Screening and detection of congenital malformation

Article Abstract:

This is one of three articles in the April 1991 issue of the American Journal of Obstetrics and Gynecology concerning the status of ultrasonography, a noninvasive technology that can be used to visualize internal organs, such as the ovaries and the uterus, as well as the developing fetus. Between 2 and 3 percent of fetuses suffer from major defects so severe that the fetus cannot survive, or the life of the infant will not be normal. Screening for such defects with ultrasound usually takes place when the mother is 16 weeks pregnant, when abortion can still be performed safely. Early diagnosis of such malformations is desirable for women who choose not to terminate their pregnancies, as well; such knowledge may affect prenatal care and the family's emotional adjustment to life with a handicapped child. Moreover, techniques are under development for treating certain defects prior to delivery. A review of the medical literature concerning routine ultrasonography in pregnancy is presented. In general, screening ultrasonography (examining all pregnant women) is accurate in identifying normal fetuses (specificity), but not very accurate at identifying those with defects (sensitivity). When used to evaluate pregnancies where clinical signs, maternal history, or previous ultrasound results indicate high-risk status, the method is much more sensitive. The gestational age at which ultrasound is performed and the skill of the clinician are critical determinants of diagnostic accuracy. A survey of radiologists and obstetrician-gynecologists revealed that opinions differed widely concerning the percentages of major malformations that are detected by ultrasonography; costs, too, varied as much as six-fold. Data are presented concerning the frequency of different types of birth defects. Based on evidence, the author does not support the routine use of screening ultrasonography in pregnancy, but does see a role for its use in cases where the risk of birth defect is elevated. Cost issues must also be considered, however. (Consumer Summary produced by Reliance Medical Information, Inc.)

Prenatal ultrasonography, Ultrasonics in obstetrics

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The role of postnatal x-ray pelvimetry after caesarean section in the management of subsequent delivery

Article Abstract:

Women who undergo cesarean section in the UK are routinely evaluated with X-ray pelvimetry (measurement of the pelvis using X-rays) after delivery to help determine the best route of delivery in subsequent pregnancies. This practice, however, is not standardized, and may not be genuinely useful for managing pregnancy. To evaluate this, a review was made of the records of 331 women who underwent cesarean section and X-ray pelvimetry at one hospital during a five-year period. Seventy-five percent of the women (248 patients) had a pelvis that was considered to be inadequate using radiologic criteria. Of these, 68 planned to deliver vaginally and 180 planned to undergo cesarean section. In fact, 76 women with inadequate pelvises attempted a trial of labor because the obstetrician questioned the role of pelvimetry; these women had similar measurements to the 172 women who underwent cesarean section. Of the 76 women who attempted vaginal delivery, 51 succeeded and 25 needed emergency cesarean sections. Of the 79 women with adequate pelvises, 18 required emergency cesarean sections. Thus, X-ray pelvimetry did not appear to be a good tool for determining the appropriate mode of delivery. In most cases, women who have undergone cesarean section can experience successful vaginal deliveries. The suggestion is made that postnatal pelvimetry be abandoned. (Consumer Summary produced by Reliance Medical Information, Inc.)

Complications and side effects, Vaginal birth after cesarean, Pelvimetry

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Second-trimester placental biopsy for rapid fetal karyotyping

Article Abstract:

Chorionic villus sampling (placental biopsy) is a method of prenatal diagnosis used to detect chromosomal abnormalities that does not involve waiting long for results and can be performed early in pregnancy, usually during the first trimester. A report of the extension of the method to women in the second trimester of pregnancy is provided. Forty procedures were performed on women with an average age of approximately 32 years and a gestational age between weeks 18 and 19. Twenty-eight patients requested chorionic villus sampling because of abnormalities in their blood levels of alpha-fetoprotein, a substance associated with failure of the spine to close during development. Seven had abnormalities on ultrasound examination; two had prior chromosomal abnormalities in pregnancy; and three had a failed previous test. Chromosomal abnormalities were found in four of the cases with abnormal ultrasound findings and in one case with abnormal serum alpha-fetoprotein. Preliminary results were obtained within a few days, and usable samples of tissue were obtained in all but two cases. No fetal loss occurred after the sampling procedure, with the exception of the pregnancies voluntarily terminated (all the abnormal fetuses). The method appears suitable for use during second-trimester pregnancy, as well as in the first trimester. (Consumer Summary produced by Reliance Medical Information, Inc.)

Testing, Genetic disorders, Chorionic villus sampling

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