A retrospective analysis of 6942 amniocentesis cases

The aim of the present study was to advance the understanding of prenatal diagnostic strategies by systematically analyzing gestational age, duration of pregnancy, clinical indications for prenatal testing, and the prevalence of chromosomal abnormalities among pregnant women undergoing amniocentesis.

This retrospective study involved 6,942 pregnant women with indications for amniocentesis who visited the Maternal and Child Health Hospital in Changzhi, Shanxi Province, between January 2018 and December 2023. Both the overall cohort and the subset of positive cases were stratified according to prenatal indications for amniocentesis into the following categories: advanced maternal age (AMA), abnormal maternal serum screening (MSS), noninvasive prenatal testing (NIPT)-positive, pathological ultrasound finding (PUF), parental chromosomal abnormality carrier (PCAC), and poor obstetric history (POH). The analysis encompassed the detection rate of chromosomal abnormalities via amniocentesis, the proportion and positive predictive value (PPV) of each indication group, the distribution of maternal age and gestational age, and the characteristic patterns of confirmed diagnostic findings. Statistical differences were evaluated via the nonparametric Mann-Whitney U test.

A total of 6,942 samples were included in the study. Of these, 38 samples (0.55%) with completely lost data were excluded. Samples with partially missing data were retained, including 18 cases (0.26%) lacking maternal age information, 23 cases (0.33%) missing gestational age data, and 8 cases (0.12%) without documented indications for prenatal diagnosis. The distribution of valid data was as follows: maternal age was available for 6,886 cases, gestational age was available for 6,882 cases, and prenatal diagnostic indications were available for 6,896 cases. A total of 557 cases of fetal chromosomal abnormalities were diagnosed, with an overall positive rate of 8.07%. Among the 6,882 valid gestational weeks analyzed, the overall range was 15-37 weeks. Specifically, 70.83% fell within 15-20.6 weeks, and 27.08% fell within 21-27.6 weeks, with positivity rates of 6.93% and 10.18%, respectively. A statistically significant difference was observed between the overall and positive groups (P < 0.05). Among the 6,886 cases with valid maternal age data, the overall age range was 17-50 years, with no significant difference observed between the overall population and positive cases. When the patients were stratified into A1-A6 age groups, statistically significant differences were observed among all groups except A1 (P < 0.05). Among the 6,896 valid cases with recorded prenatal indications, the percentages of MSS, AMA, MSS plus NIPT, NIPT, PUF, POH, and PCAC cases were 51.75%, 30.40%, 0.53%, 4.48%, 7.93%, 2.83%, and 0.40%, respectively. The corresponding PPVs were 4.12%, 8.05%, 94.59%, 42.81%, 8.66%, 5.56%, and 32.14%, respectively. Among the 557 positive cases, chromosomal abnormalities were distributed as follows: aneuploidy (65.35%), structural abnormalities (26.57%), mosaicism (7.18%), and marker chromosomes (0.54%). Autosomal aneuploidy was most frequently represented by trisomy 21, whereas 47,XXY was the most common sex chromosome aneuploidy. Structural abnormalities were most frequently represented by the 17p12 microdeletion. Regarding diagnostic approaches, 27.65% of the cases utilized a single method, 66.96% employed two methods, and 5.39% used three or more methods. Among the single-method cases, Chromosomal Microarray Analysis (CMA) was the most frequently selected technique (14.18%). For cases involving two diagnostic methods, the distribution was as follows (in descending order): karyotype plus QF-PCR (33.21%), QF-PCR plus FISH (17.24%), karyotype plus CMA (10.05%), CMA plus QF-PCR (6.28%), and CNV-seq plus QF-PCR (0.18%). The final analysis revealed that across different age and gestational age subgroups, prenatal indications, diagnostic outcomes, and invasive procedures were most concentrated in the 25-29-year age group and 15-20.6-week gestational age cohort. However, no statistically significant differences were observed among the subgroups (P > 0.05).

This study establishes that a risk-stratified approach optimizes prenatal chromosomal diagnosis: combining maternal serum screening with NIPT enhances detection (PPV 94.59%), while karyotyping and CMA respectively address numerical and structural abnormalities. NIPT proves particularly valuable for advanced maternal age, whereas ultrasound anomalies necessitate CMA. Diagnostic yield remains significant across gestational ages, supporting tailored clinical pathways. These findings underscore the importance of integrating multiple modalities for comprehensive prenatal evaluation.