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PubMed1993

Amniotic fluid volume and normal flows to and from the amniotic cavity.

The regulation of amniotic fluid volume and composition remains largely unknown. Several difficult to study pathways exist for the formation (early transfer across fetal skin, fetal urine and lung fluid production) and removal (swallowing, transmembranous and intramembranous absorption) of amniotic fluid. It appears that flows across these pathways may work in concert the vast majority of the time because amniotic fluid volume is maintained within a normal range. When significant deviations occur from this normal range, especially in the mid trimester, significant perinatal morbidity and mortality incidence results.

Amnion↗
PubMed1998

Amniotic fluid complement C3 as a marker of intra-amniotic infection.

OBJECTIVE: To determine the value of amniotic fluid (AF) complement C3 as a marker of intra-amniotic infection and to compare complement C3 with other rapid markers of intra-amniotic infection. METHODS: One hundred four women with singleton gestations, in preterm labor with intact membranes, at 23-35 weeks' gestation underwent transabdominal amniocentesis. Amniotic fluid was analyzed for white blood cell (WBC) count, lactate dehydrogenase (LDH), glucose, Gram stain, and complement C3. Cultures for aerobes, anaerobes, and mycoplasma species also were performed. The median values of complement C3, WBC, LDH, and glucose were compared between the culture-positive and -negative groups. Complement C3 was compared with WBC count, LDH, glucose, and Gram stain for sensitivity, specificity, positive and negative predictive values, and accuracy in the prediction of a positive AF culture. Descriptive statistics, receiver operating characteristic curve, Fisher exact test, and Wilcoxon rank-sum test were used for analysis. RESULTS: The prevalence of positive cultures was 11.5% (12 of 104). The culture-positive group had a significantly higher median C3 (7.0 mg/dL) than the median C3 (3.0 mg/dL) of the culture-negative group (P < .001). Also, the median values of WBC (1120.5 cells/mm3) and LDH (2697 U/L) were significantly higher and the median glucose (6.5 mg/dL) was significantly lower among women with positive AF cultures than among women with negative AF cultures (WBC=1 cell/mm3; LDH=165 U/L; glucose=45 mg/dL; P < .001). Eleven of the 12 culture-positive cases had a C3 of 5 mg/dL or more, whereas four of the 92 culture-negative cases had a C3 of 5 mg/dL (P < .001). Nine of the 12 culture-positive cases but none of the 92 culture-negative cases had a C3 of 6 mg/dL or more (P < .001). The relative risks of a positive AF culture were 65.27 (95% confidence interval [CI] 9.08, 469.27) and 31.67 (95% CI 10.40, 96.43) times greater among women with AF complement C3 levels of 5 and 6 mg/dL or more, respectively. Depending on the cutoff point used, complement C3 had similar or higher sensitivity, specificity, positive predictive value, and negative predictive value for intra-amniotic infection when compared with WBC count, LDH, glucose and Gram stain. CONCLUSION: Amniotic fluid complement C3 has value in the diagnosis of intra-amniotic infection in preterm labor with intact membranes. Complement C3 is available readily and compares favorably with other rapid markers of AF infection. This study supports the general concept of fetal inflammatory response to microbial invasion of AF.

Adult↗
PubMed1996

[Evaluation of fetal condition in pregnancy complicated by hypertension--biochemical assessment of amniotic fluid. II. Enzymes].

Sixty two samples of amniotic fluid were submitted to biochemical investigation including 31 samples from women with pregnancy complicated by hypertension (studied group with blood pressure -65 +/- 15/95 +/- 5 mm Hg) and 31 samples deriving from healthy pregnant women (control group with mean blood pressure 118 +/- 10/74 +/- +/- 9 mm Hg). The following parameters of amniotic fluid were measured: 1) aminotransferases: alanine AlAT and aspartate AspAT, 2) alkaline phosphatase (APt) and its thermostable isoenzyme (APh), 3) ceruloplasmin (Crlp), 4) alpha-amylase (alpha-Amy). The study showed pregnancy complicated by hypertension is related to fetal salivary gland's immaturity presenting decreased activity of alpha amylase in amniotic fluid. Amniotic fluids deriving from women with pregnancy complicated by hypertension showed normal activities of AlAT, AspAT, APt, APh and Crlp.

