Reasons why miscarriages occur
Miscarriage is a very common phenomenon. In recent years, the phenomenon of spontaneous miscarriage and embryonic abortion during early pregnancy has been on the rise, even accounting for 10%-20% of early pregnancies. 80% of miscarriages occur in the first trimester, which is what doctors call the early pregnancy period. There are many causes of miscarriage, mainly genetic factors, endocrine factors, immune factors, anatomical factors, infectious factors and so on. Among them, genetic factors are: genetic or chromosomal abnormalities of the embryo caused by the pregnant woman and her spouse’s own genetic or chromosomal abnormalities; and new genetic mutations or chromosomal abnormalities of the embryo during the formation of the embryo when the pregnant woman and her spouse’s own genetic or chromosomal abnormalities are normal. Some data show that embryonic genetic and chromosomal abnormalities are found in upwards of 70% of patients with recurrent miscarriage. The risk of miscarriage increases with the age of the pregnant woman. The risk of miscarriage rises to about 35% in pregnant women over 35 years of age.
Miscarriage tissue testing is essential for the next birth
Many couples pay attention to the choice of miscarriage procedure and post-abortion recovery after miscarriage or embryonic abortion, but neglect the detection of miscarriage tissue, not knowing that miscarriage tissue is crucial for the next birth. It can explain whether there is a genetic factor for this miscarriage and guide the miscarrying couple to choose the right treatment for the next pregnancy. If it is clear that the cause of two or more miscarriages is genetic, you can choose to receive preimplantation genetic diagnosis/screening (PGD/PGS) to help you conceive and avoid the great physical and psychological damage caused by one miscarriage after another. If the miscarriage is a non-genetic factor, you can further improve the examination to find other causes of miscarriage to achieve the target.
Choice of miscarriage tissue testing methods
Detection method
Indications
Description
Miscarriage tissue copy number variation
Early unexplained miscarriage or embryonic abortion
Detects 23 chromosome pairs and microdeletions and microduplications above 4Mb
Chromosome microarray
Mid to late stage ultrasound suggestive of multiple abnormalities induction of labor
Detects 23 pairs of chromosomes and microdeletions and microduplications of 100kb or more (1Mb=1000kb)
Fluorescence in situ hybridization
All available
Determined by probe type, with specific probes for each chromosome
Miscarried tissue sent for examination by
After miscarriage, rinse the flow products with sterile saline to remove as much blood clots as possible, put the rinsed flow products into sterile bags or sterile vials, and send them for examination at room temperature for 4-6 hours, and at low temperature (4 degrees, equivalent to the refrigerator’s freezing layer) within 24 hours, and field specimens can be sent in ice boxes.
Miscarriage tissue specimen selection
Early miscarriage specimens, take chorionic tissue for examination, chorionic tissue is coral-like, which is fetal tissue and can clearly detect whether there are genetic abnormalities in the fetus; at the same time, maternal blood (purple tube, 3ml) is taken for maternal blood contamination identification.
For mid- to late-stage abortions or induced products, the subcutaneous muscle or viscera of the fetus is taken for examination, without extracting maternal blood.