Karyotyping of 1 437 Cases First Trimester Spontaneous Abortus

Objective: To analyze the incidence of abnormal karyotypes in spontaneous abortus during early pregnancy. Methods: The spontaneous abortive villi samples were in vitro cultured right after curettage to analyze fetal chromosomes, the karyotypes were documented and statistical analyzed. Results: A total of 1 437 patients with an average age of 31.2± 4.4 years and mean gestational period of 66.5± 14.1 d were collected. And 1 390 cases were successfully cultured(96.73%), and 47 cases were failed(3.27%). Of the successfully cultured cases, 595 cases were normal(42.81%), 795 cases were abnormal(57.20%). The main abnormal karyotype was aneuploidy, including 571 cases(accounted for 71.82% of abnormal karyotype). The top five aneuploidies were: trisomy 16(21.54%); trisomy 22(15.41%); 45, X(14.01%); trisomy 15(4.38%); trisomy 13(4.20%). Structural abnormalities like unbalanced translocation, Robertson's unbalanced translocation, deletion, insertion, inversion, markers,etc., were in small proportion, about 3.52% of total spontaneous abortions and 6.16% of total abnormalities. Patients were divided into 35 years and ≥ 35 years old groups. The abnormal karyotype rates in the two groups were 55.30% and 63.69% respectively, with a significant difference(P=0.008); aneuploidy rates were 68.74% and 81.00% respectively with a significant difference(P=0.001). Differences of incidence of mosacism, triploidy and tetraploidy were not significant. The structural abnormalities were 8.07% and 0.50% respectively with a significant difference(P0.001). The normal and abnormal karyotype rates in the first time spontaneous abortion were 38.36% and 61.64%; 44.56% and 55.44% in the second abortion; and 47.38% and 52.62% in the third or more times abortion patients. The difference was significant. Conclusion: The main reason for spontaneous abortion in early pregnancy is abnormal fetal karyotype, and aneuploidy is the major abnormal karyotype. Incidence of abnormal karyotype and aneuploidy in aged women is increased, but structural abnormalities were decreased. The more times of spontaneous abortions, the less percentage of abnormal karyotyps, this indicates that the times of abortion is a risk factor for spontaneous abortion.