A new method of evaluating fetal lung maturity: The enzymatic lecithin determination in amniotic fluid

The concentration of phospholipids is well suited as indicator for the prognosis of a possibly postnatal respiratory distress syndrome. The method used most frequently up to now has been the determination of the lecithin/sphingomyelin ratio ($\text{L}\text{S}$ ratio) by thin layer chromatography. We have developed a specific assay for the quantitative determination of lecithin in amniotic fluid, which yields absolute concentration values and does not require the determination of a concentration ratio. Lecithin is hydrolized by phospholipase C and alkaline phosphatase. Choline is determined afterwards by a highly specific choline kinase from yeast. The total time required is less than 2 h. The usual lecithin concentration present in the 35th to 38th wk of gestation can be determined with a coefficient of variation of 2–3% (n = 30). Fetal lung maturity can be expected at a lecithin concentration above 4.7–5.1 mg/100 ml. The method compares well with the $\text{L}\text{S}$ ratio. Detailed data about clinical significance will be presented. Good precision accuracy and simple handling make enzymatic lecithin determinations suitable for routine use.     

Successful outcome of intrathoracic injection of autologous amniotic fluid in fetal reduction: report of two cases

Potassium chloride is reported to kill both monochorionic twins after injection into only one. In this study, two women undergoing in vitro fertilization and embryo transfer were pregnant with triplets containing monochorionic twinning, which were detected by ultrasound with the presence of a "twin-peak" sign. Instead of potassium chloride, intrathoracic injection of amniotic fluid was employed to sacrifice one of the monochorionic fetuses in dichorionic triplets. Our aim was to sacrifice one of the monochorionic twins in order to prevent adverse perinatal outcomes and to avoid the harmful effect of potassium chloride on monochorionic cotwins. One twin pregnancy was terminated with preterm premature rupture of membranes at 25 weeks of gestation. In the second one, two healthy babies were delivered by cesarean section at 36 weeks of gestation. The female baby weighed 2100 gm and the male baby 2600 gm, respectively. Intrathoracic injection of amniotic fluid to create a tamponade is an alternative management for fetal reduction.     

Amniotic fluid index and estimated fetal weight for prediction of fetal macrosomia: a prospective observational study

Objective: The purpose of this study was to assess the value of combining the estimated fetal weight (EFW) and amniotic fluid index (AFI) measured in term patients early in labor with intact membranes for prediction of macrosomia.

Methods: In a single center, prospective observational study, 600 patients in the first stage of labor before rupture of membranes in whom ultrasonography was performed to measure AFI and EFW, and these data were analyzed statistically to evaluate prediction of fetal macrosomia.

Results: Macrosomia occurred in 64 cases (10.6%). The AFI was significantly higher in the macrosomic group (p?=?0.001). It was noted that the area under receiver operating characteristic (ROC) curves for EFW was 0.93 and that of AFI was 0.67. Based on suggested combined EFW and AFI cutoffs of 4000?g and 164?mm, respectively, the positive predictive value (PPV) for combined parameters (92.3%) was higher than that of EFW (75%) and that of AFI (27%) and the likelihood ratio for combination (93.7%) was higher than that of EFW (24.7%) and that of AFI (21%).

Conclusion: Combined use of EFW and AFI improves prediction of macrosomia at birth rather than the EFW alone.     

Residual amniotic fluid volume predicts the sealing of preterm prelabor rupture of fetal membranes in the pre- and periviable period

ObjectivePreterm prelabor rupture of fetal membranes (pPROM) is a leading cause of preterm birth. When pPROM occurs around the pre- and periviable period, the perinatal outcome is unfavorable. However, there have been a few cases in which the leakage of amniotic fluid ceases and the ruptured fetal membranes are spontaneously sealed.Materials and methodsThe prognosis of 38 cases of pPROM at less than 27 weeks of gestation in Kyoto University Hospital were studied. The clinical factors related to the sealing of fetal membranes were investigated.ResultsSpontaneous sealing was confirmed in five patients (13%), and sealing occurred within 14 days of pPROM. Women in the no sealing group delivered at 26.3 ± 0.5 weeks of gestation, whereas women in the sealing group delivered at term at 38.8 ± 0.4 weeks (p < 0.0001). The maximum vertical pocket (MVP) of amniotic fluid at the time of pPROM diagnosis was 2.2 ± 0.3 cm in the no sealing group and 3.8 ± 0.5 cm in the sealing group (p = 0.043). All cases of sealing occurred when the MVP at diagnosis was more than 2 cm, and there were no cases of sealing if the MVP at diagnosis was less than 2 cm. In addition, the value of C-reactive protein at ROM was less than 0.4 mg/dL in all cases in the sealing group.ConclusionThe residual volume of sterile amniotic fluid at the onset of pPROM may predict the possibility of fetal membrane sealing.     

Risk factors for fatality in amniotic fluid embolism: a systematic review and analysis of a data pool

Purpose: Investigating risk factors for amniotic fluid embolism (AFE)-induced fatality.

