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PubMed1978

Determination of fetal lung maturity by fluorescence polarization of amniotic fluid.

The degree of fluorescence polarization (P value) of 1,6-diphenyl-1,3,5-hexatriene has been shown to be an excellent indicator of the lecithin/sphingomyelin (L/S) ratio in laboratory prepared liposomal dispersions. In order to test the validity of this technique in amniotic fluid, the L/S ratio and P value of 161 amniotic fluid specimens were determined. In 127 the P value was less than or equal to 0.336 and the L/S ratio was greater than or equal to 2. In 26 the P value was greater than 0.336 and the L/S ratio was less than 2 (P less than 0.05). The amniotic fluid P value is affected by blood or meconium but not by surgical lubricants or bilirubin. We concluded that the degree of fluorescence polarization of amniotic fluid indicates fetal lung maturity as reliably as the L/S ratio. However, this method has important technical and practical advantages that make it more applicable for a clinical laboratory.

Amniotic Fluid↗
PubMed2000

Successful application of extracorporeal membrane oxygenation and intra-aortic balloon counterpulsation as lifesaving therapy for a patient with amniotic fluid embolism.

A woman in labor was noted to have amniotic fluid embolism. Extracorporeal membrane oxygenation and intra-aortic balloon counterpulsation were performed post partum, and the vital signs became stable. The ensuing recovery was uneventful. We conclude that extracorporeal membrane oxygenation and intra-aortic balloon counterpulsation should be considered to save the life of a patient with amniotic fluid embolism and left ventricular failure unresponsive to medical therapy.

Adult↗
PubMed1980

Non quantitative estimation of amniotic fluid volume in suspected prolonged pregnancy.

A simple non-quantitative method of assessing the volume of amniotic fluid by ultrasound examination is described. The classification is based on the presence or absence of echo-free space between the fetal limbs and the fetal trunk or the uterine wall. In order to test the value of the classification, 150 patients with pregnancies of 42 weeks or more duration underwent ultrasound examination in the 48 hours prior to delivery. The patients classified as having "reduced" or "absent" amniotic fluid has statistically significant excess incidence of meconium stained liquor, fetal acidosis, birth asphyxia and meconium aspiration. The outcome of patients with "normal" amniotic fluid volume was excellent.

Amniotic Fluid↗
PubMed1990

Studies in fetal wound healing, VII. Fetal wound healing may be modulated by hyaluronic acid stimulating activity in amniotic fluid.

Fetal wound healing occurs rapidly and without inflammation, fibrosis, or scar formation. It is a process fundamentally different from adult wound healing. The mechanisms that underlie such unique healing properties are unknown. However, hyaluronic acid, a glycosaminoglycan component of the extracellular matrix, is prominent throughout the course of fetal wound healing, and is thought to play a major role in the healing process. Amniotic fluid contains high levels of hyaluronic acid. Amniotic fluid also contains a number of potent growth factors that are critical for fetal development. In this report, a new factor in amniotic fluid that stimulates deposition of hyaluronic acid is described. This activity is measured in an in vitro assay system in which cultured fibrosarcoma cells are used as indicator cells. Amniotic fluid thus provides two separate mechanisms for the deposition of hyaluronic acid. One is by exogenous application directly onto fetal skin wounds; the second is by providing a factor to increase the production of hyaluronic acid endogenously, by stimulating cells around the wound site. The resulting hyaluronic acid-rich area may support the ability of the fetal wound to heal with its unique properties.

Amniotic Fluid↗
PubMed1986

The assessment of foetal lung maturity by chemical analysis of amniotic fluid.

