Hours Of Amniocentesis Research Articles

A new rapid bedside test to diagnose and monitor intraamniotic inflammation in preterm PROM using transcervically collected fluid

Microbial invasion of the amniotic cavity, a clinical condition present in approximately 50% of patients with preterm prelabor rupture of membranes, is often associated with intraamniotic inflammation, a risk factor for a short admission-to-delivery interval, early preterm delivery, and neonatal complications. We previously developed a transcervical amniotic fluid collector, the device that allows the collection of fluid noninvasively from the cervical canal when membrane rupture occurs. This study was designed to determine whether rapid analysis of an interleukin-8 concentration in fluid obtained noninvasively by the transcervical amniotic fluid collector can be used to assess the risk of intraamniotic inflammation. We also compared the diagnostic performance of this point-of-care test for interleukin-8 in transcervically obtained fluid to that of a white blood cell count determined in amniotic fluid retrieved by transabdominal amniocentesis. This prospective cohort study was conducted between October 2011 and April 2017. Fluid was retrieved through both transabdominal amniocentesis and the use of a transcervical amniotic fluid collector within 24 hours of amniocentesis in patients with a singleton pregnancy and preterm prelabor rupture of the membranes (16-35 weeks of gestation). Amniotic fluid obtained via amniocentesis was cultured for aerobic and anaerobic bacteria and genital mycoplasmas; a white blood cell count was also measured in amniotic fluid. Intraamniotic infection was diagnosed when microorganisms were identified by the cultivation of amniotic fluid. Intraamniotic inflammation was defined as an elevated amniotic fluid matrix metalloproteinase-8 concentration (>23 ng/mL) assayed by enzyme-linked immunosorbent assay. Interleukin-8 in cervical fluid obtained by the collector was measured by the point-of-care test that used a test strip and scanner based on the fluorescence immunochromatographic analysis in 2019. The diagnostic indices, predictive values, and likelihood ratios of the 2 different tests were calculated. First, interleukin-8 concentration ≥9.5 ng/mL in cervical fluid, determined by the point-of-care test, was at the knee of the receiver operating characteristic curve analysis and had a sensitivity of 98% (56/57; 95% confidence interval, 91-99.96%), specificity of 74% (40/54; 95% confidence interval, 60-85%), positive predictive value of 80% (56/70; 95% confidence interval, 72-86%), negative predictive value of 98% (40/41; 95% confidence interval, 85-99.6%), positive likelihood ratio of 3.79 (95% confidence interval, 2.41-5.96), and negative likelihood ratio of 0.02 (95% confidence interval, 0.003-0.17) in the identification of intraamniotic inflammation; a concentration of matrix metalloproteinase-8 >23 ng/mL by enzyme-linked immunosorbent assay had a prevalence of 51% (57/111). Second, a cervical fluid interleukin-8 concentration ≥9.5 ng/mL had significantly higher sensitivity than a transabdominally obtained amniotic fluid white blood cell count (≥19 cells/mm3) in the identification of intraamniotic inflammation (sensitivity: 98% [95% confidence interval, 91-99.96%] vs 84% [95% confidence interval, 72-93%]; P<.05; specificity: 74% [95% confidence interval, 60-85%] vs 76% [95% confidence interval, 62-87%); positive and negative predictive values: 80% [95% confidence interval, 72-86%] and 98% [95% confidence interval, 85-99.6%] vs 79% [95% confidence interval, 69-86%] and 82% [95% confidence interval, 71-89%]) and in the identification of intraamniotic inflammation/infection (gold standard: positive culture for bacteria or a matrix metalloproteinase-8 >23 ng/mL; sensitivity: 91% [95% confidence interval, 82-97%] vs 75% [95% confidence interval, 63-85%]; P<.05). The point-of-care test was predictive of intraamniotic inflammation, based on the determination of interleukin-8 in fluid retrieved by a transcervical amniotic fluid collector. Therefore, the analysis of cervically obtained fluid by such point-of-care test may be used to noninvasively monitor intraamniotic inflammation in patients with preterm prelabor rupture of membranes.

