Reliability of 46 XX results on miscarriage specimens A review of 1222 first trimester miscarriage specimens

Capsule:
Maternal cell contamination often obscures accurate chromosome analysis of miscarriages, but testing can differentiate the maternal from fetal genome, thus improving detection of the true karyotype of pregnancy tissue.

Authors:
Ruth B. Lathi, M.D., Stephanie Lynn Fisher Gustin, M.D., Jennifer Keller, M.S., Melissa K. Maisenbacher, M.S., C.G.C., Styrmir Sigurjonsson, Ph.D., Rosina Tao, Zach Demko, Ph.D.

Volume 101, Issue 1, Pages 178-182, January 2014

Abstract:

Objective:
To examine the rate of maternal contamination in miscarriage specimens.

Design:
Retrospective review of 1,222 miscarriage specimens submitted for chromosome testing with detection of maternal cell contamination (MCC).

Setting:
Referral centers requesting genetic testing of miscarriage specimens at a single reference laboratory.

Patient(s):
Women with pregnancy loss who desire complete chromosome analysis of the pregnancy tissue.

Intervention(s):
Analysis of miscarriage specimens using single-nucleotide polymorphism (SNP) microarray technology with bioinformatics program to detect maternal cell contamination.

Main Outcome Measure(s):
Chromosome content of miscarriages and incidence of 46,XX results due to MCC.

Result(s):
Of the 1,222 samples analyzed, 592 had numeric chromosomal abnormalities, and 630 were normal 46,XX or 46,XY (456 and 187, respectively). In 269 of the 46,XX specimens, MCC with no embryonic component was found. With the exclusion of maternal 46,XX results, the chromosomal abnormality rate increased from 48% to 62%, and the ratio for XX to XY results dropped from 2.6 to 1.0.

Conclusion(s):
Over half of the normal 46,XX results in miscarriage specimens were due to MCC. The use of SNPs in MCC testing allows for precise identification of chromosomal abnormalities in miscarriage as well as MCC, improving the accuracy of products of conception testing.

  • Sandra Garcia-Herrero

    Interesting and revealing paper that shows the importance of maternal cell contamination (MCC) testing in order to evaluate real fetus chromosome status in products of conception (POC) from first trimester miscarriages.

    The substantial MCC rates differences found among different centers is striking and
    probably could be an example of the importance of the tissue collection method. In this paper, two tissue collection methods are described, uterine evacuation using suction or curettage and spontaneous passage of tissue, with high risk of maternal contamination. This manuscript emphasizes the importance of checking for maternal contamination for an accurate diagnosis. However, in high percentage of cases no conclusive results are obtained due to the presence of maternal cells. In our center another method is use to collect the tissue, histeroembryoscopy, consisting on a directed embryo or chorion biopsy performed at the beginning of the curettage (Ferro J et al, 2003). This direct method allows avoidance of MCC comparing conventional curettage.
    Therefore this technique combined with molecular analysis of fetal and
    maternal cells will improve not only accuracy but also efficiency in POC
    analysis.

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