Cytogenetic analysis of 1375 amniotic fluid specimens from pregnancies with gestational age less than 14 weeks

Our laboratory has received 1375 early amniotic fluid (EA) specimens during the past 5-year period for cytogenetics analysis. The gestational ages of the EA specimens were less than 14 weeks as estimated by ultrasound. The average volume of specimen received was 16 ml. Specimens were typically received in two collection tubes and cultured in Chang A and in supplemented MEM media using the in situ technique. Of the 1375 EA specimens received, 1356 were successfully cultured and yielded results. Abnormal results were found in 67 (4.9 per cent) of the cases. Nineteen specimens (1.4 per cent) failed to yield a result. The mean turn-around time (TAT) for all EA specimens was 8.28 days. In 1991, the average TAT for the EA specimens was 8.00 days compared with a TAT of 6.59 days for all specimens received over 14 weeks gestational age. The number of EA specimens received has increased from 1.5 per month in 1986 to 57 per month in 1991. In summary, our experience with EA specimens for cytogenetic analysis has demonstrated that the success rate is 98.6 per cent and that an increasing number of obstetricians are performing early amniocentesis as they seek to provide their patients with earlier results and an alternative to chorionic villus sampling.     

Early second-trimester sonographic appearance of occipital haemangioma simulating encephalocele

Encephalocele is the most common cause of occipital midline extracranial mass associated with hydrocephalus. A case is presented where an occipital extracranial mass associated with hydrocephalus which was detected on second-trimester ultrasound examination turned out to be a haemangioma, a relatively benign lesion. We suggest that haemangioma should be considered in the differential diagnosis of extracranial masses detected prenatally.     

Cultivated cells from mid-trimester amniotic fluids. IV. Cell type identification via one and two-dimensional electrophoresis of clonal whole cell homogenates

Clones of cultivated amniotic fluid cells that have distinct morphologic and growth characteristics (F, AF and E-type) were examined by one-dimensional SDS polyacrylamide gel electrophoresis (SDS-PAGE) and by two-dimensional electrophoresis employing isoelectric focusing and SDS-PAGE (IEF-PAGE). No qualitative differences in band pattern were observed in SDS-PAGE between the various amniotic fluid cell types, but consistent quantitative differences in the ratios of four bands of presumed filamentous proteins provided good distinction between amniotic fluid cells and postnatal skin fibroblast-like cells. By adding separation on the basis of electrical charge to that of molecular size (IEF-PAGE), we observed reproducible qualitative differences in the protein spot patterns between F and both AF and E-type amniotic fluid cells. At least eight discrete proteins appear not to be synthesized by prenatal F-type cells in comparison with their isogenic AF and E counterparts under identical culture conditions. The two-dimensional electrophoretic patterns thus confirm that F and AF amniotic cells, in spite of their morphologic and growth kinetic similarities, are developmentally distinct cell types that retain their differentiated states in culture.     

Attitudes toward abortion for fetal anomaly in the second vs. the third trimester: A survey of Parisian obstetricians

Cross-cultural differences exist in prenatal diagnosis and abortion for fetal anomaly, stemming from variations in laws, reimbursement policies, litigation, physicians' decision-making authority, and attitudes toward the prevention of handicaps. The first part of this paper discusses such differences in France and the U.S. The second part describes a survey of practising obstetricians in Paris, designed to assess (1) their attitudes toward pregnancy termination for various conditions, (2) their concern about fetal viability, (3) their desire for diagnostic certainty before justifying a late abortion, and (4) their perceived role in such decision-making. Among the 64.8 per cent (N = 217) who responded, the majority supported third-trimester termination (TTT) for diseases such as spina bifida, trisomy 21 , microcephaly, and Duchenne muscular dystrophy; 30–59 per cent supported TTT for cystic fibrosis and sickle cell disease; and 22–29 per cent supported TTT for haemophilia, tetralogy of Fallot, limb amputation, and Turner and Klinefelter syndromes. Obstetricians who approved of abortion across trimesters were less concerned with the certainty of diagnosis than its severity, more likely to think that abortion ought to be the parents' choice, but more likely to report making a recommendation to the parents about whether to abort a fetus. Such permissive abortion attitudes might imply more permissive prenatal diagnosis and abortion practice among Parisian obstetricians, which might lead to increased migration of patients from other E.C. countries. Cross-cultural variation in obstetric practice suggests that an international registry of pregnancies terminated for medical reasons, enabling further study of this issue, would be valuable.     