Clinical significance of histologic chorioamnionitis with a negative amniotic fluid culture in patients with preterm labor and premature membrane rupture.

ObjectiveTo evaluate the effect of histological chorioamnionitis (HCA) with a negative amniotic fluid (AF) culture on adverse pregnancy and neonatal outcomes and inflammatory status in the AF compartment in women with preterm labor or preterm premature rupture of membranes (PPROM).MethodsThis is a retrospective cohort study of 153 women diagnosed as having a preterm labor or PPROM (20–34 weeks) who delivered singleton gestations within 48 hours of amniocentesis. AF obtained through amniocentesis was cultured, and interleukin (IL)-6, IL-8, and metalloproteinase-9 (MMP-9) levels were determined. The placentas were examined histologically.ResultsThe prevalence of HCA with negative AF culture was 23.5% (36/153). The women with HCA but with a negative AF culture (group 2) and those with a positive AF culture (group 3) had a significantly lower mean gestational age at amniocentesis and delivery than those with a negative AF culture and without HCA (group 1). Women in group 3 had the highest levels of AF IL-6, IL-8, and MMP-9, followed by those in group 2, and those in group 1. Composite neonatal morbidity was significantly higher in groups 2 and 3 than in group 1, but this was no longer significant after adjusting for confounders caused mainly by the impact of gestational age.DiscussionIn the women who delivered preterm neonates, HCA with a negative AF culture was associated with increased risks of preterm birth, intense intra-amniotic inflammatory response, and prematurity-associated composite neonatal morbidity, and its risks are similar to the risk posed by positive AF culture.

Intra-Amniotic Infection/Inflammation as a Risk Factor for Subsequent Ruptured Membranes after Clinically Indicated Amniocentesis in Preterm Labor

The aim of this study was to determine whether intra-amniotic infection/inflammation (IAI) was associated with subsequent ruptured membranes in women with preterm labor and intact membranes who had a clinically indicated amniocentesis. This retrospective cohort study included 237 consecutive women with preterm labor (20-34.6 weeks) who underwent amniocentesis. The clinical and laboratory parameters evaluated included demographic variables, gestational age, C-reactive protein (CRP) and amniotic fluid (AF) white blood cell, interleukin-6 (IL-6) and culture results. IAI was defined as a positive AF culture and/or an elevated AF IL-6 level (>2.6 ng/mL). The primary outcome was ruptured membranes in the absence of active labor occurring within 48 hours of amniocentesis. Preterm premature rupture of membranes subsequently developed in 10 (4.2%) women within 48 hr of amniocentesis. Multivariate analysis demonstrated that only IAI was independently associated with the ruptured membranes occurring within 48 hr of amniocentesis. In the predictive model based on variables assessed before amniocentesis, only CRP level was retained. IAI is an independent risk factor for subsequent ruptured membranes after clinically indicated amniocentesis in preterm labor. Prior to amniocentesis, measurement of serum CRP level can provide a risk assessment for the subsequent development of ruptured membranes after the procedure.

The Probability of Neonatal Respiratory Distress Syndrome as a Function of Gestational Age and Lecithin/Sphingomyelin Ratio

We sought to define the risk of neonatal respiratory distress syndrome (RDS) as a function of both lecithin/sphingomyelin (L/S) ratio and gestational age. Amniotic fluid L/S ratio data were collected from consecutive women undergoing amniocentesis for fetal lung maturity at Yale-New Haven Hospital from January 1998 to December 2004. Women were included in the study if they delivered a live-born, singleton, nonanomalous infant within 72 hours of amniocentesis. The probability of RDS was modeled using multivariate logistic regression with L/S ratio and gestational age as predictors. A total of 210 mother-neonate pairs (8 RDS, 202 non-RDS) met criteria for analysis. Both gestational age and L/S ratio were independent predictors of RDS. A probability of RDS of 3% or less was noted at an L/S ratio cutoff of > or = 3.4 at 34 weeks, > or = 2.6 at 36 weeks, > or = 1.6 at 38 weeks, and > or = 1.2 at term. Under 34 weeks of gestation, the prevalence of RDS was so high that a probability of 3% or less was not observed by this model. These data describe a means of stratifying the probability of neonatal RDS using both gestational age and the L/S ratio and may aid in clinical decision making concerning the timing of delivery.

