Chromosome Analysis: Fetal Blood (Percutaneous Umbilical Blood Sampling/PUBS)

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Condition Description

This test will detect abnormalities in chromosome number and large deletions/duplications of chromosome material, as well as balanced chromosome rearrangements.

For most indications for cytogenetic testing (intellectual disability, developmental delays, autism spectrum disorders, multiple congenital anomalies, etc.) a chromosomal microarray has replaced the G-banded karyotype as the first-tier diagnostic test.  For more information about the benefits of the microarray, please click here.


Percutaneous Umbilical Blood Sampling (PUBS) is performed to test a pregnancy for a chromosome abnormality or other genetic condition, depending on the patient's family history and availability of testing. A karyotype or chromosome analysis is performed on the fetal blood sample.


PHA stimulated cultures are used for G-banded analysis. ISCN nomenclature is followed.


ISCN Nomenclature, minimum band resolution of 550.

Specimen Requirements

When sample fails to meet the acceptable criteria, please call 470.378.2200 and ask to speak with a laboratory genetic counselor (

Type: Cord Blood

Specimen Requirements:

In sodium heparin (green top) tube:
Fetal Blood (PUBS): 1-3 ml

Specimen Collection and Shipping: Ship sample at room temperature for receipt at EGL within 24 hours of collection. Do not refrigerate or freeze.

  • The EmArray Cyto (VA) may detect microdeletions/duplications that are not visible on a PUBS chromosome analysis and is recommended as a first tier diagnostic test.
  • When mosiacism is suspected but not detected on a PUBS chromosome analysis, a chromosome analysis for mosaicism (MM) in peripheral blood or a chromosome analysis on skin fibroblasts (CSKNC) may be warranted.
  • If there is a known chromosome abnormality in the family, such as a translocation, a targeted, family member chromosome study (FS) may be indicated.

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