Induced Abortion and the Risk of Rh Sensitization

Rh sensitization in abortion care: where we've been and where we're going

PURPOSE OF REVIEW

The purpose of this review is to summarize the historical context and recent literature that contribute to the debate about preventive strategies for Rhesus (Rh)-alloimmunization in abortion are.

RECENT FINDINGS

Recent studies repeatedly demonstrate that the risk of Rh-alloimmunization in first trimester abortion care is very low.

SUMMARY

Recent high-quality studies have demonstrated the physiologic presence of fetal red blood cells in maternal circulation even prior to abortion. Thus, establishing the low utility of Rh immunoglobulin prior to abortion before 12 weeks of gestation. There is yet to exist a consensus guideline that balances the desire to prevent a rare devastating outcome and the need to create practical guidelines based on evidence-based risk assessments.

Economic analysis of foregoing Rh immunoglobulin for bleeding in pregnancy <12 weeks gestation

OBJECTIVES

To perform cost analyses of foregoing RhD blood type testing and administration of Rh immunoglobulin (RhIg) for bleeding in pregnancy at <12 weeks gestation in the United States.

STUDY DESIGN

We created a decision-analytic model comparing the current standard treatment pathway for patients who have threatened, spontaneous, or induced abortion in the United States, with a new pathway foregoing RhD testing and administration of RhIg for those who are RhD-negative at <12 weeks gestation, assuming that the risk of sensitization is 0%. We derived population and cost estimates from the current literature and calculated the number needed to treat (NNT) and number needed to screen to avoid one case of fatal hemolytic disease of the fetus and newborn. We performed sensitivity analyses assuming Rh-sensitization risks of 1.5% and 3% and varying the subsequent pregnancy rates from 44% to 100%.

RESULTS

The annual savings to health care payers in the United States of foregoing RhD testing and RhIg administration with bleeding events at <12 weeks are $5.5 million/100,000 total pregnancies, assuming the sensitization risk is 0%. In sensitivity analyses with a sensitization risk of 1.5% and subsequent pregnancy rate of 84.3% foregoing Rh testing and RhIg administration would save $2.8 million/100,000 pregnancies, with a NNT of 7322 and a number needed to screen of 48,816. At a 3% sensitization rate, the current standard treatment pathway is most economical.

CONCLUSIONS

There is an opportunity to save as much as $5.5 million/100,000 pregnancies by withholding RhIg in specific situations and conserving it for use later in pregnancy.

IMPLICATIONS

Cost analyses support foregoing RhD blood type screening and RhIg administration at <12 weeks gestation if the sensitization rate is <3%. By deimplementing this low-value care, payers in the United States can save as much as $5.5 million/100,000 pregnancies and conserve RhIg for use later in pregnancy.

Management of Red Cell Alloimmunization in Pregnancy

Rhesus immune globulin has resulted in a marked decrease in the prevalence of RhD alloimmunization in pregnancy; however, antibody formation to other red cell antigens continues to occur. Evaluation for the presence of anti-red cell antibodies should be routinely undertaken at the first prenatal visit. If anti-red cell antibodies are detected, consideration of a consultation or referral to a maternal-fetal medicine specialist with experience in the monitoring and treatment of these patients is warranted. Cell-free DNA can be used to determine fetal red cell antigen status to determine whether the pregnancy is at risk of complications from the red cell antibodies. First-time sensitized pregnancies are followed up with serial maternal titers, and, when indicated, serial Doppler assessment of the peak systolic velocity in the middle cerebral artery should be initiated by 16 weeks of gestation. When there is a history of an affected fetus or neonate, maternal titers are less predictive of fetal risk; if the fetus is antigen positive, serial peak systolic velocity in the middle cerebral artery measurements should be initiated by 15 weeks of gestation because intraperitoneal intrauterine blood transfusions can be used at this gestation if needed. The mainstay of fetal therapy involves intrauterine transfusion through ultrasound-directed puncture of the umbilical cord with the direct intravascular injection of red cells. A perinatal survival rate exceeding 95% can be expected at experienced centers. Neonatal phototherapy and "top-up" transfusions attributable to suppressed reticulocytosis often are still required for therapy after delivery.

Abortion

Induced abortion is safe, is common, and reduces pregnancy-related maternal morbidity and mortality. Internal medicine physicians are uniquely positioned to counsel patients on their pregnancy options, assess medical risks of pregnancy in the context of comorbidities, refer for abortion care when the patient desires it, or provide abortion care themselves. Clinicians can also provide anticipatory guidance about what patients should expect if they seek abortion care.

