Constitutional Chromosome Analysis – Non Blood – Products of Conception

CPT Code(s)

88233, 88262

Synonym(s)

88233, 88263, 88280

Performed

Clinical & Molecular Cytogenetics Laboratory

Clinical Indication and Relevance

Indications for cytogenetic analysis on products of conception (POC) include recurrent spontaneous abortions, abnormalities on ultrasound prior to pregnancy loss, intrauterine growth retardation, confirmation of abnormal prenatal results or pregnancy loss after IVF.

Clinical Background
Fetal tissues or extra embryonic membranes are frequently used to diagnose fetal chromosome abnormalities that are associated with approximately one-half of all first trimester spontaneous abortions. The most common chromosome abnormalities seen in spontaneous miscarriages are trisomy 16 and monosomy X. In some cases where the POC karyotype revealed a structural rearrangement, parental chromosome analysis is requested. The diagnosis of an abnormal karyotype in a POC may provide a chromosomal basis for the pregnancy loss. It may also help in clarifying the risk for future miscarriages or for the birth of a chromosomally abnormal child. Abnormal POC cytogenetic results may preclude the need for extensive infertility evaluation.

Methodology

Culture / Microscopy / Karyotype

Tissues from products of conception are cultured to produce metaphase cells for G-banded chromosome analysis. Long term cultures are harvested at approximately 10-14 days, then G-banded.  Analysis and karyotyping of 20 metaphases are routinely performed and additional metaphases will be studied when indicated.

Specimen Collection / Handling Requirements

Placenta, umbilical cord, and internal fetal organs are all suitable for analysis.  If possible, please send chorionic villi.

Container:  Sterile, leak-proof containers with transport media or sterile saline (i.e. Hanks Balanced Salt Solution).

Do not place in formalin.

Minimum Specimen Requirements

Optimal Quantity: 2x2x2 cm of at least two fetal tissues, one being chorionic villi

Minimum Quantity: 1x1x1 preferably villi or fetal tissue

Storage: Room Temperature

Stability at Room Temperature: 8 hours, then refrigerate

Transportation: Avoid freezing or heating over 35°C

Turnaround time

Final report in 14-28 days

Communication

The morphologic interpretation and correlation of results on all cases is performed by a board-certified doctoral level scientist (laboratory director). The final report identifies the chromosomal sex and modal chromosome number.  If abnormalities are present, they are explained in a paragraph which helps to clarify and correlate chromosomal findings with phenotype. Genetic counseling is recommended when chromosome aberrations, mosaic conditions, or unusual results are found, along with recommendation for further testing (i.e. microarray).  References are included in the report to help the referring physician with interpretation, which include books or journals that contain appropriate information.

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