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Biomedical subjects

U Nicolini

Publications and source records attributed to U Nicolini.

At least 109 records · Page 6Linked to original sources
PubMed1989

Low amniotic pressure in oligohydramnios--is this the cause of pulmonary hypoplasia?

The mechanism by which oligohydramnios produces lung hypoplasia is not understood. The current theory that extrinsic compression of the fetal thorax causes hypoplasia, either by inhibiting breathing movements or by squeezing out lung liquid, is not supported by observational or experimental data, or by our finding of decreased amniotic pressure around the fetus in oligohydramnios. We hypothesize that lung hypoplasia results from excess loss of lung liquid because of a reduction in amniotic pressure, and hence an increase in the alveolar-amniotic pressure gradient. The magnitude of this increased pressure gradient is calculated to exceed the small standing tracheal pressure; thus low amniotic pressure overcomes the normal laryngeal retentive mechanisms and allows a larger quantity of lung liquid to escape. In the prevention of pulmonary hypoplasia, a role is suggested for the instillation of artificial amniotic fluid to restore normal amniotic pressure.

Amniotic Fluid↗
PubMed1989

Maternal-fetal glucose gradient in normal pregnancies and in pregnancies complicated by alloimmunization and fetal growth retardation.

Maternal and fetal glucose concentrations were measured simultaneously in 54 pregnancies in which fetal blood sampling was conducted between 18 and 34 weeks gestation. Twenty-five pregnancies were normal (group 1), 13 were complicated by fetomaternal alloimmunization (group 2), and 16 by intrauterine growth retardation (group 3). The maternal glucose concentration was similar in the three groups. The fetal glucose level was significantly lower in growth-retarded (mean = 2.7 mmol/L) than in normal pregnancies (mean = 3.5 mmol/L). There was a statistically significant gradient between maternal and fetal glucose concentrations in groups 1 and 3, but no gradient was found in group 2. Maternal and fetal glucose concentrations were significantly correlated in all groups, but the correlations were distinct. For a given maternal glucose concentration, fetal glucose was higher in patients with alloimmunization and lower in patients with intrauterine growth retardation than in normal pregnancies. In patients with intrauterine growth retardation, fetal PO2 correlated positively with fetal glucose and inversely with maternal fetal glucose gradient.

Blood Glucose↗
PubMed1989

Maturation of thyroid function in normal human foetuses.

The functional maturation of an independent foetal thyroid activity was investigated in the present study. Serum concentrations of total T4, free T4, TSH and TBG were measured in 23 foetuses between 18 and 31 weeks' gestational age. Foetal samples were collected by transabdominal needling from the placental cord insertion. TT4, FT4, TBG and TSH levels significantly increased with gestational age. FT4 levels were comparable with the adult range by 28 weeks' gestation; TBG levels reached adult values at approximately 30 weeks, while TT4 was lower than adult levels throughout the whole period studied. TSH values were, in all cases, higher than the normal adult range. A significant positive correlation was present between TT4 and TBG, TT4 and TSH, and TBG and TSH levels; on the contrary, no correlation was demonstrated between FT4 and TSH levels. The TSH/TT4 ratio significantly decreased with gestational age. The results suggest an incomplete responsiveness of the foetal thyroid gland to TSH, while the feedback control system between pituitary and thyroid is operating at a different set point from that in post-natal life. The normal range of thyroid parameters established is of clinical relevance for the antenatal diagnosis, and eventual treatment of thyroid disorders that may seriously damage foetal development and maturation.

Fetus↗
PubMed1989

When to perform the next intra-uterine transfusion in patients with Rh allo-immunization: combined intravascular and intraperitoneal transfusion allows longer intervals.

Data from 99 intra-uterine transfusions performed in 30 patients (31 fetuses) with Rh allo-immunization have been reviewed. Mean gestational age at the first transfusion was 23.6 weeks and mean fetal haematocrit 19.8%. The number of procedures was on average 3.2 per fetus. Survival rate was 84%. Fifty-nine intravascular transfusions were combined with intraperitoneal transfusions. Combined intravascular and intraperitoneal transfusions, when compared to intravascular transfusions alone, achieved a significantly longer interval between transfusions and also maintained a higher fetal haematocrit at the subsequent transfusion. Mean fall in fetal haematocrit was 0.98% per day with a wide range. There was a general tendency towards a less marked fall during the second interval between transfusions than in the first with the exception of those cases in which the percentage of fetal red cells at the start of the second transfusion was increased compared to that which was found at the end of the first, i.e., when fetal erythropoiesis was not suppressed.

Blood Transfusion, Intrauterine↗
PubMed1989

Fetal macrocytosis in association with chromosomal abnormalities.

Mean red cell volume (MCV) was determined in 264 fetuses between 15-41 weeks. After exclusion of anemic, hypoxic, and chromosomally abnormal fetuses, the MCV in 208 umbilical venous samples was shown to decrease with gestation (r = 0.64; P less than .001), and a normal range was constructed by linear regression analysis. An elevated MCV was found in both fetuses with triploidy, in four of five with monosomy X, and in four of ten with trisomies 18 or 21. The MCV was similarly raised in four of five fetuses with gross anomalies in whom cytogenetic cultures had failed. Significant correlations were found in chromosomally abnormal fetuses between the elevation in MCV and both the nucleated red cell (r = 0.69; P less than .01) and reticulocyte counts (r = 0.57; P less than .05). There was a similar correlation with nucleated red cells in 16 severely anemic fetuses with Rh disease, 12 of whom had a raised MCV. Elevation in MCV was unrelated to hypoxia. Macrocytosis had a sensitivity of 71% and a specificity of 95% in the second trimester for predicting an abnormal karyotype in nonanemic fetuses (kappa index 0.60). Fetal MCV may provide clinically useful information while one awaits culture results. We suggest that karyotyping be considered in fetuses undergoing blood sampling for other indications in whom the MCV is raised.

