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

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.

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.

Comparison of the Detection Rate and Specificity of Irregular Red Blood Cell Antibodies Between First-Time Pregnant Women and Women With a History of Multiple Pregnancies Among 18,010 Chinese Women

Background: There is insufficient evidence to assess the risk of the production of clinically important alloimmune irregular red blood cell (RBC) antibodies in first-time pregnant women. Methods: Using the microcolumn gel antiglobulin method, 18,010 Chinese women with a history of pregnancy and pregnant women were screened for irregular RBC antibodies, and for those with positive test results, antibody specificity was determined. The detection rate and specificity of irregular RBC antibodies in women with a history of multiple pregnancies (two or more) and first-time pregnant women were determined. Results: In addition to 25 patients who passively acquired anti-D antibodies via an intravenous anti-D immunoglobulin injection, irregular RBC antibodies were detected in 121 (0.67%) of the 18,010 women. Irregular RBC antibodies were detected in 93 (0.71%) of the 13,027 women with a history of multiple pregnancies, and antibody specificity was distributed mainly in the Rh, MNSs, Lewis, and Kidd blood group systems; irregular RBC antibodies were detected in 28 (0.56%) of the 4983 first-time pregnant women, and the antibody specificity was distributed mainly in the MNSs, Rh, and Lewis blood group systems. The difference in the percentage of patients with irregular RBC antibodies between the two groups was insignificant (χ 2 = 1.248, P > 0.05). Of the 121 women with irregular RBC antibodies, nine had anti-Mur antibodies, and one had anti-Dia antibodies; these antibodies are clinically important but easily missed because the antigenic profile of the reagent RBCs that are commonly used in antibody screens does not include the antigens that are recognized by these antibodies. Conclusion: Irregular RBC antibody detection is clinically important for both pregnant women with a history of multiple pregnancies and first-time pregnant women. Mur and Dia should be included in the antigenic profile of reagent RBCs that are used for performing antibody screens in the Chinese population.

First-trimester Procedural Abortion

First-trimester abortion is a common and safe procedure. A focused history and physical examination are essential for providing this care. Laboratory assessment can include Rh typing, hemoglobin, and cervicitis testing as indicated by a patient's risk factors. Procedural abortion in the first trimester includes cervical dilation with or without cervical preparation, and uterine evacuation utilizing a manual vacuum aspirator or electric vacuum aspirator. Complications occur rarely and are often easily managed at the time of diagnosis.

Society of Family Planning committee consensus on Rh testing in early pregnancy

Historical evidence that fetal red blood cell (RBC) exposure during early spontaneous or induced abortion can cause maternal Rh sensitization is limited. A close reading of these studies indicates that forgoing Rh immunoglobulin administration before 12-weeks gestation is highly unlikely to increase risk of Rh (D) antibody development, and recent studies indicate that fetal RBC exposure during aspiration abortion <12 weeks gestation is below the calculated threshold to cause maternal Rh sensitization, and the amount of fetomaternal hemorrhage during dilation and evacuation procedures up to 18-weeks gestation is adequately treated with 100-mcg of Rh immunoglobulin. We provide updated recommendations for Rh immunoglobulin administration based on this new evidence.

Risk factors for RhD immunisation in a high coverage prevention programme of antenatal and postnatal RhIg: a nationwide cohort study

OBJECTIVE

To evaluate which risk factors for RhD immunisation remain, despite adequate routine antenatal and postnatal RhIg prophylaxis (1000 IU RhIg) and additional administration of RhIg. The second objective was assessment of the current prevalence of RhD immunisations.

DESIGN

Prospective cohort study.

SETTING

The Netherlands.

POPULATION

Two-year nationwide cohort of alloimmunised RhD-negative women.

METHODS

RhD-negative women in their first RhD immunised pregnancy were included for risk factor analysis. We compared risk factors for RhD immunisation, occurring either in the previous non-immunised pregnancy or in the index pregnancy, with national population data derived from the Dutch perinatal registration (Perined).

RESULTS

In the 2-year cohort, data from 193 women were eligible for analysis. Significant risk factors in women previously experiencing a pregnancy of an RhD-positive child (n = 113) were: caesarean section (CS) (OR 1.7, 95% CI 1.1-2.6), perinatal death (OR 3.5, 95% CI 1.1-10.9), gestational age >42 weeks (OR 6.1, 95% CI 2.2-16.6), postnatal bleeding (>1000 ml) (OR 2.0, 95% CI 1.1-3.6), manual removal of the placenta (MRP) (OR 4.3, 95% CI 2.0-9.3); these factors often occurred in combination. The miscarriage rate was significantly higher than in the Dutch population (35% versus 12.-5%, P < 0.001).

CONCLUSION

Complicated deliveries, including cases of major bleeding and surgical interventions (CS, MRP), must be recognised as a risk factor, requiring estimation of fetomaternal haemorrhage volume and adjustment of RhIg dosing. The higher miscarriage rate suggests that existing RhIg protocols need adjustment or better compliance.

