To evaluate the performance of simultaneous amplification and testing assay for group B Streptococcus detection: comparison with real-time PCR and ddPCR assays.

BACKGROUND: To evaluate the performance of simultaneous amplification and testing (SAT) assay for the detection of group B Streptococcus (GBS) in maternal vaginal and perianal swabs compared with real-time polymerase chain reaction (RT-PCR). METHODS: We obtained vaginal and perianal swabs from 1474 pregnant women at the Obstetrics and Gynecology Hospital of Fudan University (Shanghai, China) between April 2023 and June 2023. Vaginal and perianal swabs were collected at 35-37 weeks of gestation. Swabs were tested for GBS simultaneously by using the SAT assay and RT-PCR, and a comparative analysis (kappa coefficient) was performed. Furthermore, we conducted additional droplet digital PCR (ddPCR) tests to confirm the results when there were controversial results between SAT and RT-PCR. In addition, we compared the limit of detection, technical specificity, repeatability and reproducibility of SAT-GBS with those of routine RT-PCR assays. RESULTS: In our study, the detection rate of clinical GBS according to the SAT assay was 11.5% (169/1471). The SAT assay showed a sensitivity of 91.8%, a specificity of 99.9%, a diagnostic accuracy of 98.9%, a positive predictive value (PPV) of 99.4% and a negative predictive value (NPV) of 98.8%. The kappa value between RT-PCR and SAT was 0.917. CONCLUSIONS: This SAT assay for the detection of group B Streptococcus is not only easy to perform but can also detect GBS sensitively and specifically and may be used in the regular molecular diagnosis of GBS infection among pregnancies.

Clinical application of expanded noninvasive prenatal testing for fetal chromosome abnormalities in a cohort of 39,580 pregnancies.

The aim of this study was to determine the predictive value of expanded noninvasive prenatal testing (NIPT-plus) for fetal chromosome abnormalities in the second trimester (12-26 weeks). We conducted a retrospective cohort study of 39,580 pregnancies with NIPT-plus. Screening positive cases were diagnosed with karyotyping and single-nucleotide polymorphism array analysis (SNP array)/copy number variation sequencing (CNV-seq) with follow-up. The positive predictive values (PPVs) of trisomy 21, 18, and 13 (T21, T18, and T13), sex chromosome aneuploidies (SCAs), and microdeletion and microduplication syndromes (MMS) by NIPT-plus were recorded. We assessed the predictive value of NIPT-plus based on maternal age and conventional indications. Of 39,580 pregnancies with NIPT-plus, 511 (1.3%) had prenatal screening positive results of fetal chromosome abnormality, of which 87.7% (448/511) had invasive prenatal diagnosis. NIPT-plus performed better in predicting fetal SCAs and chromosome aneuploidies for pregnancies with advanced maternal age (AMA) than young maternal age (YMA). Besides, the PPVs of T21, T13, and chromosome aneuploidies showed an upward trend when comparison was based on maternal age in 5-year subintervals. The termination rates of 45,X, 47,XXX, 47,XXY, and 47,XYY were 100% (11/11), 20.0% (3/15), 91.7% (22/24), and 7.1% (1/14) with postnatal follow-up. Last but not least, the PPV for MMS is 41.7% (30/72), which may have a positive correlation between the size of CNVs. Pregnant women with screen-positive results for common trisomies (T13, T18, and T21) were more willing to conduct invasive prenatal diagnosis compared to those with positive results for SCAs or MMS. However, the current study demonstrated SCAs and MMS had the lowest PPV. This highlights the importance of confirmatory prenatal diagnosis in those patients and the potential impact on genetic counseling and informative decision-making.

Threshold value of anti-Mullerian hormone for the diagnosis of polycystic ovary syndrome in Chinese women.

OBJECTIVE: We intended to establish the threshold for anti-Mullerian hormone (AMH) in the diagnosis of polycystic ovary syndrome (PCOS) in China. METHODS: A total of 771 women (653 with PCOS and 118 healthy controls) were enrolled. The serum AMH, follicle-stimulating hormone (FSH), luteinizing hormone (LH), FSH/LH, prolactin, estradiol, testosterone (T), dehydroepiandrosterone sulfate (DHEA-S), sex hormone-binding globulin (SHBG), 17α-OH progesterone (17α-OHP), fasting insulin (INS), fasting glucose, free androgen index (FAI%) and homeostasis model assessment for insulin resistance (HOMA-IR) index were analyzed, and the diagnostic utility of AMH, LH/FSH, T and INS was established using receiver operator characteristic (ROC) curves. With AMH, LH/FSH, T and INS as independent variables, a logistic regression model was established, and the ROC curve for combined detection was fitted with the probability value of the model. RESULTS: The serum level of FSH, LH, LH/FSH, AMH, FAI%, 17α-OHP, fasting INS, T, SHBG, DHEA-S and HOMA-IR were altered in the PCOS patients. The best compromise between sensitivity and specificity was found at an AMH cut-off level of 8.16 ng/ml and 5.89 ng/ml for the age groups 20-29 and 30-39 years, with the corresponding area under the curve being 0.846 and 0.865 respectively. The area under the ROC curve for combined detection was 0.951, which was significantly greater than that of each index. Finally, the concentration of AMH was associated with FSH, LH, LH/FSH, T, and ovarian volume in PCOS patients. CONCLUSION: The optimal AMH diagnostic threshold for PCOS was 8.16 ng/ml (20-29 years) and 5.89 ng/ml (30-39 years) in the Chinese population of this study. Moreover, serum AMH, LH/FSH, T and INS could be used in combination to improve the diagnostic specificity and sensitivity for the detection of PCOS.