Rapid karyotyping in prenatal diagnosis: A comparative study of the ‘pipette method’ and the ‘in situ’ technique for chromosome harvesting

Rapid karyotyping in the second and third trimesters has important implications for the management of pregnancies at risk. From September 1985 to March 1992, 735 amniotic fluid samples sent to our laboratory for rapid karyotyping from 64 different diagnostic centres of the Federal Republic of Germany were included in a comparative study on harvesting for chromosome analysis using the ‘pipette method’ or the ‘in situ’ technique. The average time between preparation of the amniotic fluid and verbal notification of the analysed karyotype was 5·41 days. The ‘pipette method’ needed on average 4·65 days, and the ‘in situ’ technique 5·97 days. In comparison with other more invasive techniques available for rapid karyotyping such as cordocentesis and placental biopsy, amniocentesis and subsequent chromosome harvesting using the ‘pipette method’ and/or the ‘in situ’ technique proved very useful and efficient. The overall incidence of chromosome aberrations was 15·3 per cent. The high rate of structural chromosome aberrations and uncommon aneuploidies found in our investigation (12 per cent) indicates that for rapid karyotyping in the second and third trimesters, conventional cytogenetic techniques cannot be replaced by faster techniques based on fluorescent in situ hybridization on interphase cells in the near future.     

Antenatal sonographic diagnosis of arthrogryposis multiplex Congenita

Arthrogryposis Multiplex Congenita (AMC) was suspected on ultrasound examination of a fetus at 30·5 weeks of gestation. The criteria for establishing this prenatal diagnosis as well as the importance of establishing the diagnosis at any gestational age are discussed. The diagnosis of AMC was confirmed at birth in this case.     

Aneuploidy and cystic hygroma detectable by ultrasound

During one year, five second trimester fetuses with cystic hygromata and varying degrees of oedema presented to the authors from hospitals in the West of Scotland. Two fetuses had 45X karyotypes, one each had 47XY+21 and 47XX+18 karyotypes, and the fifth had a normal 46XY karyotype. Fetal oedema detectable by ultrasound, affecting particularly the back of the neck, may be a commoner manifestation of several aneuploid syndromes than has hitherto been recognized.     

A further prenatal diagnosis of mosaic tetrasomy 12p (Pallister-Killian syndrome)

A case of mosaic tetrasomy 12p was detected in amniotic fluid cell cultures from a 28-year-old woman referred to us at 26 weeks' gestation because of hydramnios. The fetus was shown on ultrasonography to have an omphalocele and a short femur length. Labour was induced at 32 weeks. An infant with multiple congenital anomalies was delivered and died after 10 min. The diagnosis of i(12p) or Pallister-Killian syndrome was confirmed cytogenetically in fibroblast and lymphocyte cultures. Increased LDH-B activity was demonstrated in fibroblasts.     

Ultrasound evaluation of pregnancies at risk for homozygous α-thalassaemia-1

Twenty-six pregnant Chinese women who were at risk of giving birth to a fetus affected with homozygous α-thalassaemia-1 were examined serially by ultrasound. Six of these 26 pregnancies were affected. In one third of the affected pregnancies progressive fetal ascites appeared before 24 weeks gestation and these pregnancies were terminated. In the remaining two thirds abnormal estimated fetal weight-placental volume (EFW-PV) ratio and fetal growth retardation as evidenced by a falling biparietal diameter (BPD), femur length (FL) but a normal abdominal circumference (AC) was apparent by 28 weeks gestation. Increased transverse cardiac (TC) diameter was another consistent finding but appeared late. All these features appeared before the onset of fetal ascites. A normal EFW-PV ratio and fetal growth until 28 weeks gestation was a reassuring sign of normality. Abnormal EFW-PV ratio was the earliest sign to appear in affected pregnancies and a normal ratio until 28 weeks gestation had a 100 per cent predictive value.     

Preparation of high resolution chromosomes from amniotic fluid cells

A relatively simple method of obtaining high resolution chromosomes from amniotic fluid cells is described. The elongated chromosomes are achieved by adding ethidium bromide (5μg/ml) to the culture 4 1/2 hours before harvesting and the high resolution banding can be produced by usual banding procedures.