Products of Conception (POC) is a medical terminology extensively used to refer to tissues, which develop during pregnancy. This term is frequently used after pregnancy loss, like a miscarriage. POC is substantially used for the identification of fetal tissue, placenta tissue, or other derivatives from fertilization.

Chromosomal causes of miscarriages

Spontaneous miscarriage is reported in approximately 10-15% of all clinically recognized pregnancies. Chromosomal aneuploidies are often regarded as the most common cause of first-trimester miscarriage, resulting in 50% of spontaneous abortions approximately2. Aneuploidies evident from the POC involve almost every chromosome (as shown in the image below), with trisomies as the most frequent one3.


The value of testing POC

While taking into account the impact of genetic factors on miscarriages, POC testing can be regarded as immensely essential testing following an early pregnancy loss. Majority of miscarriages are caused by sporadic chromosomal abnormalities, and the chances of recurrence of such foetal aneuploidies reduce with subsequent pregnancies4. While several chromosomal abnormalities responsible for miscarriages are sporadic and possess a low recurrence risk, some abnormalities (like translocations) are presumed to significantly enhance the risk of recurrence – which might further demand parental karyotyping.

The POC testing can identify pregnancy losses related to chromosomal abnormalities, thereby, preventing patients from undergoing unnecessary and costly evaluations5. Moreover, the psychological advantage of the assessment of the aetiology of foetal loss, cannot be understated5. Additionally, if the test excludes the contribution of fetal chromosomal abnormality for the miscarriage then, other possible physiological reasons could be traced and treated. Therefore, genetic testing results can be utilised as a guide for counselling future pregnancies.


Current Challenges of POC Testing with Conventional Karyotyping

High Failure Rate Due to Culture FailureInability to Pick Up Maternal Cell ContaminationLow Resolution : 5MB is the smallest deletion/gain can detect

Advantages Of Chromosomal Microarray

  1. Evaluates hundreds of genetic conditions across the genome with a single test.
  2. Detects aneuploidy (including monosomy, trisomy, and sex chromosome abnormalities) and triploidy.
  3. Independent of cell culture; thus reducing test failure rates, frequently seen with karyotype.
  4. Identifies deletions and duplications in regions which are commonly associated with well-characterized microdeletion and microduplication syndromes.
  5. Provides enhanced coverage of the subtelomeric regions, often undetectable with the traditional chromosome analysis.
  6. Rules out maternal cell contamination (MCC) in cases where maternal blood gets mixed along with a tissue sample.
  7. Often permits delivery of results on suboptimal specimens, which is not feasible with traditional cytogenetic tests.

Lifecell Diagnostics’ Products of Conception (POC) testing Option:

Test Description:

This test package evaluates fetal cells after a pregnancy loss and is performed using a combination of chromosomal microarray and advanced QF PCR to detect chromosomal or other genetic abnormalities in the evaluation of miscarriages and IUFD.

Test Packages


Chromosomal Microarray Analysis

  • Highly sensitive test with >99% sensitivity detection for chromosomal deletion & duplication
  • Whole genome coverage (18,018 CNV & 148,450 SNP)
  • Increased coverage density targeting 396 empirically selected regions relevant for prenatal loss ( 25markers/100kb)
  • Can detect low level of mosaicism
  • A minimum resolution of 500kb for loss/ gain and 5MB for LOH/AOH
  • Detects MCC
  • TAT- 10 Days

QF PCR-EXTENDED with 20 Common Microdeletions and Duplications

  • Targeted Rapid diagnostic test using DNA
  • Covers Triploidies and most common aneuploidies- 18,13,21,15,16,22 & Gonosomes
  • Detects MCC
  • 20- Microdeletions & Duplication
  • TAT : 2 Days

References

  1. Rai R, Regan L. Recurrent miscarriage. Lancet. 2006;368(9535):601-611. doi:10.1016/S0140-6736(06)69204-0.
  2. van den Berg MMJ, van Maarle MC, van Wely M, Goddijn M. Genetics of early miscarriage. Biochim Biophys Acta. 2012;1822(12):1951-1959. doi:10.1016/j.bbadis.2012.07.001.
  3. Shen J, Wu W, Gao C, et al. Chromosomal copy number analysis on chorionic villus samples from early spontaneous miscarriages by high throughput genetic technology. Molecular Cytogenetics. 2016;9(1):7. doi:10.1186/s13039-015-0210-z.
  4. Recurrent Miscarriage, Investigation and Treatment of Couples (Green-top Guideline No. 17). Royal College of Obstetricians & Gynaecologists. https://www.rcog.org.uk/en/guidelines-research-services/guidelines/gtg17/. Accessed July 2, 2019.
  5. Sahoo T, Dzidic N, Strecker MN, et al. Comprehensive genetic analysis of pregnancy loss by chromosomal microarrays: outcomes, benefits, and challenges. Genet Med. 2017;19(1):83-89. doi:10.1038/gim.2016.69.