Comparison of six sonographic signs in the prenatal diagnosis of spina bifida.

AIMS: To compare the diagnostic accuracy of sonographic signs that may be looked for in fetuses with spina bifida. METHODS: Forty-nine fetuses affected by spina bifida were enrolled, at a gestational age of 18-28 weeks. The following sonographic signs were looked for: "lemon" sign, small cerebellum, effaced cisterna magna, small posterior fossa, ventriculomegaly and direct visualization of a spinal defect. RESULTS: The "lemon" sign was present in 53%, a small cerebellum in 96%, an effaced cisterna magna in 93%, a small posterior fossa in 96%. Ventriculomegaly was present in 40/49 (81%) cases and was severe in 20 fetuses and borderline in the remaining 20. The spinal defect was missed in one fetus presenting the cerebellar and posterior fossa signs. In two fetuses, the myelomeningocele was present without cranial signs of Chiari II malformation and in both cases the defect was covered by intact skin. CONCLUSIONS: Our results confirm the usefulness of evaluation of the posterior fossa in the diagnosis of spina bifida, particularly in cases of small spinal defects that may be missed at ultrasound. Conversely, myelomeningocele covered by intact skin was not associated with the cranial signs of Chiari II malformation.

Sonographic diagnosis of fetal cerebral ventriculomegaly: an update.

Dilatation of the fetal cerebral ventricles (ventriculomegaly) is a generic sonographic sign that is common to several pathological entities carrying different prognoses. The main causes of fetal ventriculomegaly are aqueductal stenosis, Chiari II malformation, Dandy-Walker complex, and agenesis of the corpus callosum. Ventriculomegaly is easily recognized by ultrasound by measuring the atrial width. This simple measure allows the recognition of mild forms of ventricular dilatation and is used in screening for ventriculomegaly. However, although the diagnosis of ventriculomegaly is easy, the prenatal identification of the cause of ventricular dilatation is a more difficult task. For this purpose the evaluation of the posterior fossa in association with the visualization of the corpus callosum is useful. Research into the causes of ventriculomegaly is clinically useful, since the prognosis mainly depends on the etiology and on the presence of associated abnormalities. In this article the role of prenatal sonography in determining the cause of the ventriculomegaly is reviewed, as well as the prognostic value of the prenatal sonographic findings.

The midsagittal view of the fetal brain: a useful landmark in recognizing the cause of fetal cerebral ventriculomegaly.

AIM: To evaluate the positive predictive value of the midsagittal view of the fetal brain in recognizing the cause of ventriculomegaly diagnosed with traditional axial scan. METHODS: Fifty-eight pregnant women, referred to our Center following a generic diagnosis of ventriculomegaly have been evaluated: 38 had marked and 20 had borderline ventriculomegaly. The fetal brain was scanned by the midsagittal view using a transabdominal probe in fetuses in breech presentation or transverse lie and a transvaginal probe in fetuses in cephalic presentation. The possible cause of ventriculomegaly was postulated by combining the findings of the corpus callosum/cavum septi pellucidi complex with those of the posterior fossa. The prenatal diagnoses were compared with the anatomical specimens of aborted fetuses or with postnatal neuroimaging. RESULTS: The prenatal diagnoses were confirmed in 54/58 cases (PPV 93.1%). In the marked ventriculomegaly group, one case of partial agenesis of the corpus callosum was mistaken for a complete agenesis. In the group of borderline ventriculomegaly, two cases of partial agenesis of the corpus callosum were confused with a complete agenesis, while one case of suspected isolated ventriculomegaly was diagnosed after birth as partial agenesis of the corpus callosum. CONCLUSIONS: The sagittal scan of the fetal brain is a useful source of information and allows the contemporary view of both corpus callosum and posterior fossa, where various typical sonographic findings are present in ventriculomegaly.

Fetal subependymal cysts with normal neonatal outcome. A case report.

The authors report the prenatal sonographic diagnosis of subependymal cysts, confirmed by in utero MRI, in an apparently uneventful pregnancy. The sonographic appearance of the lesions, the obstetric management and the postnatal follow-up to one year are described. Special attention is paid to prenatal factors of neurological morbidity, rather than intrapartum and postnatal, thus emphasizing the importance of early and sequential evaluation of the developing fetal brain. Diagnosis, clinical significance and outcome of prenatal subependymal cysts are necessary for parental counselling and obstetric management. Furthermore, the detection of a prenatal brain injury may have remarkable medico-legal implications.

Prenatal diagnosis and postnatal outcome of cardiac rhabdomyomas.

AIMS: To evaluate the sonographic appearance of suspected fetal cardiac rhabdomyomas and their evolution until delivery and in the postnatal period. METHODS: The study group consisted of 6 patients at 23-37 weeks of gestation referred to our Ultrasonic Unit, between March 1992 and December 1998, for suspected fetal cardiac rhabdomyomas. RESULTS: The cardiac tumors were single in three cases and multiple in the other cases. The size ranged from 11 to 47 mm. In two cases the tumors arose from the right ventricle, in one case from the interventricular septum and in three cases from the left ventricle. Five infants are alive and in satisfactory hemodynamic compensation, but three of them developed tuberous sclerosis. In two infants a regression in the maximum diameter of the tumor masses has been observed. One child underwent surgical treatment at the age of six months and the baby died after surgery. CONCLUSIONS: Two-dimensional and Doppler echocardiography are useful non invasive methods to diagnose fetal cardiac rhabdomyomas and to monitor their influence on the fetal cardiac function. However they do not allow us to recognize which fetuses presenting with features compatible with rhabdomyomas will develop tuberous sclerosis.