Indications For 24-Hour FISH confirmation of Prenatal trisomy (13, 18, 21, X, Y)
- Abnormal NIPT / Cell-free DNA
- Advanced maternal age (>35 years of age)
- Previous pregnancy with chromosomal abnormality
- Recurrent spontaneous miscarriage
- Family history of a chromosomal abnormality
- Abnormal maternal serum screening results
- Abnormal ultrasound findings
STAT 24-hour detection of aneuploidy for chromosomes 13, 18, 21, X & Y, via fluorescence in situ hybridization (FISH) assay in interphase cells from prenatal samples. All FISH analysis is confirmed by routine cytogenetic analysis.
Collection Procedure
- Amniotic fluid Discard the first 2 ml of fluid to reduce the risk of maternal cell contamination. Aseptically transfer the specimen into sterile plastic 15 ml conical tubes labeled with patient’s name and date of birth.
- CVS Aseptically transfer the specimen into sterile plastic conical tubes containing sterile transport medium (provided by CytoGenX). Label tube with patient’s name and date of birth.
A completed test requisition form must be included with every sample. A transport kit is available upon request.
Specimen Requirements
3- 5cc of amniotic fluid or 3mg of CVS is used for FISH analysis (this is in addition to the normal amount collected for chromosome analysis). This is not a standalone test and must be ordered with standard cytogenetic analysis.
Specimen Container
Sterile 15ml screw-cap container
Methodology
Fluorescence in situ hybridization is performed on interphase cells to detect aneuploidy of chromosomes 13, 18, 21, X & Y. Results are confirmed by cytogenetic analysis.
Transport Temperature
Room temperature (DO NOT refrigerate, freeze or centrifuge)
Causes for Rejection
Frozen specimen, large amount of blood, inappropriate container
Turnaround Time
24hrs