Advances in the understanding of the neonatal respiratory distress syndrome have led to a proliferation of amniotic fluid tests. Measurement of pulmonary surfactant production is the most direct means of assessing pulmonary maturity. Assays of surfactant are subjected to certain pre-analysis sources of variation, such as variability in amniotic fluid volume, sample collection site, centrifugation speed and time, and contamination with blood and/or meconium. Amniotic fluid surfactant assays can be divided into biochemical and functional tests. When properly performed, both approaches yield results that correlate well with clinical findings. However, no single method has achieved the distinction of total reliability and universal applicability. In most tests the value for mature lungs is almost 99% accurate. On the other hand, immature values have very low accuracy. Therefore, it is advisable to perform an additional test or to repeat the determination. The determination of the lecithin/sphingomyelin ratio is characterized by sufficient accuracy for routine analyses. For scientific studies we recommend the use of a capillary gas-chromatographic method allowing an accurate assessment of dipalmitoylphosphatidylcholine, the most important surfactant constituent.

Amniotic Fluid↗
PubMed1985

Characteristics of maltase activity in amniotic fluid.

The nature and origin of maltase activity present in amniotic fluid, and used as a marker enzyme in the prenatal monitoring of cystic fibrosis, has been studied. Using monoclonal antibodies against human intestinal disaccharidases and via heat inactivation experiments it is shown that the maltase activity found in amniotic fluids from pregnancies of 16-24 wk of gestational age originates completely from sucrase-isomaltase; no maltase-glucoamylase could be detected. With various monospecific antibodies the possible contribution of non-intestinal brush border enzymes to the total maltase pool could be excluded: neither renal nor lysosomal maltase appeared to be present.

Amniotic Fluid↗
PubMedDate not supplied

[Polymorphism of prolactin in amniotic fluid of women at various times of pregnancy].

The level and molecular forms of prolactin (PRL) in amniotic fluid of pregnant women were investigated at various time of pregnancy with the help of radioimmunoassay, electrophoresis in polyacrylamide gel and immune blotting technique using poly- and monoclonal antibodies to human hypophyseal prolactin (PRL). Changes in the level of immunoreactive PRL in amniotic fluid had the shape of a Gaussian curve with a maximum at 22-29 weeks. Amniotic PRL was characterized by molecular polymorphism. A conclusion has been made that amniotic fluid PRL in pregnancy presents an independent pool of hormones, unrelated to hypophyseal PRL.

Amniotic Fluid↗
PubMed2003

Swallowing, urine flow, and amniotic fluid volume responses to prolonged hypoxia in the ovine fetus.

OBJECTIVE: Four days of hypoxia produce an extensive fetal polyuria with little change in amniotic fluid volume in the ovine fetus. We hypothesized that fetal swallowing and intramembranous absorption would increase with prolonged hypoxia to offset the polyuria. STUDY DESIGN: After a 24-hour normoxic period, nine ovine fetuses were subjected to 4 days of hypoxia induced by lowering maternal inspired oxygen content. Seven fetuses were monitored for 5 days as normoxic time controls. Measurements included fetal swallowed volume by a computerized system with Transonic flow probes, urine production by gravity drainage, and amniotic fluid volume by an indicator dilution technique. Data were averaged over 12-hour intervals, and a three-factor repeated-measures analysis of variance was used for statistical testing. RESULTS: During days 2 to 5, arterial oxygen tension was 20.7+/-1.1 (SE) mm Hg in the normoxic and 13.9+/-0.8 mm Hg in the hypoxic fetuses (P<.0001). Urine flow was unchanged over time in the normoxic fetuses and increased gradually from 693+/-88 to 2189+/-679 mL per day during hypoxia (P<.0001). The prehypoxia swallowed volume was similar in the two groups, averaging 447+/-95 mL per day. Although transiently decreased in eight of nine hypoxic fetuses, the 12-hour average swallowed volumes were not significantly different at any time in the hypoxic versus normoxic fetuses (P=.62). Amniotic fluid volume increased in the hypoxic fetuses relative to that in the normoxic fetuses (520+/-338 mL vs -226+/-136 mL, P<.01), although the increase was small (P<.01) relative to the excess volume of urine (4269+/-1306 mL). Estimated intramembranous absorption increased from 209+/-95 mL per day during normoxia to average 1032+/-396 mL per day during hypoxia. CONCLUSIONS: The current study supports the concept that prolonged hypoxia produces a progressive fetal polyuria with relatively small changes in amniotic fluid volume. Concomitantly, hypoxia does not induce prolonged changes in fetal swallowing; rather, intramembranous absorption greatly increases, thereby preventing severe polyhydramnios.

