title: Prenatal screening: invasive diagnostic approaches.
abstract: BACKGROUND
  Fetal invasive procedures provide ovular samples that are helpful in establishing diagnosis, etiology, and prognosis when ultrasonography and MRI show a central nervous system (CNS) anomaly or when the fetus is at high risk of such pathology.
  
  
  METHODS
  Invasive procedure techniques are amniocentesis, fetal blood sampling (FBS), and chorionic villous sampling (CVS). They provide material for fetal DNA, biochemical analysis, or identification of various infectious agents.
  
  
  RESULTS
  The main complications are miscarriage and premature delivery. Counseling the parents about the risks and benefits of these procedures is therefore mandatory.
  
  
  CONCLUSIONS
  Amniocentesis may be performed as early as 15 weeks' gestation and is the most widely used invasive technique. FBS is performed after 18 to 20 weeks of pregnancy and CVS may be carried out after 11 weeks. Indications for invasive techniques include DNA and cytogenetic analysis, diagnosis of neural tube defects, identification of infectious agents (toxoplasmosis, cytomegalovirus, rubella, and varicella), and etiology of intracerebral hemorrhage (fetal platelets and coagulation factors).
authors.affiliation: Service de Gynecologie Obstétrique, Hôpital Nord, Chemin des Borrellys, 13015 Marseille, France. Claude.D'ercole@mail.ap-hm.fr
authors.forename: Claude
authors.initials: C
authors.lastname: d'Ercole
authors.forename: Raha
authors.initials: R
authors.lastname: Shojai
authors.forename: Raoul
authors.initials: R
authors.lastname: Desbriere
authors.forename: Cécile
authors.initials: C
authors.lastname: Chau
authors.forename: Florence
authors.initials: F
authors.lastname: Bretelle
authors.forename: Laurence
authors.initials: L
authors.lastname: Piéchon
authors.forename: Léon
authors.initials: L
authors.lastname: Boubli
mesh_terms: D000649:Amniocentesis / Q000379:methods; D015193:Chorionic Villi Sampling / Q000379:methods; D020732:Cytogenetic Analysis / Q000379:methods; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D005315:Fetal Diseases / Q000175:diagnosis*; D005333:Fetus; D005865:Gestational Age; D006801:Humans; D007239:Infections / Q000097:blood / Q000453:epidemiology; D008279:Magnetic Resonance Imaging; D008403:Mass Screening; D008967:Molecular Biology / Q000379:methods; D009436:Neural Tube Defects / Q000097:blood / Q000175:diagnosis / Q000235:genetics; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000009:adverse effects / Q000379:methods*; D012306:Risk; D016216:Ultrasonography, Prenatal