Severe oligohydramnios with intact membranes: an indication for diagnostic amnioinfusion.

OBJECTIVE: To quantify the improvement in ultrasonographic fetal imaging following diagnostic amnioinfusion for the indication of unexplained midtrimester oligohydramnios. METHODS: Patients referred for unexplained midtrimester oligohydramnios were retrospectively reviewed. Videotapes of those undergoing diagnostic antenatal amnioinfusion were analyzed for quality of visualization of routinely imaged structures before and after the infusion procedure. RESULTS: The overall rate of adequate visualization of fetal structures improved from 50.98 to 76.79% (p < 0.0001). In fetuses having preinfusion-identified obstructive uropathy, there was improvement in identification of associated anomalies from 11.8 to 31.3%. CONCLUSIONS: Several authors have suggested that diagnostic amnioinfusion can facilitate fetal imaging and increase diagnostic precision in the setting of unexplained severe oligohydramnios. We have quantified the improvement in the rate of optimal visualization of fetal structures which likely translates, in experienced hands, into this observed improved diagnostic precision. Of particular importance is the improvement in appreciation of associated anomalies in cases of obstructive uropathy in which such findings may determine whether or not invasive fetal therapy is indicated.

Amniotic fluid lamellar body count: cost-effective screening for fetal lung maturity.

OBJECTIVE: To create a highly specific cascade testing scheme for fetal lung maturity using the lamellar body count, lecithin/sphingomyelin ratio (L/S), and phosphatidylglycerol. METHODS: A nondedicated hematology analyzer (Sysmex NE 1500, Toa Medical Electronics, Los Angeles, CA) was used to determine the lamellar body counts of 209 unspun amniotic fluid specimens. Maximally specific lamellar body count cutoffs for biochemical maturity and immaturity were determined using receiver operating characteristic curves. Biochemical lung maturity was defined as either a mature L/S ratio or phosphatidylglycerol. Biochemical lung immaturity was defined as both an immature L/S ratio and an immature phosphatidylglycerol. RESULTS: A lamellar body count of less than 8000 (n = 17) was 100% specific for biochemical lung immaturity (positive predictive value = 100%, negative predictive value = 86%). A lamellar body count of greater than 32,000 was 98% specific for biochemical lung maturity (positive predictive value = 99%, negative predictive value = 63%). CONCLUSION: Testing only specimens where the lamellar body count was greater than 8000 and less than or equal to 32,000 for the L/S ratio and phosphatidylglycerol would preclude the need for 76% of all L/S and phosphatidylglycerol assays. Because the lamellar body count is quick, simple, and universally available, it could serve as an extremely cost-effective screening test for fetal lung maturity.

Adrenomedullin levels in normal and preeclamptic pregnancy at term.

OBJECTIVE: To describe maternal plasma levels of adrenomedullin (AM), a hypotensive and natriuretic peptide, in normal and preeclamptic women at term. STUDY DESIGN: Maternal plasma AM levels were determined in 13 preeclamptic and 15 normotensive primigravidas by radioimmunoassay. Plasma samples were obtained with the patients in the lateral recumbent position before the administration of any medications. RESULTS: Women with preeclampsia had significantly elevated AM levels when compared with normotensive controls (42.3 +/- 10.5 pg/mL versus 16.9 +/- 3.1 pg/mL, P < .011). CONCLUSION: In this pilot study, AM levels were significantly increased at term in preeclamptic women.

In utero progression of isolated renal pelvis dilation.