Alkaline Phosphatase↗
PubMed1989

Myoglobin in third trimester amniotic fluid of human pregnancy--a potential indicator of fetal hypoxia.

195 amniotic fluid samples from the third trimester were examined for their content of myoglobin by means of radio-immunoassay. 151 of the samples were obtained intrapartum, the rest (44) was taken antepartum by transabdominal amniocentesis within one week prior to delivery. Depending on the myoglobin levels measured, different amniotic fluid groups were defined: (A) amniotic fluids containing no myoglobin or traces of it (less than 3 ng/ml), (B) amniotic fluids with moderately elevated myoglobin levels (3-10 ng/ml), (C) amniotic fluids with high myoglobin levels (greater than 10 ng/ml). Myoglobin levels above 3 ng/ml could be measured in 98 of the 151 samples taken intrapartum. In the amniotic fluids drawn antepartum the proportion of "myoglobin-positive" samples (greater than 3 ng/ml) amounted to only 22.7% (10 out of 44 samples). In pregnancies with amniotic fluids showing high myoglobin levels intrapartum, the prevalence of meconium staining of the samples, pathological cardiotocograms intrapartum and metabolic acidoses in umbilical artery blood samples was significantly higher than in pregnancies with myoglobin-negative amniotic fluids. The frequency of cesarean sections for fetal distress rose with increasing myoglobin levels in amniotic fluid, being 5.7, 13, and 18.2% in Group A, B and C respectively. In the pregnancies in which the amniotic fluid samples were taken antepartum, the prevalence of meconium-stained amniotic fluid increased with elevating amniotic fluid myoglobin (p less than 0.05, Group A vs. Group C). The frequency of cesarean sections for fetal distress and of neonatal depression immediately after delivery was considerably heightened in the cases with myoglobin-positive amniotic fluids antepartum compared to those with myoglobin-negative liquor.(ABSTRACT TRUNCATED AT 250 WORDS)

Amniocentesis↗
PubMed2001

Expression of aquaporin-8 in human placenta and chorioamniotic membranes: evidence of molecular mechanism for intramembranous amniotic fluid resorption.

OBJECTIVE: The intramembranous pathway of amniotic fluid absorption has recently been recognized as a critical regulatory path for amniotic fluid resorption, which contributes importantly to amniotic fluid volume homeostasis. Yet, the underlying molecular and cellular mechanisms for water absorption across the amniotic membranes remain unknown. We hypothesize that amniotic fluid water is absorbed across aquaporin water channels in the chorioamniotic membranes. Recently the water channel aquaporin-8 complementary DNAs for mice, rats, and humans have been cloned; and aquaporin-8 has been found to be expressed in the placenta and in other organs. The objective of the present study was to determine whether aquaporin-8 is expressed in human chorioamniotic membranes. STUDY DESIGN: Freshly frozen human amnion, chorion, placenta, and umbilical cord of a normal term pregnancy were used in this study. Reverse transcriptase-polymerase chain reaction was used to determine the aquaporin-8 gene expression. In situ hybridization with biotin-labeled aquaporin-8 riboprobe was undertaken to localize the cellular expression of aquaporin-8 gene in these human fetal membranes. RESULTS: Using reverse transcriptase-polymerase chain reaction, we have demonstrated that aquaporin-8 is expressed in human amnion, chorion, and placenta. Further studies of in situ hybridization of aquaporin-8 identified aquaporin-8 gene expression in epithelial cells of chorion and amnion and of the syncytiotrophoblasts and outer layer trophoblasts of placenta. CONCLUSION: This is the first study that demonstrates the expression of aquaporin-8 water channel in human chorioamniotic membranes. These results suggest that aquaporin-8 may be a water channel that mediates amniotic fluid resorption by way of the intramembranous pathway.

Amnion↗
PubMed1991

Amniotic fluid glucose concentration as a marker for intra-amniotic infection.