Absorption↗
PubMed1985

alpha-Fetoprotein: relationship between maternal serum and amniotic fluid levels.

Levels of alpha-fetoprotein were determined in 297 paired samples of maternal serum and amniotic fluid from patients with normal pregnancies at 16 to 17 completed weeks of gestation. Gestational ages were determined by menstrual history and ultrasonography, and the assays for alpha-fetoprotein were performed by a single reference laboratory. The results of the study failed to demonstrate any statistical relationship between the concentrations of alpha-fetoprotein in these two fluid compartments (r = 0.006). This finding was confirmed when the results at 16 and 17 weeks were analyzed individually. These findings indicate that amniotic fluid levels of alpha-fetoprotein cannot be predicted by those levels determined in maternal serum, and that simple diffusion is an inadequate explanation for the transfer of alpha-fetoprotein from amniotic fluid to maternal serum. The lack of correlation also emphasizes that the sensitivity and specificity of maternal serum alpha-fetoprotein screening for neural tube defects must continue to be based upon the detection rates in large population studies and the determination of "normal" values by reference laboratories.

Adult↗
PubMed1993

The ferning and nitrazine tests of amniotic fluid between 12 and 41 weeks gestation.

Most studies investigating the usefulness of ferning and nitrazine methods for detecting the presence of amniotic fluid following ruptured amniotic membranes have employed samples from vaginal pooling. Reported accuracies are 84 to 100% for the ferning test and 87 to 97% for the nitrazine test. Our study was designed to determine if these tests are applicable throughout gestation. Samples were obtained from amniocenteses between 14 and 42 weeks. Part I: Of 112 samples allowed to dry on a slide for 3 minutes only, 86.6% were ferning positive and 100% were nitrazine positive. Flame-drying increased the presence of ferning to 96.4%. Part II: 363 samples were allowed to dry completely for up to 10 minutes. All samples were ferning and nitrazine positive. Part III: 17 samples were tested for ferning and nitrazine at 1 hour, and again at 1 week. Sixty-six samples were tested within 1 week and again at 2 weeks. All samples remained ferning and nitrazine positive. Therefore optimal analysis of suspected amniotic fluid occurs when specimens are air-dried for 10 minutes. These tests may be reliably performed at gestations of 12 to 41 weeks.

Amniotic Fluid↗
PubMed1982

[Acetylcholinesterase of amniotic fluid: application to prenatal diagnosis of neural tube closing defects. I. Quantitative tests].

Acetylcholinesterase (AChE) in amniotic fluid from 165 normal pregnancies and 38 abnormal pregnancies was measured, using a direct assay of AChE activity after inhibition of ChnS with ethopropozine ("Lysivane"). Samples from normal pregnancies of 16-24 weeks gestation have a mean AChE activity of 2,7 U/1 and those obtained at 26-40 weeks have a mean level of 0,6 U/l. Contamination of amniotic fluid with fetal or maternal blood was observed to elevate AChE activity leading to uninterpretable results. Assays in artificial mixtures of amniotic fluid with maternal or fetal blood confirm the risk related to added erythrocyte number. Higher mean AChE activity, 8 U/l, was observed in association with open NTD, but in 7 cases the level was as in normal pregnancy. Elevated levels of AChE were found in association with Turner's syndrome (1) and intra uterine death (2); no increase was observed in 7 cases of omphalocele or laparoschisis, in 6 cases of atresia and 2 cases of hydrocephaly. In practice frequent occurence of bloody samples, specially from abnormal pregnancies, limits application of the test for antenatal open NTD diagnosis. This test appears as and useful preliminary stage providing informations for realization and interpretation of gel electrophoresis of cholinesterases.

Acetylcholinesterase↗
PubMed1989

Effect of amniotic fluid volume on umbilical cord length.

