Sonographic detection of monoamniotic twins.

The true incidence of monoamniotic twinning has been almost impossible to determine accurately because it requires closer inspection of the membranes and placenta at delivery than is usually performed. Sonography of 3440 patients presenting for genetic amniocentesis identified 39 twin gestations, one of which was monoamniotic (0.026%). Prospectively with ultrasound, four of the twin gestations had been thought to be monoamniotic. A more recent case of suspected monoamniotic twinning revealed two sacs when newer computer-based real-time equipment with variable focusing capability and improved spatial resolution was used. Sonographic diagnosis of monoamniotic twinning must be accurate since it identifies patients at higher risk for cord accidents. These patients need obstetrical care appropriate for a pregnancy at high risk. In addition, failure to identify a second sac that could harbor a chromosomally abnormal fetus has both medical and legal implications. State-of-the-art ultrasound equipment and attention to detail is required.

Detection of neural tube defects with alpha-fetoprotein measurement in amniotic fluid. A protocol for managing elevated values.

The clinical efficacy of rocket immunoelectrophoresis (RIE) and radioimmunoassay (RIA) methods for the measurement of amniotic fluid alpha-fetoprotein (AFP) were compared in separate series of over 1,000 pregnancies each. Using a mean +3 SD limit, 21 of 1,414 pregnancies monitored with RIE and 21 of 1,006 monitored with RIA were interpreted as having borderline elevated values. Five of the elevated AFP values in each series represented abnormal fetuses. No neural tube defects went undetected, although one was recognized only with ultrasound. Only two of seven abnormal fetuses had a family history of neural tube defects, indicating that maternal serum AFP measurement is an important preventive measure in pregnancies that are not recognized as at high risk. The data support the use of commercially available RIA kits for amniotic fluid AFP measurement and suggest a protocol for management of elevated values.

Prenatal counseling: a statewide telephone service.

The University of Michigan has provided a statewide prenatal counseling service for obstetricians and pregnant patients since 1974. Using a toll-free telephone hot line, 5204 inquiries have been made, relating to genetic conditions, exposure to potential teratogens, and obstetric or medical complications during early pregnancy. Up-to-date and accurate information has been supplied by a team of nurses and physicians with backgrounds in genetics or maternal-fetal medicine. Calls were taken by perinatal nurse counselors and referred to the appropriate medical specialist. The number of inquiries has increased from 3 per week in 1974 to 30 per week in 1981. Genetic amniocenteses, performed in response to 46% of all inquiries, provided financial support for the project. The authors consider the statewide use of this self-supported prenatal counseling service to be encouraging and recommend that this format be used at other institutions.

The effect of ultrasonography on midtrimester genetic amniocentesis complications.

Midtrimester amniocentesis for antenatal genetic diagnostic purposes is a relatively new procedure. The assumption that placental localization before amniocentesis will reduce the numbers of abortions, bloody taps, and missed taps has resulted in the routine use of diagnostic ultrasound for placental localization. This study consists of two groups undergoing midtrimester amniocentesis. The groups were distinguished by the use and absence of the use of ultrasound data prior to amniocentesis. Comparisons between the groups failed to support the contention that the routine use of ultrasound reduces the complications of midtrimester amniocentesis. Our findings support other published data concluding that the routine use of ultrasound does not help to reduce the number of midtrimester amniocentesis complications.