Department of Clinical Biochemistry, Training and Research Hospital, Usak University, Usak, Turkey.
Biochem Med (Zagreb). 2023 Feb 15;33(1):011001. doi: 10.11613/BM.2023.011001.
Serum samples are generally used for the measurement of human chorionic gonadotrophin (hCG) to calculate second-trimester maternal screening results. Lower hCG concentrations correlate with a lower calculated risk of Down syndrome (DS). Hence, erroneously low hCG results due to fibrin clot may lead to misinterpretation. We present a 23-year-old woman with a pregnancy of 17+3 weeks. Blood was taken into the Becton-Dickinson (BD) vacutainer SST-II Advance tube (Ref: 367955). The hCG test was performed on Immulite 2000 XPi analyser (Siemens Healthcare Diagnostics Inc, Tarrytown, USA) with original reagents. The results of the same sample were found as 2566 U/L, 18,153 U/L, and 7748 U/L. Three consecutive results after removal of the small fibrin clot and recentrifugation were 18,878, 20,255, and 22,339 U/L. The risk of DS and MoM for the concentration of 2556 U/L hCG was < 1/10,000 and 0.14, respectively. For a hCG concentration of 20,255 U/L, these values were 1/5632 and 1.13, respectively. Laboratory professionals and technicians should be aware that erroneously low hCG results can be measured with the Immulite 2000 XPi due to interference from small fibrin clots. Falsely underestimated hCG values reduce the MoM values and thus the calculated risk of DS.
血清样本通常用于测量人绒毛膜促性腺激素（hCG），以计算中期妊娠母体筛查结果。较低的 hCG 浓度与唐氏综合征（DS）的计算风险较低相关。因此，由于纤维蛋白凝块导致的错误低值 hCG 结果可能导致错误解读。我们介绍了一位 23 岁的女性，怀孕 17+3 周。从 Becton-Dickinson（BD）SST-II Advance 管（Ref：367955）中采集血液。hCG 测试在 Immulite 2000 XPi 分析仪（美国西门子医疗诊断公司）上使用原始试剂进行。同一样本的结果分别为 2566 U/L、18153 U/L 和 7748 U/L。去除小纤维蛋白凝块并再次离心后，连续三次的结果分别为 18878 U/L、20255 U/L 和 22339 U/L。浓度为 2556 U/L 的 hCG 的 DS 和 MoM 风险分别为 <1/10000 和 0.14。对于 20255 U/L 的 hCG 浓度，这些值分别为 1/5632 和 1.13。实验室专业人员和技术人员应该意识到，由于 Immulite 2000 XPi 受到小纤维蛋白凝块的干扰，可能会测量到错误的低值 hCG 结果。错误地低估 hCG 值会降低 MoM 值，从而降低 DS 的计算风险。
