Umbilical cord blood gas assessment of twins.

Umbilical cord arterial and venous blood gas values were compared in 63 twin pairs, of which 57 pairs had birth weights of 1500 g or more each. Small differences between the first and second twins existed for PO2, PCO2, and pH. However, bicarbonate values did not differ significantly. These cord gas differences represent minor respiratory aberrations, as reflected by a tendency toward carbon dioxide retention by the second twin. Route of delivery, time interval between deliveries, and nonvertex presentations were not associated with significant deviations from these observed acid-base patterns.

Radioimmunoassay of digoxin in serum using monoclonal antibodies and assessment of interference by digoxin-like immunoreactive substances.

We used 7 monoclonal antibodies (MoAbs) and one polyclonal antibody to develop radioimmunoassays (RIAs) for digoxin in serum or plasma. These RIAs were tested for measuring apparent digoxin concentrations in serum from patients receiving the drug, from normal individuals, and in cord blood plasma. We found that two MoAbs cross-reacted significantly with substances in cord blood. The magnitude of cross-reactivity was dependent on the incubation time and temperature. Under equilibrium conditions, one antibody gave apparent digoxin values in cord blood plasma averaging 2.15 ng/ml. We suggest that this cross-reactivity is partially due to progesterone and 17-hydroxyprogesterone in cord blood plasma. The antibody that shows high cross-reactivity with digoxin-like immunoreactive substances may prove a useful tool for studies dealing with characterization of the cross-reacting compounds.

Cordocentesis: role in assessment of fetal condition.

Cordocentesis for prenatal diagnosis has allowed extensive progress in our knowledge of human fetal physiology. It is now being used to guide obstetric management of acquired fetal diseases (e.g., timing of delivery and intrauterine therapy). The most established indications are blood disorders (e.g., fetal anemia and thrombocytopenia) and further investigation of potentially correctable fetal malformation, but it is being used increasingly in placental insufficiency (e.g., fetal hypoxia and hypoglycemia).

[The assessment of the safety of vacuum extraction deliveries under routine epidural block].

To assess the safety of vacuum extraction (V.E.) deliveries under continuous lumbar epidural block (E.B.) with Bupivacain, the modified Krebs score in CTG, Apgar score, cord arterial blood acid-base balance, hypoxanthine, CPK, CPK-BB, Neuron specific enolase and c-AMP were examined. A total of 74 full term oxytocin-induced labors were divided into three groups: A) 21 cases by V.E. under E.B., B) 34 cases under E.B. only, and C) 19 cases without V.E. or E.B. There was no difference in age, gestational weeks in the three groups. However, the incidence of primiparas was highest in group A. Though CTG showed a temporary low Krebs score in group A within 30 minutes after the initiation of E.B., it was found that there was no significant difference between the three groups 30 minutes before parturition. The apgar score, cord arterial blood pH, PO2 and B.E. were also found to be similar in all three groups. Among various kinds of substances in the cord blood, both CPK-BB and c-AMP showed a striking rise in group A, compared to groups B and C. Therefore, the use of V.E. under E.B. might be hazardous to the well-being of the newborn infant.

[Follow-up and evaluation by means of brain stem evoked potentials of a pediatric population diagnosed as having had fetal distress]. / Seguimiento y valoración mediante potenciales evocados de tronco cerebral de una población pediátrica diagnosticada de sufrimiento fetal.

A population of 80 patients affected with foetal distress is analyzed classifying it according to a qualitative variable (Apgar test) to which we assigned three category levels: normal/low/very low; and a quantitative variable, the pH from the umbilical artery being more or less than 7.15. We also studied all the clinical variables and complications derived from the base illness and their relationship. Four subpopulations were established which were studied by means of brain stem potential audiometry over 3 years, establishing that in those patients whose pH is less than 7.15 and their Apgar test is low/very low there exists a very high incidence of hypoacusis, characterized as sensorineural in 13.3%, conductive in 13.3%, not classifiable in 60%, and retrocochlear in 13.3%. There was a tendency to improve in 26.6%. Four of the 24 patients that are in this group wear an auditory prosthesis as an indication of the important damage suffered. There is no relationship in our study between the hypoacusis and the tests of the clinical variables which confirms the foetal distress.

Low-level lead exposure, social class, and infant development.

A prospective cohort study was conducted to assess the association between early development and low-level prenatal and postnatal lead exposure. Infants' performance between 6 and 24 months on the Mental Development Index of the Bayley Scales of Infant Development declined with increasing concentration of lead in blood, but the decline varied with children's age at exposure, level of exposure, and socioeconomic status. Within the second year of life, the performance of children in lower socioeconomic strata was adversely affected at lower levels of prenatal exposure (blood lead levels of 6 to 7 micrograms/dl) than was the performance of children in higher socioeconomic strata. However, even the performance of these advantaged infants was lower when cord blood lead level exceeded 10 micrograms/dl, well below the figure currently regarded as the maximum permissable level for young children. Exploratory analyses suggested that early postnatal blood lead levels between 10 and 25 micrograms/dl were also associated with lower Mental Development Index scores, but only among children in lower socioeconomic strata.

