Molecular Pathology Laboratory Network

CYTO PN

Chromosome analysis, cytogenetic analysis, karyotyping, prenatal diagnosis

Analysis of cultured amniocytes using G-banding

CPT codes by report:
88235 – Culture initiation
88269 – Chromosome analysis, in situ
88280 – Chromosome analysis, additional karyotype
88285 - Additional cells
88267 – Chromosome analysis, flask (sometimes required in place of 88269)
88291 – Interpretation and report

7-10 days

20-30 mL amniotic fluid in 2-3 sterile tubes, analysis can be attempted on smaller volumes

18-25°C for 48 hours

Specimen exposed to extreme temperature; Insufficient number of cells; Specimen exposed to fixative; Specimen obtained in syringe or tube toxic to cells

46,XY: normal male / 46,XX: normal female

For cytogenetic analysis with AFP, order test code: AF

Trans abdominal amniocentesis is usually performed at 15 to 19 weeks gestation, although it can be performed as early as 11 to 14 weeks. Generally, 20 to 30cc of amniotic fluid are obtained for prenatal diagnosic studies. Amniotic fluid consists of a fluid component and a cellular component that are separable by low speed centrifugation. The supernatant is used for studies such as alpha-fetaprotein (AFP) and acetylcholinesterase (AChE) to detect open neural tube defects and other fetal malformations. The cell pellet is grown in culture to obtain a sufficient number of cells for prenatal chromosome studies.

Chromosome analysis of cells obtained from amniotic fluid allows the detection of cytogenetic abnormalities in the fetus. Adjunct studies such as fluorescence in situ hybridization (FISH) can also be performed on cytogenetic preparations obtained from amniotic fluid. Indications for prenatal chromosome analysis include advanced maternal age, abnormal maternal serum screen, abnormal ultrasound, previous pregnancy or child with a chromosome abnormality, and/or a parent with a balanced chromosome rearrangement