Methods: A systematic review of cases of AFE available on PubMed, Scielo, Scopus and AJOL databases that occurred from 1990 to 2015 was carried out. After careful reading of titles, abstracts and full texts, case reports of AFE were reviewed. Risk factors for AFE were considered as independent variables in logistic regression models. The first model was built on the whole data pool. The second model was built on typical cases of AFE, according to the classical triad of symptoms (heart, lungs, coagulopathy). The dependent variable was fatality in both models.

Results: 177 cases of AFE were assessed in the first model, while 121 typical cases of AFE were assessed in the second model. Among typical cases of AFE, only oxytocin infusion during labour increases the likelihood of death (odds ratio 2.890, 95% confidence interval 1.166–7.164, p?=?0.022). No risk factors for fatality were found in the whole data pool.

Conclusions: Further research on national registries should focus on the behaviour of oxytocin infusion during labour in AFE cases.     

Absorbance of amniotic fluid at 650 nm as a fetal lung maturity test: A comparison with the lecithin/sphingomyelin ratio and tests for disaturated phosphatidylcholine and phosphatidylglycerol

We compared absorbance of amniotic fluid at 650 nm (A₆₅₀) against the lecithin/sphingomyelin ratio, the quantity of disaturated phosphatidylcholine, and the presence or absence of phosphatidylglycerol in 374 uncontaminated amniotic fluid samples. In addition, we studied these measures of fetal lung maturity in 80 pregnancies where neonatal outcomes were known. Statistical analysis revealed a significant association between increasing absorbance and biochemical indices of lung maturation. Our results indicate that A₆₅₀ of amniotic fluid is useful as a measure of lung maturity but that the greatest utility may be for samples with either low absorbance (<0.10) or high absorbance (>0.20). Because of large false positive and false negative values between these two absorbances, other lung maturity estimates should be used when absorbances fall within this range. Therefore, A₆₅₀ may be most useful as a screen or as part of a battery of lung maturity estimates. We are exploring these possibilities as a means of providing better fetal lung maturity estimates.     

Fetal death: A condition with a dissociation in the concentrations of soluble vascular endothelial growth factor receptor-2 between the maternal and fetal compartments

Objective.?An anti-angiogenic state has been implicated in the pathophysiology of preeclampsia, fetal growth restriction and fetal death. Vascular endothelial growth factor (VEGF), an indispensible angiogenic factor for embryonic and placental development exerts its angiogenic properties through the VEGF receptor (VEGFR)-2. A soluble form of this protein (sVEGFR-2) has been recently detected in maternal blood. The aim of this study was to determine if fetal death was associated with changes in the concentrations of sVEGFR-2 in maternal plasma and amniotic fluid.

Study Design.?Maternal plasma was obtained from patients with fetal death (n?=?59) and normal pregnant women (n?=?134). Amniotic fluid was collected from 36 patients with fetal death and the control group consisting of patients who had an amniocentesis and delivered at term (n?=?160). Patients with fetal death were classified according to the clinical circumstances into the following groups: (1) unexplained; (2) preeclampsia and/or placental abruption; (3) chromosomal and/or congenital anomalies. Plasma and amniotic fluid concentrations of sVEGFR-2 were determined by ELISA. Non-parametric statistics and logistic regression analysis were applied.

Results.?(1) Patients with a fetal death had a significantly lower median plasma concentration of sVEGFR-2 than normal pregnant women (p?<?0.001). The median plasma concentration of sVEGFR-2 in patients with unexplained fetal death and in those with preeclampsia/abruption, but not that of those with congenital anomalies, was lower than that of normal pregnant women (p?=?0.006, p?<?0.001 and p?=?0.2, respectively); (2) the association between plasma sVEGFR-2 concentrations and preterm unexplained fetal death remained significant after adjusting for potential confounders (OR: 3.2; 95% CI: 1.4–7.3 per each quartile decrease in plasma sVEGFR-2 concentrations); (3) each subgroup of fetal death had a higher median amniotic fluid concentration of sVEGFR-2 than the control group (p?<?0.001 for each); (4) the association between amniotic fluid sVEGFR-2 concentrations and preterm unexplained fetal death remained significant after adjusting for potential confounders (OR: 15.6; 95% CI: 1.5–164.2 per each quartile increase in amniotic fluid sVEGFR-2 concentrations); (5) among women with fetal death, there was no relationship between maternal plasma and amniotic fluid concentrations of sVEGFR-2 (Spearman Rho: 0.02; p?=?0.9).

Conclusion.?Pregnancies with a fetal death, at the time of diagnosis, are characterized by a decrease in the maternal plasma concentration of sVEGFR-2, but an increase in the amniotic fluid concentration of this protein. Although a decrease in sVEGFR-2 concentration in maternal circulation depends upon the clinical circumstances of fetal death, an increase in sVEGFR-2 concentration in amniotic fluid seems to be a common feature of fetal death. It remains to be determined if the perturbation in sVEGFR-2 concentrations in maternal and fetal compartments observed herein preceded the death of a fetus.