The role of blood gas and acid-base assessment in the diagnosis of intrapartum fetal asphyxia.

The diagnosis of fetal asphyxia requires a blood gas and acid-base assessment demonstrating a significant metabolic acidosis. However, the fetus may tolerate an asphyxial insult without central nervous system injury because of the fetal cardiovascular adaptation to hypoxemia. Prediction of the significance of an asphyxial insult to the fetus requires a measure of both the duration and degree of the asphyxia as well as an expression of the fetal compensatory response to the asphyxia.

Fetal haemoglobin measurement in the assessment of red cell isoimmunisation.

A reference range of fetal haemoglobin concentration (g/dl) was established from umbilical cord blood samples obtained by cordocentesis (n = 200) or at delivery (n = 10). In normal pregnancy the mean fetal haemoglobin increases linearly from 11 g/dl at 17 weeks' gestation to 15 g/dl at 40 weeks' gestation and one standard deviation is approximately 1 g/dl. The haemoglobin was also measured in fetal blood from 154 red cell isoimmunised pregnancies from 17 to 36 weeks' gestation. In 48 fetuses with ultrasound features of hydrops the haemoglobin was 7-10 g/dl below the normal mean for gestation. It is proposed that in pregnancies complicated by red cell isoimmunisation the severity of the disease should be assessed and treated on the basis of the deviation of the fetal haemoglobin from the normal mean for gestation into mild (haemoglobin deficit less than 2 g/dl), moderate (deficit 2-7 g/dl), and severe (deficit greater than 7 g/dl).

The assessment of fetal blood samples.

Fetal blood sampling under ultrasound control is rapidly expanding the study of human fetal biology. Pure fetal blood is required for prenatal diagnosis, establishment of reference ranges for biologic measurements, and assessment of fetal welfare. We present here the methods that we have developed to detect contamination in more than 1500 samples. These include hematologic indexes, blood smear, erythrocyte antigens, beta-human chorionic gonadotropin, and coagulation factor assays. The tests are relatively simple, inexpensive, and widely available. No single test is reliable in all situations, and it is necessary to perform all the tests on each sample of fetal blood. In the clinical setting where irrevocable action may be taken as a consequence of our results, we require absolute assurance of the purity of the sample.

Ion-selective sensors for assessment of the fetus.

Frequent measurement of pH and PCO2 levels of fetal blood during labour provides an insight into the presence and nature of fetal asphyxia, effectiveness of in utero resuscitation and the need for operative delivery. A pH measuring system utilizing a hydrogen ion-selective polymer membrane built into a fetal probe suitable for making intermittent measurements on the fetal scalp during labour is described. Probe design, construction of electrodes and preliminary results obtained using the system in vitro are presented.

Assessment of total immunoreactive lactoferrin in hematopoietic cells using flow cytometry.

Cell-associated lactoferrin (Lf) was analyzed using a new method involving cell permeabilization, indirect immunofluorescence staining, and flow cytometry. Statistical techniques to evaluate the results for percentage of positive cells, relative fluorescence and homogeneity of Lf distribution were also devised. Most normal adult neutrophils (97.1 +/- 0.3% (SEM), range 92.7-99.6%, n = 41) had brilliant fluorescence homogeneously distributed among the cells. There was significantly greater homogeneity of neutrophil Lf distribution in post-menopausal than pre-menopausal females. In chronic myelogenous leukemia (n = 13) and cord blood (n = 7), fractions of Lf-positive neutrophils were decreased (77.3 +/- 7.5%, range 13.3-96.3%; 71.4 +/- 9.3, range 32.0-95.6%, respectively). Normal monocyte-rich isolates had moderate fluorescence (28.7 +/- 3.6%, range 9.3-76.8%, n = 22). Among blood lymphocyte-rich preparations, 13.1 +/- 1.3% of cells had weak positivity (range 4.9-26.6%, n = 19); monoclonal B and T lymphocytes had similar parameters. No other cells had detectable Lf. Our results were significantly correlated with those obtained manually (r = 0.98, P less than 0.001), and are consistent with Lf quantity and distribution determined using other methods.

Haematolytic disease due to ABO incompatibility: incidence and value of screening in an Asian population.

