Placental grade and pulmonary maturity in premature fetuses

The correlation between the placental echographic appearances and pulmonary maturity was studied in 32 cases of normal pregnancy between the 29th and 33d weeks. The placental appearance was classified according to Grannum's criteria, and an amniocentesis was performed in each case. Both an L/S ratio and a foam stability (Clements') test were performed on the amniotic fluid. There were 10 cases of grade I and 22 cases of grade II placenta in the series. There was one mature L/S ratio in each placental grade; both had intermediate results with Clements' test. These findings differ significantly from those published in the literature on the subject, which are based on investigations in more mature fetal populations.     

Determination of amniotic fluid palmitic acid concentration for the estimation of fetal lung maturity

Palmitic acid concentrations in amniotic fluid (AF) were determined in 135 patients with normal and pathological pregnancies between the 27th and 42nd week of gestation. There was a sharp rise in the mean palmitic acid concentration after the 34th weeks of gestation from 2.7 μg/ml to 9.9 μg/ml at term. This increase is almost identical with the rise of AF-lecithin. It was found that between 70% and 100% of AF-palmitic acid originates from lecithin. 65 patients were delivered within 24 h after amniotic fluid sampling. 7 infants of these patients developed a respiratory distress syndrome (RDS). In all cases with RDS AF-palmitic acid concentration was far below 5 μg/ml. Assuming an AF-palmitic acid concentration > 5 μg/ml for characterising fetal lung maturity (= no RDS), there were no false negative results, but 16% false positive results. However, the determination of AF-palmitic acid concentration seems to be a most reliable method for the assessment of fetal lung maturity.     

The evaluation of fetal lung maturity by amniotic fluid analysis.

The frequent necessity for termination of pregnancy before the spontaneous onset of labor requires that we be able to accurately predict fetal lung maturity. We have used amniotic fluid studies for evaluation of fetal lung maturity and have found that (1) a "fat" cell concentration of 30% or more, or (2) a creatinine concentration of 2.0 mg/100 ml or more, or (3) a lecithin:spingomyelin (L:S) ratio of 2.0 or greater all correlated well with fetal maturity. Since each of these studies is open to a variety of possible errors, the use of several different ones adds reliability to the estimation of fetal lung maturity.     

Lipid content of amniotic fluid cells

The lipid content of fetal cells was determined in 45 samples of human amniotic fluid. Free and total cholesterol were estimated using a gas chromatographic method, and glycerides were evaluated through the enzymatic assay of their glycerol content. The number of orange cells was estimated after staining with Nile Blue sulphate.

The chemically measured lipid content appeared closely related to the number of orange cells. Total cholesterol and glycerides showed a sharp increase after the 37th week of pregnancy. These tests seem to assess fetal maturity successfully, providing a further useful aid in the management of high-risk pregnancies.

The chemical determination of cell-associated lipids showed good accuracy and reliability and, when compared with the histochemical method, allowed a better evaluation of progressive lipid accumulation within the amniotic fluid cells.     

羊水样本卵磷脂和鞘磷脂检测超高效液相色谱串联质谱方法的建立及应用

目的建立检测羊水中卵磷脂和鞘磷脂(L/S)的超高效液相色谱串联质谱(UPLC-MS/MS)方法,以便准确、高效地预测胎儿肺成熟度。方法收集孕32~39周孕妇分娩时的羊水样本23份。依据新生儿Apgar评分标准,有3例胎儿胎肺未成熟、20例胎儿胎肺成熟。另收集孕18周孕妇羊水样本7份作为基线对照,建立检测羊水中卵磷脂和鞘磷脂水平的UPLC-MS/MS方法,计算卵磷脂/鞘磷脂(L/S)比值,同时采用板层小体计数(LBC)法检测板层小体(LB),评价2种方法在预测胎肺成熟度中的价值。结果建立的检测羊水中卵磷脂和鞘磷脂的UPLC-MS/MS方法精密度良好,离子峰强度和保留时间均在可检测范围内,主成分分析(PCA)显示6个质控样本聚类良好。以L/S比值=10作为判断胎肺成熟度与不成熟的临界值,UPLC-MS/MS的敏感性和特异性均为100%。以LB=50×10^9/L作为判断胎肺成熟度与不成熟的临界值,LBC法的敏感性和特异性分别为80%和95%。结论建立了检测羊水中卵磷脂和鞘磷脂水平的UPLC-MS/MS方法,其结果可靠,可以准确、高效地预测胎肺成熟度。     

