L.C. Allen

Pregnancy outcome after gestational exposure to amiodarone in Canada

OBJECTIVEnOur purpose was to quantitate the risk of perinatal thyroid dysfunction and other amiodarone-induced adverse effects among infants exposed in utero to amiodarone.nnnSTUDY DESIGNnA historic cohort study of gestational exposure to amiodarone was conducted by contacting Canadian cardiac electrophysiologists.nnnRESULTSnTwelve cases were identified. Of six with first-trimester exposure, one child had congenital nystagmus with synchronous head titubation. There was one case each of transient neonatal hypothyroidism (9%) and hyperthyroidism (9%). A fourth child, exposed to amiodarone from 20 weeks gestation, had developmental delay, hypotonia, hypertelorism, and micrognathia. Four small-for-gestational-age infants were also exposed to beta-blockers, which in addition to maternal cardiac disease, have been recognized to cause growth restriction. beta-Blockers may also have contributed to bradycardia in one of the three fetuses in whom this was observed.nnnCONCLUSIONSnGestational exposure to amiodarone may be complicated by perinatal hypothyroidism or hyperthyroidism and possibly neurologic abnormalities, intrauterine growth retardation or fetal bradycardia. Concomitant beta-blocker therapy should probably be avoided. Full neonatal thyroid function tests and developmental follow-up are recommended.

Amniotic fluid testosterone and follicle-stimulating hormone assay in the prenatal determination of fetal sex

Amniotic fluid testosterone was assayed by radioimmunoassay in 812 samples taken at 16 weeks gestation at the time of genetic amniocentesis. In each of 361 samples (45% of total), correct assignment of fetal sex was made where the testosterone level was above 33.8 ng/ml for male fetuses and below 16.2 ng/ml for female fetuses. In each of 159 of 353 (45%) samples assayed for follicle-stimulating hormone (FSH), levels were below 7.6 mlU/ml for male fetuses and above 10.9 mlU/ml for female fetuses. By combining the two assays in the testosterone/FSH ratio, correct assignment of sex was made in each of 282 samples (80%). The percentage of samples in which correct assignment was achieved was greater for female fetuses (ratio less than 2.2 in 161/187 [86%]) than for male fetuses (ratio greater than 3.4 in 121/166 [72%]). The testosterone/FSH ratio holds promise as a rapid biochemical screening tool in the prenatal diagnosis of fetal sex in X-linked disorders.

Amniotic fluid lecithin/sphingomyelin ratio, palmitic acid, palmitic acid/stearic acid ratio, total cortisol, creatinine, and percentage of lipid-positive cells in assessment of fetal maturity and fetal pulmonary maturity: A comparison

Lecithin/sphingomyelin (L/S) ratio, creatinine, percentage of lipid-positive cells, palmitic acid, palmitic acid/stearic acid (P/S) ratio, and total cortisol were analyzed as tests for fetal maturity and fetal pulmonary maturity in 164 samples of amniotic fluid from 121 patients. Fifty samples were taken within 72 hours of delivery. The best tests for fetal maturity (37 weeks) with differential percentages were L/S ratio, palmitic acid, and P/S ratio. In the assessment of fetal pulmonary maturity, we studied an additional 174 samples in which only L/S ratio, creatinine, and lipid-positive cells were analyzed. All tests showed a high predictive value of an immature (positive) result was much less for all six parameters; the three best tests were total cortisol (33%), lipid-positive cells (26%) and L/S ratio (14%).

A clinical approach to the use of predictive values in the prenatal diagnosis of neural tube defects

The rationale of calculating predictive values to interpret the amniotic fluid alpha-fetoprotein (AFP) test has been examined and applied to amniotic fluid AFP testing from one Canadian center. Such predictive value ccalculations may be misleading if they fail to make use of the actual magnitude of the test result or the results of other investigations. The alculation of predictive values has thus been extended to take into account magnitude of the test results, the clinical history, and the results of other investigations. The interpretation of an abnormal amniotic fluid AFP test that is followed by a normal result of a careful ultrasound scan of the fetal back is that there is a 54.5% chance that the fetus has spina bifida if there is a previous history of spina bifida. There is a 12.5% chance if there is a negative family history. These calculations lead to informed genetic counseling and rational decision making with regard to the continuation of the pregnancy.

Effects of hemoglobin variants on Hb A1c determinationsusing bio-rad columns

In the column chromatographic determination of Hb A1c, hemoglobin variants affect Hb A1c results and column patterns. Samples from several patients with hemoglobin variants were run on Bio-Rad Hb A1c columns to demonstrate these patterns. Columns should be examined during the run to detect the presence of Hb F which migrates very rapidly, and after the run to detect abnormal column patterns. Hb A1c levels in patients heterozygous for Hb S or C are low but may be interpreted in relation to the patients level of Hb A. On the other hand, Hb A1c results on patients with homozygous Hb S, Hb C, or high levels of Hb F cannot be interpreted.

False positive amniotic fluid alpha fetoprotein levels resulting from contamination with fetal blood: Results of an experiment☆☆☆

The finding of an elevated level of alpha fetoprotein (AFP) in amniotic fluid is of value in the prenatal diagnosis of open neural tube defects. The present study was done to determine the amount of fetal blood required in amniotic fluid to produce a significant and misleading increase in AFP. Fetal blood was obtained at hysterotomy, and measured volumes were added to amniotic fluid samples. Bethe-Kleihauer tests, red cell counts, and AFP determinations were done. On the average, at 16 weeks gestation, contamination of 5 ml. of amniotic fluid with 22 mul of fetal blood will results in an increase in AFP of 1.6 mg. per deciliter. Fetal cells in a much lower concentration can readily be detected by the Bethe-Kleihauer technique. A Bethe-Kleihauer test and red cell count should be done on all blood-stained amniotic fluid samples to determine the amount of fetal blood present. The contribution of the fetal blood AFP can then be estimated and must be considered in the interpretation of the total amniotic fluid AFP result.

Assessment of Four Enzyme Immunoassay Kits for Serum β‐hcg Screening

Abstract This pilot study evaluates four qualitative serum β‐human chorionic gonadotropin (β‐hCG) enzyme immunoassay kits for both routine pregnancy testing and screening for ectopic pregnancy. We found that the Tandem-E HCG assay had the lowest limit of detection, and longest turnaround time. Tandem ICON HCG assay had the shortest turnaround time. The Vis-Con II was the most economical batch test. The Quest assay kit was both fast and simple and had the lowest cost for stat testing.

Comparison of two immunoassay methods for the determination of alpha-fetoprotein in amniotic fluid

We compared two immunoassay methods for determination of alpha-fetoprotein in amniotic fluid. The two methods showed a very good correlation and this is further confirmed by the clinical study. The electroimmunoassay (rocket immunoelectrophoresis) seems suitable for a small laboratory, whereas radioimmunoassay may be a better choice for a large laboratory.

Assay of erythrocyte glucose-6-phosphate dehydrogenase on the GEMSAEC analyser.

A procedure for the assay of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) in erythrocytes on the GEMSAEC centrifugal analyzer using a modification of Beutlers procedure is described. Glucose-6-phosphate dehydrogenase activity is corrected for the contributing activity of 6-phosphogluconate dehydrogenase (EC 1.1.1.44) by using a two-cuvet system in which the activity of the sample incubated with 6-phosphogluconic acid is subtracted from the activity produced in the presence of the combined substrates, glucose-6-phosphate and 6-phosphogluconic acid. An overlay program on the GEMSAEC computer for calculation of results, and the use of a yeast glucose-6-phosphate dehydrogenase control which is stable frozen in dilute solution are discussed.