To study effect of amniotic fluid volume on umbilical cord length, 939 pregnant women at 24-41 weeks of gestation, including 10 twin cases, 51 preterm premature rupture of the membranes (PROM) and 70 premature delivery cases, were examined for their amniotic fluid volume within a week of delivery by the ultrasound procedure and these 949 newborns were also examined for umbilical cord length and incidence of fetal distress. In the polyhydramnios group (pocket size of more than 8 cm), 8 of 20 infants (40%) had longer cords and 6 infants (30%) had shorter cords, while only one of 49 infants (2%) with oligohydramnios (pocket size of less than 2 cm) had a longer cord and 36 infants (73.5%) had shorter cords than the mean cord length (+/- SD) of the normal group. The 20 twins had significantly shorter cords than those of the normal group (P less than 0.05) and the polyhydramnios group (P less than 0.01). The PROM group showed significantly higher incidence of oligohydramnios (P less than 0.05) and fetal distress (P less than 0.01), which suggests that intrauterine space availability is important for assuring fetal well-being.

Amniotic Fluid↗
PubMedDate not supplied

Amniotic fluid and maternal blood characteristics in severe mid-trimester twin-twin transfusion syndrome.

OBJECTIVE: To investigate the concentrations of metabolic variables in the amniotic fluid of the recipient twin and maternal blood and to correlate them with clinical features, which are characteristic for the course of pregnancies with twin-twin transfusion syndrome (TTS). MATERIALS AND METHODS: In 109 pregnancies with severe mid-trimester TTS, we measured the concentrations of interleukin-6 (IL-6), alpha-fetoprotein (AFP), sodium, potassium, total protein, beta2-microglobulin and osmolality in the amniotic fluid of the recipient twin prior to laser coagulation of the vascular anastomoses and compared them to a control group of 92 singleton pregnancies. We measured the pulsatility index (PI) of ductus venosus flow velocity waveforms in the recipient twin and performed a retrospective chart analysis for complete maternal blood count before and after the procedure. RESULTS: All variables, except osmolality, IL-6 and AFP were significantly lower in the TTS group. There was a significant positive correlation between PI in the ductus venosus and the amniotic fluid AFP concentrations (r = 0.355; p < 0.001). There was a significant fall in complete maternal blood count after laser therapy (p < 0.001) and a significant correlation between the amount of amniotic fluid drained and the fall of maternal Hb (r = -0.261; p = 0.03) and hematocrit (r = -0.212; p = 0.01). CONCLUSION: Pathophysiologic changes in TTS do not only occur at the inter-twin level of placental vascular anastomoses but also at the materno-fetal level of fluid exchanges. AFP is correlated to the severity of congestive heart failure of the recipient twin.

Amniotic Fluid↗
PubMed1981

Prenatal diagnosis of Gaucher disease. Assay of the beta-glucosidase activity in amniotic fluid cells cultivated in two laboratories with different cultivation conditions.

Sixteen pregnancies at risk for Gaucher disease -- six with the Norrbottnian form, one with a juvenile form with a similar clinical course to the patients from Norrbotten and nine with the infantile from -- have been monitored by the assay of beta-glucosidase activity in cultivated amniotic fluid cells with natural labelled glycosylceramide as substrate. Two methods of cultivation were compared in respect of their effect on the activity of lysosomal enzymes. No significant difference was found between the two marker enzymes, beta-galactosidase and N-acetyl-beta-glucosaminidase, but the beta-glucosidase activity was significantly higher in the cells cultivated with one of the methods. In four of the pregnancies at risk, the beta-glucosidase activity in the cultivated amniotic fluid cells was less than 5% of that in the two control materials. These fetuses were regarded as affected with Gaucher disease and were aborted. Differentiation between controls and Gaucher heterozygotes was not possible in cultivated amniotic fluid cells. The diagnosis of Gaucher disease in the amniotic fluid cells was confirmed in three of the four cases by the assay of the beta-glucosidase activity in the liver nd brain of the aborted fetuses. The glucosylceramide content of the liver from two aborted fetuses was not augmented. The beta-glucosidase activity was examined in seven placentas from pregnancies at risk for Gaucher disease and found to be in agreement with that in the cultivated amniotic fluid cells.

