1. What is abortion?
Abortion refers to those who are pregnant less than 28 weeks and whose fetal weight is less than 1,000 g and who abort the pregnancy. They can be divided into natural abortion and induced abortion.
The incidence of spontaneous abortion is 10% ~ 15%, which is mostly caused by embryo chromosomal abnormalities. It is reported in the literature that 50% of abortions with pregnancy less than 12 weeks are caused by embryo chromosomal factors, while 1/3 of abortions in the second trimester are caused by embryo chromosomal abnormalities.
Recurrent miscarriage refers to spontaneous abortion ≥ 2 times, of which about 50% ~ 60% are embryo chromosomal abnormalities.
Types of chromosomal abnormalities include abnormal numbers of chromosomes and structural abnormalities. The majority of chromosomal abnormalities in spontaneous abortion are number abnormalities, about 86%, structural abnormalities are 6%, and chromosomal chimerics account for 8%.

 2. How to avoid maternal pollution when collecting abortion tissue?

If it is a miscarriage in the first trimester (unformed fetus), try to collect fetal villi or fetal buds.
If it is a mid / late pregnancy miscarriage (the fetus is already formed), it is recommended that doctors take the sampling priority as: umbilical cord blood, umbilical cord tissue (close to the fetus), and fetal heart blood. Other fetal tissues are not conducive to this test. The size of soybean particles collected from aborted tissues (both are fetal tissues), and the checklist must clearly indicate the tissue location, which is convenient for laboratory personnel to interpret.