Amniotic fluid heat shock protein 70 concentration in histologic chorioamnionitis, term and preterm parturition

Objective. Heat shock protein (HSP) 70, a conserved member of the stress protein family, is produced in almost all cell types in response to a wide range of stressful stimuli, and its production has a survival value. Evidence suggests that extracellular HSP70 is involved in the activation of the innate and adaptive immune response. Furthermore, increased mRNA expression of HSP70 has been observed in human fetal membranes following endotoxin stimulation. This study was conducted to determine the changes in amniotic fluid HSP70 concentrations during pregnancy, term and preterm parturition, intra-amniotic infection (IAI), and histologic chorioamnionitis.Study design. A cross-sectional study was conducted in 376 pregnant women in the following groups: (1) women with a normal pregnancy who were classified into the following categories: (a) women in the mid-trimester (14–18 weeks) who underwent amniocentesis for genetic indications and delivered normal infants at term (n=72); (b) women at term not in labor (n = 23); and (c) those at term in labor (n = 48). (2) Women with spontaneous preterm labor and intact membranes who were subdivided into the following categories: (a) preterm labor who delivered at term without IAI (n = 42); (b) preterm labor who delivered preterm without IAI (n = 57); and (c) preterm labor and delivery with IAI (n = 30). (3) Women with preterm prelabor rupture of membranes (PROM) with (n = 50) and without (n = 54) IAI. Among patients with preterm labor with intact membranes and preterm PROM who delivered within 72 hours of amniocentesis, placenta, umbilical cord, and chorioamniotic membranes were collected and assessed for the presence or absence of acute inflammatory lesions in the extraplacental membranes (histologic chorioamnionitis) and/or umbilical cords (funisitis). HSP70 concentrations in amniotic fluid were determined using a sensitive and specific immunoassay. Non-parametric statistics were used for analysis. A p value of <0.05 was considered statistically significant.Results. Immunoreactive HSP70 was detected in 88% (332/376) of amniotic fluid samples. The median amniotic fluid HSP70 concentration was significantly higher in women at term without labor than in those in the mid-trimester (term no labor: median 34.9 ng/mL, range 0–78.1 ng/mL vs. mid-trimester; median 6.6 ng/mL, range 0–20.8 ng/mL; p<0.001). Among patients with spontaneous preterm labor and preterm PROM, those with IAI had a significantly higher median amniotic fluid HSP70 concentration than those without IAI (preterm labor with IAI: median 82.9 ng/mL, range 0–500 ng/mL vs. preterm labor without IAI: median 41.7 ng/mL, range 0–244 ng/mL; p = 0.001; preterm PROM with IAI: median 86.5 ng/mL, range 0–428 ng/mL vs. preterm PROM without IAI: median 55.9 ng/mL, range 14.9–299.9 ng/mL; p = 0.007). There was no significant difference in the median amniotic fluid HSP70 concentration between patients with preterm labor who delivered preterm without IAI and those who delivered at term (p = 0.6). However, among patients with preterm labor without IAI, there was an inverse relationship between amniotic fluid concentration of HSP70 and the amniocentesis-to-spontaneous delivery interval (Spearman's Rho = −0.26; p = 0.02). Patients with histologic chorioamnionitis/funisitis had a significantly higher median amniotic fluid HSP70 concentration than those without inflammation (inflammation: median 108.7 ng/mL, range 0–500 ng/mL vs. without inflammation: median 67.9 ng/mL, range 7.1–299.9 ng/mL; p = 0.02). Women at term in labor had a median amniotic fluid concentration of HSP70 significantly higher than those not in labor (term in labor: median 60.7 ng/mL, range 0–359.9 ng/mL vs. term not in labor: median 34.9 ng/mL, range 0–78.1 ng/mL; p = 0.02).Conclusions. Intra-amniotic infection, histologic chorioamnionitis, and term parturition are associated with elevated amniotic fluid HSP70 concentrations. HSP70 plays a role in the host defense mechanism by activating the innate arm of the immune response in women with intrauterine infection. The mechanisms of preterm and term parturition in humans may involve extracellular HSP70.

