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PubMed1984

Vasopressin concentration in amniotic fluid as an index of fetal hypoxia: mechanism of release in sheep.

Hypoxia is a potent stimulus to the release of vasopressin in fetal sheep and, in turn, plasma concentrations of the hormone correlate inversely with fetal oxygenation. Because the fetal kidney contributes to vasopressin clearance, we propose that measurement of increased amounts of vasopressin in amniotic fluid would be indicative of fetal hypoxia. We therefore measured concentrations of vasopressin in amniotic fluid under resting conditions, during and after fetal hypoxia, and with intravenous and intra-amniotic administration of vasopressin in 15 chronically instrumented fetal lambs 111-141 d gestation. In the resting state mean (+/- SE) vasopressin concentrations in amniotic fluid (1.6 +/- 0.3 pg . ml-1) did not differ from those in maternal (1.4 +/- 0.4 pg . ml-1) or fetal (1.8 +/- 0.2 pg . ml-1) plasma. After exposure of the ewe to 10% O2 or partial occlusion of the umbilical cord, vasopressin concentrations in fetal plasma increased significantly (P less than 0.001) to 200 +/- 59 pg . ml-1 with a delayed increase in amniotic fluid concentrations (P less than 0.03) to 15.8 +/- 4.5 pg . ml-1. This rise in concentration of vasopressin in amniotic fluid was sustained for at least 24 h and levels at that time were highly correlated with peak plasma concentrations (r = 0.83, P less than 0.001). Intravenous infusion of vasopressin into the fetus was accompanied by an equally significant (P less than 0.02) and sustained increase of vasopressin in amniotic fluid. After intraamniotic injection of vasopressin, levels remained increased for at least 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Amniotic Fluid↗
PubMed1987

Amniotic fluid erythropoietin correlates with umbilical plasma erythropoietin in normal and abnormal pregnancy.

In the human fetus, elevated plasma erythropoietin levels have been found in high-risk pregnancies at delivery. We examined the relationship of amniotic fluid erythropoietin and umbilical plasma erythropoietin at delivery in 17 normal pregnancies, 41 hypertensive pregnancies, and 37 insulin-treated diabetic pregnancies terminated by elective cesarean section without labor. An additional 27 insulin-treated diabetic patients were studied after undergoing variable durations (86-1184 minutes) of labor. Erythropoietin was analyzed using a highly sensitive and specific radioimmunoassay technique. Fetal plasma erythropoietin concentrations were elevated above the control upper range (50.3 mU/mL) in 59% of the hypertensives and in 38% of the diabetics. The amniotic fluid erythropoietin values were significantly lower than the umbilical plasma erythropoietin values in each study group. Although the umbilical plasma erythropoietin values in the abnormal pregnancy groups differed considerably from the corresponding levels in the controls, the ratio of amniotic fluid erythropoietin to umbilical plasma erythropoietin was approximately the same in controls, hypertensives, and diabetics. Furthermore, the plasma and amniotic fluid levels (In transformed) correlated highly significantly in all three individual groups in absence of labor. In the diabetic labor group, this relationship was nonsignificant. We conclude that in the absence of labor, amniotic fluid erythropoietin reflects fetal plasma erythropoietin. We speculate that amniotic fluid erythropoietin may be an antepartum indicator of fetal hypoxemia.

Amniotic Fluid↗
PubMed1986

Positive amniotic fluid acetylcholinesterase: distinguishing between open spina bifida and ventral wall defects.

The ratio of amniotic fluid acetylcholinesterase to pseudocholinesterase was determined by scanning densitometry on 43 amniotic fluid samples with positive acetylcholinesterase associated with open fetal defects. The mean ratio was 0.587 (range 0.204 to 0.979) in 21 amniotic fluid samples from pregnancies affected with open spina bifida and 0.052 (range 0.026 to 0.075) in 12 pregnancies affected with ventral wall defects. These data confirm previous observations and indicate that scanning densitometry of electrophoretic gels is a useful method for distinguishing between open spina bifida and ventral wall defects in the fetus.