Rh D Immune Globulin Administration After Abortion or Pregnancy Loss at Less Than 12 Weeks of Gestation

This Clinical Practice Update provides revised guidance on Rh testing and Rh D immune globulin administration for individuals undergoing abortion or experiencing pregnancy loss at less than 12 0/7 weeks of gestation. This document updates Practice Bulletin No. 225, Medication Abortion Up to 70 Days of Gestation (Obstet Gynecol 2020;136:e31-47); Practice Bulletin No. 200, Early Pregnancy Loss (Obstet Gynecol 2018;132:e197-207); and Practice Bulletin No. 181, Prevention of Rh D Alloimmunization (Obstet Gynecol 2017;130:e57-70).

A tale of two societies: implications of conflicting Rh-immunoglobulin guidelines

National guidance conflicts regarding the use of RhD immune globulin administration <12w. Recent Society for Maternal Fetal Medicine (SMFM) guidelines suggest liberal use of this product while other guidelines, including Society of Family Planning and the World Health Organization, propose a more conservative approach. Medicine is not practiced in a vacuum, and potential harms must include not only individual but communal and public health effects. We aim to critically examine the practical implications of the new SMFM guidelines with a focus on equity and access.

Estimating the cost of Rh testing and prophylaxis in early pregnancy: A time-driven activity-based costing study

OBJECTIVE

To estimate the cost of Rhesus (Rh) testing and prophylaxis for first-trimester vaginal bleeding in the ambulatory setting.

STUDY DESIGN

We used time-driven, activity-based costing to analyze tasks associated with Rh testing and prophylaxis of first-trimester vaginal bleeding at one hospital-based outpatient and two independent reproductive health clinics. At each site, we observed 10 patients undergoing Rh-typing and two patients undergoing Rh prophylaxis. We computed the costs of blood Rh-typing by both fingerstick and phlebotomy, cost of locating previous blood type in the electronic health record (available for 69.8% of hospital-based patients), and costs associated with Rh immune globulin prophylaxis. All costs are reported in 2021 US dollars.

RESULTS

The hospital-based clinic reviewed the electronic health record to confirm Rh-status (cost, $26.18 per patient) and performed a phlebotomy, at $47.11 per patient, if none was recorded. The independent clinics typed blood by fingerstick, at a per-patient cost of $4.07. Rh-immune globulin administration costs, including the medication, were similar across facilities, at a mean of $145.66 per patient. Projected yearly costs for testing and prophylaxis were $55,831 for the hospital-based clinic, which was the lowest-volume site, $47,941 for Clinic A, which saw 150 patients/month, and $185,654 for Clinic B, which saw 600 patients/month.

CONCLUSIONS

Rh testing and prophylaxis for first-trimester vaginal bleeding generates considerable costs for outpatient facilities, even for Rh-positive patients with a prior blood type on record.

IMPLICATIONS

Rh testing and prophylaxis for first-trimester bleeding generate considerable costs even for Rh-positive patients and those with a previously known blood type. These findings highlight the need to reconsider this practice, which is no longer supported by evidence and already safely waived in multiple medical settings in the United States and around the world.

Self-performed Rh typing: a cross-sectional study

OBJECTIVE

To evaluate whether patients are capable and willing to self-administer and interpret an EldonCard test to determine their Rh status.

METHODS

This was a cross-sectional study in Honolulu, HI, USA of pregnancy-capable people aged 14-50 years who did not know their blood type and had never used an EldonCard. Participants independently completed EldonCard testing, determined their Rh type and answered a survey on feasibility and acceptability. Separately, a blinded clinician recorded their interpretation of the participant's EldonCard. When available, we obtained blood type from the electronic health record (EHR). We measured Rh type agreement between participant, clinician and EHR, as well as participant comfort and acceptability of testing.

RESULTS

Of the 330 total participants, 288 (87.3%) completed testing. Patients and clinicians had 94.0% agreement in their interpretation of the EldonCard for Rh status. Patient interpretation had 83.5% agreement with EHR while clinician and EHR had 92.3% agreement. Sensitivity of EldonCard interpretation by patient and clinician was 100%. Specificity was 83.2% for patients and 92.2% for clinicians. Two patients (of 117) had Rh-negative blood type in the EHR. The vast majority of participants found the EldonCard testing easy (94.4%) and felt comfortable doing the testing (93.7%). Participants with lower education levels felt less confident (p=0.003) and less comfortable with testing (p=0.038); however, their ability to interpret results was similar to others (p=0.051).

CONCLUSIONS

Patient-performed Rh typing via the EldonCard is an effective and acceptable option for patients, and could be used as a primary screening test for Rh status.

[Prevention of Rh D alloimmunization in the first trimester of the pregnancy: French College of Obstetricians and Gynecologists guidelines for clinical practice]

OBJECTIVE

To provide recommendations for the prevention of Rh D alloimmunization in the first trimester of pregnancy.

