Effect of blood in amniotic fluid on the detection of phosphatidylglycerol

Evaluation of the new amniostat-FLM test for the detection of phosphatidylglycerol in contaminated fluids

The Amniostat-FLM rapid slide test (Hana Biologics, Inc., Alameda, Calif.) for detection of phosphatidylglycerol has previously been evaluated and has shown good correlation with the more sophisticated two-dimensional thin-layer chromatographic method. A new, ultrasensitive kit has now been released with a lower level of detection of 0.5 microgram of phosphatidylglycerol per milliliter of fluid. This is the first report of this new kit, which we used with vaginal pool samples and with contaminated amniocentesis samples. We evaluated this kit for concordance with thin-layer chromatography results as well as fetal outcome. Of 48 vaginal pool samples, 41 (85%) showed concordance, whereas 39 of 42 (93%) contaminated amniocentesis samples were concordant, for an overall concordance of 89% (80 of 90 samples). Sixty-seven infants were delivered within 72 hours of the test and there were no cases of hyaline membrane disease in the presence of a positive test result. We conclude that this new, ultrasensitive kit is a good, time-saving, and reliable test for the detection of phosphatidylglycerol without the development of false-positive results even when tested on the worst possible fluid samples. A review of clinical studies involving the Amniostat-FLM is also presented.

Current perspectives in assessment of fetal pulmonary surfactant status with amniotic fluid

In recent years, improvements in analytical methodology and clinical management of maternal-fetal diseases have altered the understanding of data from amniotic fluid analysis. Delays in phospholipid production or lung function are not currently reported in maternal diabetes. Fetal lung function following glucocorticoid therapy or premature membrane rupture is uncoupled from amniotic fluid phospholipid concentrations, which do not have the usual significance in these circumstances. Phosphatidylglycerol (PG) is present prior to the usual time it is detected by thin layer chromatography (TLC) methods, which vary in sensitivity for PG. Consequently, the significance of its "absence" is highly varied. These observations are discussed in light of the earlier methods and data, along with new perceptions of the functions of the individual phospholipids and apoproteins, the regulatory mechanism of surfactant production, and the relationship of amniotic fluid components to neonatal lung function.

Effect of blood and meconium on the determination of phospholipids in amniotic fluid using high pressure liquid chromatography

This paper presents the evaluation of the effects of blood and meconium on the determination of the phospholipids phosphatidylglycerol (PG), phosphatidylinositol (PI), phosphatidylethanolamine (PE), phosphatidylcholine (PC), sphingomyelin (SP) and lysolecithin (LL) in amniotic fluid. Phospholipids were analyzed by a new method using high pressure liquid chromatography (HPLC), which is based on the procedure of BRIAND et al. The method was extended for quantitative determination with lysolecithin as internal standard. The HPLC equipment consisted of two pumps, an HPLC programmer, an HPLC oven, a UV detector and an integrator. The chromatographic separation was achieved on a 25 cm DIOL-column and a 6 cm guard column packed with silica SI 60. The oven temperature was 55 degrees C and the detector wave length was 201 nm. The chromatographic mobile phase was composed of two solvents, acetonitrile and water. A solvent gradient was run from 2.4% water to 15% water between 5 and 13 minutes. Phospholipids were extracted according to the procedure of GLUCK. Before extraction 40 micrograms of LL as internal standard were added to 2.0 ml amniotic fluid. In a standard solution the phospholipids PE, PC, SP and LL were baseline separated, in the case of PG and PI a perpendicular division of the peaks was necessary. To evaluate the effect of contamination by blood and meconium, various amounts of blood and meconium were added to uncontaminated amniotic fluid samples. Contamination by blood caused a rise of the concentrations of PC, PE and SP up to tenfold. PG and PI concentrations were not affected by blood staining.(ABSTRACT TRUNCATED AT 250 WORDS)

Amniostat-FLM: an initial clinical trial with both vaginal pool and amniocentesis samples

Amniostat-FLM, a new rapid slide agglutination test, was compared with thin-layer chromatography as a method for detecting phosphatidylglycerol in amniotic fluid. This is the first reported use of Amniostat-FLM to evaluate vaginal pool and contaminated vaginal pool amniotic fluid. One hundred one of 161 amniotic fluid samples were collected from the vaginal pool. Thirty-nine of these were contaminated. Vaginal pool amniotic fluid, whether contaminated or not, did not adversely effect the ease of performance, reliability, or interpretation of Amniostat-FLM. This test seems ideally suited to institutions where 24-hour availability of thin-layer chromatography is not available. In institutions where it is available, Amniostat-FLM could be used as a screening test. Amniostat-FLM was found to be significantly less sensitive when compared with thin-layer chromatography in detecting the presence of phosphatidylglycerol. At our institution the screening of amniotic fluid samples with Amniostat-FLM before use of thin-layer chromatography was only cost effective at greater than or equal to 34 weeks of gestation.

