Article Abstract:
Ultrasonography is a method in which sound waves are used to visualize internal body structures. Transvaginal ultrasonography is a modification of ultrasonography in which the transducer, or device that sends and receives the sound wave signals, is inserted into the vagina. This modified ultrasonographic method permits a more detailed examination of the fetus in the first trimester, and may be useful in detecting congenital abnormalities (birth defects). Early diagnosis of congenital defects reduces the anxiety of waiting for testing at a later period, and avoids the expense and increased risk associated with an abortion in the second trimester of pregnancy. The usefulness of transvaginal ultrasonography in detecting congenital abnormalities in the first trimester was assessed, and the limitations of this diagnostic technique are discussed. The results showed that 33 embryos with structural defects were diagnosed by transvaginal ultrasonography over a period of two years, in a group of 622 women. Thus the rate of these structural defects was 0.5 percent; this low rate may be due to the large number of mothers with a low risk of having pregnancies with congenital defects. Twenty-two of 33 women whose fetuses had congenital abnormalities were considered high-risk patients. Experience with transvaginal ultrasonography and a thorough understanding of the development and growth of the embryo is recommended before use of this method in diagnosing fetal abnormalities in the first trimester of pregnancy. (Consumer Summary produced by Reliance Medical Information, Inc.)
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Article Abstract:
Although prenatal diagnosis has rapidly changed the practice of reproductive medicine, techniques for visualizing the fetus have been applicable only in the second and third trimesters of pregnancy. It is now possible, using a rigid fiberoptic endoscope, to directly observe an embryo as early as five weeks of gestation. Care was taken to penetrate the chorion, or outer covering of the amniotic sac which encloses the fetus within the uterus, at a 90 degree angle. Progress of the endoscope was monitored using ultrasonography to observe for placental separation (from the uterine wall) or rupture of the amniotic sac. In the first clinical trials of the device, 100 women, at 5 to 13 weeks gestation, volunteered for fiberoptic endoscopic examination prior to voluntary termination of their pregnancies. In the overwhelming majority of cases, the embryo was successfully visualized. In five cases, however, the amnion was ruptured, and in one case the fetus was killed. Furthermore, the degree of sensitivity of the developing fetal retina to the light used by the fiberoptic instrument is not known. The risks involved prevent the technique from being used unless the value of the information to be obtained outweighs the potential dangers. (Consumer Summary produced by Reliance Medical Information, Inc.)
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Article Abstract:
The left umbilical artery may be absent more frequently than the right artery in fetuses that have a congenital absence of an umbilical artery. Absence of the left umbilical artery may be associated more often with other congenital defects than absence of the right artery, although absence of either artery may be associated with other congenital defects. Researchers studied 77 fetuses with a single umbilical artery as diagnosed by ultrasound. Twenty of the fetuses had other developmental defects (26%), 16 of which were a missing left umbilical artery. Six fetuses had abnormal chromosomes, and all six lacked the left umbilical artery. Pregnant women suspected of having a single umbilical artery should receive ultrasound examinations and echocardiograms of the fetal heart.
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