Evaluation of the lemon and banana signs in one hundred thirty fetuses with spinal bifida

Article Abstract:

Spina bifida is a birth defect characterized by the abnormal development of the nerve tube. The defect prevents the bone structures housing the spinal cord from closing, leaving the nerves completely or partially exposed. Fetuses with open spina bifida have additional deformities in the skull and brain. Ultrasound, the use of high frequency sound to visualize internal structures, can be used to detect defects of the brain and skull of the fetus. The two markers, the lemon sign (scalloping in the frontal bone of the brain) and the banana sign (curvature of the two cerebral hemisphere of the brain) are abnormal shapes appearing on ultrasonographic images, and the presence of these lemon- or banana-shaped brain images has been associated with spina bifida. The accuracy of the two ultrasonographic markers used to identify neural tube defects were evaluated in 1,561 high-risk fetuses. One hundred thirty of the fetuses had open spina bifida. The age of the fetus was related to the appearance of the two markers. The lemon sign was found in 98 percent of the spina bifida fetuses younger than 24 weeks in gestational age and in 13 percent of those older than 24 weeks. Abnormalities in the cerebellum of the brain were present in 95 percent of the spina bifida fetuses regardless of fetal age. The banana sign was the predominant defect in 72 percent of the fetuses less than 24 weeks' gestation and an 'absent' cerebellar abnormality was the predominant feature in 81 percent of the fetuses older than 24 weeks' gestation. As these fetuses advanced in age, the growth retardation and brain abnormalities became worse. Disproportionate size of the ventricles (spaces) in the brain and the circumference of the skull was also present throughout gestation. These ultrasonographic markers are useful in identifying fetuses at risk for open spina bifida. (Consumer Summary produced by Reliance Medical Information, Inc.)

Abnormalities, Brain, Brain abnormalities, Spina bifida, Prenatal ultrasonography, Ultrasonics in obstetrics

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Prediction of fetal anemia by measurement of the mean blood velocity in the fetal aorta

Article Abstract:

Although fetal anemia may have a number of different causes, one of the primary causes is the immunization of the mother against foreign antigens on the fetal red blood cells. However, even when fetal anemia is anticipated, careful measurement of the anemia is important for proper clinical management. A fetal hematocrit (the percentage of red blood cells in a given volume of blood), which may be performed on a blood sample obtained from the umbilical cord during cordocentesis, is the definitive measurement. It would be beneficial if this information could be obtained in a simpler fashion. Since some reports have indicated an inverse correlation between fetal hematocrit and aortic blood flow, as measured by Doppler ultrasonography, an attempt was made to determine if this method could serve as a useful measure of fetal anemia. Doppler ultrasonography was used to measure fetal aortic blood flow at the same time that fetal blood was sampled from 68 pregnant women who had been referred due to red blood cell isoimmunization. In hydropic fetuses, that is fetuses in which water has accumulated in the tissues, aortic velocity decreased with worsening anemia. In fetuses without hydrops, however, aortic velocity increased with worsening anemia, presumably due to increased cardiac output to compensate for the decreased oxygen-carrying capacity of the blood. However, although a fetus with high aortic velocity is likely to be anemic, and a fetus with normal aortic velocity is unlikely to be anemic, there is sufficient overlap in the measured aortic velocities that the Doppler measurement cannot be used effectively do distinguish the degree of fetal anemia. (Consumer Summary produced by Reliance Medical Information, Inc.)

Anemia, Measurement, Fetal blood, Doppler ultrasonography, Erythroblastosis fetalis

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Diagnosis of the Meckel-Gruber syndrome at eleven to fourteen weeks' gestation

Article Abstract:

The Meckel-Gruber syndrome may be detected in the first trimester of pregnancy by ultrasound scans in both low-risk and high-risk populations. The Meckel-Gruber syndrome is a fatal genetic disorder marked by cyst-filled kidneys, gap in the skull, and more than five fingers or toes on hands or feet. Researchers performed first trimester ultrasound examinations on nine pregnancies with a high risk of Meckel-Gruber syndrome. The three characteristic findings of Meckel-Gruber syndrome were detected in four of the nine fetuses. One fetus with Meckel-Gruber syndrome was detected in a low-risk group of 21,477 pregnancies.

Birth defects

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