Correlation of real-time ultrasonic placental grading with amniotic fluid lecithin/sphingomyelin ratio

Placental grading with real-time ultrasound was performed on 235 patients who underwent amniocentesis for determination of the lecithin/sphingomyelin (L/S) ratio between 31 and 44 weeks' gestation. Grades I, II, and III placentas were encountered in 88, 72, and 75 patients, respectively. Forty-eight percent of Grade I, 69% of Grade II, and 92% of Grade III placentas had mature L/S ratios (L/S greater than or equal to 2.0). All of the 52 patients with a Grade III placenta who underwent repeat cesarean section at term gestation had mature L/S ratios. However, 37% of the pregnancies complicated by maternal or fetal disease, with Grade III placentas, had immature L/S ratios. The gestational age of these six patients ranged from 34 to 37 weeks. These results suggest that a Grade III placenta in normal term gestation has a good correlation with fetal pulmonary maturity as predicted by the amniotic fluid L/S ratio.     

The use of ultrasound in the prediction of fetal pulmonary maturity

Previous studies suggest that ultrasound criteria of biparietal diameter (BPD) and/or placental grade permit elimination of amniocentesis for pregnancy dating. To evaluate the potential risks and benefits of such a modified approach to determining fetal maturity, this prospective study, in which a BPD of ≥9.2 cm or a Grade III placenta was used instead of amniotic fluid analysis, was undertaken. One hundred fifty-three infants were delivered electively between March 1981, and January 1982, on the basis of ultrasound parameters of pulmonary maturity. None of the electively delivered infants developed respiratory distress syndrome. We conclude from these preliminary results that the ultrasonically determined BPD of ≥9.2 cm Grade III placenta is at least as sensitive as the lecithin/sphingomyelin ratio in predicting pulmonary maturity in our patient population.     

The relationship of placental grade, fetal lung maturity, and neonatal outcome in normal and complicated pregnancies

Ultrasonically diagnosed maturity changes in the placenta, Grades 0 to III, have been previously shown to correlate with fetal lung maturity. In a prospective study of 230 term and preterm complicated pregnancies, we compared the relationship between sonographic placental grading, amniotic fluid phospholipids, and neonatal outcome. The frequencies of gestational age less than 38 weeks, lecithin/sphingomyelin (L/S) ratio less than 2.0, negative phosphatidylglycerol, and neonatal hyaline membrane disease were found to decrease as placental grade advanced from 0 to III. Patients were divided into subgroups on the basis of maternal complications. In patients with Grade III placentas, the frequencies of gestational age less than 38 weeks and L/S ratio less than 2.0 were significantly increased when the subgroup of patients with chronic hypertension was compared individually to both of the subgroups, repeat cesarean section deliveries, and Classes A, B, and C diabetes mellitus (both with p less than 0.05) All three infants who developed hyaline membrane disease in association with Grade III placentas were from pregnancies of less than 38 weeks complicated by chronic hypertension. These findings suggest that the presence of a Grade III placenta is affected by both gestational age and pregnancy complications. Hence, when an elective cesarean section delivery is being planned near term gestation, a Grade III placenta is a reliable predictor of lung maturity. In preterm complicated pregnancies, an ultrasound-diagnosed Grade III placenta may still be associated with hyaline membrane disease.     

The ultrasonic changes in the maturing placenta and their relation to fetal pulmonic maturity.

A practical classification of placental maturity changes has been developed based on a review of multiple ultrasound evaluations of placental texture over a 4 year period. This classification grades placentas from 0 to 3 according to specific ultrasonic findings at the basal and chorionic plates as well as within the substance of the organ itself. The placentas of 129 patients were graded according to this system at the time of ultrasound evaluation. Eighty-six patients had placentas classified as Grade 1 or greater and all of these had lecithin-sphingomyelin (L/S) ratio determinations performed. Mature L/S ratios (2.0) were found in 68% of Grade I (21/31), 88% of Grade II (28/32), and 100% of Grade III placentas (23/23). These results suggest a correlation between maturational changes of the placenta as seen by ultrasound and fetal pulmonic maturity as indicated by L/S ratio.     

