RESUMO
BACKGROUND AND OBJECTIVES: Fetal RHD genotyping of cell-free maternal plasma DNA from RhD negative pregnant women can be used to guide targeted antenatal and postnatal anti-D prophylaxis for the prevention of RhD immunization. To assure the quality of clinical testing, we conducted an external quality assessment workshop with the participation of 31 laboratories. MATERIALS AND METHODS: Aliquots of pooled maternal plasma from gestational week 25 were sent to each laboratory. One sample was fetal RHD positive, and a second sample was fetal RHD negative. A reporting scheme was supplied for data collection, including questions regarding the methodological setup, results and clinical recommendations. The samples were tested blindly. RESULTS: Different methodological approaches were used; 29 laboratories used qPCR and two laboratories used ddPCR, employing a total of eight different combinations of RHD exon targets. Fetal RHD genotyping was performed with no false-negative and no false-positive results. One inconclusive result was reported for the RHD positive sample. All clinical conclusions were satisfactory. CONCLUSION: This external quality assessment workshop demonstrates that despite the different approaches taken to perform the clinical assays, fetal RHD genotyping is a reliable laboratory assay to guide targeted use of Rh prophylaxis in a clinical setting.
Assuntos
Técnicas de Genotipagem/normas , Sistema do Grupo Sanguíneo Rh-Hr/genética , Éxons , Feminino , Feto/metabolismo , Humanos , Plasma/química , Plasma/metabolismo , Gravidez , Diagnóstico Pré-Natal/normas , Reação em Cadeia da Polimerase em Tempo Real , Sistema do Grupo Sanguíneo Rh-Hr/sangue , Imunoglobulina rho(D)RESUMO
BACKGROUND AND OBJECTIVES: Fetal RHD genotyping of cell-free fetal DNA from RhD-negative pregnant women can be used to guide targeted antenatal and postnatal anti-D prophylaxis for the prevention of RhD immunization. To assure the quality of clinical testing, we conducted an external quality assessment workshop with the participation of 28 laboratories. MATERIALS AND METHODS: Aliquots of pooled maternal plasma were sent to each laboratory. One sample was positive, and the second sample was negative for fetal RHD, verified by pre-workshop testing using quantitative real-time PCR (qPCR) analysis of RHD exons 4, 5, 7 and 10. Plasma samples were shipped at room temperature. A reporting scheme was supplied for data collection, including questions regarding the methodological setup, results and clinical recommendations. Different methodological approaches were used, all employing qPCR with a total of eight different combinations of RHD exon targets. The samples were tested blindly. RESULTS: Fetal RHD genotyping was performed with no false-negative and no false-positive results. One inconclusive result was reported for the RHD-positive sample, and four inconclusive results were reported for the RHD-negative sample. All clinical conclusions were satisfactory. CONCLUSION: This external quality assessment workshop demonstrates that despite the different approaches taken to perform the clinical assays, fetal RHD genotyping is a reliable laboratory assay to guide targeted use of Rh prophylaxis in a clinical setting.
Assuntos
Doenças Fetais/prevenção & controle , Reação em Cadeia da Polimerase em Tempo Real , Isoimunização Rh/prevenção & controle , Sistema do Grupo Sanguíneo Rh-Hr/sangue , Imunoglobulina rho(D)/genética , Educação Continuada , Éxons , Feminino , Doenças Fetais/genética , Feto , Genótipo , Humanos , Gravidez , Diagnóstico Pré-Natal/métodos , Garantia da Qualidade dos Cuidados de Saúde , Controle de Qualidade , Qualidade da Assistência à Saúde , Reprodutibilidade dos Testes , Isoimunização Rh/genética , Sistema do Grupo Sanguíneo Rh-Hr/genética , Imunoglobulina rho(D)/sangue , Imunoglobulina rho(D)/químicaRESUMO
OBJECTIVE: To describe fetomaternal hemorrhage (FMH) during second-trimester dilation and evacuation (D&E) to evaluate if Rhesus-immune globulin (RhIG) 100 mcg (used in the United Kingdom) and 300 mcg (used in the United States) provide adequate prophylaxis. STUDY DESIGN: We conducted an exploratory prospective descriptive study of women undergoing D&E between 15â¯weeks 0â¯days and 23â¯weeks 6â¯days of gestation. Enrolled participants had Kleihauer-Betke testing on specimens obtained before and after D&E. We assessed the main outcome measures of FMH in mL suggesting need for more than 100 mcg and 300 mcg RhIG (FMH of 10â¯mL and 30â¯mL fetal whole blood, respectively) and association of postprocedure FMH with demographic characteristics and procedure-related variables. RESULTS: The 300 participants had a mean gestational age of 19â¯weeks 6â¯days±2â¯weeks 2â¯days. The median preprocedure FMH was 0â¯mL (range 0-50â¯mL) with 2 (0.67%) women exceeding 10â¯mL (19â¯mL and 50â¯mL). The median postprocedure FMH was 1â¯mL (range 0-60â¯mL). Almost all participants had postprocedure FMH <10â¯mL (n=295, 98.3%) and <30â¯mL (n=298, 99.3%). All participants under 18â¯weeks had FMH <10â¯mL. We found no demographic or procedure-related factors to be predictive of FMH quantity. CONCLUSIONS: FMH occurring with routine second-trimester D&E procedures is minimal. Adequate prophylaxis with RhIG 100 mcg and 300 mcg occurred in >98% of women and in all cases <18â¯weeks of gestation. This study is the first step to potentially reducing the dose and costs of RhIG administration with D&E. IMPLICATIONS: This study is a first step in quantifying fetomaternal hemorrhage with routine dilation and evacuation procedures; larger trials are needed, especially to understand why some women have recognizable hemorrhage preprocedure. If dosing requirements are too high with current guidelines, lower doses will result in resource and cost savings.