Background:
Chromosome analysis of amniocytes by G-banded karyotype is used to determine the chromosomal constitution of the fetus, and can be very useful in addressing abnormal ultrasound findings and abnormal maternal serum screen results, as a large fraction of such abnormal findings are the result of a chromosome abnormality. Additionally, fetal sex is determined during the course of the investigation, which may have implications when sex chromosome -associated disorders are suspected.
Amniocytes are collected and cultured from amniotic fluid, which is generally sampled at 15 to 18 weeks gestation. Complete karyotype analysis is performed. Reflex fluorescent in situ hybridization (FISH) may be included to confirm certain abnormal chromosome results and/or to address specific clinical abnormalities. If performed, FISH will be billed with the chromosome analysis.
Indications for amniotic fluid chromosome analysis include:
- advanced maternal age
- abnormal maternal serum screen
- abnormal fetal ultrasound
- previous child with a chromosome abnormality
- family history of a chromosome abnormality
Methodology:
G-banded chromosome analysis
Reflex testing to FISH, as appropriate
Specimen Requirements:
Amniotic Fluid: 18-24 mL.
- Discard or separately collect first one or two mL fluid (can be used for AFP).
- If fluid is bloody, add 0.5 mL sodium heparin (1000 units/mL) to each 10 mL of fluid and mix well.
- Keep at room temperature.
- Prior to sending a sample, please call Client Services for shipping kits and instructions: (855) 535-1522 or (503) 494-5400.
Test Performed (Days):
Mon - Sat
Turn Around Time:
10-11 Days
Shipment Sensitivity Requirements:
- Keep specimen at room temperature during transit.
- Call Client Services for shipping kits and insturctions: (855) 535-1522 or (503) 494-5400.
- Do not use the cold pack provided in the KDL shipping kit.
- Ship the specimen overnight express, using the FedEx priority overnight label provided. The specimen must arrive at the lab no more than 24 hours after collection.
References:
Additional Info:
Please include detailed clinical information related to the reason for referral to cytogenetics.
After hours, please leave message at (855) 535-1522 for the on call cytogenetic technologist.