Relationship of placental grade to fetal pulmonary maturity and respiratory distress syndrome

Real-time sonographic placental grading was performed on 215 patients who had amniocentesis for determination of fetal pulmonary maturity between 26 and 42 weeks of gestation. The results of this placental grading were correlated with clinical gestational age and fetal pulmonary maturity, assessed by lecithin-sphingomyelin ratio, phosphatidylglycerol, and the subsequent presence or absence of respiratory distress syndrome. This study showed a statistically significant correlation of placental grade with gestational age, pulmonary maturity, and respiratory distress. Grade 3 placentas were seen in 20% of the cases studied, and in every instance was associated with an absence of subsequent neonatal respiratory distress. Placental grade appeared to be an accurate predictor of fetal pulmonary maturity in the population studied.     

Performance of lecithin-sphingomyelin ratio as a reflex test for documenting fetal lung maturity in late preterm and term fetuses

Objective: To determine if infants delivered after immature or indeterminate TDx-FLM II testing and a mature reflex test are at increased risk for neonatal respiratory complications. Methods: The primary analysis compared neonatal respiratory morbidity (RDS or TTN) in 34–39-week fetuses delivered after either (i) mature TDx-FLM II testing, or (ii) indeterminate or immature TDx-FLM II and a positive reflex test (PG or L/S ratio). Results: Fifty patients delivered after mature TDx-FLM II, and 30 after immature or indeterminate TDx-FLM II with an L/S ≥2.0. Respiratory morbidity was significantly higher in the group delivered after mature reflex testing compared with mature TDx-FLM II (23% vs. 2%, p?<?0.01). When PG was present, there were no cases of RDS or TTN. Conclusions: Utilizing L/S ratios as a reflex test to confirm lung maturity was associated with a high risk for respiratory morbidity, particularly when PG was not present.     

Use of femur length measured by ultrasonography to predict fetal maturity

The ultrasonographic criteria of biparietal diameter greater than or equal to 9.2 cm and a grade III placenta have been shown to correlate with fetal maturity in the fetus of a nondiabetic mother in our population. These two criteria have helped reduce the incidence of third-trimester amniocenteses by 66.6% at our institution. Occasionally, however, because of fetal position, we are unable to obtain an accurate biparietal diameter. We therefore carried out a prospective study of 120 patients to evaluate the relationship between femur length of greater than or equal to 7.3 cm and fetal maturity. In this study, the addition of the femur length criterion increased the specificity of the ultrasonographic criteria for fetal maturity from 66.6% to 85%. The data suggest that femur length could be used along with the biparietal diameter and placental grade as an alternative to amniocentesis in term nondiabetic pregnancies.     

Amniotic fluid OD 650 as a rapid indicator of fetal pulmonary maturity

Amniotic fluid OD 650 (optical density at 650 nm) greater than 0.15 has been associated with mature L/S ratios. This study compared OD 650 with the L/S ratio on 235 uncontaminated amniotic fluid specimens. Follow-up was obtained on 138 neonates delivered within 72 hours of amniocentesis. Of 124 amniotic fluid specimens with OD 650 greater than 0.15, 109 had mature L/S ratios. Only 3 of 96 neonates with OD 650 greater than 0.15 developed respiratory distress syndrome; 8 of 42 neonates with OD 650 values less than 0.15 developed it. The false-positive rate (2.1%) compared favorably with that of the L/S ratio (2.9%). A higher false-negative rate (24.6%) decreased the efficiency of OD 650 as an indicator of fetal pulmonary maturity. An OD 650 greater than 0.15 appears to be a rapid, reliable indicator of fetal lung maturity.     

