P15.17: Normal intracranial translucency at 11–13 + 6 weeks in Chinese population

Abstract

To evaluate the intracranial translucency (IT) at 11–13 + 6 week gestation fetuses in Chinese population. We conducted a prospective study including consecutive 366 singletons pregnancy women enrolled the first trimester combined test, the ultrasound include fetal NT, NB, TBF-WF, DV-WF, and FMF, and the maternal serum include free-β human chorionic gonadotropin (β-hCG) and pregnancy associated plasma protein (PAPP-A) at 11–13 + 6 weeks. During performed scan, two lines that define the IT are the posterior border of the brain stem anteriorly and the choroid plexus of the fourth ventricle posterioly also scan. All of the cases were checked the spinal bifida sign that were the lemon sign and banana sign. Which has led to the replacement of biochemical assessment with ultrasonography at 20 to 22 weeks. After the fetus delivery, well observation the fetal spine condition. There are 381 enrolled at 11–13 + 6 weeks first trimester screening including NT, NB, TBF, DVF, FMF angle measurement. There were 5 twins pregnancy excluded and only 371 cases the singleton, in which 5 chromosomal anomalies also excluded. There were 64 unsuccessfully measured IT and with 366 cases normal karyotype or low risk assessment successfully measured IT. The mean IT at CRL 45–55, 56–65, 66–75, and 76–85 were 1.67, 1.94, 2.0, and 2.11 mm respectively. The mean CRL 65.86 mm and mean IT 1.96 mm. The cranial translucency (IT) is none related to maternal age, serum free β-hCG and PAPP-A. It is increased the size with the gestational age. The algorithms with linear regression is IT (mm) = 0.0151X(CRL) + 0.9629, r2 = 0.1341. In the study group, all of the cases were checked the fetal cranial with ultrasonngraphlly showed none spina bifida signs of the ‘lemon sign’ and the ‘banana sign’ at 20 to 22 weeks and after the fetus delivery, observation the fetal spine condition normally. In 11–13 + 6 weeks scan, the mid-sagittal plane of the intracranial translucency is leaner increase the size with gestational age.