The population in Singapore is predominantly Asian, with Chinese forming the major ethnic group. The incidence of haemolytic disease of the newborn (HDN) due to Rh incompatibility is very low. The true incidence of HDN due to ABO incompatibility is unknown. Early discharge is practised in Singapore making it important to predict severe HDN due to ABO incompatibility as this would constitute the main cause of haemolysis next to G6PD deficiency. One thousand, six hundred and eight baby-maternal pairs were typed for ABO, Rh, and tested for direct Coombs' test, maternal titre, cord bilirubin and haptoglobin levels. Two hundred and fifty-one were found to be ABO incompatible, with 141 group A and 110 group B babies. The incidence of HDN due to ABO incompatibility was 3.7% of all group O mothers. Coombs' test, maternal antibody titre, cord bilirubin and haptoglobin levels were of low predictive value for severe HDN due to ABO incompatibility. The data further support the notion that it is not cost effective to screen for ABO incompatibility.

Cordocentesis in the assessment of the small-for-gestational age fetus.

Fetal blood sampling by cordocentesis in a group of 239 severely small-for-gestational age fetuses revealed a high incidence of chromosomal anomalies (17%). Furthermore, some of the fetuses were hypoxemic and demonstrated abnormalities in carbohydrate, lipid and protein metabolism. There were significant correlations between the degree of fetal hypoxemia and abnormalities in Doppler measurements of impedance to flow in the maternal uterine arteries and in the fetal umbilical artery, and of mean blood velocity measured in the fetal descending thoracic aorta and in the common carotid artery. Maternal hyperoxygenation in some cases improved fetal oxygenation and corrected some of the abnormalities in the Doppler measurements of fetal circulation.

Iron stores in pregnant Nigerians and their infants at term.

Serum ferritin and blood haemoglobin were evaluated as indices of iron status in 65 pregnant Nigerians and in the cord blood of their full-term infants. All the mothers had taken iron and folate supplementation throughout pregnancy. The mean gravidity was 3.3 +/- 2.0. The mean cord ferritin concentration of 135.9 micrograms/l (77.6-238.2 micrograms/l) was 3.6 times the maternal level of 38.1 micrograms/l (17.3-83.8 micrograms/l). Parity had no effect on the haemoglobin or serum ferritin concentrations of the mothers or those of their babies. Maternal haemoglobin or serum ferritin concentrations correlated significantly (P less than 0.01) with cord levels, in babies with mothers of parity greater than or equal to 5. Infants of mothers with low iron stores (less than 20 micrograms/l) had significantly lower serum ferritin concentrations than infants of iron-replete mothers, which suggests variation in amounts of iron received during intrauterine growth. In order to ensure adequate iron stores in newborn infants, continual use of supplementary oral iron should be encouraged in pregnant Nigerians.

Assessment of passive and transplacental exposure to tobacco smoke.

Although tobacco smoke has been shown to be highly genotoxic in various experimental systems, most nonmolecular methods designed to assess exposure to mutagens are too insensitive to detect passive exposure to tobacco smoke. Biochemical markers of intake--cotinine and thiocyanates in body fluids--were shown to be elevated after occupational, passive or transplacental exposure to tobacco smoke, while no response was seen in the frequency of sister chromatid exchanges (SCE) in cultured blood lymphocytes. After occupational exposure to environmental tobacco smoke, the intake marker levels are generally less than 5% of the levels found in active smokers, while cord blood levels (representing fetal exposure) are at about the same level as in the mothers at the time of delivery.

Single-probe spectrophotometry in the assessment of fetal oxygenation.

Six sheep fetuses were monitored with a single-probe tissue spectrophotometer. This spectrophotometer provides continuous digital output of the index of hemoglobin that is saturated with oxygen. To vary the fetal pO2, each maternal ewe was given room air, 100% oxygen, 12% oxygen, and 100% nitrogen via rebreathing bag. Fetal venous (N = 4) or arterial (N = 2) blood was analyzed for pO2. There was excellent correlation between the index of hemoglobin saturated with oxygen and the fetal pO2. The single-probe spectrophotometer overcomes two of the technical problems encountered when a double-probe spectrophotometer is used.

Value of acetylated haemoglobin assay in fetal assessment.

Acetylation of fetal haemoglobin, probably a post-translational, intracellular, enzyme-mediated reaction, depends upon an adequate supply of glucose and oxygen to the fetus and the nature of the diabetes (if present) in the mother. These complicating factors limit the general usefulness of acetylated fetal haemoglobin assay in fetal assessment.

Complement activation in fetuses: assessment by the levels of complement components and split products in cord blood.

The whole complement activity (CH50) and concentrations of components (C1q, C3, and C4) and C3 split product (C3d) were determined in the cord blood of 172 newborns between 16 and 42 weeks of gestation. Histological examination of their placentas revealed that the extent of complement activation was significantly higher in those with some degree of inflammation in the amnion than in those with normal amnion. The correlation between the complement levels and gestational age was higher in those with no amnionitis. In some cases the level of C3d at an early gestational age was as high as that in adults. The C3 activation system seems to be well developed even before week 25 of gestation. Among the complement components, C3d was the most sensitive indicator of placenta inflammation. As placenta inflammation may reflect intrauterine infection, the measurement of C3d levels may be of diagnostic value.