Preliminary report on a new and noninvasive method for the assessment of fetal lung maturity

OBJECT: Several patterns of fetal breathing movements (FBMs), i.e. abdominal wall movements (AWm), thoracic wall movements (TWm) and nasal fluid flow velocity waveforms (NFFVW), were investigated by ultrasound (US) technology and related to fetal pulmonary maturity and immaturity, i.e. fetal lung maturity (FLM) tests, in order to validate the hypothesis that they may indicate whether the fetal lung is mature or immature, regardless of gender, weight and gestational age. MATERIAL AND METHODS: We prospectively enrolled 143 high-risk pregnancies in which a complete US study of FBMs and FLM tests was performed. Among them 43 women satisfied the inclusion criteria. US-FLM was defined as the presence of regular NFFVW detected by pulsed Doppler and spectral analysis, or irregular NF-FVW synchronous with TWm detected by M-mode. An US guided amniocentesis was performed in order to collect amniotic fluid (AF) and FLM was evaluated by L/S (lecithin/sphingomyelin) determination, presence of phosphatidylglycerol (PG) and lamellar bodies (LBs) count. At the end of the study the diagnostic accuracy of US-FLM was compared to that of FLM tests. RESULTS: Diagnostic accuracy for US evaluation of FLM was as follows: sensitivity: 89.6%; specificity: 85.7%; PPV: 92.8%; NPV: 80%. Diagnostic accuracy of FLM tests was as follows: sensitivity: 100%; specificity: 51.7%; PPV: 100%; NPV: 50%. L/S determination predicted lung maturity with a sensitivity of 100%; specificity of 93.1%; PPV of 100%; NPV of 87.5%. CONCLUSION: Presence of regular NFFVW or irregular NFFVW and TWm correlate accurately with conventional FLM tests. We suggest that this noninvasive procedure may be helpful for assessing FLM, particularly under certain circumstances, e.g., oligo-anhydramnios, laboratory logistic equipment difficulties or heavily stained AF samples, amniocentesis refusal, religious concerns.     

超声检测胎儿骨骺次级骨化中心和胎盘分级的临床意义

目的:探讨超声测量胎儿骨骺次级骨化中心和胎盘分级对评估孕龄和胎肺成熟度的临床意义。方法:前瞻性研究从359例孕龄准确的单胎孕妇中获得的518人次超声检查结果,分析胎儿股骨远端次级骨化中心(DFSOC)、胫骨近端次级骨化中心(PTSOC)和胎盘分级与孕龄的关系。选取其中在分娩前1周内接受超声检查且资料完整的184例孕妇,根据新生儿是否发生呼吸窘迫综合征(RDS)分为RDS组(15例)和non-RDS组(169例)。比较两组的DFSOC和PTSOC显示率及胎盘分级情况,并采用Logistic回归分析校正孕周影响,了解DFSOC、PTSOC和胎盘分级与出生后发生RDS的相关性。结果:(1)DFSOC、PTSOC和胎盘分级与超声检查孕周之间均呈正相关,Spearman相关系数分别为0.831、0.716和0.859(P均0.001)。(2)DFSOC、PTSOC和胎盘Ⅰ级以上分别预示胎儿至少已32周、37周和35周的准确度高达88.03%、89.58%和91.51%。(3)RDS组和non-RDS组的DFSOC、PTSOC显示率及胎盘分级比较,差异均有统计学意义(P均0.001);但校正分娩孕周的影响后,三者与出生后的RDS的发生均无显著相关性(P0.05)。结论:胎儿DFSOC、PTSOC和胎盘分级有助于临床上评估某些关键的孕龄,但并不是评估胎肺成熟度的可靠指标。     

Glycosylated hemoglobin as a predictor of fetal pulmonic maturity in insulin-dependent diabetes at term.