Anemia↗
PubMed1988

Consequences of fetomaternal haemorrhage after intrauterine transfusion.

Fetomaternal haemorrhage was studied after 68 consecutive fetal intravascular transfusions performed in 20 patients with Rh isoimmunisation. alpha Fetoprotein concentration was assayed in maternal blood taken before, and immediately after each transfusion and three and 24 hours later. An increase of 50% or more in the concentration in any of the samples after transfusion was considered to indicate fetomaternal haemorrhage. Fetal alpha fetoprotein concentration in blood sampled before transfusion was also assayed and the amount of fetomaternal haemorrhage calculated. Fetomaternal haemorrhage occurred in 21 of 32 patients with an anterior placenta and in six of 36 with a posterior or fundal placenta. The mean estimated volume of haemorrhage was 2.4 ml, which was on average equal to 3.1% of the total fetoplacental blood volume. When the volume of fetomaternal haemorrhage at the first transfusion was greater than 1 ml there was a greater increase in maternal Rh (D) antibody titres and a greater fall in fetal packed cell volume. Sampling of fetal blood should not be routinely done early in patients with Rh isoimmunisation, and intrauterine transfusion should be delayed as long as possible. Sampling sites other than the placental cord insertion reduces the risk of fetomaternal haemorrhage.

Blood Transfusion, Intrauterine↗
PubMed1988

Prenatal diagnosis of carbamoyl-phosphate synthetase deficiency by fetal liver biopsy.

In a pregnancy at risk for carbamoyl-phosphate synthetase (CPS) deficiency, prenatal diagnosis was attempted by fetal liver biopsy, performed at 18 weeks of gestation. CPS activity was absent and the diagnosis was confirmed after termination of the pregnancy. The technique employed for fetal liver biopsy is described together with an evaluation of its possible role in prenatal diagnosis.

Biopsy, Needle↗
PubMed1988

The fetal intrahepatic umbilical vein as an alternative to cord needling for prenatal diagnosis and therapy.

Seventy-one fetal blood samplings (FBS) were attempted from the intrahepatic portion of the umbilical vein (IHV) at 18-34 weeks; 54 were attempted primarily and 17 secondarily after a failed attempt at the placental cord insertion. Fetal blood was obtained in 89 per cent of the cases. Intravascular transfusion (IVT) was attempted on 31 occasions and successful in 24 (77 per cent). In all cases of failed sampling or transfusion via the IHV, prenatal diagnosis and/or therapy was accomplished using alternative procedures. On only one occasion was the procedure postponed. There were no losses or neonatal morbidity attributable to the procedure. FBS from the IHV may be considered as an alternative approach to sampling the placental cord insertion. It is recommended in cases where the approach to the placental cord insertion is difficult or hazardous.

Blood Specimen Collection↗
PubMed1988

Fetal blood sampling.

Fetal blood sampling is now performed in many centres through different approaches (fetoscopy, placentacentesis, cardiac puncture, umbilical cord needling, intrahepatic vein puncture) for prenatal diagnosis of congenital defects, management of intrauterine growth retardation and fetal therapy. One hundred and thirty-nine fetal blood samples have been performed during a 10 month period at Queen Charlotte's Maternity Hospital, London, using an individualized approach. One failure to obtain fetal blood occurred and there were four fetal losses, three of which followed an intrauterine transfusion in very severely affected fetuses. Two of these losses were associated with peculiar circumstances (see above). The procedure-related risk is nowadays more difficult to evaluate than in the past, when most fetal blood samplings were carried out in the second trimester for prenatal diagnosis. Most case studies, and ours as well, are not homogeneous and high-risk patients such as those with Rhesus disease or intrauterine growth retardation are also included. It seems, however, that transabdominal needling of the cord, at either placental or fetal insertion, is a low-risk procedure although a larger number of cases should be collected to draw definite conclusions about sampling from the intrahepatic vein. Fetoscopy also has a low risk in experienced hands, but the training period is certainly longer and the application in the second half of the pregnancy has been limited to a few cases. It is likely to be used only very little in the future. A flexible approach to fetal blood sampling allows the best choice of technique and utilizes the advantages of each technique.

Female↗
PubMed1988

Changes in fetal acid base status during intravascular transfusion.

Umbilical venous pH, PCO2, PO2, and base excess was measured immediately before and after 72 intravascular transfusions in 34 fetuses with erythroblastosis fetalis. In 67 uncomplicated transfusions, infused adult blood led to a mean (95% confidence intervals) fall in pH (0.037, CI 0.029 to 0.044) and base excess (2.03, CI 1.61 to 2.45) and a mean rise in PCO2 (0.24 kPa, CI 0.13 to 0.35). These changes correlated significantly with the increase in fetal haemoglobin and packed cell volume. Five transfusions were associated with complications within six hours: intrauterine death in two, fetal-distress necessitating delivery in two, and preterm labour in one. Two had pre-existing acidosis, whereas two of the three with normal blood gas and acid base measurements before transfusion had acute changes that were outside the normal ranges that had been established in uncomplicated transfusions.

Acid-Base Equilibrium↗
PubMed1987

Fitting growth curves to head and abdomen measurements of the fetus: a multicentric study.

Three different mathematical models were fitted to ultrasonic measurements of the biparietal diameter, head circumference, and abdomen circumference obtained from 1,426 healthy fetuses. The linear cubic function gives coefficients comparable with most previous studies, but it does not thoroughly explain fetal growth throughout pregnancy. Both the exponential-power function and the logistic-logarithmic function fit the raw data well and theoretically reflect the biological phenomena of human fetal growth. The characteristics of each model are discussed.

Abdomen↗