title: Cytogenetic evaluation of 1000 cases of chorionic villus sampling.
abstract: BACKGROUND
  Chorionic villus sampling (CVS) is used routinely as a first trimester diagnostic procedure for fetal karyotyping in at-risk pregnancies. The success of the procedure is dependent on the experience of the operator performing it. The objective of this study was to determine the relationship between an operatorcontrolled clinical and laboratory setting and the safety and reliability of CVS service.
  
  
  METHODS
  One thousand patients had a CVS procedure for a variety of indications, such as advanced maternal age, previous child with chromosome abnormality, etc. Both transcervical and transabdominal procedures were performed, according to placental location and uterine environment. For cytogenetic diagnosis, direct and short-term cultures were set up according to standard laboratory protocol.
  
  
  RESULTS
  Cytogenetic results were obtained in 99.6% of studies with 94.5% normal (46,XX or 46,XY), with the remaining having a variety of numerical and structural chromosomal abnormalities. Maternal cell contamination was found in 2% of the first 262 cases, while the overall rate observed in the 1000 samples was 0.5%. Level II mosaicism was observed in 0.8% and level III mosaicism observed in 0.9% of cases, respectively. The overall rate of pregnancy loss of chromosomally normal pregnancies within 28 weeks of gestation was 2.8%. No limb reduction defects were seen in any infant post-CVS.
  
  
  CONCLUSIONS
  Our record demonstrates that experienced operators can deliver a safe and reliable CVS service.
authors.affiliation: Genetics Institute of Florida, West Palm Beach, Florida, and Jefferson Medical College, Philadelphia, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Iqbal
authors.forename: G F
authors.initials: GF
authors.lastname: Manko
authors.forename: J
authors.initials: J
authors.lastname: Trabin
authors.forename: C
authors.initials: C
authors.lastname: Virelles
authors.forename: L
authors.initials: L
authors.lastname: Jackson