In insulin dependent diabetic (IDDM) gestations, fetal pulmonary maturity is delayed in the presence of suboptimal glycemic control. Serum glycosylated hemoglobin (HbA1c) provides a means of assessing glycemic control. We evaluated maternal HbA1c in IDDM pregnancies at term undergoing amniocentesis for lung maturity to establish if euglycemia is associated with improved fetal lung maturity. Between July 1995 and June 1996, IDDM patients undergoing amniocentesis at term for lung maturity studies had a maternal serum sample analyzed for HbA1c. Fetal lung maturity was established by the presence of phosphatidylglycerol (PG) in amniotic fluid. HbA1c was considered elevated if >6.2%. Mean HbA1c level was 6.8% (range 4.4 to 9.9%). PG was present in 54% of patients with elevated HbA1c (7/13) versus 80% of those with normal HbA1c (8/10) (p = 0.4). Although birth weight was higher in the elevated than in the normal HbA1c group (3770 +/- 514 vs. 3215 +/- 610 g), no association was present between birth weight and HbA1c level (r = 0.22, p = 0.4). The rate of a mature pulmonic profile at term is not significantly different between IDDM women with good or poor glycemic control. HbA1c values should not be used to predict the presence or absence of amniotic fluid PG.     

A blind comparison study of the lung phospholipid profile, fluorescence microviscosimetry, and the lecithin/sphingomyelin ratio

Two hundred thirty-six amniotic fluid samples from 215 patients were analyzed for the acidic phospholipids, phosphatidylglycerol (PG) and phosphophatidylinositol (Pl), using two-dimensional chromatography. One hundred seventy-eight samples were compared for gestational age, 166 were compared with lecithin/sphingomyelin (L/S) ratios, and 56 compared with the FELMA microviscosimeter. Although Pl could be detected by the sixteenth gestational week, PG was not found earlier than the thirty-fifth week. Median L/S ratio in samples not containing PG was 1.94, while PG-positive fluid had a median ratio of 3.72 (p less than 0.001). One hundred twelve infants born within 72 hours were evaluated for outcome. No instance of hyaline membrane disease (HMD) occurred in any neonate with detectable PG regardless of L/S ratio, while 2 of 67 (3%) infants with mature L/S ratios developed HMD. The FELMA technique did not mispredict maturity in any neonate who subsequently developed HMD. Two samples contained PG but the neonates were delivered free of lung disease. The phospholipid lung profile appears to be the most accurate method for the evaluation of fetal lung maturity, while the FELMA technique, although less sensitive, is more rapid.     

Fetal lung maturity in pregnancies complicated by insulin-dependent and gestational diabetes: a matched cohort study.

OBJECTIVE: To study fetal lung maturity (FLM) as determined by amniotic fluid (AF) tests in diabetic pregnancies (DP) under euglycemic metabolic control, in comparison with matched controls (C). PATIENTS AND METHODS: From 514 consecutive pregnancies where amniocentesis was performed for FLM assessment, we selected 45 glycemic controlled DP. Nineteen DP were Type I (IDDM) and 26 pregnancies were diagnosed Type III (GDM). Cases were matched to C by therapy with corticosteroids, gestational age at amniocentesis, pregnancy complications other than diabetes and gender. FLM was determined by the shake test and lamellar bodies (LB) count, lecithin/sphingomyelin (L/S) ratio (planimetric and stechiometric) and phosphatidylglycerol presence (PG). DP were further sub-divided according to gestational age period at amniocentesis, type of diabetes, associated therapy and fetal malformations. RESULTS: RDS (n=2) and neonatal wet lung (n=5) were diagnosed in neonates from diabetic mothers. We found no statistical difference when comparing FLM indices between DP and C groups: shake test 3.1:1+/-1.2 vs. 2.7:1+/-1.2, P<0.40; planimetric L/S 3.4+/-1.4 vs. 3.1+/-2.0, P<0.27; stechiometric L/S 8.2+/-7.4 vs. 7.1+/-6.1, P<0.54; percentage of PG positivity 57% vs. 46%, P<0.13; lamellar bodies count (X10(3)/microl) 42.8+/-36.9 vs. 41.5+/-30.4, P<0.72. No differences were found between DP and controls for subgroups according to gestational age, type of Diabetes (IDDM or GDM), congenital lesions and associated therapy. CONCLUSIONS: In euglycemic, metabolically controlled diabetic patients FLM is not delayed, however an increased risk for neonatal wet lung should be considered.     

