ĐÁNH GIÁ SỰ SAI LỆCH KẾT QUẢ XÉT NGHIỆM DOUBLE TEST VÀ TRIPLE TEST TRONG CÁC ĐIỀU KIỆN BẢO QUẢN MẪU KHÁC NHAU

Abstract

Objective: To determine the rate of technical deviation in biochemical risk calculated by Double test under different sample storage conditions using the concentrations of biochemical markers free beta- hCG and PAPP-A; To evaluate the change in the concentrations of AFP, beta-hCG, and uE3 determined by triple test at different storage periods. Subjects & methods: The descriptive, comparative cross-sectional study was conducted at Ho Chi Minh City University of Medicine and Pharmacy. Double test: Serum samples were obtained from 15 women 11 – 13 weeks into their pregnancies who underwent first-trimester prenatal screening. Free beta-hCG and PAPP-A concentrations were determined under the following storage conditions: separated and analyzed within 12 hours; stored at 2-8°C for 96 hours and 120 hours (with and without serum separation). Triple test: Using retrospective data from 818 pregnant women at 15-21 weeks and 6 days of gestation, the concentrations of AFP, beta-hCG, and uE3 were compared among four different sample groups with storage times of 24, 48, 72, and 96 hours. Quantitative immunoassays were performed on Immulite 2000 and 1000 systems, and the risks were calculated using PRISCA 5.0. Further data analysis was performed on SPSS.  Results: Double test: Compared to samples analyzed within 12 hours at room temperature, we observed the following in samples stored at 2-7 °C. After 96 hours: the median free beta-hCG and PAPP-A concentrations showed no statistically significant difference; the calculated biochemical risks were 10% lower in both separated and unseparated samples. After 120 hours: the median PAPP-A concentration at 11 weeks of gestation was 16.1% higher in serum separated samples and 3.5% higher in unseparated samples; no difference was observed in the median free beta-hCG concentration across all gestational ages. The biochemical risk was 15% and 11% lower in separated and non-separated samples, respectively. Triple test: Compared to 24-hour storage, AFP concentration was 21.4%lower at 48-hour storage, 23% lower at 72-hour storage, and 31,9% higher at 96-hour storage. Beta-hCG concentration showed gradually increasing values with longer storage times: 38% higher at 48 hours, 37.2%higher at 72 hours, and 47.9%higher at 96 hours. uE3 concentration was 41.9.% higher at 48 hours and unchanged at 72 hours and 96 hours. However, this change only occurred at a few specific gestational weeks. Conclusion: Storing samples at 2-8°C for 96 hours did not alter free beta-hCG and PAPP-A concentrations; however, the calculated biochemical risk was lowered by 10%. When samples were stored for 120 hours at 2-8°C, the free beta-hCG concentration did not change, the median PAPP-A concentration was 16.1% higher at 11 weeks of gestation, and the biochemical risk was lowered by approximately 15%. A 48-hour storage time resulted in lower AFP and higher UE3 levels. Storage times of 72 hours and 96 hours increased AFP concentration. Beta-hCG concentration gradually increased with longer sample storage times at 48, 72, and 96 hours compared to 24 hours.