Chromosome analyses on tissue samples are performed to detect abnormal chromosome number, such as trisomies, and structural rearrangements as a cause for pregnancy loss, or to diagnose tissue limited mosaicism.
A minimum of 20 metaphases are examined and 2 karyotypes are prepared. If attempts to establish tissue in culture fail, chromosome analysis cannot be performed. In some cases of culture failure, fluorescence in situ hybridization (FISH) can be attempted to rule out the presence of common aneuploidies.
- Obtain 3-4 mm3 of desired tissue using asceptic technique.
- Place in a sterile, screw-top tube filled with tissue culture medium or saline solution.
- Label container with patient's name, a second patient identifier, and the type of tissue obtained.
Products of conception or fetal tissue
- Submit 0.5 to 1 cm3 sample from the fetal side of the placenta at the site of cord insertion.
- If possible, also obtain a 0.5 to 1.0 mm3 sample from one or two of the following tissues:
- Place each tissue sample in a separate, tightly sealed, sterile container with cytogenetic transport media or sterile saline solution.
- Label each container with the patient’s name and type of sample.
- Maintain sample(s) at room temperature and transport to the Colorado Genetics Laboratory immediately. If it is necessary to hold a tissue sample overnight, please refrigerate. Do not freeze.
- Formalin fixed tissues are not appropriate for chromosome analysis. However, parrafin embedded or formalin fixed tissues are accepted for FISH for Chromosome Abnormalities Common in Pregnancy Loss.
The sample must be accompanied by a complete Test Request Form. Please include pertinent clinical and family history. If the sample is products of conception/fetal tissue, include the gestational age at the time of specimen collection.