Effect of meconium on the detection of phosphatidylglycerol

Phosphatidylglycerol determination has been used as an additional parameter in the evaluation of fetal lung maturity. Meconium was added to aliquot samples of amniotic fluid after phosphatidylglycerol determination. On those amniotic fluid samples without phosphatidylglycerol, phosphatidylglycerol standard and meconium were added. Two-dimensional thin-layer chromatography was performed to detect the phosphatidylglycerol spot. Our results show that lightly stained meconium contamination of amniotic fluid does not hinder the detection of the phosphatidylglycerol spot on the chromatographic plate.

Amniotic fluid phosphatidylglycerol: an early indicator of fetal lung maturity

In a study of 766 amniotic fluids, collected from pregnancies between 26 weeks and term, phosphatidylglycerol (PG) was identified in a greater proportion than was a mature lecithin/sphingomyelin (L/S) ratio at all gestational ages between 28 and 38 weeks regardless of the underlying pregnancy complication. The early appearance of PG was particularly striking in amniotic fluids obtained after preterm rupture of membranes. Since PG has been previously shown to be a useful indicator of the risk of neonatal respiratory distress syndrome, its appearance before a mature L/S ratio suggests that its detection offers a considerable advantage in the management of high-risk obstetric problems in which the earliest possible indication that the fetal lungs are mature is required.

Amniotic fluid phosphatidylglycerol and the lecithin/sphingomyelin ratio in the assessment of fetal lung maturity

Based on the analysis of 561 amniotic fluid samples obtained within 72 h of delivery, including 288 samples collected from the vagina, the detection of phosphatidylglycerol (PG) in the fluid together with the determination of the lecithin/sphingomyelin (L/S) ratio gave an accurate prediction of the risk of the newborn infant developing respiratory distress syndrome (RDS). In the presence of PG, regardless of the L/S ratio, only 0.6% of the babies developed RDS, while absent PG was associated with an 82.8% incidence of RDS. The predictive ability was improved by knowing the L/S ratio since in the presence of both PG and a mature L/S ratio (greater than 2.0), no baby developed RDS whereas 3.4% of them did when the ratio was immature despite the presence of PG. The test appears to be a useful determinant of the risk of RDS in babies born to diabetic mothers and it seems particularly effective in assessing amniotic fluid collected vaginally. It is recommended that laboratories dealing with amniotic fluid from high-risk pregnancies should detect PG as well as measuring the L/S ratio.

A rapid qualitative method for detecting phosphatidylglycerol in amniotic fluid

A fast, reliable and inexpensive procedure of the qualitative determination of phosphatidylglycerol (PG) in amniotic fluid, using one-dimensional thin layer chromatography and a phosphorus-specific spray, is described. The method detects amounts of PG exceeding 1 microgram or 1.7% of total phospholipids in amniotic fluid. Contamination with serum does not influence the results. Excessive amounts of meconium interfere with the chromatography. The presence of PG was always associated with a mature L/S ratio (greater than 2), whereas its absence did not necessarily exclude lung maturity.

Determination of phosphatidylglycerol in amniotic fluid by a simple one-dimensional thin-layer chromatography method

Phosphatidylglycerol (PG) in amniotic fluid is the second important component of lung surfactant phospholipids and may be clinically useful in assessing fetal lung maturity in utero. Although methods for PG determination are available, there are shortcomings in clinical application. We developed an alternative reliable one-dimensional thin-layer chromatography(TLC) method for separating and quantitating PG in amniotic fluid. A mini-TLC plate (8 X 10 cm) was prepared from silica gel H containing 5% ammonium sulfate. The plate was first developed in tetrahydrofuron/dimethoxymethane/methanol/2N ammonium hydroxide (30.0:20.6:5.6:3.0 v/v) and then in chloroform/methanol (60.9, v/v) in the same direction. PG was clearly separated from other phospholipids and neutral lipids, even when large amounts of other phospholipids were present on the TLC plate. The density of the charred PG was directly proportional to the amount of PG up to 8 nmol. The content of PG in nmol in the specimen can be quantitated by comparing with a standard PG. Up to 10% of blood serum or 3% meconium showed no detectable PG, nor did these substances affect PG quantitation in amniotic fluid. This method is sensitive and accurate. It is also time-saving and economical.