This is not a stand-alone test, the volume must be sufficient to include classical chromosome analysis. The first 1.0-2.0 mL should be expressed into a separate tube to clear the specimen of possible maternal cells.
Distribute the rest of the specimen between 3 screw-top sterile polystyrene or polypropylene tubes. For cytogenetics testing, all drawn amniotic fluid should be sent, properly labeled, to the Cytogenetics laboratory. Do not refrigerate, freeze, or expose to extreme temperatures. Keep specimen at ambient temperature and transport within 24 hours. Maintain sterility do not split specimen or open tube.
Bloody amniotic fluid samples are not appropriate for FISH testing due to the possibility of maternal cell contamination. However, to insure the completion of the classical cytogenetics testing, if gross blood is present, add 0.25 mL of sodium heparin (1,000 units/mL) aseptically to each tube immediately after the tap. Addition of heparin should be noted on the tube.