Modified method of determining phosphatidylglycerol in amniotic fluid to assess fetal maturity]

In this study the amniotic fluid of 111 cases were analyzed to assess fetal maturity by a modified method of determining phosphatidylglycerol. The L/S ratio was also determined in the amniotic fluid by thin layer chromatography at the same time. This method was found especially valuable where the L/S ratio was not less than 2.0 and the newborn infant did not have RDS. Here the fetal maturation was characterized by an early appearance of PG. Clinical evaluation showed that the rate of accuracy to assess fetal maturity of PG was 97.3%, significantly higher when compared with the 86.5% by L/S ratio (P less than 0.01). The false negative rate for PG was 5%. PG analysis in amniotic fluid as markers of surfactant seems to be of value as an additional index of prenatal evaluation of lung maturity. The modified method of PG assessment in amniotic fluid is a better method for estimating fetal maturity.     

When is an amniocentesis for fetal maturity unnecessary in nondiabetic pregnancies at risk?

For several years standard obstetric practice has been to perform an amniocentesis for evaluation of fetal maturity. In order to provide a more definitive answer as to which pregnancies need an amniocentesis, a group of 294 nondiabetic pregnant women in whom an amniocentesis for the evaluation of fetal maturity had been performed for clinical indications were evaluated. Three predictors of fetal maturity—obstetric estimate of gestational age, fetal biparietal diameter, and ultrasonic determination of placental maturation—were evaluated for their ability to predict three outcomes of fetal maturity, including positive amniotic fluid phosphatidylglycerol, pediatric estimate of gestational age ≥38 weeks, and absence of hyaline membrane disease. A fetal biparietal diameter of ≥90 mm was present in 36% of the total population and was associated with 97% term delivery, 87% positive amniotic fluid phosphatidylglycerol, and 0% hyaline membrane disease. The results associated with an obstetric estimate of gestational age of ≥38 weeks were similar. In the present data set over one third of clinically indicated amniocenteses could potentially be avoided without losing any predictive capability for fetal maturity.     

No Correlation Between Ultrasound Placental Grading at 31–34 Weeks of Gestation and a Surrogate Estimate of Organ Function at Term Obtained by Stereological Analysis

We test the experimental hypothesis that early changes in the ultrasound appearance of the placenta reflect poor or reduced placental function. The sonographic (Grannum) grade of placental maturity was compared to placental function as expressed by the morphometric oxygen diffusive conductance of the villous membrane. Ultrasonography was used to assess the Grannum grade of 32 placentas at 31–34 weeks of gestation. Indications for the scans included a history of previous fetal abnormalities, previous fetal growth problems or suspicion of IUGR. Placentas were classified from grade 0 (most immature) to grade III (most mature). We did not exclude smokers or complicated pregnancies as we aimed to correlate the early appearance of mature placentas with placental function. After delivery, microscopical fields on formalin-fixed, trichrome-stained histological sections of each placenta were obtained by multistage systematic uniform random sampling. Using design-based stereological methods, the exchange surface areas of peripheral (terminal and intermediate) villi and their fetal capillaries and the arithmetic and harmonic mean thicknesses of the villous membrane (maternal surface of villous trophoblast to adluminal surface of vascular endothelium) were estimated. An index of the variability in thickness of this membrane, and an estimate of its oxygen diffusive conductance, were derived secondarily as were estimates of the mean diameters and total lengths of villi and fetal capillaries. Group comparisons were drawn using analysis of variance. We found no significant differences in placental volume or composition or in the dimensions or diffusive conductances of the villous membrane. Subsequent exclusion of smokers did not alter these main findings. Grannum grades at 31–34 weeks of gestation appear not to provide reliable predictors of the functional capacity of the term placenta as expressed by the surrogate measure, morphometric diffusive conductance.     