The objective of this study to determine the risk of in uteroprogression of renal pelvis dilation when detected on antenatal ultrasound examination. We reviewed 230 fetuses with evidence of renal pelvis dilation. At least one exam was subsequently performed prior to delivery in all cases. Renal pelvis dilation was defined as an anterior-posterior renal pelvis measurement > 4 mm at < 32 weeks' and > 7 mm at > or = 32 weeks' gestation. Hydronephrosis was considered to be present when the renal pelvis measured +10 mm independent of gestational age. Multiple gestations and fetuses with additional congenital anomalies were excluded. The mean gestational age at diagnosis was 24 weeks. Renal pelvis dilation progressed to hydronephrosis in a total of 10.9% (25 of 230) of fetuses. There was a 3.3% chance of unilateral renal pelvis dilation progressing to hydronephrosis versus 26.0% in bilateral dilation (OR 10.4 [95% Cl 3.5-33.3]). Of those fetuses with progression, 80% had bilateral dilation (p < 0.0001). There was no difference in progression between right and left kidneys. Additionally, gender, gestational age at diagnosis and delivery, and birth weight did not differ between those fetuses with and without progression. The hydronephrosis in 7 of 25 (28%) regressed to pyelectasis on a subsequent ultrasound exam. Thus, the overall rate of progression of renal pelvis dilation to persistent hydronephrosis was 7.8% (18 of 230). In conclusion, the risk of isolated renal pelvis dilation progressing to hydronephrosis is low. Although bilateral pelvis dilation carries a higher risk for progression, no fetus in our study required in utero intervention. A follow up scan prior to delivery may be considered to identify those fetuses who will require postpartum intervention.

Meconium drug screening of stillborn infants: a feasibility study.

OBJECTIVE: Meconium drug testing of liveborn infants is highly sensitive (87%) and specific (100%). Accurate knowledge of drug use in mothers of stillborns would be beneficial. We determined the feasibility of noninvasive meconium drug screening for opiates and cocaine in stillborns. METHODS: Stillborn infants delivered at our hospital had meconium collected using a 4-mm spatula inserted into the anus. Specimens were analyzed using gas chromatography. Charts were reviewed. RESULTS: Of the 30 specimens obtained, 26 were below the optimal amount needed (0.5 g). Regardless, all samples were analyzed and three were positive for cocaine (10%), none for opiates. Two of the 3 positive samples were of 'insufficient quantity'. In one, the presumptive cause of fetal demise was diabetes, with no additional factors suggesting substance abuse. The other fetal loss was due to idiopathic preterm labor at 21.5 weeks, with a positive UDS. CONCLUSION: In this pilot study, inability to obtain an optimal volume of meconium occurred frequently. However, important and unexpected laboratory data were generated even with 'insufficient quantity'. This highlights the need to develop more refined methodologies for this screening tool in stillborn fetuses.

Meconium does not guarantee fetal lung maturity.

OBJECTIVE: In utero passage of meconium may represent a response to hypoxic stress or a normal maturational event. When found during the third trimester, one may be tempted to use its presence as prima facie evidence of fetal lung maturity. The purpose of our study was to determine the frequency of meconium-stained fluid in the third trimester and the incidence of biochemical and physiologic lung immaturity in these fetuses. METHODS: Amniotic fluid specimens obtained at our institution from 1991 through 1993 (n = 2,377) were analyzed for maturity and visually inspected for meconium. Perinatal outcome was obtained for intramural deliveries occurring within 3 days of amniotic fluid collection (n = 905). Gestational age was defined as the best obstetric estimate based on menstrual dates, clinical examination, and ultrasound results. RESULTS: Meconium staining was present in 2.7% (n = 64) of specimens. Although meconium-stained specimens were more likely to have mature lecithin-sphingomyelin (L:S) ratios (OR 2.1, 95% confidence interval [CI] = 1.2-3.6) and phosphatidylglycerol (PG) concentrations (OR 3.8, CI 2.2-6.7), 17.2% were immature for both L:S and PG (n = 11, CI = 9.9-28.2%). When analysis was limited to fetuses delivering intramurally within 3 days of amniotic fluid collection, respiratory distress syndrome occurred in 3.0% (CI = 0.5-15%) with meconium-stained fluid. CONCLUSIONS: The presence of meconium in amniotic fluid does not guarantee lung maturity. The same consideration of the risks of prematurity must be given to the fetus with meconium-stained fluid as given to the fetus with clear fluid.

Transvaginal ultrasonography for all placentas that appear to be low-lying or over the internal cervical os.

