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Biomedical subjects

N M Fisk

Publications and source records attributed to N M Fisk.

At least 199 records · Page 11Linked to original sources
PubMed1990

Limited role of fetal blood sampling in prediction of outcome in intrauterine growth retardation.

Fetal acid-base status was evaluated on 66 blood samples taken for rapid karyotyping from 58 growth-retarded fetuses. Before blood sampling, doppler blood flow studies of the umbilical artery showed end-diastolic frequencies to be absent in 32 fetuses (group 1) and present in 26 (group 2). Fetuses with chromosomal (n = 4) or structural (n = 8) abnormalities were excluded from subsequent analysis. Gestational age at blood sampling (27.8 [95% CI 26.5-29.1] vs 32.2 [30.4-34.1] weeks) and time from sampling to delivery (median 2 (range 0-35] vs 14 [0-77] days) were significantly lower in group 1 than group 2. There were no perinatal deaths in group 2 whereas mortality in group 1 was 65.4%. There were significant differences between the groups at blood sampling in pH, pO2, pCO2, base equivalents, and nucleated-red-cell count, but within group 1 these measurements were similar in surviving fetuses and those who died perinatally. Since acid-base determination does not predict perinatal outcome in growth-retarded fetuses, fetal blood sampling has a limited role in monitoring fetal wellbeing.

Acid-Base Imbalance↗
PubMed1990

Fetal cystic hygromata: insights gained from fetal blood sampling.

Twelve second-trimester fetuses with cystic hygroma underwent fetal blood sampling for rapid karyotyping, haematologic evaluation, and blood gas analysis. An abnormal karyotype was found in seven cases: monosomy X in five, trisomy 21 in one, and trisomy 13 in the other. Eight of ten fetuses undergoing blood gas analysis showed hypoxaemia, five of which were growth-retarded. Nine pregnancies were terminated. Of the remaining three, only one fetus survived the perinatal period.

Blood Gas Analysis↗
PubMed1990

Continuing controversy in alloimmune thrombocytopenia: fetal hyperimmunoglobulinemia fails to prevent thrombocytopenia.

Two patients with severe alloimmune thrombocytopenia were managed by weekly intrauterine platelet transfusions at 25 to 36 weeks. In one patient high-dose immunoglobulin was also administered weekly to the mother, and high maternal and fetal immunoglobulin levels were achieved. Fetal platelet counts were similar in both patients. The only variable that affected fetal platelet concentration was the posttransfusion platelet count from the previous transfusion.

Blood Transfusion, Intrauterine↗
PubMed1990

Effects of fetal intravenous glucose challenge in normal and growth retarded fetuses.

Fetal intravenous glucose challenge test (0.75 g/kg of estimated fetal weight) was performed at 26-33 weeks gestation in 9 patients undergoing fetal blood sampling (FBS) by ultrasound guided needling from the umbilical vein. The indication for FBS was rapid karyotyping for fetal malformations in 5 (control group) and severe intrauterine growth retardation in the remaining 4 (IUGR group). Fetal blood samples were taken before the glucose infusion and after 1, 3, 5, 10 and 15 min; glucose and insulin were assayed on each occasion and acid-base balance at 0 and 5 min. Basal fetal pO2, pH, glucose and insulin were lower in the IUGR group than in controls. Following the glucose challenge, fetal glucose levels were similar in the two groups, but in the IUGR group the latter part of the glucose curve was characterized by a slower and delayed return to basal levels. In control fetuses the insulin response following the glucose challenge peaked at 3 min while in IUGR no change in insulin concentration was detected. Fetal pO2 did not change in either group; the median change in fetal pH was significantly different between the two groups (controls: +0.01; IUGR: -0.04; P less than 0.05) and there was a significant correlation between basal pO2 and the change in fetal pH (r = 0.79) (P less than 0.02). These results support the concept of a low energy state in IUGR. Fetal glucose supplementation in IUGR is unlikely to be of benefit and may even exacerbate underlying acidosis.

Blood Glucose↗
PubMed1990

Fetofetal transfusion syndrome: do the neonatal criteria apply in utero?

Thirteen fetuses (five twin, one triplet) were compromised by fetofetal transfusion syndrome in six pregnancies, five in the mid trimester, and one in the third trimester. This diagnosis, which was suspected because of ultrasound findings of discordant growth, discordant amniotic fluid volumes, concordant external genitalia, and monochorial placentation, was confirmed postnatally in each. Nine fetuses underwent blood sampling to aid diagnosis and assessment of fetal wellbeing. In contrast to fetofetal transfusion syndrome investigated postnatally, a difference in haemoglobin concentration of 50 g/l or more in utero was found in only one pregnancy, which was near term, although all had fetal erythroblastaemia and a difference in weight of 20% or more. In vivo confirmation of shared circulation was achieved in two pregnancies by transfusing adult Rh negative red cells into the smaller fetus and then detecting them by Kleihauer testing in blood aspirated from the larger. Invasive procedures also yielded information on fetal blood gas measurements (acidaemia in four and hypoxaemia in six) and amniotic pressure (raised in two). We suggest that comparison of haemoglobin concentrations is inaccurate in fetofetal transfusion syndrome in utero, the diagnosis of which may necessitate detection of a shared circulation using a marker such as adult red cells.