Abdominal Muscles↗
PubMed1979

Amniotic fluid phosphatidylinositol and phosphatidylglycerol. II. Diabetic and preeclamptic pregnancies.

139 samples of amniotic fluid from diabetic women collected during 34-39 weeks of pregnancy showed higher levels of lecithin, phosphatidylinositol (PI) and phosphatidylglycerol (PG) indicating an accelerated surfactant synthesis as compared to that observed in normal pregnancies (13). In ten infants with respiratory distress syndrome (RDS) delivered from diabetic mothers the lecithin/sphingomyelin (L/S), PI/S and PG/S ratios were generally low. Only four samples showed definitely immature L/S ratios, whereas the amniotic fluid content of PG in all samples was unmeasurable or low. In 56 samples of amniotic fluid collected during the third trimester from preeclamptic pregnancies PI/S and PG/S ratios after 36-37 weeks were comparable with those of normal pregnancies. In 11 neonates with subsequent RDS the L/S ratios were immature, and PG was critically low or lacking in the majority of the samples. No convincing association between the PI content and development of RDS could be observed in any of the groups.

Amniotic Fluid↗
PubMed1999

Application of a semiautomatic boundary detection algorithm for the assessment of amniotic fluid quantity from ultrasound images.

The aim of this study was to develop a computer-assisted method to evaluate amniotic fluid volume (AFV). This was done by automatically detecting the boundaries of the amniotic fluid portion in 2-D ultrasonographic images. The study population consisted of 36 low-risk patients that were selected at random from a healthy population undergoing routine pregnancy follow-up. For each patient, images of the four quadrants of the uterus were digitized into a PC. The amniotic fluid portion in each ultrasonographic image was automatically detected, and its area was calculated. Its area was also manually determined by an expert physician (R. T.). The areas automatically detected by the algorithm were highly correlated with the areas manually delimited by the expert: r2 = 0.9722 (p < 0.01). The areas calculated by the program provide a good measure for the areas determined by the expert and may, therefore, be used for calculating the actual amniotic fluid volume.

Algorithms↗
PubMed1986

Disaturated phosphatidylcholine as a fetal lung maturity test: lack of interference by seminal ejaculate as a contaminant in vaginally pooled amniotic fluid samples.

Seminal ejaculates obtained from four men were added to amniotic fluid pools. Lecithin/sphingomyelin ratios in amniotic fluid were significantly lowered in the presence of small amounts of contaminating semen. In contrast, the determination of disaturated phosphatidylcholine was not affected by the presence of this contaminant.

Amniotic Fluid↗
PubMed1997

Quantitative analysis of the toxicity of human amniotic fluid to cultured rat spinal cord.

It has been proposed that the myelodysplastic components of a myelomeningocele are secondarily damaged as the result of exposure to amniotic fluid, the so-called 'two-hit' hypothesis. The critical time at which this secondary insult might occur has not been clearly defined. The present study addresses this issue by quantitatively assessing the toxic effects of human amniotic fluid of various gestational ages upon organotypic cultures of rat spinal cord. Using an assay for lactate dehydrogenase efflux to evaluate toxicity in such spinal cord cultures, we found that the amniotic fluid became toxic at approximately 34 weeks' gestation. This toxic effect of amniotic fluid appears to emerge rather suddenly. Accordingly, it seems reasonable to suggest that prevention of exposure of vulnerable spinal cord tissue to this toxicity by surgical closure of a myelomeningocele defect prior to the emergence of toxicity in amniotic fluid may prevent injury to vulnerable myelodysplastic spinal cord tissue.

Amniotic Fluid↗
PubMed1999

Involvement of fibrinolytic factors in mid trimester amniotic fluid with development of severe early-onset preeclampsia.