Evaluation of two assays of functional surfactant in amniotic fluid: surface-tension lowering ability and the foam stability index test

We characterize two assays of total amniotic fluid surfactant that are based on function: the surface-tension lowering ability of extracts of amniotic fluid lipid (I) and the foam stability index test (II). I is determined on chloroform extracts of amniotic fluid. II is defined as the highest ethanol volume fraction of an amniotic fluid-ethanol mixture that will permit a stable foam to form after 30 s of vigorous shaking. The relationship of I to disaturated phosphatidylcholine concentrations (after osmium tetroxide treatment of the amniotic fluid lipid extract) is in the expected theoretical form of a hyperbolic function. The relation between values for II and disaturated phosphatidylcholine concentrations showed a consistent bias, suggesting that components other than disaturated phosphatidylcholine contribute to stable foam formation. Phosphatidylclycerol concentrations did not appear to account for this bias. The relation between I to II values suggest that both assays measure total surfactant. I, II, and concentration of disaturated phosphatidyl choline are all excellent indicators of fetal pulmonary maturity. From a practical standpoint, the foam stability index test is the most efficient approach to routine assessment of fetal pulmonary status.     

Palmitic acid concentrations and lecithin/sphingomyelin ratios in amniotic fluid.

Palmitic acid concentrations and L/S ratios have been estimated in amniotic fluid specimens with and without centrifugation and cold acetone precipitation. Although the number of cases was small, both of these measurements in uncentrifuged fluid seemed to reflect only indirectly on lung maturation in normal pregnancy while with centrifuged fluid the L/S value predicted RDS in one infant more reliably than palmitic acid concentration.     

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.     

Reactivity of amniotic fluid alpha-fetoprotein with concanavalin A-sepharose in pre-natal diagnosis of fetal malformations

The proportion of concanavalin A-non-reactive alpha-fetoprotein was determined in 215 amniotic fluid samples from second trimester pregnancies. the median percentage for concanavalin A-non-binding alpha-fetoprotein was 35.5% at the 15th week and 32.2% at the 18th gestational week. Nineteen of the 23 pregnancies with various fetal malformations showed highly elevated total alpha-fetoprotein levels. In this group, the value for non-reactive alpha-fetoprotein was below the normal range in 12 out of 13 samples collected at 15-17 weeks of pregnancy and in four out of six samples at 18-19 weeks. Four pathological pregnancies had only moderately elevated total alpha-fetoprotein levels (5.3-7.9 SD above the mean) and two of these samples had a low percentage of the concanavalin A-non-binding fraction. The amniotic fluid alpha-fetoprotein concentration was between 3 and 5 SD and over 5 SD above the mean in four and seven normal pregnancies, respectively. The concanavalin A-fractionation classified correctly 10 out of these 11 cases. The results indicate that the determination of the proportion of concanavalin A-non-binding alpha-fetoprotein is a useful supplementary test to the total alpha-fetoprotein assay.     

Fetal lung maturity tests on the 10,000 X g pellet

Centrifugation has a profound effect on tests of fetal lung maturity performed on amniotic fluid. We have investigated the effect of a 700 X g centrifugal force for 10 min and a 10,000 X g force for 20 min on a battery of tests. While 91% of the OD650 was removed by the 10,000 X g centrifugal force, the supernatant fraction retained 34% and 38% of the L/S ratio and enzymatic lecithin respectively, when compared to the sample before centrifugation. Phosphatidylglycerol, when present in an amniotic fluid, was always absent from the 10,000 X g supernatant but present in the pellet formed by this centrifugal force. The pellet after 10,000 X g was unsuitable for OD650 and L/S ratio determinations but contained 63% of the enzymatic lecithin. When the pellet tests were subjected to a clinical trial, respiratory immaturity did not occur when phosphatidylglycerol was present or when the 10,000 X g pellet may be a useful means of detecting amniotic fluid surfactant and thus determining fetal lung maturity.     

Noradrenaline to adrenaline ratio in amniotic fluid as an index of fetal maturity

Amniotic fluid lecithin to sphingomyelin ratio (L/S) and adrenaline concentration, noradrenaline concentration, and noradrenaline to adrenaline ratio (NA/A) were measured in 50 normal women late in pregnancy. Between gestation weeks 37 and 43 the maturity-linked increase in L/S ratio was accompanied by similar increases in NA/A ratio and noradrenaline but by decreases in adrenaline concentration. Although the amniotic fluid NA/A ratio reflects fetal sympathetic nervous system development rather than pulmonary development as mirrored by the L/S ratio, a high correlation existed between log NA/A and L/S, indicating that the NA/A ratio could provide a further index of fetal maturity.     

