ABSTRACT
OBJECTIVE: To construct valid reference standards reflecting optimal cerebroplacental ratio and to explore its physiological determinants. METHODS: A cohort of 391 low-risk pregnancies of singleton pregnancies of nonmalformed fetuses without maternal medical conditions and with normal perinatal outcomes was created. Doppler measurements of the middle cerebral artery and umbilical artery were performed at 24-42 weeks. Reference standards were produced, and the influence of physiological determinants was explored by nonparametric quantile regression. The derived standards were validated in a cohort of 200 low-risk pregnancies. RESULTS: Maternal body mass index was significantly associated with the 5th centile of the cerebroplacental ratio. For each additional unit of body mass index, the 5th centile was on average 0.014 lower. The derived 5th, 10th, and 50th centiles selected in the validation cohort were 5, 9.5, and 51% of the measurements. CONCLUSIONS: This study provides methodologically sound prescriptive standards and suggests that maternal body mass index is a determinant of a cutoff commonly used for decision-making.
ABSTRACT
Introduction: We aimed to compare the amniotic fluid interleukin (IL)-6 concentrations measured using the automated electrochemiluminescence immunoassay method and ELISA, and to establish an IL-6 concentration cut-off value for intra-amniotic inflammation (IAI) in preterm prelabor rupture of membranes (PPROM), which can be used in the automated electrochemiluminescence immunoassay method.Materials and methods: A total of 120 women with PPROM were included in this study. Amniotic fluid samples were obtained through transabdominal amniocentesis. IL-6 concentrations were assessed using both the automated electrochemiluminescence immunoassay method and ELISA, the current gold standard. IAI was defined as an amniotic fluid IL-6 concentration of ≥2600 pg/mL measured using ELISA.Results: A correlation between both assays was found (Spearman's rho = 0.97; p < .0001). Based on the receiver-operating characteristic curve for the identification of IAI (area under the curve = 0.99), a cut-off value of ≥3000 pg/mL was selected for the automated electrochemiluminescence immunoassay method with a sensitivity of 88%, specificity of 99%, positive predictive value of 97%, negative predictive value of 96%, and likelihood ratio of 76.Conclusions: For amniotic fluid IL-6 concentrations assessed using the automated electrochemiluminescence immunoassay method, a cut-off value of 3000 pg/mL was indicated for diagnosing IAI in women with PPROM.