Adegoke Adeniji

OC12.02: Spina bifida detection at 11–14 weeks: systematic analysis of technical factors associated with false‐positive and false‐negative image interpretation

Objectives: Screening at 11–14 weeks is changing from a simple NT measurement to a comprehensive first trimester anomaly scan. However, the detection of open neural tube defect (NTD) before 14 weeks is still a challenge, since lemon and banana signs, used in second trimester ultrasound, are rarely present. Aim of the study is to seek for simple first trimester signs to alert the examiner for the presence of NTD. Methods: The midsagittal view of the face used for NT and nasal bone measurements was analyzed in normal fetuses and fetuses with NTD. The region between the brain stem and occipital bone, includes the 4th ventricle (intracranial translucency = IT), the choroid plexus of the 4th ventricle and the future cisterna magna. Results: In normal fetuses between 11–14 weeks there is an increase in the anterior posterior diameters of posterior fossa structures. Fetuses with NTD detected prospectively and retrospectively showed however abnormal values due to the downward shifting of the brain stem. Conclusions: In the plane used for NT measurement the evaluation of the posterior part of the brain between the brain stem and the occipital bone appears to be the clue in suspecting NTD at the 11–14 weeks scan. Further prospective studies are needed to find the sensitivity of these observations during routine screening.

OC12.03: Visualization of the fourth ventricle in first trimester fetuses with a normal spine versus spina bifida

Objectives: Screening at 11–14 weeks is changing from a simple NT measurement to a comprehensive first trimester anomaly scan. However, the detection of open neural tube defect (NTD) before 14 weeks is still a challenge, since lemon and banana signs, used in second trimester ultrasound, are rarely present. Aim of the study is to seek for simple first trimester signs to alert the examiner for the presence of NTD. Methods: The midsagittal view of the face used for NT and nasal bone measurements was analyzed in normal fetuses and fetuses with NTD. The region between the brain stem and occipital bone, includes the 4th ventricle (intracranial translucency = IT), the choroid plexus of the 4th ventricle and the future cisterna magna. Results: In normal fetuses between 11–14 weeks there is an increase in the anterior posterior diameters of posterior fossa structures. Fetuses with NTD detected prospectively and retrospectively showed however abnormal values due to the downward shifting of the brain stem. Conclusions: In the plane used for NT measurement the evaluation of the posterior part of the brain between the brain stem and the occipital bone appears to be the clue in suspecting NTD at the 11–14 weeks scan. Further prospective studies are needed to find the sensitivity of these observations during routine screening.

OC12.05: Visualization and measurement of the cisterna magna and maximal posterior fossa translucency for spina bifida screening at 11–13 weeks gestation

Methods: We retrospectively assessed the 2D and/or 3D dates from the pregnancies undergoing routine ultrasound examination at 11–13 weeks’ gestation during 2009–2010, as part of screening for chromosomal abnormalities. Our targets of evaluation consisted in: spine aspect, cranium and intracranial anatomy of choroids plexus, thalamic angle, cerebellum aspect and antero-posterior measurement of the fourth ventricle in the mid-sagital view of the fetal face, recently described (2009) as intracranial translucency (IT). Results: All the 1749 fetuses without NTD presented measurable IT with median values at 11–13+6 weeks between 1.39 and 2.62 mm. From the cases diagnosed with open spina bifida, 2 underwent 11–13+6 scan in our clinic and both cases presented abnormal early neurosonogram: in one case we found abnormalities in cranium shape, choroids plexus, IT and aspect of the cerebellum; in the second case the only detectable sign was IT not detectable/measurable. Both of them resulted in sacral spina bifida and none presented abnormalities in the first trimester spine evaluation. Measurement of the IT is reproducible and in 95% of cases the difference between two consecutive measurements by the same or two sonographers is <5%; and second, the measurements of the FMF angle obtained by 3D and 2D ultrasound are similar. Conclusions: The mid-sagittal view of the face as routinely used in screening for chromosomal defects could offer an important diagnostic marker for the detection of CNS anomalies in the very early pregnancy.