Adult↗
PubMed1990

Plasma renin activity in fetal disease.

Fetal plasma renin activity (PRA) was measured in 42 pregnancies. Compared to control fetuses, PRA was elevated in three of four hypoxemic fetuses, in two of five with hydrops and in two of five with uropathies. PRA did not change with transfusion in seven alloimmunized fetuses. This study demonstrates PRA in human fetuses and suggests that the renin-angiotensin system can respond to stimuli in fetal life.

Fetal Diseases↗
PubMed1990

Fetal blood sampling from the intrahepatic vein: analysis of safety and clinical experience with 214 procedures.

Transabdominal fetal blood sampling under ultrasonic guidance was performed at the intrahepatic vein on 214 occasions in 177 fetuses. In 72 cases, an intravascular transfusion was also attempted at the same site. In 91.1% of the samplings, more than 1 mL of pure fetal blood was obtained, and in 89.9% of transfusions, fetal hematocrit or platelet concentration was raised to a satisfactory level. Fetal bradycardia and intraperitoneal bleeding occurred in 2.3% of the cases. Among fetuses at low risk, there was only one intrauterine death, which occurred 3 weeks after the procedure, and one spontaneous abortion in a patient with twin pregnancy. In fetuses with Rh/Kell alloimmunization or perinatal alloimmune thrombocytopenia, the survival rate was 86%. Four liver enzymes were assayed in the blood of 13 fetuses that underwent transfusions at the intrahepatic vein and 13 controls in whom the site of sampling was the umbilical vein at the placental cord insertion. No differences were found between the groups at the subsequent transfusion 2-5 weeks later. The intrahepatic vein is an alternate site of sampling/transfusion when access is difficult or failure occurs at the placental cord insertion. This approach minimizes the risks of fetal blood loss, fetomaternal hemorrhage, arterial vasospasm, and cord tamponade.

Blood Specimen Collection↗
PubMed1990

Amniotic pressure in disorders of amniotic fluid volume.

Amniotic pressure was measured in 49 pregnancies with abnormal quantities of amniotic fluid. Among 17 with polyhydramnios, the pressure was always above the normal mean for gestation and exceeded the upper limit of normal in nine. In polyhydramnios, amniotic pressure correlated positively with the depth of the deepest pool (r = 0.65, P = .04) and negatively with fetal PO2 (r = -0.57, P = .03) and pH (r = -0.56, P = .04). Amniotic pressure was raised in all those with a deepest pool of greater than 15 cm, and was normal in all with a deepest pool less than 15 cm. Amniotic pressure fell significantly with drainage of amniotic fluid in those with raised pressure (mean 12.7 mmHg, 95% confidence interval 7.0-18.3; P = .002) but not in those with normal pressure (mean 0.3, 95% confidence interval -3.2 to +3.9; P = .82). Restoration of normal amniotic pressure in one pregnancy was accompanied by marked improvement in fetal acid-base status. Among 24 pregnancies with severe oligohydramnios, amniotic pressure was always below the normal mean, falling below the lower limit of normal in eight; whereas in another eight pregnancies with mild/moderate oligohydramnios, amniotic pressure was scattered evenly within the normal range. Amnioinfusion of 55-500 mL of normal saline in cases of severe oligohydramnios led to a significant rise in pressure (4.7 mmHg, 95% confidence interval 3.5-5.9; P less than .0001). We conclude that amniotic pressure is high in polyhydramnios and low in oligohydramnios. Pressure monitoring may be beneficial during amnioinfusion and therapeutic amniocentesis.

Acid-Base Equilibrium↗
PubMed1989

Intrauterine manometry: technique and application to fetal pathology.