MATERIALS AND METHODS

The quality of evidence of the literature was assessed following the GRADE methodology with questions formulated in the PICO format (Patients, Intervention, Comparison, Outcome) and outcomes defined a priori and classified according to their importance. An extensive bibliographic search was performed on Pubmed, Cochrane, EMBASE, and Google Scholar databases. The quality of evidence was assessed (high, moderate, low, very low) and a recommendation was formulated: (i) strong, (ii) weak, or (iii) no recommendation. The recommendations were reviewed in two rounds with reviewers from the scientific board of the French College of the OB/GYN (Delphi survey) to select the consensus recommendations.

RESULTS

The three recommendations from PICO questions reached agreement using the Delphi method. It is recommended not to administer Rh D immunoglobulin before 12 weeks of gestation to reduce the risk of alloimmunization in case of abortion or miscarriage, in RhD negative patients when the genitor is RhD positive or unknown (Weak recommendation. Very low-quality evidence). It is recommended not to administer Rh D immunoglobulin before 12 weeks of gestation to reduce the risk of alloimmunization in cases of bleeding in an ongoing intrauterine pregnancy (Weak recommendation. Very low-quality evidence). The literature data are insufficient in quality and quantity to determine if the injection of Rh D immunoglobulin reduces the risk of alloimmunization in the case of an ectopic pregnancy (No recommendation. Very low-quality evidence).

CONCLUSION

Even though the quality of evidence from the studies is very low, it is recommended not to administer Rh D immunoglobulin in case of abortion, miscarriage or bleeding before 12 weeks of amenorrhea. The quality of evidence was too low to issue a recommendation regarding ectopic pregnancy.

Society for Maternal-Fetal Medicine Statement: RhD immune globulin after spontaneous or induced abortion at less than 12 weeks of gestation

Guidelines for the management of first-trimester spontaneous and induced abortion vary in terms of rhesus factor D (RhD) testing and RhD immune globulin (RhIg) administration. These existing guidelines are based on limited data that do not convincingly demonstrate the safety of withholding RhIg for first-trimester abortions or pregnancy losses. Given the adverse fetal and neonatal outcomes associated with RhD alloimmunization, prevention of maternal sensitization is essential in RhD-negative patients who may experience subsequent pregnancies. In care settings in which RhD testing and RhIg administration are logistically and financially feasible and do not hinder access to abortion care, we recommend offering both RhD testing and RhIg administration for spontaneous and induced abortion at <12 weeks of gestation in unsensitized, RhD-negative individuals. Guidelines for RhD testing and RhIg administration in the first trimester must balance the prevention of alloimmunization with the individual- and population-level harms of restricted access to abortion.

Guideline No. 448: Prevention of Rh D Alloimmunization

OBJECTIVE

This guideline provides recommendations for the prevention of Rh D alloimmunization (isoimmunization) in pregnancy, including parental testing, routine postpartum and antepartum prophylaxis, and other clinical indications for prophylaxis. Prevention of red cell alloimmunization in pregnancy with atypical antigens (other than the D antigen), for which immunoprophylaxis is not currently available, is not addressed in this guideline.

TARGET POPULATION

All Rh D-negative pregnant individuals at risk for Rh D alloimmunization due to potential exposure to a paternally derived fetal Rh D antigen.

OUTCOMES

Routine postpartum and antepartum Rh D immunoprophylaxis reduces the risk of Rh D alloimmunization at 6 months postpartum and in a subsequent pregnancy.

BENEFITS, HARMS, AND COSTS

This guideline details the population of pregnant individuals who may benefit from Rho(D) immune globulin (RhIG) immunoprophylaxis. Thus, those for whom the intervention is not required may avoid adverse effects, while those who are at risk of alloimmunization may mitigate this risk for themselves and/or their fetus.

EVIDENCE

For recommendations regarding use of RhIG, Medline and Medline in Process via Ovid and Embase Classic + Embase via Ovid were searched using both the trials and observational studies search strategies with study design filters. For trials, the Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Database of Abstracts of Reviews of Effects via Ovid were also searched. All databases were searched from January 2000 to November 26, 2019. Studies published before 2000 were captured from the grey literature of national obstetrics and gynaecology specialty societies, luminary specialty journals, and bibliographic searching. A formal process for the systematic review was undertaken for this update, as described in the systematic review manuscript published separately.

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the SOGC's modified GRADE approach. See Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional [weak] recommendations).

INTENDED AUDIENCE

The intended users of this guideline include prenatal care providers such as obstetricians, midwives, family physicians, emergency room physicians, and residents, as well as registered nurses and nurse practitioners.

TWEETABLE ABSTRACT

An updated Canadian guideline for prevention of Rh D alloimmunization addresses D variants, cffDNA for fetal Rh type, and updates recommendations on timing of RhIG administration.

SUMMARY STATEMENTS

RECOMMENDATIONS.