Magnetic resonance imaging of the fetus: A study of 20 cases performed without curarization

Twenty patients underwent magnetic resonance imaging (MRI) at a mean gestational age of 32 weeks. There were 12 patients with suspected fetal brain abnormality and four with intrauterine growth retardation (IUGR), while the remaining four cases were studied for other reasons. The MRI examinations were performed on a 0.5 Tesla machine, with surface coils. One minute acquisition time T1 sequences were used. All the studies were performed without fetal curarization, and only under maternal sedation using flunitrazepam given per os 1 h before MRI examination. Three examinations were incomplete because of fetal movement artefacts. In the remaining cases, MRI allowed the examination of fetal brain anatomy. In five cases, it helped to differentiate isolated hydrocephalus and corpus callosum agenesis. Sub-ependymal nodules were depicted in a case of fetal tuberous sclerosis. One suspected arachnoid cyst was proved to be an ultrasound artefact. Decreased fetal fat on MR images was correlated with low birth weight in cases of IUGR. Due to its better spatial resolution, ultrasonography was more accurate for the diagnosis of facial and lumbar anomalies. Fetal MRI may be performed without curarization. Surface coils allow the detailed analysis of brain parenchyma, and thus MRI is especially useful in the difficult prenatal diagnosis of fetal brain abnormalities.     

Parental reaction and adaptability to the prenatal diagnosis of fetal defect or genetic disease leading to pregnancy interruption

The objective of the study was to evaluate the psychological reaction of two groups of parents to a pregnancy termination after they had undergone a prenatal diagnostic procedure. The analysis involved interviews with a study group of 76 patients who were at risk of giving birth to a child with a genetic disease or defect and a comparison group of 124 who had a pregnancy termination after a major anomaly had been detected by routine ultrasound and who were not at known risk for a genetic disease. Only patients in the study group had received counselling before the prenatal diagnosis and were aware that the fetus could be affected. The overall reaction of the comparison group was one of shock, denial of fetal abnormality, and guilt over ‘abandoning the fetus’. A feeling of guilt was expressed by patients in the comparison group (73 per cent versus 29 per cent) in the period immediately following the interruption. One-third of patients in both groups felt obliged to undergo a therapeutic abortion. More patients in the study group than in the comparison group expressed the need to see a psychiatrist at the time of the study (19 per cent versus 7 per cent) and viewed future pregnancies as a replacement for the lost pregnancy (63 per cent versus 19 per cent). The recommendations of the study focus on information sessions to personnel, nursing support, analgesia during the expulsion period, an atmosphere of respect that should be present at the time that the fetus is viewed, the anticipation of mourning, and the long-term follow-up of the couple to ensure that counselling for future pregnancies and psychological support are provided when needed.     

Detection of fetal cells in transcervical samples and prenatal diagnosis of chromosomal abnormalities

Transcervical samples collected by lavage, aspiration, and cytobrush from women between 6 and 13 weeks of gestation were tested for the presence of fetal cells using fluorescence in situ hybridization (FISH) with probes for chromosomes X, Y, 1, and 21, and by polymerase chain reaction (PCR) amplification of DNA sequences derived from chromosomes X, Y, and 21. With a few exceptions, a good correlation was observed between the results of sexing the fetuses using FISH or PCR on transcervical cell (TCC) samples retrieved by lavage and those obtained by testing fetal (placental) tissue. In a comparative study between TCC samples collected by lavage or cytobrush, the sex of the fetus was correctly diagnosed by PCR amplification of a Y-derived DNA sequence. Variable results were observed with samples obtained by aspiration, mainly because this procedure was found to be more prone to failure to remove thick mucus without previous injection of physiological saline. Chromosome 21-derived small tandem repeats (STRs) of fetal origin were successfully detected in about 40 per cent of TCC samples recovered by lavage. Two cases of chromosomal abnormalities, one of trisomy 21 and one of triploidy, were detected in TCC samples in the course of our investigations.     

环境污染物浓缩铀诱发雄性机体的生殖毒性研究

在不同水平浓缩铀￣（２３５）ＵＯ＿２Ｆ＿２内污染诱发机体生殖毒性的研究中，观察到浓缩铀可诱发精子畸形，主要呈现双头和无钩精子。浓缩铀诱发精原细胞染色体畸变，则以染色体断片为主，对初级精母细胞可产生染色体断片和易位，出现多价体。浓缩铀可致精子ＤＮＡ链断裂，其断裂片段则可随￣（２３５）ＵＯ＿２Ｆ＿２摄入量的加大而增多，浓缩铀引起遗传物质的损伤，可诱发胎鼠显性致死突变和骨骼畸形增生，而其诱发骨骼畸形的发生率则与睾丸浓缩铀的摄入量呈正相关。     

Human chorionic gonadotropin levels in pregnancies with aneuploid fetuses

Maternal serum human chorionic gonadotropin (hCG) and the free alpha-hCG subunit were evaluated in 249 women from 9 to 11 weeks gestation who subsequently underwent chorionic villus sampling for determination of fetal karyotype and in 20 women of 18 or more weeks gestation who were ascertained to have an aneuploid fetus by genetic amniocentesis. Seven of the first-trimester pregnancies were determined to be aneuploid and six had hCG levels in the normal range (one triploid pregnancy had elevated hCG levels) whereas 12 of the 20 secondtrimester cases had abnormal hCG levels and an additional three had elevated levels of alpha-hCG. This study confirms the previous report of abnormal maternal serum hCG levels in women with an aneuploid fetus at ≥ 18 weeks gestation and demonstrates that hCG evaluation is not useful at 9–11 weeks gestation for selecting pregnancies at risk for fetal aneuploidy.     

Fetal blood sampling and cytogenetic abnormalities

From September 1984 to April 1991, we performed cytogenetic analysis on fetal blood samples from 214 second-and third-trimester pregnancies. One hundred and thirty-four cases were referred to consider the possibility of chromosomal mosaicism following amniocyte studies. The confirmation rate of mosaicism is at 0 per cent (0/9), 1·4 per cent (1/70), and 40 per cent (22/55) for cases of level I, level II, and level III mosaicism, respectively. Four out of 17 cases were positive for the diagnosis of fragile X syndrome. Of 63 cases with abnormal ultrasound findings, blood disorders, or other genetically related clinical conditions, 11 were found to have a chromosome abnormality. Fetal blood sampling is a valuable adjunct to other methods in the prenatal diagnosis of chromosomal mosaicism or pseudomosaicism. It is also useful when rapid cytogenetic diagnosis is desired because of malformations detected in pregnancies at a late gestational age.