Conventional karyotype
- Requires in vitro cell culture
- 42% of the tests performed are not informative due to tissue degradation
- 33.3% are false negatives due to maternal contamination
- Results are provided in 2-4 weeks
- Low resolution analysis
NGS (POC)
- it does not require in vitro culture
- More than 98% of tests performed have conclusive results
- This technique rules out false negatives caused by maternal cell contamination
- Results are obtained in 1 week
- Higher resolution than conventional karyotyping
50% of first trimester miscarriages are due to chromosomal abnormalities In women who undergo assisted reproduction this number exceeds 60%
What is POC?
NGS is a molecular technique that allows all 24 chromosomes to be studied in order to rule out aneuploidies in fetal tissue.
- It does not require in vitro culture before the analysis. Thereby increasing the proportion of cases which obtain results reducing the time required to acquire them.
- In addition, the analysis of microsatellite markers in blood collected allows maternal cell contamination to be detected reducing the chances of false negatives.
What is POC useful for?
- Aneuploidies are chromosomal abnormalities that can lead to spontaneous miscarriages and chromosomal disorders in newborns (babies).
- Chromosomal abnormalities are responsible for 50% of first trimester miscarriages occuring in both spontaneous conceptions and pregnancies resulting from assisted reproductive treatments.
- Genetic diagnosis of the Products of Conception (POC) is necessary to identify the etiology of a gestation failure and to ensure appropriate counseling is provided to the couple.
Who is POC indicated for?
It is recommended to any couple who have suffered a pregnancy loss, but especially to those who have experienced recurrent miscarriages or are undergoing assisted reproductive treatments.
How should the sample be collected?
The sample is obtained either by direct biopsy after pre-curettage hysteroembryoscopy (which is then collected and transported in a 10 ml conical tube in sterile saline solution), or in conventional curettages samples (as far as possible avoiding the inclusion of maternal tissue) that are placed in a urine collection vial containing sterile saline. It is essential to also include 5 ml of maternal blood collected in an EDTA vial.
How should the sample be shipped?
The sample is transported at room temperature in a sealed tube or urine collection vial using appropriate protective measures for shipment. The sample must be shipped within 48 hours. The sample should be stored at 4°C/ 39°F at the place of origin before transport.
How long does it take to obtain results?
The laboratory protocol requires between 24h - 48h. The reports are issued within 1 week after we receive the sample.
Identifying the cause of pregnancy loss may be of great benefit to couples who have experienced recurrent miscarriages
Limitations
This technique does not detect structural chromosomal abnormalities and cannot identify: low degree mosalcism aneuploidies, triploldy/tetraploidy, uniparental disomy, deletions or duplications smaller than 10Mb.
Campos-Galindo I, Martinez-ConejeroJA, Garcia-Herrero S, Ayala-Alvarez G, Rubio lluesa C. Tecnologia BACs-on-BeadsTm aplicada at diagnOstico prenatal y al estudio citogenetko de restos abortions. Diag Pren. 2012 Volume 23, Issue 2, April-June 2012: 76-82. Ferro, Jaime; Martinez, Ma.Carmern Lam, Coral; Pellicer, Antonio; Remohi, Jose; Serra, Vicente. Improved accuracy of hysteroembryoscopic biopsies for karyotyping early missed abortions. Fertility and Sterility vol. 80 issue 5 November, 2003. p. 1260-1264.
Martinez MC, Mendez C, Ferrol, Nicolas M, Serra V, Landeras J. Cytogenetic analysis of early nonviable pregnancies after assisted reproduction treatment. Fertil Steril. 2010 Jan;93I1):289-92
