(Potential) false-negative diagnoses in chorionic villi and a review of the literature.
OBJECTIVE
To assess the incidence of (potential) false-negative findings of cytogenetic diagnosis in STC-villi and/or LTC-villi and to determine the best strategy for karyotyping chorionic villi in order to avoid false-negative results.


METHODS
2476 chorionic villus samples were received for prenatal cytogenetic investigations. Karyotyping was routinely performed on STC- and LTC-villi preparations by G-banding. Fluorescence in situ hybridization (FISH) analyses were performed in addition to standard chromosome analysis when necessary. Sometimes follow-up investigations like amniocentesis were performed before a definite prenatal cytogenetic result could be reported.


RESULTS
In 2389/2476 (96.5%) of the cases, both STC- and LTC-villi were investigated. Normal STC- with abnormal LTC-villi results and finally an abnormal fetal karyotype were detected in ten cases (10/2389; 0.42%); in 9/10 of the cases the indication was fetal ultrasound abnormalities. Normal STC- and LTC-villi and finally an abnormal fetal karyotype were detected in two cases (2/2389; 0.08%).


CONCLUSIONS
The most reliable technique for prenatal diagnosis after chorionic villus sampling (CVS) is the combination of the analysis of both STC- and LTC-villi to reduce the incidence of false-negative findings to a minimum. In the case of fetal ultrasound abnormalities with a small amount of villi available, the investigation of LTC-villi is recommended over that of STC-villi.
Department of Clinical Genetics, Erasmus Medical Center, 3000 DR Rotterdam, The Netherlands. c.d.f.vandenberg@erasmusmc.nl
Cardi
C
van den Berg
Diane
D
Van Opstal
Joke
J
Polak-Knook
Robert Jan
RJ
Galjaard
D015193:Chorionic Villi Sampling / Q000379:methods* / Q000592:standards*; D025063:Chromosome Disorders / Q000175:diagnosis*; D005188:False Negative Reactions; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis*; D006801:Humans; D007621:Karyotyping; D011247:Pregnancy