Impaired placental development is a well-known pathogenesis in preeclampsia. The present study was undertaken to elucidate the involvement of fibrinolytic factors in amniotic fluid in midtrimester with development of severe early-onset preeclampsia. Amniotic fluid was obtained by amniocentesis at 15 to 18 weeks of gestation. All specimens were retrospectively identified according to the hospital records as coming from gestations that later had severe early-onset preeclampsia (severe preeclamptic group, n = 9) or gestations with normal outcomes (control group, n = 73). Fibrinolytic factors such as tissue plasminogen activator (t-PA), plasminogen activator inhibitor type 1 (PAI-1), and t-PA-PAI-1 complex (PAI-C) of specimens were measured by enzyme-linked immunoassay. In the control group, concentrations of t-PA as well as PAI-1 in amniotic fluid remained at similar levels from 15 to 18 weeks, although PAI-1 levels were more than 10 times higher compared with t-PA levels. Levels of t-PA and PAI-1 in the severe preeclamptic group were not different from those of the control group. PAI-C levels gradually decreased from 15 through 18 weeks of gestation in the control group. PAI-C levels of the severe preeclamptic group were significantly lower than those of the control group (55.5 +/- 18.0% versus control; mean +/- standard deviation [SD], p <0.001). PAI-C, as the most specific indicator of the early stage of fibrinolytic activities, showed lower levels in midtrimester amniotic fluid in the severe preeclamptic group, suggesting fibrinolytic activities of amniotic fluid may have a significant role in the development of severe early-onset preeclampsia via impaired placental development in the latent stage of preeclampsia.

Adult↗
PubMed1983

gamma-Glutamyl transpeptidase in human amniotic fluid and in fetal tissues.

The activity of gamma-glutamyl transpeptidase (GGT) was measured in 360 amniotic fluid samples from second and third trimester pregnancies with fetal and maternal disorders. The enzyme level was within the normal range in all but one of the 18 second trimester pregnancies with congenital malformations. On cellulose acetate electrophoresis, GGT fractionated as an alpha 1-band in all mid-trimester samples tested. Highly elevated GGT values were found in five samples from the third trimester gestations with fetal gastroschisis, hydrops fetalis and Meckel's syndrome. The enzyme in these samples showed alpha 1-mobility while most of the third trimester amniotic fluids contained GGT with beta-mobility. Considerable GGT activity was observed in several fetal tissues that are in contact with the amniotic fluid. Highest levels were found in meconium and bile from a second trimester fetus. The total activity and electrophoretic mobility of GGT in late amniotic fluid and in urine from newborns was similar.

Amniotic Fluid↗
PubMed1998

Foetal compromise by spontaneous foetal heart rate deceleration in reactive non-stress test and decreased amniotic fluid index.

One hundred and sixty-three consecutive pregnant women with > 32 weeks gestation, undergoing non stress test (NST) and amniotic fluid index (AFI) determination were divided into six groups according to the amniotic fluid index and the nature of decelerations of foetal heart rate. Foetuses with antepartum decelerations had statistically significantly increased incidence of intrapartum decelerations, caesarean section due to intrapartum foetal distress, cord complications and small for gestational age infants. More so with decreased amniotic fluid index (p < 0.001). Low 5 minute apgar score was also significantly increased (p < 0.05). Prediction of foetal compromise might be done by spontaneous decelerations in reactive non-stress tests and with an amniotic fluid index < or = 5 cm.

Adult↗
PubMed1982

Amniotic fluid beta-endorphin and alpha-melanocyte--stimulating hormone immunoreactivity in normal and complicated pregnancies.

beta-Endorphin (beta-EP) and alpha-melanocyte--stimulating hormone (alpha-MSH) are members of a family of peptides which are found in the intermediate lobe of the fetal pituitary gland and placenta. In the present study, concentrations of immunoreactive beta-EP (i beta-EP) and alpha-MSH were determined by radioimmunoassay in the amniotic fluid compartment of both normal (n = 72) and complicated (n = 44) pregnancies. In normal pregnancies, there was a significant (p less than 0.05) fall in the mean amniotic fluid i beta-EP from the second to third trimester (from 175 to 132 pg/ml). A similar, but not statistically significant, decline in the mean amniotic fluid concentrations of alpha-MSH (from 46 to 34 pg/ml) was also noted. Concentrations of amniotic fluid i beta-EP showed a significant correlation with alpha-MSH (r = 0.61, p less than 0.001). Significant elevations of mean amniotic fluid i beta-EP but not alpha-MSH were found in pregnancies complicated by intrauterine growth retardation (215 pg/ml, p less than 0.001) and premature labor (225 pg/ml, p less than 0.001). Our findings suggest that levels of i beta-EP and alpha-MSH in amniotic fluid decrease from the second to the third trimester of pregnancy, and that elevation in i beta-EP concentration in amniotic fluid, in all probability, reflects the secretion of beta-EP by the fetus in response to fetal distress.

