title: Third trimester screening for alloimmunisation in Rhc-negative pregnant women: evaluation of the Dutch national screening programme.
abstract: OBJECTIVE
  To evaluate the effect of red blood cell (RBC) antibody screening in the 27th week of pregnancy in Rhc-negative women, on detection of alloimmunisation, undetected at first trimester screening ('late' alloimmunisation), and subsequent haemolytic disease of the fetus and newborn (HDFN), to assess risk factors for late alloimmunisation.
  
  
  METHODS
  Prospective cohort and nested case-control study.
  
  
  METHODS
  The Netherlands.
  
  
  METHODS
  Two-year nationwide cohort.
  
  
  METHODS
  Prospective inclusion of Rhc-negative women with negative first trimester screening and of screen-negative controls. Assessment of incidence and numbers needed to screen (NNS) of late alloimmunisation and HDFN; logistic regression analysis to establish risk factors for late alloimmunisation.
  
  
  METHODS
  Late alloimmunisation, HDFN.
  
  
  RESULTS
  Late alloimmunisation occurred in 99 of 62 096 (0.159%) Rhc-negative women; 90% had c/E antibodies and 10% non-Rhesus antibodies. Severe HDFN (fetal/neonatal transfusion) occurred in two of 62 096 (0.003%) of Rhc-negative women and 2% of late alloimmunisations; moderate HDFN (phototherapy) occurred in 20 children [22.5%; 95% confidence interval (CI), 13.8-31.1%]. Perinatal survival was 100%. The NNS to detect one HDFN case was 2823 (31 048 for severe, 3105 for moderate HDFN). Significant risk factors were former blood transfusion [odds ratio (OR), 10.4; 95% CI, 1.14-94.9], parity (P-1: OR, 11.8; 95% CI, 3.00-46.5; P > 1: OR, 7.77; 95% CI, 1.70-35.4) and amniocentesis/chorionic villus sampling during current pregnancy (OR, 9.20; 95% CI, 1.16-72.9).
  
  
  CONCLUSIONS
  Additional screening of Rhc-negative women improved the detection of late alloimmunisation and HDFN, facilitating timely treatment, with a NNS of 2823. Independent risk factors for late alloimmunisation were blood transfusion, parity and chorionic villus sampling/amniocentesis in the current pregnancy. The occurrence of most factors before the current pregnancy suggests a secondary immune response explaining most late alloimmunisations.
  
  
  CONCLUSIONS
  Third trimester screening for alloimmunisation in Rhc-neg women improves detection and treatment of severe HDFN.
authors.affiliation: Department of Obstetrics, Leiden University Medical Centre, Leiden, the Netherlands.
authors.forename: Y M
authors.initials: YM
authors.lastname: Slootweg
authors.affiliation: Department of Obstetrics and Gynaecology, Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands.|Department of Experimental Immunohaematology, Sanquin Research, Amsterdam, the Netherlands.|Department of General Practice, University Medical Centre, Groningen, the Netherlands.
authors.forename: J M
authors.initials: JM
authors.lastname: Koelewijn
authors.affiliation: Department of Obstetrics, Leiden University Medical Centre, Leiden, the Netherlands.
authors.forename: I L
authors.initials: IL
authors.lastname: van Kamp
authors.affiliation: Centre for Clinical Transfusion Research, Sanquin Research, Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden, the Netherlands.
authors.forename: J G
authors.initials: JG
authors.lastname: van der Bom
authors.affiliation: Department of Obstetrics, Leiden University Medical Centre, Leiden, the Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: Oepkes
authors.affiliation: Department of Experimental Immunohaematology, Sanquin Research, Amsterdam, the Netherlands.|Leiden University Medical Centre, Department of Translational Immunohematology, Leiden, the Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: de Haas
mesh_terms: D000649:Amniocentesis / Q000706:statistics & numerical data; D001803:Blood Transfusion / Q000706:statistics & numerical data; D015193:Chorionic Villi Sampling / Q000706:statistics & numerical data; D004899:Erythroblastosis, Fetal / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D005260:Female; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007518:Isoantibodies / Q000097:blood; D008403:Mass Screening / Q000706:statistics & numerical data*; D009426:Netherlands / Q000453:epidemiology; D010298:Parity; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D015397:Program Evaluation; D012203:Rh Isoimmunization / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D012204:Rh-Hr Blood-Group System / Q000276:immunology*; D012307:Risk Factors; D012720:Severity of Illness Index; D015996:Survival Rate
chemical_list: D007518:Isoantibodies; D012204:Rh-Hr Blood-Group System
keywords: Alloimmunisation; Rhc-negative; incidences; risk factors; screening