Exploring cortical subplate evolution using magnetic resonance imaging of the fetal brain

The subplate is a transient structure essential for normal development of the cortex. We used magnetic resonance imaging of the fetal brain to assess cortical subplate evolution between 20 and 35 weeks gestation. Two-dimensional measures of diameter were obtained for the cortex, subplate and fetal white matter. The subplate was originally seen as a continuous band at early gestations measuring up to 4.5 mm. It became magnetic resonance invisible from approximately 28 weeks initially from the depths of the sulci and then from the tops of the gyri. The disappearance of the subplate was regional, involuting most rapidly in the parietal lobe and remaining prominent in the anterior temporal lobe up to 35 weeks. x

Circulating hematopoietic progenitor cells in first trimester fetal blood

The yolk sac and aorto-gonad-mesonephros region are well recognized as the principal sites of hematopoiesis in the developing embryo, and the liver is the principal site of hematopoiesis in the fetus. However, little is known about circulating hematopoietic stem and progenitor cells in early fetal life. We investigated the number and characteristics of circulating progenitors in first trimester blood of 64 human fetuses (median gestational age, 10(+4) weeks; range, 7(+6)-13(+6) weeks). CD34+ cells accounted for 5.1 +/- 1.0% of CD45+ cells in first trimester blood, which is significantly more than in term cord blood (0.4 +/- 0.03%; P =.0015). However, the concentration of CD34+ cells (6.6 +/- 2.4 x 10(4)/mL) was similar to that in term cord blood (5.6 +/- 3.9 x 10(4)/mL). The total number of progenitors cultured from unsorted mononuclear cells (MNCs) in first trimester blood was 19.2 +/- 2.1 x 10(3)/mL, which is similar to that in term cord blood (26.4 +/- 5.6 x 10(3)/mL). All lineages were seen: colony-forming unit-GEMM (CFU-GEMM), CFU-GM, BFU-e, BFU-MK, and CFU-MK. Clonogenic assays of CD34+ cells purified from first trimester samples produced mainly two lineages: BFU-e (39.0 +/- 9.6 x 10(3)/mL CD34+ cells) and CFU-GEMM (22.6 +/- 4.7 x 10(3)/mL CD34+ cells). Short-term liquid culture of first trimester blood MNCs in SCF + IL-3 + Flt-3 (stem cell factor + interleukin-3 + Flt-3) increased, by 7-fold, the numbers of CFU-GEMM and induced a dramatic increase in BFU-e (65.6 +/- 12.1-fold). These data show that significant numbers of committed and multipotent progenitors with capacity for expansion circulate in first trimester fetal blood and can be CD34 selected. These cells should be suitable targets for gene transfer and stem cell transplantation and, because fetal hematopoietic progenitors have been demonstrated in the maternal circulation from early gestation, may also be manipulated for noninvasive prenatal diagnosis of major genetic disorders. (Blood. 2000;95:1967-1972)

Human fetal and maternal noradrenaline responses to invasive procedures

Fetal and maternal plasma noradrenaline responses to invasive procedures were determined in pregnancies of 18 to 37 wk gestation. Fetal umbilical venous blood sampling was performed either from the placental cord insertion, which is not innervated, or the intrahepatic vein, which is innervated, and thus may be more stressful for the fetus. Samples from diagnostic procedures, as well as from transfusion procedures, were compared between the two sites. Fetal plasma levels were significantly elevated in blood samples obtained from the intrahepatic vein compared with those from the placental cord insertion during diagnostic procedures [p < 0.05, geometric means and 95% confidence intervals (CI) were 0.67 nmol/L (0.43-1.04) and 0.36 nmol/L (0.25-0.54), respectively]. Plasma levels in samples taken before transfusion from the intrahepatic vein were also significantly higher than those from the placental cord insertion. After transfusion, there was a significant rise in fetal plasma noradrenaline levels at both sites; however, after transfusion through the intrahepatic vein, the rise was substantially greater than after transfusion through the placental cord insertion (p < 0.05, change, mean deltaNA, and 95% CI were 0.67 (0.37-1.22), and 0.20 (0.12-0.33), respectively). The deltaNA was significantly associated with the duration of the stimulus (the time the needle remained in situ) (p = 0.05, adjusted R2 = 0.48) and with gestational age. Maternal levels rose substantially and equally after transfusions at either site (mean deltaNA and 95% CI, 6.46 nmol/L, 1.74 to 11.18 and 9.49 nmol/L, 6.24 to 12.75 for the intrahepatic vein and placental cord insertion groups, respectively). There was no significant correlation between baseline fetal and maternal levels (r = 0.08, n = 41) or between deltaNA pre- and posttransfusion maternal and fetal values in either group. These results indicate that the fetus is capable of mounting an independent noradrenaline stress response to a needle transgressing its trunk from 18 wk gestation. The effect was observable in samples taken at a mean of 5.6 min after needling. The lack of correlation between maternal and fetal levels suggests that virtually no noradrenaline crosses the placenta directly, and that the observed fetal responses are not due to direct transport from the mother.

Haematological indices at fetal blood sampling in monochorionic pregnancies complicated by feto-fetal transfusion syndrome

36 MCDA twin pregnancies with FFTS investigated by fetal blood sampling (FBS) were studied over a 10-year period (1988-1997). The haematological data obtained at FBS were compared between the donor and recipient fetuses. It was shown that the donor fetus had a significantly lower haematocrit (35.7 per cent versus 47.2 per cent; p < 0.001), haemoglobin (12.2 g/dl versus 15.8 g/dl; p < 0.001), and red blood cell count (2.9 x 10(12)/l versus 3.8 x 10(12)/l; p = 0.006) compared with the recipient fetus. A haematocrit discordancy of > 15 per cent, however, was found in only 25 per cent of twin pairs. There were no significant inter twin differences in the remaining indices. The study concluded that although there are significant differences in haematocrit and red cell mass between the donor and recipient fetuses, only a minority of fetuses will have degrees of discordancy suggested in the literature to be diagnostic. We suggest that FBS does not have a role in establishing the diagnosis of FFTS, although its role in determining the degree of haematocrit discordancy to assist in timing of delivery remains to be evaluated.

