Trisomy FISH Screen (13,18,21,X,Y) (Amniotic Fluid)

Turnaround Time

4 days

CPT Code(s)

88235, 88275, 88271 x4, 88291

Cost

$1144

• Trisomy 13
• Trisomy 18
• Trisomy 21 also Down syndrome

The trisomy screen can be used as a rapid initial screen for some of the more common aneuploidies. FISH should be used in conjunction with G-banded chromosome analysis.

FISH: Fluorescence in situ hybridization is a molecular cytogenetic technique in which fluorescently labeled DNA probes are hybridized to metaphase spreads or interphase nuclei.

This test can be performed from direct amniotic fluid or on cultured amniocytes. If sending direct fluid for microarray only, 10-20 ml of amniotic fluid is requested. Chromosomes and/or FISH will require an additional 10-15 ml of fluid. If sending cultured flasks, 2x T25 confluent flasks are required. Parental samples are recommended to accompany prenatal specimen for microarray analysis. 4-5 mls of peripheral blood should be collected on each parent in an EDTA (lavender top) tube. Additional specimen types for parental samples include saliva and extracted DNA.

Amniotic Fluid: Specimen should be kept at room temperature; do not freeze or refrigerate. Specimen should be sent by courier or overnight mail to arrive at the laboratory the next day.