Chromosome Analysis, Amniotic Fluid With Reflex to SNP Microarray (Reveal®)
Also known as: Karyotype, Amniotic Fluid With Reflex to Microarray
Use
The chromosome analysis determines fetal karyotype. A normal chromosome analysis will reflex to a high-resolution SNP microarray analysis targeting 2.695 million copy-number and allele-specific genome sites. The SNP assay will detect chromosomal imbalances that could be associated with developmental delay/congenital anomalies. It provides possible detection of uniparental disomy of any chromosome, the percent and location of homozygosity, including the degree of identity by descent.
Special Instructions
Pertinent medical findings must accompany the request, and a copy of any prior Non-Invasive Prenatal Testing (NIPT) studies should be included. Samples from twin pregnancies should be properly labeled and submitted separately, each with its own request form.
Limitations
The culture success rate is over 99%, but failures may occur due to a lack of amniocytes in the sample or contamination by bacteria or yeast. The SNP microarray does not detect balanced rearrangements, low-level mosaicism (below 10%), marker chromosomes containing only heterochromatin, or tetraploidy. Balanced chromosomal alterations and mosaicisms below certain thresholds may not be detected. Empiric studies have found the detection threshold for mosaicism varies depending on segment size, with whole-chromosome mosaicism below 10% sometimes undetected.
Methodology
Chromosomal / Cytogenetics (SNP Microarray)
Biomarkers
LOINC Codes
- 62389-2
- 64095-3
- 64096-1
- 64092-0
- 64091-2
- 64093-8
- 62356-1
- 64094-6
- 48002-0
- 48672-0
- 50398-7
Result Turnaround Time
7-11 days
Related Documents
For more information, please review the documents below
Specimen
Amniotic Fluid
Volume
15-20 mL
Minimum Volume
5 mL
Container
Sterile plastic conical tube
Collection Instructions
Discard first 2 mL to avoid contamination. Collect in a 20 mL sterile syringe, transfer to sterile tubes, and complete the test request form. Store at room temperature.
Patient Preparation
Preferably have had an ultrasound to verify fetal life, detect multiple gestation, confirm gestational age, and localize placenta.
Storage Instructions
Maintain specimen at room temperature. Do not refrigerate or freeze.
Causes for Rejection
Suitability determined by the Cytogenetics laboratory.