Nomogram of Intracranial Translucency in the First Trimester Ultrasound of Pregnant Women at Thammasat University Hospital
Tongta Nanthakomon MD*, Densak Pongrojpaw MD*, Athita Chanthasenannont MD*, Charintip Somprasit MD*, Chamnan Tanprasertkul MD*, Komsun Suwannarurk MD*
Affiliation : * Department of Obstetrics and Gynaecology, Faculty of Medicine, Thammasat University, Pathumthani, Thailand
Objective : The aim of the study was to determine normative values of intracranial translucency (IT) by ultrasonography in
singleton pregnant women patient at Thammasat University Hospital during the first trimester.
Material and Method: The first trimester singleton pregnant women (11-13 weeks) underwent routine ultrasonography
screening. The gestational age was calculated by measuring the length of the embryo or fetus from the top of its head to bottom
of the buttocks (crown-rump length; CRL) and IT of the brain region in the mid-sagittal planefetal face position. Repeated
ultrasonography was performed in the second trimester period as well as after birth infant check-up for disability.
Results : One hundred and ninety one singleton pregnant women were examined by an ultrasonography to measure CRL, GA
and IT. The average age was 29.71+5.09 years (16-39 years). All participants were healthy without a history of anomaly in
previous pregnancies. Half of cases were nulliparity. Participants were followed until birth. There was no open neural tube
defect baby in this study. Median GA, CRL and IT in this study were 12.6+0.7 weeks, 64.0+10.2 (40.0-80.9) and 1.3+0.3 (0.5-
2.5) mm, respectively. IT measurement value increased in correlation with increasing CRL and advancing GA (p<0.05).
Conclusion : IT values increased significantly with CRL and GA increasing.
Keywords : First trimester, Intracranial translucency, Ultrasound
