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Rapid neonatal FISH

Also known as: Urgent neonatal karyotype with Rapid FISH

Test category:

Reproductive - Neonatal diagnosis

Use of test


Chromosome analysis can detect balanced and unbalanced rearrangements, and numerical changes of autosomes and sex chromosomes. The identification of such abnormalities provides diagnostic and prognostic information.

This test involves rapid assessment of the number of selected chromosomes followed by rapid assessment of the structure and number of all chromosomes.


In an affected baby, an abnormal result usually provides a genetic diagnosis and the basis for genetic counselling. A normal result does not exclude a genetic or heritable basis for the disorder.

There is a separate test for Rapid prenatal FISH.

Ethical considerations:

This is an assay for mutations which may be heritable or de novo. It may raise issues of ethics or consent that are different from most other investigations ordered in the routine care of a patient.


Analysis of the number of selected chromosomes by fluorescent in situ hybridisation (FISH) followed by analysis of all metaphase chromosomes by light microscopy.

Requesting the test


This test is usually requested by a paediatrician, obstetrician, or clinical geneticist.

Sample required:

1-5 mL blood in lithium heparin. Specimens may be collected by the requesting practitioner.

To help ensure the quality of the test, a genetic test should be done with a dedicated sample whenever possible i.e. a sample collected specifically for that test rather than a sample that is used for multiple tests.

We recommend that the patient or another adult check the labelling of request forms and sample tubes.

Special instructions:

Please include details of any clinical abnormalities in the patient being tested, and the results of chromosome studies in relatives.

Turnaround time:

15 business days for karyotype and FISH study; 3 business days for FISH alone.


This test has a Medicare rebate which, subject to the requirements of the Medicare descriptor being met, may cover all or part of the cost.

The price varies according to the specific clinical conditions for a particular patient. Please contact Sonic Genetics on 1800 010 447 for more information.


The Medicare details, including descriptor and schedule fee, are listed under MBS item 73291.

Click here for our billing policy.