Amniotic Fluid↗
PubMed1997

Amniotic fluid volume in normal singleton pregnancies.

OBJECTIVE: To evaluate the amniotic fluid (AF) volume in normal singleton pregnancies from 15 to 40 weeks. METHODS: This prospective study evaluated the AF volume in singleton pregnancies undergoing amniocentesis for genetic assessment of fetal karyotype, preterm labor, or fetal lung maturity. Amniotic fluid volume was determined using a dye dilution technique. To assess the relationship between AF volume and estimated gestational age, a nonlinear regression model was applied. RESULTS: One hundred forty-four normal singleton pregnancies had AF volume evaluated. There was wide variability in the measured AF volumes with a significant (P < .01) increase in AF volume as a function of gestational age. Growth curve modeling estimated that AF volume continued to increase until 40 weeks' gestation. Analyses of the observed AF volume indicated that AF volume nearly doubled after 30 weeks' gestation. CONCLUSION: In contrast to other reports indicating that maximal AF volume in singleton gestations is expected early in the third trimester, we observed the attainment of maximal AF volume near term.

Adult↗
PubMed1979

(15S)-15 methyl prostaglandin F2 alpha levels in amniotic fluid and blood in second trimester abortions.

A single intra-amniotic injection of (15S)-15 methyl prostaglandin F2 alpha (THAM) was used to induce second trimester abortion in five patients. Serial levels of (15S)-15 methyl prostaglandin F2 alpha were subsequently measured in amniotic fluid and plasma by radioimmunoassay. The slow removal of this drug from the amniotic fluid was documented. Plasma levels of (15S)-15 methyl prostaglandin F2 alpha increased fourfold to sevenfold after clinical rupture of the membranes in three patients, supporting the fact that prostaglandins are well absorbed from the vagina. Because this analogue of prostaglandin can cause marked peripheral bronchoconstriction when administered systemically, it is best to avoid its use in patients with a history of asthma.

Abortion, Induced↗
PubMed1993

Delayed onset of coagulopathy following amniotic fluid embolism: two case reports.

Two cases of amniotic fluid embolism with markedly similar clinical presentations occurred in the same unit in a 6 month period. Both patients were under general anaesthesia for caesarean section at the time of embolism. Having been successfully extubated and found to be haemodynamically stable, they developed a coagulopathy after an interval of 2 hours. There had been initial uncertainty as to the diagnosis in the first patient and the haematological sequelae were not fully anticipated. Experience in dealing with the first patient who died, may have influenced the survival of the second. The diagnosis of amniotic fluid embolism should be considered at an early stage in all cases of maternal collapse and the appropriate preparations made to combat a potential coagulopathy.

Journal Article↗
PubMed1989

Intrapartum Doppler velocimetry, amniotic fluid volume, and fetal heart rate as predictors of subsequent fetal distress. I. An initial report.

This study examines the usefulness of umbilical artery Doppler velocimetry, amniotic fluid volume assessment, and fetal heart rate data in the early intrapartum period as predictors of subsequent fetal distress. A total of 109 patients seen in the latent phase of labor in the labor and delivery area were studied. Both an abnormal initial fetal heart rate and an amniotic fluid index less than or equal to 5.0 cm were associated with a significant increase in the incidence of intrapartum fetal distress. Conversely, a systolic/diastolic ratio greater than 3.0 by Doppler ultrasonography was not associated with increased fetal morbidity. Overall, the sensitivities, specificities, and positive predictive values of the fetal heart rate tracing and the amniotic fluid volume assessment were comparable. Doppler systolic/diastolic ratios showed very poor sensitivity and positive predictive value. We conclude that the fetal heart rate tracing or the assessment of amniotic fluid volume in the early intrapartum period are reasonable predictors of subsequent fetal condition. The lack of patients with the absence of or reverse umbilical velocity preclude conclusions with regard to Doppler systolic/diastolic ratios for this purpose.

Adolescent↗