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Test Code HLX FISH Constitutional CASE   Prenatal Aneuploidy FISH Panel

Performing Laboratory

Northwell Health Laboratories


Fluorescence In Situ Hybridization (FISH)

Reference Values

See report.


TAT 24 - 48 Hours

Test Classification and CPT Coding

88271 x 5 - DNA probe, each

88275 x 4 - interphase in situ hybridization

88291 - interpretation and report

Physician Office Specimen Requirements

Please provide a reason for referral with each specimen. The laboratory will not delay or reject testing if this information is not provided, but appropriate testing and interpretation may be compromised.

Amniotic Fluid

Optimum timing for specimen collection is during 16th-18th weeks of gestation, but specimens collected at other weeks of gestation are also accepted. Draw 20 mL to 25 mL of amniotic fluid in a sterile syringe (we strongly recommend Pharmaseal amniocentesis tray distributed by Cardinal Health Company. Discard the first 2 mL of amniotic fluid, and send remainder (minimum volume:  3 mL) to laboratory. When using a Pharmaseal Amniocentesis Kit, transfer the amniotic fluid into provided transport containers. If Pharmaseal amniocentesis tray is not available, use a Becton-Dickinson syringe; and transport specimen as follows. Remove needle and transfer specimen to 2 screw-capped, sterile 15-mL centrifuge tubes. Place tubes in a Styrofoam® container. Fill remaining space with packing material. Unavoidably, about 1% to 2% of mailed-in specimens are not viable. Bloody specimens are undesirable. If the specimen does not grow in culture, you will be notified within 7 days of receipt. Label container with patient’s name and laboratory control number. Send specimen room Temperature. Specimen cannot be frozen.



Chorionic Villus

Obtain 20 mg to 30 mg (minimum volume:  3 mg) of a chorionic villus specimen (CVS) by the transabdominal or transcervical method. Transfer CVS to a Petri dish containing transport medium. Using a stereomicroscope and sterile forceps, assess the quality and quantity of the villi; and remove any blood clots and maternal decidua. Transfer the CVS by using sterile technique to 1 or 2, 15-mL centrifuge tube(s) with 15 mL of transport medium. Label centrifuge tube(s) with patient’s name and laboratory control number. Send specimen refrigerated. Specimen cannot be frozen.

Day(s) and Time(s) Performed

Monday through Friday

Computer Interface Code

PDM #  5160320

Used For

Rapid identification of the most common aneuploidies detected in prenatal specimens:

  1. Patau syndrome (trisomy 13)
  2. Edwards syndrome (trisomy 18)
  3. Down syndrome (trisomy 21)
  4. Sex chromosome abnormalities