This study evaluated the use of amniotic fluid (AF) glucose concentration as a rapid indicator of intra-amniotic infection. Amniotic fluid glucose concentrations were measured in 86 pregnancies and compared with AF cultures. There were 14 positive cultures with a mean AF glucose of 7.1 mg/dL (range 1-24) and 72 negative cultures with a mean AF glucose of 30.4 mg/dL (range 5-66), a significant difference (P less than .001). An AF glucose of less than or equal to 5 mg/dL had a positive predictive value of 90%; an AF glucose of greater than 20 mg/dL had a 98% negative predictive value. Amniotic fluid glucose can be obtained rapidly and inexpensively, and may be of use in the diagnosis of intra-amniotic infection.

Amniotic Fluid↗
PubMed1979

A blocking factor in amniotic fluid causing leukocyte migration enhancement.

Amniotic fluid was found to cause significant leukocyte migration enhancement during the second and third trimester of pregnancy and in the early postpartum period when compared to the migration area obtained with an ovarian tumor homogenate antigen (p less than 0.01), choriocarcinoma spent medium (p less than 0.01), and placental pool homogenate (p less than 0.01). Only borderline significance (p less than 0.1) was obtained when migration enhancement with AF was compared between pregnant and nonpregnant female control patients, indicating minimal unspecific activity of AF. Migration enhancement with autologous amniotic fluid was slightly larger than with homologous amniotic fluid, but the difference did not reach significance (p less than 0.4). None of the control antigens caused migration enhancement; placental pool homogenate in concentrations above 4 mg. per cent caused migration inhibition but did not in lower concentrations. The enhancing effect of AF could be abolished by dilution but not by addition of excessive antibody to estrogen of HCG. It is suggested that a blocking factor is present in AF preventing recognition of fetoplacental antigen by the maternal immune system. Thus in vitro leukocyte migration enhancement may correlate to in vivo graft enhancement.

Amniotic Fluid↗
PubMed1982

The effect of gestational age on amniotic fluid glucose in pregnancy complicated by diabetes mellitus.

Amniotic fluid glucose was measured in 189 amniotic fluid samples from 117 well-controlled Class A to F diabetic pregnant women from 32 to 40 weeks' gestation. A simultaneous maternal plasma glucose level was determined at each amniocentesis. Samples were obtained with the mother in the fasting or nonfasting (3.8 hours after breakfast) state. Amniotic fluid glucose correlated significantly with simultaneous maternal glucose (r = 0.562; p = 0.001). A significant downward linear trend of mean amniotic fluid glucose with advancing gestational age was demonstrated (p less than 0.01). No trend of mean simultaneous maternal glucose with gestational age was seen. These results were not affected by maternal prandial status at the time of amniocentesis. It is concluded that amniotic fluid glucose decreases with advancing gestational age in well-controlled diabetic pregnant women independent of maternal glycemic levels. Studies of amniotic fluid glucose and/or its relationship to other metabolic hormones must take this into account.

Amniocentesis↗
PubMed1979

Antibacterial activity of amniotic fluid.

The antibacterial activity of amniotic fluid against Escherichia coli in the last month of pregnancy was reduced in an unselected sample of mothers delivering in Cape Town. Amniotic fluid zinc, required for normal antibacterial activity, was also reduced. These findings offer an explanation for the high incidence of amniotic fluid infection previously reported.

Amniotic Fluid↗
PubMed1985

The role of amniotic fluid in fetal nutrition.

The contribution of amniotic fluid to fetal growth and gastrointestinal tract development was studied in a rabbit model. In the fetal rabbit, at 23 days gestation, 3 conditions were surgically produced: (1) prevention of swallowing of amniotic fluid by esophageal ligation (n = 8); (2) esophageal ligation but insertion of an esophageal cannula distally to allow continuous infusion into the stomach of bovine amniotic fluid to mimic fetal swallowing (n = 7); and (3) sham operation (n = 7). Fetuses were delivered by Caesarean section at 28 days gestation. Esophageal ligation resulted in significant reductions of birth weight and crown-rump length and a trend to decreased liver weight when compared to sham operated controls. Additionally, marked reductions in gastric and intestinal tissue weight and gastric acidity were found following esophageal ligation. These reductions in both somatic and gastrointestinal tract growth and gastric function were reversed by infusion of amniotic fluid intragastrically. We conclude that amniotic fluid provides 10% to 14% of the nutritional requirements of the normal fetus, and that amniotic fluid contains a potent and as yet undefined gastrointestinal tract trophic factor.

Amniotic Fluid↗
PubMedDate not supplied

Human and ovine amniotic fluid composition differences: implications for fluid dynamics.