A technique is described for measuring pressure within the amniotic cavity and within fetal vessels and/or body compartments. Two saline-filled catheters were connected at one end to needles inserted during indicated invasive procedures and at the other to silicon strain gauge transducers. In 36 pregnancies with normal liquor volume, stable intra-amniotic pressure (IAP, range 1-14 mmHg) increased with gestation (r = 0.48, p less than 0.01). In pregnancies complicated by severe oligohydramnios, IAP was less than or equal to 1 mm Hg and rose to normal levels with saline amnioinfusion. Raised IAP (range 17-26 mm Hg), found in pregnancies with gross polyhydramnios, fell with drainage of amniotic fluid. Subtraction manometry was used to determine supra-amniotic pressure within the intervillus space, umbilical vein, umbilical artery, abdominal and thoracic cavities, and the urinary tract in normal and/or pathological fetuses. Low intravesical and intrapelvicalyceal pressures (median 6.5, range 2-10 mm Hg) were noted in fetuses with obstructive uropathies. Intrauterine subtraction manometry appears to be a useful tool in the understanding of fetal pathophysiology and may be of clinical benefit in the therapeutic drainage and infusion of amniotic fluid and in the assessment of certain fetal disease states.

Amniotic Fluid↗
PubMed1989

Pathophysiology of pressure changes during intrauterine transfusion.

Intraperitoneal and umbilical vein pressure readings were obtained during intrauterine transfusion in patients with Rh alloimmunization. In 15 nonacidotic fetuses, mean umbilical vein pressure before transfusion (4.5 mm Hg, SD = 2.3) increased by 4.6 mm Hg (delta umbilical vein pressure confidence intervals +2.8 to +6.4; p less than 0.0001) with transfusion. delta Umbilical vein pressure correlated positively with the increase in hematocrit level (r = 0.55; p less than 0.05) and negatively with gestational age (r = -0.58; p less than 0.05). Basal umbilical vein pressure was raised in the only acidotic fetus, whereas delta umbilical vein pressure was 0. Intraperitoneal pressure was recorded in 11 fetuses before and after transfusion, five of which were associated with fetal heart rate changes or preexisting ascites. Basal intraperitoneal pressure (2.5 mm Hg, confidence intervals 1.4 to 3.6) was significantly lower than basal umbilical vein pressure (confidence intervals, 3.2 to 5.8; p less than 0.02). In uncomplicated intraperitoneal transfusions, intraperitoneal pressure rose significantly (delta intraperitoneal pressure = +5.8; confidence intervals 2.9 to 8.8; p less than 0.005). In four transfusions associated with fetal bradycardia or tachycardia, delta intraperitoneal pressure (range, 16 to 26) was greater than in uncomplicated transfusions (range, 1 to 9). delta Intraperitoneal pressure was 0 in the fetus with ascites. These results implicate increases in umbilical vein pressure and intraperitoneal pressure in immediate complications of intrauterine transfusion, and support a role for intraperitoneal pressure monitoring during intraperitoneal transfusion.

Acid-Base Equilibrium↗
PubMed1989

Fetal hyperinsulinism in anencephaly.

Insulin was measured in the blood collected in utero from three midtrimester anencephalic fetuses. The hyperinsulinism found could be due to an underutilization of glucose in the absence of most of the brain and could be responsible for the relatively normal growth in anencephaly despite the absence of the hypothalamohypophysial axis.

Anencephaly↗
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

Labor outcome of juvenile primiparae in a population with a high incidence of contracted pelvis.

Labor outcome of primiparae less than 17 years was compared with non-juvenile primiparae in a population with a high incidence of contracted pelvis. Juvenile primiparae were referred to hospital on the basis of age, whereas non-juveniles were referred for an obstetric complication. There was no statistical difference in rates of cesarean section, Ventouse, operative delivery, low birth weight, or perinatal mortality between 538 juveniles and 5294 older "high risk" mothers. Symphysiotomy rates were actually higher in the juveniles (12.6% vs. 9.7%, P less than 0.05). These data support the practice of hospital referral for juvenile African women in labor.

Adolescent↗
PubMed1989

Lack of effect of high-dose antioestrogen on the maturation and in-vitro fertilization of human oocytes.

Thirty-four women requesting laparoscopic sterilization underwent a fixed schedule regimen for multiple follicular development which included norethisterone and clomiphene citrate. Follicle aspiration for oocyte recovery was attempted laparoscopically 34 h after administration of 5000 IU human chorionic gonadotrophin (HCG). Nineteen women were given 80 mg tamoxifen orally 4 h prior to HCG injection, while 15 acted as controls. There was no statistical difference in fertilization rates in vitro between tamoxifen-treated patients and controls (80 and 68% respectively). In addition, the morphological characteristics of the oocytes, the rates of cleavage, and the concentrations of oestradiol, progesterone and androstenedione in follicular fluid were similar in the two groups. Tamoxifen was detected in substantial amounts in follicular fluids of patients given tamoxifen. These results suggest that high-dose tamoxifen, in clinically used doses, does not adversely affect the final stages of maturation or the fertilization and early cleavage of human oocytes.

Female↗