Validation of a simple rapid high performance liquid chromatographic method for amniotic fluid lecithin/sphingomyelin ratios

A simple, rapid and sensitive HPLC method for the determination of L/S ratios in amniotic fluids is described. The method is based on isocratic separation in the normal phase with UV detection. The procedure has good precision and was validated clinically and by comparison with a routine TLC method. Although L/S ratios differed from those obtained by TLC, the clinical correlation between these methods was good. In single and serial samples from 39 mothers (42 babies) the HPLC method predicted respiratory distress syndrome (RDS) in all 9 babies with L/S ratios less than 7. No babies with ratios above 7 developed RDS. This method has potential clinical usefulness for the assessment of fetal lung maturity.     

Evaluation of the shake test to predict respiratory distress syndrome

An analysis of the relationship of amniotic fluid shake test titers and the subsequent fetal lung maturity as evinced by the development of the respiratory distress syndrome (RDS) has been conducted. Over a four-year period, 131 amniotic fluid samples were tested within 48 hours of delivery. RDS was diagnosed in 16 infants. When the shake test was positive at a 1:2 dilution, one child developed a mild case of RDS (2.3%). If the test was postivie at a 1:4 dilution, none developed RDS. RDS occurred in 15% of the cases with a positive test at a 1:1 dilution and in 30% of the cases with a negative test. This test has proved to be an excellent screening method for predicting fetal lung maturity if it is positive at 1:2 or greater. If the result is positive at a 1:1 dilution, or negative, other methods must be used for assessment. Its advantages are its rapidity, simplicity, and low cost.     

Multicenter evaluation of TDx test for assessing fetal lung maturity

"TDx Fetal Lung Maturity," an automated assay that measures the relative concentrations of surfactant and albumin in amniotic fluid, was compared with the lecithin/sphingomyelin (L/S) ratio and phosphatidylglycerol determination at five clinical sites. A total of 695 amniotic fluid samples were analyzed, of which 312 were followed by delivery of the infant within three days of sample collection. Of these 312, 24 developed respiratory distress syndrome and seven developed transient tachypnea. With the cutoff for maturity set at a surfactant/albumin value of 50 mg/g, the assay showed a sensitivity of 0.96 and a specificity of 0.88 for all samples, compared with a sensitivity of 0.96 and a specificity of 0.83 for the L/S ratio. The combination of rapid assay (30 min), accurate results, and uniformity among testing centers makes the TDx assay a very promising method.     

Sonographically detected free-floating particles in amniotic fluid predict a mature lecithin-sphingomyelin ratio

Amniocentesis for the determination of fetal lung maturity is associated with some morbidity, and so the prediction of a mature fetus by noninvasive means could be useful in managing certain high-risk patients. In the first portion of this study, 467 amniotic fluid specimens were classified into one of five groups based on the turbidity and particulate matter present. The mean lecithin: sphingomyelin (L/S) ratios and the proportion of mature L/S values increased with increasing turbidity of the amniotic fluid. In the second portion of this study, the presence of amniotic fluid free-floating particles (FFPs) detected by real-time ultrasound was correlated with fetal lung maturity. When FFPs were present, the L/S was uniformly mature, but when FFPs were absent, the L/S was mature in 74% of patients (P less than 0.01). Among the patients in whom the L/S ratios were mature, 39/110 were associated with positive FFPs (sensitivity = 35%). This preliminary study suggests that the presence of FFPs on real-time ultrasound could be used to confirm fetal lung maturity.     

Placental grading in the complicated or high-risk pregnancy.

A classification of the changes seen in the placentas of nondiabetic, non-high-risk obstetrical patients, and its relationship to fetal pulmonary maturity, has been the subject of two recent reports. Successful (100 per cent) correlation has been concluded from these studies when a Grade III placenta has been demonstrated in gestations of 33 weeks to term. To determine whether the same high degree of reliability would hold for the diabetic and high-risk obstetrical patient, 78 such patients were analyzed. All except one delivered at 33 weeks to term, and all had amniotic fluid lecithin-sphingomyelin (L/S) ratio determinations within 48 hours of sonographic placental grading and within seven days of delivery. Of the Grade III placentas (n = 13), 23 per cent had "immature" L/S ratios. However, there was no case of infantile respiratory distress syndrome (IRDS) in infants of patients with Grade III placentas. These findings suggest that placental grading may need to be part of a multifactorial assessment of fetal maturity in the diabetic or high-risk pregnancy.     