OBJECTIVE: The ovine model is frequently utilized to extrapolate data regarding fetal and amniotic fluid dynamics to human pregnancy. The ovine amnion is highly vascularized, facilitating intramembranous exchange of water and solutes between the amniotic fluid and fetal plasma. In comparison, the relatively avascular human amniotic membrane may have a reduced potential for intramembranous absorption. In view of these anatomical differences, we hypothesized that comparison of human and ovine amniotic fluid composition would provide insight into differences in the mechanisms of amniotic fluid exchange. METHODS: Amniotic fluid was sampled from 43 patients upon hospital admission, and from 27 ovine ewes at five days following amniotic fluid catheter placement. Both human (32 to 39 weeks' gestation) and ovine pregnancies (125 to 136 days' gestation) were sampled during the last 20% of gestation. Samples were analyzed for osmolality and sodium, potassium and chloride concentrations. The contribution of electrolytes to amniotic fluid osmolality and changes in osmolality and electrolyte composition versus gestational age were assessed by regression and covariance analysis. RESULTS: Mean (+/-SEM) amniotic fluid sodium concentration (134.6+/-1.9 vs. 127.1+/-2.0 mEq/1) was greater and potassium (4.6+/-0.1 vs. 6.1+/-0.6 mEq/l) and osmolality (263.9+/-3.7 vs. 285.1+/-1.6 mOsm/kg) less in human than sheep. The range of amniotic fluid osmolality was greater in human (223 to 336 mOsm/kg) than in sheep (274 to 298 mOsm/kg). Human amniotic fluid osmolality was highly correlated with amniotic fluid sodium (r = 0.97) and chloride (r = 0.96) while ovine amniotic fluid osmolality was only weakly correlated with amniotic fluid sodium (r = 0.75) and chloride (r = 0.51). The slope of the regression line of amniotic fluid sodium and osmolality was greater for human than for sheep amniotic fluid (P < 0.0001). The percent of amniotic fluid osmolality accounted for by sodium, chloride and potassium concentrations was greater for human (97%) than for sheep (86%; P < 0.0001). CONCLUSIONS: The results suggest that human amniotic fluid osmolality is comprised almost entirely of the major electrolytes while alternative solutes (e.g., fructose) contribute to ovine amniotic fluid osmolality. Extrapolation of fetal and amniotic fluid dynamics from ovine models to humans should incorporate differences in amniotic fluid osmolality and electrolyte composition.

Amniotic Fluid↗
PubMed1996

Application of a new perchloric acid treatment method to measure endotoxin in both amniotic fluid and cord blood by an endotoxin-specific chromogenic Limulus test in intra-amniotic infection.

Endotoxin in both amniotic fluid and cord blood was measured to detect intra-amniotic fetal infection. Both amniotic fluid and cord blood plasma were pretreated by a perchloric acid treatment, and the endotoxin level was measured by Endospecy test. Cut off values for endotoxin in amniotic fluid and cord blood were 8.5 pg/mL and 7.6 pg/mL, respectively. Escherichia coli intra-amniotic infection caused respiratory distress syndrome (RDS)-mimicking pneumonia. Abnormally high values of endotoxin in both amniotic fluid and cord blood were detected. Intra-amniotic infection caused by Gram-positive bacteria (group B streptococci, Enterococcus fecalis) was shown to be endotoxin negative in both amniotic fluid and cord blood. In cases of negative amniotic fluid culture, measurement of the value of endotoxin in the amniotic fluid is useful in identifying intra-amniotic fetal infection.

Amniotic Fluid↗
PubMed2004

Regulatory response to washout of amniotic fluid in sheep.