The purpose of this study was to determine in what percentage of cases the assessment of placental localization using transabdominal sonography (TAS) was changed after transvaginal sonography (TVS) was applied. TVS was prospectively performed on all pregnant women of at least 15 weeks' gestation, when the placental edge using TAS appeared to be over or within 2 cm (low-lying) of the internal cervical os. The time required for the TVS scan and the distance of the placental edge from the internal cervical os were recorded. Of the 168 patients entered into the study, 131 were analyzed. Landmarks were poorly seen in 50% of the cases when using TAS. In 66 cases, the placenta appeared low or possibly over the internal cervical os using TAS, but a definitive diagnosis could not be made due to suboptimal visualization. In the remaining 65 cases, visualization of the internal os and placental edge was possible using both TAS and TVS. In this group, there was a change in the diagnosis in 26% of the cases after TVS was performed. Our results suggest that optimal visualization of the placental edge and internal cervical os is usually difficult with TAS when the placenta appears low-lying or over the internal cervical os. The assessment of placental localization was changed in over one-quarter of cases (26%) after transvaginal sonography was performed. The use of transvaginal ultrasound should be seriously considered when the placenta appears to be low or over the internal cervical os by transabdominal ultrasound.

The use of second-trimester transvaginal sonography to predict placenta previa.

Our objective was to determine the incidence and rate of persistence of placenta previa diagnosed at 15-20 weeks' gestation by using transvaginal sonography (TVS), and to describe the characteristics of TVS that predict placenta previa at delivery. Patients having placental tissue within 20 mm of the cervical os were prospectively identified by transabdominal ultrasound and underwent TVS. The distance of the placental edge from the cervical os was measured in millimeters. Characteristics of TVS predicting placenta previa at delivery were analyzed by logistic regression. The incidence of placenta previa diagnosed by TVS at 15-20 weeks was 1.1%; 14% persisted until delivery. Gestational age at the time of TVS and the distance of the placental edge to the cervical os helped predict placenta previa at delivery. Between 15 and 24 weeks' gestation, placenta overlapping the internal os by > or = 10 mm identified patients at risk of placenta previa at delivery with 100% sensitivity and 85% specificity. The use of TVS in the second trimester to diagnose placenta previa resulted in a lower incidence than was historically reported with the use of transabdominal ultrasound. The distance of the placental edge from the cervical os helps identify patients at risk of previa at delivery.

Lung maturity tests. Relation to source, clarity, gestational age and neonatal outcome.

OBJECTIVE: To determine whether gestational age is a significant determinant of neonatal outcome, irrespective of biochemical lung maturity. The effects of specimen source and clarity on the reliability of biochemical tests for predicting respiratory distress syndrome are also evaluated. STUDY DESIGN: Perinatal outcome was analyzed for 904 neonates undergoing amniotic fluid maturity studies within three days of delivery from 1991 to 1993. The relationships of gestational age and biochemical maturity to neonatal outcome were examined using multivariate analysis of covariance. Test reliability was evaluated using log-linear analysis of multiway frequency tables. RESULTS: Gestational age was a better predictor of neonatal outcome than biochemical lung maturity. Gestational age significantly correlated with every measure of outcome except intraventricular hemorrhage and jaundice. Test reliability was not significantly influenced by specimen source or clarity. CONCLUSION: Results obtained using contaminated amniotic fluid are reliable when the proper technique is used. Irrespective of biochemical maturity, neonatal outcome is significantly related to gestational age. Gestational age, and not just biochemical maturity, should be considered when timing delivery.

Effects of tumor necrosis factor-alpha on human trophoblast cell adhesion and motility.

