title: Screening in pregnancy for fetal or neonatal alloimmune thrombocytopenia: systematic review.
abstract: BACKGROUND
  Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a potentially devastating disease, which may lead to intracranial haemorrhage (ICH), with neurological damage as a consequence. In the absence of screening, FNAIT is only diagnosed after bleeding symptoms, with preventive options limited to a next pregnancy.
  
  
  OBJECTIVE
  To estimate the population incidence of FNAIT and its consequences to prepare for study design of a screening programme.
  
  
  METHODS
  An electronic literature search using MEDLINE, EMBASE and Cochrane database, and references of retrieved articles. No language restrictions were applied.
  
  
  METHODS
  Prospective studies on screening for human platelet antigen 1a (HPA-1a) alloimmunisation in low-risk pregnant women.
  
  
  METHODS
  Two reviewers independently assessed studies for inclusion and extracted data. Main outcome data were prevalence of HPA-1a negativity, HPA-1a immunisation, platelet count at birth and perinatal ICH. We aimed to compare outcome with and without intervention.
  
  
  RESULTS
  HPA-1a alloimmunisation occurred in 294/3028 (9.7%) pregnancies at risk. Severe FNAIT occurred in 71/227 (31%) immunised pregnancies, with perinatal ICH in 7/71 (10%). True natural history data were not found because interventions were performed in most screen-positive women.
  
  
  CONCLUSIONS
  Screening for HPA-1a alloimmunisation detects about two cases in 1000 pregnancies. The calculated risk for perinatal ICH of 10% in pregnancies with severe FNAIT is an underestimation because studies without interventions were lacking. Screening of all pregnancies together with effective antenatal treatment such as intravenous immunoglobulin may reduce the mortality and morbidity associated with FNAIT.
authors.affiliation: Department of Obstetrics, Leiden University Medical Centre, Leiden, the Netherlands.
authors.forename: M M
authors.initials: MM
authors.lastname: Kamphuis
authors.forename: N
authors.initials: N
authors.lastname: Paridaans
authors.forename: L
authors.initials: L
authors.lastname: Porcelijn
authors.forename: M
authors.initials: M
authors.lastname: De Haas
authors.forename: C E
authors.initials: CE
authors.lastname: Van Der Schoot
authors.forename: A
authors.initials: A
authors.lastname: Brand
authors.forename: G J
authors.initials: GJ
authors.lastname: Bonsel
authors.forename: D
authors.initials: D
authors.lastname: Oepkes
mesh_terms: D016824:Antigens, Human Platelet / Q000097:blood*; D005260:Female; D006684:HLA-DR Antigens / Q000097:blood; D059826:HLA-DRB3 Chains; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D039661:Integrin beta3; D054238:Perinatal Mortality; D011247:Pregnancy; D011256:Pregnancy Outcome; D018566:Pregnancy, High-Risk; D011296:Prenatal Diagnosis / Q000379:methods*; D011446:Prospective Studies; D054098:Thrombocytopenia, Neonatal Alloimmune / Q000175:diagnosis*
chemical_list: D016824:Antigens, Human Platelet; D006684:HLA-DR Antigens; D059826:HLA-DRB3 Chains; C061248:ITGB3 protein, human; D039661:Integrin beta3