To test the hypothesis that a substance present in the amniotic fluid could serve as a regulator of amniotic fluid volume, we drained and discarded amniotic fluid while replacing it with lactated Ringer solution that was isotonic to amniotic fluid. Seven ewes with singleton fetuses at 119 +/- 1 days of gestation (mean +/- SE) were instrumented with multiple indwelling catheters in the pedal artery, pedal vein, and amniotic cavity. During the exchange periods, an average of 3,019 +/- 171 ml/day of lactated Ringer solution was infused into the amniotic cavity while an equal amount of amniotic fluid was pumped out and discarded. During the control period, amniotic fluid composition and volume were not altered. Exchange and control periods started with the same amniotic fluid volume, lasted 3 or 4 days, and were randomized with regard to order. Amniotic fluid volume measured by vacuum drainage was 556 +/- 98 ml at the end of the control period and 986 +/- 209 ml (P = 0.03) at the end of the exchange period. Fetal arterial blood gases, hemodynamic parameters and the osmolality gradient between fetal plasma and amniotic fluid were not altered by the exchange process. A linear relationship between the control amniotic fluid volume and the volume at the end of the exchange period (P = 0.003) suggests that the animals with larger control volumes responded to isovolumic dilution with a larger volume increase. We conclude that amniotic fluid may contain a substance that regulates amniotic volume.

Absorption↗
PubMed1994

Direct volume measurement at midtrimester amnioinfusion in relation to ultrasonographic indexes of amniotic fluid volume.

OBJECTIVE: Our purpose was to investigate the relationship between amniotic fluid volume and semiquantitative ultrasonographic assessment of amniotic fluid in the midtrimester. STUDY DESIGN: Sixteen pregnancies between 16 and 28 weeks with minimal amniotic fluid (severe oligohydramnios or anhydramnios) and intact membranes were studied at the time of clinically indicated amnioinfusion. The amniotic fluid index and deepest pool measurement were determined before and immediately after the procedure. Correlations were sought by means of standard regression techniques with amniotic fluid volume (i.e., volume infused) on the basis of the assumption that amniotic fluid volume before amnioinfusion was effectively nil. RESULTS: There was a significant linear relationship between amniotic fluid index and volume infused (y = 7.336 + 0.015x; R2 = 0.30, p < 0.05). However, no correlation with the deepest pool measurement technique was found (R2 = 0.11, p > 0.05). CONCLUSION: Amniotic fluid index is preferable to deepest pool measurement in assessing amniotic fluid volume in the second trimester of pregnancy. The low variance (30%) suggests that better predictors of amniotic fluid volume are still required.

Amniotic Fluid↗
PubMedDate not supplied

Amniotic fluid embolism. A case report.

Amniotic fluid embolism is a rare, yet catastrophic event. In the United States it occurs in 1 per 20,000 to 30,000 births. With an 86% maternal mortality rate, amniotic fluid embolism is responsible for 10-15% of all maternal deaths. This article presents a case study of a CNM's experience with a maternal and fetal death resulting from an amniotic fluid embolism. Pathogenesis and appropriate management are also presented.

Embolism, Amniotic Fluid↗
PubMed1993

[Significance of amniotic fluid cytokines measurement in threatened preterm labor and premature rupture of the membranes].

The purpose of this study was to elucidate the significance of measurements of cytokines in the amniotic fluid. Amniotic fluid was retrieved by transabdominal amniocentesis from 113 women in the following groups: Preterm labor (N = 58), PROM (N = 21) and term elective C/S (N = 34). Tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta), were measured with a commercially available ELISA. Interleukin-6 (IL-6) was measured by bioassay and newly developed "luminescencer EIA". 1. Amniotic fluid concentrations of TNF-alpha, IL-1 beta and IL-6 in cases of term elective C/S were 22.8 +/- 19.2 pg/ml, 8.1 +/- 5.2 pg/ml and 166.8 +/- 126.1 pg/ml, respectively. 2. Significantly higher levels of TNF-alpha, IL-1 beta, IL-6 were found among the cases who failed to respond to tocolysis (i.e. delivery within 48 hrs of amniocentesis). In contrast, no significant difference in such conventional markers of infection as maternal serum CRP was noted. 3. According to the degree of histopathologic chorioamnionitis (Blanc), significantly higher concentrations of IL-1 beta, IL-6 were found among the of stage III cases than those in stage II irrespective of the rupture of the membranes (IL-1 beta: 1.36 +/- 0.41 ng/ml vs 76.6 +/- 20.1 pg/ml, IL-6: 31.98 +/- 4.55 ng/ml vs 5.22 +/- 0.92 ng/ml). Significant correlation was also found between the concentrations of IL-1 beta, IL-6 and the pathological degree of funitis (Nakayama, stage 0 < stage I, stage II < stage III).(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Threatened↗