[First trimester and second-trimester integrated screening for Down's syndrome].

OBJECTIVE: To evaluate the effect of first and second-trimester integrated screening so as to provide an efficient screening protocol for Down's syndrome. METHODS: Using the dissociation-enhanced lanthanide fluorescent immunoassay (DELFIA), the freeβhCG (beta human chorionic gonadotropin), PAPP-A (pregnancy associated plasma protein-A) and NT (nuchal translucency) value of type B ultrasound were assayed in the pregnancy serum during the first trimester (11-13W(+6) d) and free βhCG and AFP (alpha fetoprotein) during the second trimester(15-20W(+6) d). By the risk calculation software, the risks during both trimesters and their integrated risk were calculated for each patient respectively. Amniocentesis and venepuncture were employed for diagnosing the high-risk patients (> 1/270). Electronic network follow-up was carried out after delivery. RESULTS: In a total of 4237 pregnant women, 98 were found to carry a high risk during the first trimester, 241 during the second trimester and 101 during the integrated screening respectively. And 2, 3 and 4 cases were diagnosed with Down's symptom at a detection rate of 50%, 75% and 100% and a detection efficiency of 1:50, 1:80 and 1:25 respectively. CONCLUSION: Integrated screening is superior to either the first or second-trimester screening. With a lower false positive rate and a higher detection rate, it reduces the chance of invasive puncture. Advanced type B ultrasonic technology is needed to improve the first-trimester diagnostic efficiency and to develop a better integrated screening protocol.