.; Martinez, Christian; Tsao, Patricia Y.; Zhao, Ling; Goldberg, Alisa B.; Hannum, Curtiss; Putt, Mary E.; Luning Prak, Eline T.; Schreiber, Courtney A.
- Abstract
Key Points: Question: Is administration of Rh immunoglobulin necessary for individuals undergoing induced first-trimester abortion care? Findings: In this prospective study, 505/506 participants (99.8%) undergoing induced first-trimester abortion care had postprocedure fetal red blood cell counts below the published threshold for Rh sensitization. Three participants exceeded the threshold at baseline; no additional participants crossed this threshold after induced abortion. Meaning: Rh testing or immunoglobulin administration following induced first-trimester abortion is unnecessary. Importance: While population-level data suggest Rh immunoglobulin is unnecessary before 12 weeks' gestation, clinical evidence is limited. Thus, guidelines vary, creating confusion surrounding risks and benefits of Rh testing and treatment. As abortion care in traditional clinical settings becomes harder to access, many people are choosing to self-manage and need to know if ancillary blood type testing is necessary. Objective: To determine how frequently maternal exposure to fetal red blood cells (fRBCs) exceeds the most conservative published threshold for Rh sensitization in induced first-trimester abortion. Design, Setting, and Participants: Multicenter, observational, prospective cohort study using high-throughput flow cytometry to detect circulating fRBCs in paired maternal blood samples before and after induced first-trimester abortion (medication or procedural). Individuals undergoing induced first-trimester abortion before 12 weeks 0 days' gestation were included. Paired blood samples were available from 506 participants who underwent either medical (n = 319 [63.0%]) or procedural (n = 187 [37.0%]) abortion. Exposure: Induced first-trimester abortion. Main Outcomes and Measures: The primary outcome was the proportion of participants with fRBC counts above the sensitization threshold (125 fRBCs/5 million total RBCs) after induced first-trimester abortion. Results: Among the 506 participants, the mean (SD) age was 27.4 (5.5) years, 313 (61.9%) were Black, and 123 (24.3%) were White. Three of the 506 participants had elevated fRBC counts at baseline; 1 of these patients had an elevated fRBC count following the abortion (0.2% [95% CI, 0%-0.93%]). No other participants had elevated fRBC counts above the sensitization threshold after induced first-trimester abortion. The median change from baseline was 0 fRBCs, with upper 95th and 99th percentiles of 24 and 35.6 fRBCs, respectively. Although there was a strong association between the preabortion and postabortion fRBC counts, no other baseline characteristic was significantly associated with postabortion fRBC count. Conclusions and Relevance: Induced first-trimester abortion is not a risk factor for Rh sensitization, indicating that Rh testing and treatment are unnecessary before 12 weeks' gestation. This evidence may be used to inform international guidelines for Rh immunoglobulin administration following first-trimester induced abortion. This cohort study aims to determine how frequently maternal exposure to fetal red blood cell count exceeds the most conservative published threshold for Rh sensitization in induced first-trimester abortion.
- Subjects
ABORTION; BLOOD cell count; ERYTHROCYTES; CORD blood; BLOOD groups; PREGNANCY tests; RED blood cell transfusion
- Publication
JAMA: Journal of the American Medical Association, 2023, Vol 330, Issue 12, p1167
- ISSN
0098-7484
- Publication type
Article
- DOI
10.1001/jama.2023.16953