The sign is explored in the mid-sagittal plane of the fetal face and is defined as an absence of intracranial translucency (IT). We present a case report of prenatal.
20th World Congress on Ultrasound in Obstetrics and Gynecology
fluid (CSF) into amniotic cavity leading to caudal brain displacement. Conversely, ACM is absent in closed spinal dysraphism (CSD). In first trimester fetuses with OSD may have absence of IT due to caudal displacement of brain resulting in compression of the fourth ventricle. We report a case of fetus with normal IT in the first trimester and with the development of ACM in the second trimester. 31 year old primigravida presented for first trimester screening in 13 weeks. NT was 5.1 mm (3.18 MoM) and there was small omphalocoele and fetal edema. CVS was performed with karyotype 46,XY. In 16 weeks we diagnosed ACM (lemon and banana signs, atrial width 8 mm), omphalocoele, contractures of upper extremities and clenched hands. However, no spinal defect was localized. Because of strong suspicion to Edwards syndrome, we opted for iterative invasive testing. Amniocentesis was performed with karyotype 46,XY and normal AF-AFP of 16.4 IU/l (1.72 MoM). After counseling partners elected for termination of pregnancy. Anomalies noted at autopsy included CSD in sacral region, omphalocoele, contractures of extremities with fibrous bands, ventricular septal defect, facial dysmorphism. We retrospectively reviewed first-trimester images and 3D volumes and found normal IT and fourth ventricle. The possible explanation of inconsistent combination of ACM and normal IT in our case is that leakage in the first trimester was probably not sufficient enough for caudal brain displacement and compression of the fourth ventricle. Later leakage increased resulting in ACM, however, normal AF-AFP indicated CSF leaking probably not into amniotic cavity. Possible mechanism of CSF leakage in CSD explains exceedingly rare condition of dorsal enteric fistula opening into spinal canal which is associated with other malformation of viscera. This condition would correspond to our case.
P25.14 Three-dimensional transvaginal ultrasound diagnosis of open spina bifida at 13+2 weeks of gestation with an absent intracranial translucency D. Markov, E. Pavlova, P. Markov MC ‘Markovs’, Sofia, Bulgaria Spina bifida (SB) is the most common abnormality of the fetal central nervous system. Although sonographic diagnosis of open SB in midgestation is feasible, prenatal detection in the first trimester is still a challenge. Recently, a new ultrasound (US) marker of open SB at the 11–13+6 weeks scan has been described. The sign is explored in the mid-sagittal plane of the fetal face and is defined as an absence of intracranial translucency (IT). We present a case report of prenatal diagnosis of open SB at 13+2 weeks of gestation with an absent IT and discuss the added value of three-dimensional (3D) transvaginal (TV) US. Case report: A 31-year-old gravida 1, para 0, presented at 13+2 w.g. for a routine first trimester scan. The examination was performed with Voluson 730 Expert (GE Healthcare, US). A viable fetus (CRL = 67 mm) with normal nuchal translucency (NT = 1.48 mm) and present nasal bone was found. 3D TV US was performed due to presence of obvious distortion of the fetal spine. Reconstruction of the mid-sagittal plane of the fetal brain with static volume contrast imaging (VCI) revealed absence of the IT. The direct signs of open SB in the lumbo-sacral region were confirmed both in B-mode and with 3D surface rendering TV US. No other fetal abnormalities were detected. The patient opted for termination of pregnancy performed at 14+5 w.g. The diagnosis was confirmed post abortem. Discussion: It has recently been suggested that absence of the IT in the mid-sagittal plane of the fetal face might be a useful first trimester marker for open SB. TV US is the method of choice in all cases of suspected structural abnormality at the 11–13+6 scan. We suggest that TV 3D US with adequate volume data acquisition and appropriate angle insonation might substantially improve the visualization of IT. The latter approach is especially useful when additional techniques such as static VCI are employed. Hopefully, this might improve the prenatal diagnosis of open SB in the first trimester.
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Poster abstracts
P25.15 Intracranial translucency (IT) at 11+0 to 13+6 weeks in Chinese population M. Chen1,4 , H. Chen1,2 , H. Wang3,1 , T. Leung1 , D. Sahota1 , T. Lao1 , T. Lau1 1 Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Shatin, New Territories, China; 2 Department of Diagnostic Ultrasound, Guangzhou Obstetrics and Neonatal Hospital, Guangzhou, China; 3 Department of Ultrasound, the Second Clinical Medical College of Jinan University, Shenzhen People’s, Shenzhen, China; 4 Department of Diagnostic Ultrasound, Shangahi 1st Maternity and Infant Hospital, Tongji University, Shanghai, China
Objectives: To establish the reference range of intracranial translucency (IT) in the first trimester in a Chinese population. Methods: In a prospective study from Mar 2007 to June 2007, three-dimensional (3D) volumes of the fetal profile in the midsagittal plane were recorded from 102 normal pregnancies screened for trisomy 21 by the combination of fetal nuchal translucency (NT) thickness, maternal serum free β-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11+0 to 13+6 weeks. 3D volumes were examined using multiplanar techniques. In this plane the fourth ventricle presents as an intracranial translucency (IT) between the brain stem and choroid plexus. The anteroposterior diameter of IT in each case was measured. The relationship between IT with the other parameter was also examined. Results: The intracranial translucency (IT) at first trimester ranged from 1.35 mm to 2.6 mm. There was no significant association between the IT with NT, nasal bone length, serum PAPP-A or β-hCG. The intraobserver and interobserver agreement were assessed in 20 (19.6%) normal cases. Mean (SD) differences of two observers was −0.015 (0.132) mm (P > 0.05). For each observer, mean (SD) between the 2 paired measurements were −0.001 (0.097) mm, and 0.010 (0.085) mm, respectively (P > 0.05). Conclusions: In the first trimester, the intracranial translucency (IT) is visible. IT is not related to serum biochemistry.
P25.16 Intracranial translucency (IT) reference range for Chilean population at the 11–13+6 weeks scan ˜ 1,2 , G. Rencoret1,2 , J. Leiva2 , C. Diaz2 , C. Barrera2 , H. Munoz M. Rodriguez1 , V. Toledo1 , A. Germain2 UNF HCUC, Universidad de Chile, Santiago, Chile; 2 UMF, Clinica las Condes, Santiago, Chile
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Objectives: The mid sagital view of the face can be used for early detection of spina bifida. In this view, the fourth ventricle appears in between the brain stem and the coroidal plexus and can be assessed and measured. In the absence of this image an open spinal defect can be suspected. Our objective is to determine the normal range of the IT in a mid sagital view of the fetal face between 11–14 weeks for Chilean population. Methods: The 11–14 week ultrasound screening is performed in our center using the guidelines of the fetal medicine foundation. We searched for all our digital stored images of a mid sagital view of the fetal face al 11–14 weeks between november 2009 and march 2010. The images were examined by two operator who measured the anteroposterior diameter of the fourth ventricle as described by Chaoui et al. The IT and CRL was measured in all cases. The mean was calculated for CRL, NT and IT. Regression analysis was used to determine the significance of the association between the IT and CRL. Results: We examined 239 pictures of which 206 (86%) could be assessed. One fetus was diagnosed with spina bifida at the 22 weeks scan and the 11–14 week images examined. In this case the IT could not be assessed nor measured by both operators. The
Ultrasound in Obstetrics & Gynecology 2010; 36 (Suppl. 1): 168–305