Amniotic Fluid↗
PubMed1992

[High resolution electrophoresis of serum aand amniotic fluid].

In a sample group of 92 women undergoing prenatal echo-guided transabdominal amniocentesis between the 12th and 23rd week of pregnancy the Authors analysed amniotic fluid and maternal serum using the recently developed method of high resolution protein electrophoresis in order to identify the presence of particular proteins in the amniotic fluid which are pathognomonic for a number of maternofetal pathologies. The results obtained in normal and pathological pregnancies or in the case of twins showed a marked dispersion in amniotic fluid of total protein concentrations depending on the period of gestation; in addition, albumin, alpha 1-antitrypsin, alpha 2-glycoprotein acid, alpha 2-macroglobulin and beta 2-protein were also found. Plasma levels of prealbumin, albumin, alpha 1-glycoprotein acid and IgG were slightly reduced, whereas there was a marked increase in ceruloplasmin, transferrin and fibrinogen; C3 and haptoglobin levels were normal. It is therefore possible to ascertain that amniotic fluid proteins analysed by high-resolution 15-band electrophoresis did not vary qualitatively or quantitatively until the 23rd week of gestation and in those cases of twin or pathological pregnancies examined no anomalous band was found in the protein electrophoresis of maternal serum or amniotic fluid which might prove useful in prenatal diagnosis.

Amniotic Fluid↗
PubMed1983

Fluorometric procedure for determining "lamellar body" phospholipids in the particulate fraction of amniotic fluid after filtration.

A rapid (30-min) semiautomated continuous-flow procedure is described for use in assessing the phospholipids of the particulate ("lamellar body") fraction of human amniotic fluid. The method is based on measuring the difference in fluorescence of 1,6,-diphenyl-1,3,5-hexatriene added to amniotic fluid before and after micropore filtration. The filtration step removes "lamellar body" particles, which are considered to contain the fetal lung surfactant. The phospholipid values for the filtered particles are independent of background fluorescence, which increases when amniotic fluid is contaminated by bilirubin pigments or blood components. Over a wide range (3-150 mumols/L) the fluorescence increases linearly with the phospholipid concentration of the amniotic fluid. There is a good agreement between the value for particulate "lamellar body" phospholipid, the ratio of the "lamellar body" phospholipids to total amniotic fluid phospholipids, and the lecithin/sphingomyelin ratio.

Amniotic Fluid↗
PubMed2001

Amniotic fluid embolus: a review of the literature.

PURPOSE: To review the literature since 1979 to determine the natural history, etiology, diagnosis and potential treatment of amniotic fluid embolus (AFE). SOURCE: English language articles and books published between June 1976 and June 1998 were identified by a computerized medline search using the title or text word amniotic fluid embolus. This same search strategy was repeated and updated to October 1999 by an independent individual using both Medline and Embase. The search was also expanded to include Science Citation Index listing Morgan's 1979 review article. All relevant publications were retrieved and their bibliographies were scanned for additional sources. PRINCIPAL FINDINGS: Randomized controlled trials are not possible with amniotic fluid emboli. The majority of the literature consists of clinical reports combined with occasional limited reviews. Knowledge obtained from these reports suggests that amniotic fluid emboli present as a spectrum of disease that ranges from a subclinical entity to one that is rapidly fatal. Because cases are sporadic and the diagnosis is often unconfirmed, little progress has been made towards understanding its etiology or defining the risk factors. Present management is empirical and directed towards the maintenance of oxygenation, circulatory support and the correction of coagulopathy. CONCLUSION: Amniotic fluid embolus continues to be a life-threatening but potentially reversible complication unique to pregnancy. It cannot be predicted nor prevented. Review of the literature reveals that there are no standardized investigational methods or protocols to confirm the diagnosis in suspected cases.

