RESUMEN
OBJECTIVES: Chorioamniotic separation (CAS) at the time of standard amniocentesis (AC) is a risk factor for postprocedural complications and should be avoided. The aim of this study was to quantify procedure-related risks after AC with a 29G-needle in cases of CAS, and evaluation of perinatal outcome in CAS after 15 weeks' gestation (GW). METHODS: Retrospective analysis of genetic AC with a pencil-point 29G needle after 15 completed GW in pregnancies, in which the fetal membranes were not yet fused. Included into the study were women aged 16-44 years with at least 15 completed GWs referred for second trimester AC to identify fetal chromosomal aberrations. RESULTS: 437 ACs were made in total with the 29G-needle. The median maternal age was 30 (16-44) years. 145 cases showed CAS where the distance between chorion and amnion was 0.10-10.02 mm at AC. 38 pregnancies were terminated, 37 of which had a genetic disorder. The risk of aneuploidy increases by a factor of 2 (95% CI 1.4-2.8) for every 1 mm of CAS enlargement. No procedure-related complications were found up to two weeks after the AC. CONCLUSIONS: CAS seems to be massively underreported. Early diagnosis in case of CAS is something to strive for as CAS could be an indicator of genetic abnormalities - a "soft marker". With the atraumatic 29G needle, the risk of complications after AC in CAS seems to be very low.