PROBLEM: Adhesive interaction between trophoblast cells and uterine endometrial basement membrane is one of the critical processes in embryo implantation. This interaction is directly or indirectly regulated by hormones, growth factors, and cytokines. Since tumor necrosis factor-alpha (TNF-alpha) is synthesized by both decidual and trophoblast cells, we hypothesized that TNF-alpha may play a regulatory role in trophoblast cell invasion. To test this hypothesis, we have used in vitro models to determine the effect of TNF-alpha on human trophoblast cell adhesion and motility, two major steps in trophoblast invasion. METHODS: The effect of TNF-alpha on the motility of extended-lifespan first trimester trophoblasts (HTR) and JEG-3 choriocarcinoma cells was tested using the phagokinetic track motility assay. An in vitro adhesion assay was used to determine the effect of TNF-alpha on the adhesion of HTR and JEG-3 cells to laminin, a major basement membrane component. In addition, the effect of TNF-alpha on the surface expression of the laminin receptor beta 1 integrin subunit was examined using flow cytometry. RESULTS: HTR or JEG-3 cells strongly adherent to laminin which was not significantly altered by TNF-alpha treatment. We also measured the effect of TNF-alpha on the surface expression of beta 1 integrin on HTR and JEG-3 cells; no difference was observed between control and treatment groups. Interestingly, the motility of both HTR and choriocarcinoma JEG-3 cells was significantly inhibited by TNF-alpha. CONCLUSIONS: The role of TNF-alpha in human embryo implantation is currently unknown. Our data demonstrate that TNF-alpha does alter trophoblast cell adhesion to laminin, but significantly inhibits trophoblast cell motility in vitro, suggesting that TNF-alpha may play a regulatory role in trophoblast cell invasion.

Brain natriuretic peptide and cyclic guanosine-3',5' monophosphate in pre-eclampsia.

The objective of this study is to determine the possibility that pre-eclampsia, a disease characterized by altered vascular tone, may result in altered levels of fetal BNP and cGMP, and to determine whether pre-eclampsia alters the maternal-fetal relationship of BNP and cGMP. Paired maternal and umbilical venous plasma levels of BNP and cGMP were determined in 13 pre-eclamptic and 9 normotensive primigravidas in the third trimester. Statistical analysis was performed using multivariate analysis of variance, linear regression, and canonical correlation. Overall, levels of cGMP were lower in pre-eclampsia (P < 0.03). Pre-eclampsia was also associated with an altered maternal-fetal relationship for BNP and cGMP (P < 0.008, P < 0.02, respectively). With pre-eclampsia, the maternal:fetal ratio was reduced for BNP and was increased for cGMP. Because of its role as a second messenger for many vasoactive hormones, we hypothesize that fetal cGMP levels may better reflect overall vascular tone than do individual hormones. Altered BNP and cGMP maternal-fetal homeostasis raises the possibility of maternal-fetal coordination of vascular control.

Pulmonary hypoplasia: pathogenesis, diagnosis, and antenatal prediction.

OBJECTIVE: To review published data pertaining to the pathogenesis, antenatal prediction, and neonatal diagnosis of pulmonary hypoplasia. DATA SOURCES: A computerized search of articles published through February 1995 was performed on the MEDLINE data base. Additional sources were identified through cross-referencing. METHODS OF STUDY SELECTION: All available references were reviewed initially by the authors, and their impact on the clinical significance of this condition was summarized. DATA EXTRACTION AND SYNTHESIS: Pulmonary hypoplasia can be understood best by first defining the embryology of lung development. Although pulmonary hypoplasia can occur as a primary event, most cases are secondary to congenital anomalies or pregnancy complications. Several methods have been proposed to predict the subsequent occurrence of pulmonary hypoplasia, but no single criterion has adequately confirmed sensitivity and specificity for clinical decision making. CONCLUSION: For patients with premature rupture of membranes, the gestational age at time of rupture carries the highest risk correlation with subsequent pulmonary hypoplasia.

Centile-based ultrasound morphometric tables.

Current ultrasound morphometric tables estimate centiles assuming normal distribution and similar variation throughout gestation. Our goal was to develop normative tables for biparietal diameter, femur length and average abdominal diameter using actual centiles. We studied the last complete ultrasound examination from 9510 singleton, live pregnancies without major malformations delivered at our hospital. Actual 5th, 10th, 50th, 90th and 95th centiles were calculated for each week and compared to estimates based on means and standard deviations. With advancing gestational age, variation in average abdominal diameter increased and variation in biparietal diameter and femur length remained stable. The largest difference between an actual and an estimated centile limit was 2 mm for biparietal diameter or femur length and 3 mm for average abdominal diameter. Differences between true and estimated centile limits were less than the intraobserver variation of the ultrasound measurements and therefore clinically unimportant.