title: Procedure-related complications of amniocentesis and chorionic villous sampling: a systematic review.
abstract: OBJECTIVE
  To compile a systematic review of complications related to genetic amniocentesis and chorionic villus sampling (CVS) to provide benchmark data for counseling and performance assessment of individual operators.
  
  
  METHODS
  We searched the MEDLINE database for articles published after January 1, 1995, that reported data for at least 100 women with singleton pregnancies with genetic amniocentesis after 14 weeks of pregnancy and reports of CVS carried out transabdominally between 10 and 14 weeks.
  
  
  METHODS
  For amniocentesis, 29 articles fulfilled search criteria. Sixteen studies fulfilled search criteria for CVS.
  
  
  RESULTS
  After genetic amniocentesis, pooled pregnancy loss within 14 days was 0.6% (95% confidence interval [CI] 0.5-0.7), rising to 0.9% (95% CI 0.6-1.3) for pregnancy loss before 24 weeks and 1.9% (95% CI 1.4-2.5) for total pregnancy loss. Corresponding figures for CVS were 0.7%, 1.3%, and 2%. The data on multiple insertions showed large heterogeneity, ranging from 0.2% to 2.9% for amniocentesis (pooled risk 2.0%, 95% CI 0.9-3.6) and from 1.4% to 26.6% for CVS (pooled risk 7.8%, 95% CI 3.1-14.2). Only five amniocentesis studies provided controls, but none was matched for gestational age. Pooled relative risks for fetal loss before 28 weeks and total pregnancy loss were 1.46 (95% CI 0.86-2.49) and 1.25 (95% CI 1.02-1.53), respectively.
  
  
  CONCLUSIONS
  Although the risks of pregnancy loss are relatively low, lack of adequate controls tends to underestimate the true added risk of prenatal invasive procedures.
authors.affiliation: Department of Perinatology, University Clinical Center Maribor, Maribor, Slovenia.
authors.forename: Faris
authors.initials: F
authors.lastname: Mujezinovic
authors.forename: Zarko
authors.initials: Z
authors.lastname: Alfirevic
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology*; D000649:Amniocentesis / Q000009:adverse effects*; D015193:Chorionic Villi Sampling / Q000009:adverse effects*; D000013:Congenital Abnormalities / Q000175:diagnosis; D005260:Female; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D012307:Risk Factors