A novel technique for visualization of the normal and cleft fetal secondary palate: angled insonation and three-dimensional ultrasound.

OBJECTIVE: To evaluate the effectiveness of a novel approach to the visualization of the fetal secondary palate using three-dimensional (3D) ultrasound. METHODS: Sonographic examinations were performed in normal fetuses and in one fetus with cleft lip and palate. To avoid acoustic shadowing from the alveolar ridge, the secondary palate was insonated at a 45 degrees angle in the sagittal plane, and 3D ultrasound was used to reconstruct axial and coronal planes. RESULTS: The secondary palate was successfully visualized in 10 of 15 normal fetuses, both in the axial and coronal planes. In the fetus with cleft lip and palate the lesion of the secondary palate was clearly demonstrated, particularly in the coronal plane. CONCLUSION: Angled insonation and 3D ultrasound allow clear visualization of normal and cleft secondary palate.

Prenatal diagnosis of open and closed spina bifida.

OBJECTIVE: To identify criteria useful for differentiating closed from open spina bifida antenatally. PATIENTS AND METHODS: A retrospective study of cases of spina bifida diagnosed in a referral center between 1997 and 2004. RESULTS: Of 66 cases of fetal spina bifida diagnosed at a median gestational age of 21 (range, 16-34) weeks, detailed follow-up was available for 57. Of these, open defects were found in 53 (93.0%) and closed defects in four (7.0%). Closed spina bifida was associated in two cases with a posterior cystic mass with thick walls and a complex appearance, while in two cases the spinal lesion could not be clearly differentiated from an open defect, particularly at mid-gestation. Open spina bifida was always associated with typical alterations of cranial anatomy, including the so-called 'banana' and 'lemon' signs, while in closed spina bifida the cranium was unremarkable. When the data were available, levels of amniotic fluid alpha-fetoprotein were always abnormally elevated with open spina bifida and within normal limits with closed forms. CONCLUSION: In this study 7% of cases of spina bifida diagnosed in utero were closed. The differentiation between open and closed forms is best shown by the sonographic demonstration of abnormal or normal cranial anatomy.

Accurate neurosonographic prediction of brain injury in the surviving fetus after the death of a monochorionic cotwin.

OBJECTIVE: To assess the feasibility of the prenatal diagnosis using fetal neurosonography of brain injuries in the surviving fetus after the demise of a monochorionic cotwin. METHODS: This was a retrospective observational study in the period 1990-2004 of monochorionic twin pregnancies with a single fetal demise. A detailed sonographic evaluation of the intracranial anatomy of the surviving twin had been performed whenever possible using a multiplanar approach and from 1999, fetal magnetic resonance imaging was offered as well. Postnatal follow-up was obtained in all cases. RESULTS: In six of nine cases, abnormal neurosonographic findings were identified including intracranial hemorrhage, brain atrophy, porencephaly and periventricular echogenicities evolving into polymicrogyria. Prenatal diagnosis of brain lesions was confirmed postnatally and all affected infants who survived had severe neurological sequelae. Two fetuses had normal cerebral structures both on the prenatal neurosonogram and on postnatal imaging and were following normal developmental milestones, one at 1 and the other at 5 years of age. In one case the neurosonographic examination was suboptimal and the infant was found at birth to have a porencephalic cyst. Fetal magnetic resonance imaging was performed in two cases and confirmed the ultrasound diagnosis. CONCLUSIONS: Prenatal neurosonography is a valuable tool for the prediction of neurological outcome in fetuses surviving after the intrauterine death of a monochorionic cotwin. Although our experience is limited, we suggest that magnetic resonance imaging should also be offered.

Diagnosis of midline anomalies of the fetal brain with the three-dimensional median view.

OBJECTIVE: To investigate the effectiveness of a simplified approach to the evaluation of the midline structures of the fetal brain using three-dimensional (3D) ultrasound. METHODS: Sonographic examinations were performed in normal fetuses and in cases with anomalies involving the midline cerebral structures. Two-dimensional (2D) median planes were obtained by aligning the transducer with the anterior fontanelle and midline sutures by either transabdominal or transvaginal scans. Median planes were also reconstructed using 3D ultrasonography from volumes acquired from transabdominal axial planes of the fetal head (3D median planes), by either multiplanar analysis of static volumes or volume contrast imaging in the coronal plane (VCI-C). 2D and 3D median planes were compared qualitatively and quantitatively by measuring the corpus callosum and cerebellar vermis. RESULTS: 2D median planes could be visualized in 54/56 normal fetuses. 3D median planes were obtained in all, usually more easily and rapidly. There was a good correlation between 2D and 3D images. Measurements of the corpus callosum and cerebellar vermis were highly correlated, with mean variations of 6% and 14%, respectively. The abnormal group included 13 fetuses (five with partial or complete agenesis of the corpus callosum, six with posterior fossa malformations, two with a combination of these two anomalies). In all cases the diagnosis could be made by both 2D and 3D views and was always confirmed by postnatal investigation. Although 2D median views were of better quality, 3D images were always adequate for diagnosis, both in normal and abnormal fetuses. CONCLUSIONS: 3D median planes are obtained more easily than 2D ones, and allow an accurate diagnosis of normal cerebral anatomy and anomalies. The 3D approach may be valuable particularly for rapid assessment of fetal cerebral anatomy in standard examinations.

Sonographic diagnosis of congenital anomalies during the first trimester.

Current ultrasound technology allows an examination of fetal anatomy and the detection of anomalies at 12-15 weeks. Studies assessing the accuracy of early sonographic diagnosis prior to 15 weeks of pregnancy were reviewed. In expert hands the detection rate is about 40 per cent for major extra-cardiac anomalies and 65 per cent for major cardiac defects. However, due to technical and practical limitations, sonographic assessment of fetal anatomy in the first trimester cannot replace the midtrimester scan and should be restricted to couples whose fetus is at increased risk for malformation.