Medication to Manage Abortion and Miscarriage

Abortion and miscarriage are common, affecting millions of US women each year. By age 45, one in four women in the USA will have had an abortion, and at least as many will have had a miscarriage. Most individuals seeking abortion services do so before 10 weeks' gestation when medication abortions are a safe and effective option, using a regimen of oral mifepristone followed by misoprostol tablets. When a pregnancy is non-viable before 13 weeks' gestation, it is referred to as an early pregnancy loss or miscarriage and can be managed using the same mifepristone and misoprostol regimen. Given their safety and efficacy, mifepristone and misoprostol can be offered in ambulatory settings without special equipment or on-site emergency services. As more patients find it difficult to access clinical care when faced with an undesired pregnancy or a miscarriage, it is important for general internists and primary care providers to become familiar with how to use medications to manage these common conditions. We summarize the most recent evidence regarding the use of mifepristone with misoprostol for early abortion and miscarriage. We discuss clinical considerations and resources for integrating mifepristone and misoprostol into clinical practice. By learning to prescribe mifepristone and misoprostol, clinicians can expand access to time-sensitive health services for vulnerable populations.

The concentration of fetal red blood cells in first-trimester pregnant women undergoing uterine aspiration is below the calculated threshold for Rh sensitization

OBJECTIVES

To calculate the minimum fetal red blood cell concentration required to cause maternal Rh sensitization; validate the use of a flow cytometry protocol below that concentration; preliminarily assess the concentrations of fetal red blood cells in pregnant women before and after uterine aspiration.

STUDY DESIGN

Using pre-existing literature, we calculated the lowest concentration of fetal red blood cells found to cause sensitization within adult female circulation. We validated a two-color flow cytometry protocol using fluorescently labeled antibodies to Hemoglobin F (expressed by fetal red blood cells and adult F cells) and Carbonic Anhydrase (expressed in red blood cells during the third trimester and postnatally) by titrating second trimester cord blood into non-pregnant adult blood. We applied this flow cytometry protocol in a prospective cohort study of 42 pregnant women at 5-12 weeks gestational age undergoing uterine aspiration for induced or spontaneous abortion.

RESULTS

The calculated threshold for causing Rh sensitization was 250 fetal red blood cells per 10 million total red blood cells. We showed a linear relationship between observed and expected fetal red blood cell fractions in titrated samples. Fetal red blood cell counts were more reliable when samples acquired by flow cytometry contained at least 1 million red blood cells. All 37 subjects with evaluable paired samples demonstrated fetal red blood cell concentrations below the calculated threshold for Rh sensitization both pre- and post-procedure. The fetal RBC concentrations increased from a mean of 4.5 (median 0, range 0-57) fetal RBCS pre- to a mean of 8.6 (median 2, range 0-32) fetal RBCs post- per 10 million total RBCs (p < 0.001).

CONCLUSIONS

Flow cytometry was capable of separately quantifying fetal red blood cells and maternal F cells to very dilute concentrations. Fetal red blood cell exposure in the first trimester was well below the calculated threshold for maternal Rh sensitization in our cohort. Larger studies are warranted to confirm our pilot study findings, fill this evidence gap and inform universal guidelines for administering Rh immunoglobulin after first trimester uterine aspiration.

IMPLICATIONS

Fetal red blood cell exposure following first trimester uterine aspiration is well below the calculated threshold for maternal Rh sensitization in our cohort.

Anti-D prophylaxis for rhesus D (RhD)-negative women having an abortion of a pregnancy up to 13+6 weeks' gestation: a systematic review and new NICE consensus guidelines

BACKGROUND

In order to develop the 2019 National Institute for Health and Care Excellence (NICE) national guideline on abortion care for the National Health Service1 we undertook a systematic review comparing anti-D prophylaxis to no prophylaxis in rhesus D (RhD)-negative women undergoing medical or surgical abortion of pregnancy at ≤13+6 weeks' gestation METHODS: We searched Embase, Medline and the Cochrane Library on 19 October 2018. We also consulted experts and checked reference lists for any missed trials. Eligible studies were randomised controlled trials and non-randomised comparative studies, published in English from 1985 onwards, comparing anti-D prophylaxis to no anti-D prophylaxis in RhD-negative women undergoing medical or surgical abortion at ≤13+6 weeks' gestation, and reporting subsequent anti-D isoimmunisation/sensitisation or subsequent affected pregnancy. These outcomes were to be analysed as risk ratios in Review Manager 5.3 using the Mantel-Haenszel statistical method and a fixed or random effect model. The overall quality of the evidence was planned to be assessed using GRADE.

RESULTS

The search identified 426 potentially relevant studies of which none met the inclusion criteria. Recommendations for practice were therefore based on the clinical expertise of the guideline committee.

CONCLUSIONS

(1) Offer anti-D prophylaxis to women who are Rhesus D negative who are having an abortion after 10+0 weeks' gestation. (2) Do not offer anti-D prophylaxis to women who are having a medical abortion up to and including 10+0 weeks' gestation. (3) Consider anti-D prophylaxis for women who are rhesus D negative and are having a surgical abortion up to and including 10+0 weeks' gestation.