Interference by endogenous glycerol in an enzymatic assay of phosphatidylglycerol in amniotic fluid

We investigated the possibility of interference by endogenous glycerol with the enzymatic measurement of phosphatidylglycerol in amniotic fluid. Phosphatidylglycerol is an important indicator of fetal lung maturity. The concentrations of glycerol and phosphatidylglycerol in amniotic fluid were measured by using a coupled enzymatic assay with and without phospholipase D (EC 3.1.4.4). The precision of the assay was acceptable (within-run CV = 1.2%, between-run CV = 4.8%). Endogenous glycerol content was demonstrated to be approximately 10-20 times that of phosphatidylglycerol. This high proportion of endogenous glycerol in amniotic fluid would preclude the accurate enzymatic determination of amniotic fluid phosphatidylglycerol unless the glycerol is first removed. Nor can the actual phosphatidylglycerol concentration be determined by subtracting the endogenous glycerol concentration from the total glycerol, which includes that glycerol derived from phosphatidylglycerol. With a usual range of 9 +/- 7 mumol/L, the error for a given phosphatidylglycerol measurement of +/- 6.6 mumol/L (+/- 2 SD) clearly is too high for this assay to be clinically useful. There was no correlation between concentration of endogenous glycerol or apparent phosphatidylglycerol in amniotic fluid and the lecithin/sphingomyelin ratio of the sample.     

妊娠期肝内胆汁淤积综合征终止妊娠时间与围生儿预后的关系分析

目的探讨妊娠期肝内胆汁淤积症（ICP）终止妊娠时间与围生儿预后的关系。方法对近2年来在本院住院分娩的119例ICP病例进行回顾性分析。结果按终止妊娠的时间分为≤34^＋6周、35周-、36周-、37周～、38周-、39周-、40周-7组。37周前,羊水胎粪污染率、新生儿窒息率以35周-最高,≤34^＋6-周最低,37周以后随着孕周的增加羊水胎粪污染率及新生儿窒息率逐渐增高;37周前的低体重儿发生率较高,37周及以后发生率已很低;总胆汁酸（TBA）值〉50umol／L较TBA≤50umol／L者羊水胎粪污染率明显增加,但新生儿窒息率无明显差异,76％在37周前已终止妊娠,≤34^＋6-周占12％;孕妇胆红素升高者羊水胎粪污染及新生儿窒息率明显增加,63％在37周前终止妊娠,≤34^＋6周仅占7．89％。结论TBA〉50umol／L者羊水胎粪污染率较高,胆红素升高者羊水胎粪污染率及新生儿窒息率均较高,应尽可能在37周前终止妊娠,特别是胆红素明显升高者应尽可能在35周前终止妊娠;TBA≤50umol／L且无胆红素升高者可在37周左右终止妊娠,尽量不超过38周。     

Hydroxyproline and creatinine levels in normal amniotic fluid

Summary Total hydroxyproline and creatinine concentrations as well as their ratios were determined in 29 amniotic fluid samples from normal pregnancies between the 16th and 20th week of gestation. Total hydroxyproline and creatinine levels, and their ratios, were not statistically different considering either the values at each week or those of the whole 5-week period. Our results, compared with the few others reported in the literature, can provide indications useful for defining the normal range in amniotic fluid, in relation to the weeks of gestation.     

The monitoring of pregnancy in rhesus-sensitized women by a quantitative determination of bilirubin in amniotic fluid (author's transl)]

The prognostic accuracy of spectro photometric examination of the amniotic fluid and of a specific method for the determination of free bilirubin in the amniotic fluid are compared. Amniocentesis was carried out 166 times in 85 sensitized rhesus-negative pregnant women. Spectro photometric examination gave a misleading assessment in 28% of the cases. This applied particularly to Liley's Zone II, in which the presence or absence of haemolytic disease of the newborn was incorrectly predicted in up to 70% of the cases. By contrast, on evaluation of the cases using specific determination of free bilirubin, not a single value obtained after the 34th week of pregnancy led to false assessment of the fetal condition. There is a stong correlation between the extent of fetal damage and the bilirubin content of the amniotic fluid.