Role of lamellar body count for the prediction of neonatal respiratory distress syndrome in non-diabetic pregnant women

Objective Lamellar body count is a new and fast technique to establish the presence of fetal lung maturity. We have assessed the predictive ability of lamellar body count for neonatal respiratory distress syndrome (RDS) in a non-diabetic population.Study design We accessed a cohort of amniocenteses in non-diabetic women from 1998 to 2002 (n=102). Neonatal RDS was defined as need for surfactant, intubation, or continuous positive airway pressure (CPAP) in the setting of chest X-ray findings consistent with RDS. The predictive ability of lamellar body count was compared with those of lecithin/sphingomyelin (L/S) ratio and presence of phosphatidylglycerol (PG) using logistic regression analysis. The optimal threshold value of lamellar body count for prediction of neonatal RDS was established with receiver operating characteristic (ROC) curve analysis.Results Lamellar body count ROC curve analysis identified a lamellar body count >37,000 l^–1 as optimal diagnostic threshold for diagnosis of lung maturity, having a negative predictive value of 98%. Lamellar body count and PG, but not L/S ratio, added significantly to the prediction of RDS.Conclusions Lamellar body count is a reliable predictor of fetal lung maturity in non-diabetic women and it can replace the L/S ratio.     

Distribution of Placental Grading by Gestational Age

Objective: to describe the ultrasonography-based gestation-specific placental grading distribution in a Chinese population.Methods: ultrasonographic examination of placentae was performed in 5,476 normal pregnancies (more than 95% first births) in five obstetric ultrasound laboratories in Central-South China between January 1, 1992 and December 31, 1993. A gestation-specific placental grading distribution was presented and compared with previous studies.Results: the gestational ages of the patients included in this study ranged from 16 to 40 weeks. The gestation-specific distribution of placental grading showed patterns similar to those observed previously, with grade III placentae starting to occur at 32 weeks and increasing to 32.3 percent at 40 weeks of gestation.Conclusions: the occurrence of grade III placentae is too high in preterm and too low in term pregnancies. Ultrasonographic placental grading alone is not a reliable measure of fetal pulmonary maturity.     

The prognostic meaning of the selection parameters amniotic fluids samples and frequency occurrence respiratory distress newborn

Prenatal diagnosis of amniotic fluid enables the evaluation of fetal lungs maturity. The aim of the study is to evaluate prognostic significance of measurement of concentration of lamellar body count (LC) in comparison with other laboratory investigations for prenatal fetal lung maturity evaluation. The study was carried out on 60 amniotic fluid collections obtained by amniocentesis of pregnant women, hospitalized in Polish Mother's Health Centre between August 1998-January 2000. Following tests were performed: phosphatydyloglicerol concentration (PG), concentration of lamellar body (CLC), optical density-reading absorbance in wave length 400, 570, 650 nm. Test PG showed 70% specificity and 100% sensitivity, LC 70% specificity; 100% sensitivity. PG and LC showed good correlation for the assessment of fetal lung maturity. The study involved small number of patients pointed out the necessity of continuation quantitative investigation of LC to confirm diagnostics utility for the assessment of fetal lung maturity.     

Amniotic fluid phospholipid profile in multiple pregnancy and the effect of zygosity

Because respiratory distress syndrome (RDS) may occur in one twin but not the other it may be misleading to assess fetal lung maturity using amniotic fluid from only one sac. We compared the amniotic fluid lecithin/sphingomyelin (L/S), phosphatidyl glycerol/sphingomyelin (PG/S) and phosphatidyl inositol/sphingomyelin (PI/S) ratios between co-twins and co-triplets in 32 sets of twins and three set of triplets. In the twin pregnancies we found a weak correlation for L/S ratio but a much improved one for PG/S and PI/S. The concordance between sacs for all three ratios was better in monozygotic than in dizygotic twins. The efficacy of amniotic fluid PG in the determination of fetal lung maturity was demonstrated and the discrepancies between the sacs was much less for PG than for the L/S ratios. Employing the L/S ratio combined with the presence or absence of PG should reduce false results to a minimum.