Point-to-point telemedicine using the ISDN

Two pilot telemedicine trials were established, one using basic-rate ISDN (minor injuries service) and one using primary-rate ISDN (remote fetal scanning). Preliminary results were most encouraging. In the first 10 months of operation, 49 patients with minor injuries were managed successfully using telemedicine. Preliminary calculations suggest that the use of a low-cost telemedicine link was extremely cost-effective in comparison with the cost of providing conventional medical cover. In the first six months of operation the fetal scanning link was used for 39 consultations in 29 patients. In 25 cases (86%) a definitive diagnosis was made using the telemedicine link and physical referral was avoided. However, the current cost of the required hardware (approximately 35,000 pounds per end) is likely to militate against the widespread introduction of the technique, especially since the principal savings are intangible from the perspective of any hospital considering purchase. From the point of view of its use as an information transport system for telemedicine, the ISDN proved reliable (only one failure to establish a connection on demand). Picture quality was acceptable in most cases.

Utility of fetal intraperitoneal saline infusion in the prenatal evaluation of diaphragmatic hernia

The diagnosis of a diaphragmatic hernia at 18 weeks gestation by instillation of normal saline into the fetal peritoneal cavity under ultrasound guidance is described. The procedure established the diaphragmatic defect with certainty, outlined the contents of the hernia within the thorax, and demonstrated the degree of secondary lung compression.

Acute twin-twin transfusion: a possible mechanism for brain-damaged survivors after intrauterine death of a monochorionic twin

Intrauterine death of one twin in monochorionic pregnancies is associated with increased mortality and morbidity for the survivor. This has been attributed to the consequences of intrauterine disseminated intravascular coagulation (DIC) initiated by the dead twin. We describe a case in which the fetal cerebral and renal lesions typically found in survivors occurred without any derangement in coagulation. Instead, acute twin-twin transfusion was suggested by the presence of severe anemia in the surviving fetus at delivery. We suggest that the lesions frequently found in the survivors are often due to acute hemodynamic and ischemic changes resulting from acute twin-twin transfusion at the time of intrauterine death, rather than to late-onset DIC. This hypothesis has an important implication for future management: Intervention must occur before intrauterine death if neurologic sequelae in the survivor are to be prevented.

When does death occur in an acardiac twin? Ultrasound diagnostic difficulties

Fetal acardia is a rare abnormality of multiple pregnancies, which is lethal for the affected fetus and can cause death in 50% of normal co-twins. Antenatal recognition with early ultrasound is essential to institute a prospective management to improve the outcome. Our communication outline the difficulties which may be encountered in ultrasound diagnosis. In particular the problem of distinguishing a fetal heart from large pulsating mediastinal vessels, which can be present in these fetuses, and the difficulty of diagnosing death in an acardiac fetus. Our report confirms that the co-twin remains at increased risk of sudden death, even without ultrasound evidence of cardiac failure or biochemical compromise. The finding in this fetus of intravascular fibrin deposits suggests the possibility of acute disseminated intravascular coagulation, not previously reported in association with an acardiac twin.

Visualization of fetal intra-abdominal organs in second-trimester severe oligohydramnios by intraperitoneal infusion

Fetal intraperitoneal infusion of saline was performed in two patients with severe oligohydramnios at 24 and 25 weeks' gestation in order to enhance visualization of intra-abdominal organs. Renal agenesis was easily diagnosed. The technique can be considered as an alternative to artificial instillation of amniotic fluid in the differential diagnosis of conditions associated with severe oligohydramnios.

The frequency of chromosome anomalies in human preimplantation embryos after in-vitro fertilization

Previous studies have reported chromosome aberrations in human pre-embryos after in-vitro fertilization (IVF). Although the reason for these abnormalities is not clear, there is evidence that they can arise during gametogenesis, fertilization or cleavage. The present study has examined further the incidence of chromosome abnormalities in human pre-embryos after IVF, using oocytes recovered from normal volunteer women and from women undergoing infertility treatment in an embryo-replacement programme. Chromosome preparations were performed for 75 pre-embryos. Of these 35 (47%) gave at least one metaphase in which analysis was possible. The overall incidence of abnormal pre-embryos was 40% (14/35). The absolute frequency of aberrations was 9% for trisomies, 3% for polyploidies, 26% for structural anomalies and 3% for hypodiploidies. Five pre-embryos were found to be mosaics, three of which had each one trisomic metaphase. In five of the pre-embryos multiple anomalies were found. In 13 of the 14 abnormal pre-embryos the aberrations were found in only one metaphase. The present study demonstrates that trisomic mosaicism may not be a rare event in human pre-embryos. Further evidence is provided that mitotic non-disjunction is important for the production of aberrations in human pre-embryos.

Clinical experience with 50 cases of first-trimester fetal diagnosis by chorionic biopsy

Prenatal diagnosis by chorionic biopsy was undertaken between the eighth and 12th weeks of pregnancy in 50 patients at risk of chromosomal or genetic abnormalities. Samples from 45 patients were karyotyped. A DNA analysis for the detection of homozygous beta-thalassaemia was undertaken in five patients. The sample from one patient at risk of haemophilia in the fetus was subjected to DNA analysis after a male fetus was confirmed on karyotyping. Abnormal karyotypes were detected in four fetuses while three had homozygous beta-thalassaemia.