Adult↗
PubMed2000

Plasminogen, alpha(2)-antiplasmin and complexes of plasmin-alpha(2)-antiplasmin (PAP) in amniotic fluid and blood plasma of parturient women.

The aim of the present study was to determine whether the following components of the fibrinolytic system are present in amniotic fluid: plasminogen, plasmin and alpha(2)-antiplasmin, and plasmin-alpha(2)-antiplasmin (PAP) complexes. The study group consisted of 30 healthy women giving birth at term; 10 nonpregnant women constituted a control group. Plasminogen and alpha(2)-antiplasmin were studied by using an amidolytic method, and PAP by an ELISA method. The levels of plasminogen and alpha(2)-antiplasmin in amniotic fluid are low, 1.57+/-0.82 and 6.80+/-3.09%, respectively, of the values in blood plasma. The PAP concentration in amniotic fluid (70.61+/-14.28 microg/l) was also lower than in blood plasma (247.19+/-111.39 microg/l). We concluded that in amniotic fluid plasminogen and alpha(2)-antiplasmin are present, but at a concentration lower than in plasma. The presence of PAP in amniotic fluid is an evidence of two processes in the amniotic cavity: (i) plasmin generation, and (ii) plasmin inactivation by alpha(2)-antiplasmin.

Adult↗
PubMed1983

Ultrasonographic demonstration of floating particles in amniotic fluid.

This prospective study of 131 pregnant women was designed to determine the incidence and significance of floating particles in amniotic fluid. Floating particles ranging in size from 1 to 5 mm were seen in the amniotic fluid of pregnant women at 15 to 40 weeks' gestation. Since vernix is rarely present before 35 weeks' gestation, a source other than flakes of vernix must be sought to explain the floating particles in amniotic fluid in early gestations. There was no significant difference in the sizes or numbers of particles at different gestational ages (from 15 to 40 weeks). Therefore, it is concluded that ultrasonographic demonstration of floating particles in amniotic fluid cannot be considered an indicator of fetal maturity.

Amniotic Fluid↗
PubMed1989

Improved immunoassay for the determination of surfactant protein A (SP-A) in human amniotic fluid.

A simple, improved immunoassay for the determination of human surfactant protein A (SP-A) in human amniotic fluid was developed. The immunoreaction with a monoclonal antibody PC6-immobilized plastic bead, peroxidase-labeled monoclonal antibody PE10 and amniotic fluid sample diluting in the buffer containing 0.6% sodium dodecyl sulfate/2% Triton X-100, was carried out simultaneously at 45 degrees C for 30 min in test tubes. After washing the bead with 2% skimmilk in phosphate buffered saline containing 1% Triton X-100, the peroxidase reaction was developed by adding the substrate reagent and the absorbance was measured. The amniotic fluid obtained at full term was used as a standard instead of purified SP-A, because of the stability of the antigenicity. This immunoassay method was used to measure SP-A in 69 samples of amniotic fluid from 22 to 41 weeks of gestation. The result indicated that the SP-A values obtained by the present immunoassay can be used for predicting the fetal lung maturity. This simplified monoclonal immunoassay completed the measurement within 1 hr, and so it could be used routinely in clinical laboratory.

Amniotic Fluid↗
PubMed1986

Oxytocinase activity in human amniotic fluid and its relationship to gestational age.

Oxytocinase (EC 3.4.11.3) activity in amniotic fluid samples obtained from 200 normal pregnant women (mean age, 28 years) between 14 and 40 weeks of gestation and during active labor was assayed using S-benzyl-L-cysteine-p-nitroanilide (BCN) and L-leucine-p-nitroanilide (LN) separately as substrates. With both substrates, amniotic fluid oxytocinase activity correlated inversely with gestational age; the level of the enzyme, which was highest in early pregnancy, decreased exponentially to a minimum near term and during labor. However, whether oxytocinase activity in the amniotic fluid is of any significance for the maintenance and/or termination of pregnancy remains to be established.

Aminopeptidases↗