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Chromosome Analysis and AFP with Reflex to AChE, Fetal Hgb, Amniotic Fluid

Test code(s) 14591

Yes, there are other studies that may be appropriate. There are many causes for fetal anomalies, some of which are genetic. In the absence of clinical suspicion for a specific genetic disorder, a microarray analysis may be performed to detect subtle deletions and duplications (Chromosomal Microarray, Prenatal, ClariSure® Oligo-SNP, test code 90927). If clinical suspicion exists for a specific disorder, there may be other genetic testing available. Please contact Quest Genomics Client Services at 866-GENE-INFO to discuss the case with a genetic counselor and for information on adding additional testing.

No. Please call Quest Genomics Client Services at 866-GENE-INFO to discuss this case with a genetic counselor. We need to know the specific genetic abnormality in the family, so we can determine whether the test’s resolution was sufficient to detect the abnormality.

This assay can rule out:

  • Trisomies such as trisomy 21 (Down syndrome), trisomy 18, and trisomy 13
  • Sex chromosome abnormalities such as Turner syndrome (45,X) and Klinefelter syndrome (47,XXY)
  • Most rearrangements, including Robertsonian translocations and inversions
  • Marker chromosomes
  • Mosaicism at or above 14% (at a 95% confidence level)
  • Most microscopically visible structural abnormalities

In addition to chromosome abnormalities, this test can detect conditions associated with an elevated alpha fetoprotein (AFP). Such conditions include open neural tube defects, abdominal wall defects, esophageal and duodenal atresia, and congenital hydronephrosis.

Fetal blood contamination of the specimen can cause an elevated AFP; therefore, a fetal hemoglobin test is performed to rule out a false-positive result. An acetylcholinesterase test is also performed to further clarify the cause of the elevated AFP. The presence of acetylcholinesterase is associated with an open neural tube defect, anencephaly, gastroschisis, other ventral wall defects, teratoma, hypoplasia of heart and lung, fetal demise, and fetal hemoglobin contamination. 

The fetal hemoglobin and the acetylcholinesterase tests are reported using separate CPT codes at an additional charge.

This assay cannot detect:

  • Subtle rearrangements, microduplications, and most microdeletion syndromes, including DiGeorge, Prader-Willi, Angelman, Williams, and Smith-Magenis syndromes
  • Mosaicism below 14% (at a 95% confidence level)
  • Single gene disorders such as fragile X syndrome, cystic fibrosis, Marfan syndrome, neurofibromatosis, etc.

Yes. The Maternal Cell Contamination Study, STR Analysis test (test code 10262X [10477X for NY]) can be performed if a maternal blood sample is submitted. If you are considering adding MCC studies to a completed prenatal case, please call Quest Genomics Client Services at 866-GENE-INFO to speak with a genetic counselor.

This FAQ is provided for informational purposes only and is not intended as medical advice. A clinician’s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.

Document FAQS.35 Version: 3
Version 3 effective 04/15/2016 to present
Version 2 effective 06/20/2014 to 04/14/2016
Version 1 effective 11/19/2012 to 06/19/2014
Version 0 effective 03/28/2012 to 11/18/2012