The intensity of the fetal inflammatory response in intraamniotic inflammation with and without microbial invasion of the amniotic cavity

Intraamniotic inflammation is a risk factor for adverse pregnancy and neonatal outcome, regardless of the presence or absence of a positive amniotic fluid (AF) culture. The purpose of this study was to determine whether the intensity of a fetal inflammatory response (FIR) differs between cases of intraamniotic inflammation with microbiologically proven infection and cases with negative AF cultures. The FIR was examined in 89 cases of women with preterm premature rupture of membranes who delivered singleton preterm newborn infants within 48 hours of amniocentesis. AF was cultured for aerobic and anaerobic bacteria and for genital mycoplasmas. AF white blood cell (WBC) count and matrix metalloproteinase-8 (MMP-8) determinations were performed to assess the presence of intraamniotic inflammation. Intraamniotic inflammation was defined as an elevated AF MMP-8 concentration (>23 ng/mL). The intensity of the FIR was determined by the umbilical cord plasma concentrations of C-reactive protein (CRP). Patients were divided into 3 groups according to the presence or absence of intraamniotic inflammation and AF culture results: group 1, without intraamniotic inflammation and with a negative AF culture (n = 28); group 2, with intraamniotic inflammation and with a negative AF culture (n = 26); group 3, with a positive AF culture (n = 35). Neonates who were born to mothers with intraamniotic inflammation and negative AF cultures had a significantly higher median umbilical cord plasma CRP concentration than did those without intraamniotic inflammation and a negative AF culture (P < .005) but a significantly lower median cord plasma CRP concentration than did those with proven AF infection (P < .05). Patients with intraamniotic inflammation and a negative AF culture had significantly higher median AF MMP-8 concentrations and WBC count than did those without intraamniotic inflammation and a negative AF culture (P < .001). However, there was no significant difference in the median AF MMP-8 and WBC count between patients with intraamniotic inflammation and a negative AF culture and those with proven AF infection (MMP-8, P > .1, and WBC, P = .09). Intraamniotic inflammation without documented AF infection is a risk factor for a systemic FIR. However, the magnitude of the FIR in those cases was lower than in those with documented AF infection.

Funisitis in term pregnancy is associated with microbial invasion of the amniotic cavity and intra-amniotic inflammation

Objective. Funisitis is the histologic counterpart of the fetal inflammatory response syndrome, which is a multisystemic disorder associated with impending preterm delivery and adverse neonatal outcome. The purpose of this study was to examine the relationship between funisitis and the microbiologic status of amniotic fluid (AF) and AF white blood cell (WBC) count in patients at term.Methods. The relationship between the presence of funisitis, AF culture, and AF WBC count was examined in 832 consecutive patients who delivered a term neonate within 72 hours of amniocentesis. AF was cultured for aerobic and anaerobic bacteria, as well as for mycoplasmas. Funisitis was diagnosed in the presence of neutrophil infiltration into the umbilical vessel walls or Wharton's jelly. AF WBC count was analyzed in a hemocytometer chamber. Nonparametric statistics were used for data analysis.Results. Funisitis was present in 4% (30/832) of cases. A positive AF culture was more common in cases with funisitis than in those without funisitis (17% vs. 5%; p < 0.05). Patients with funisitis had a significantly higher median AF WBC count than those without funisitis (median >1000 cells/mm3 vs. median 2 cells/mm3; p < 0.001). The frequency of funisitis and of a positive AF culture was 1% in women without labor and with intact membranes and the frequencies and the median AF WBC count increased in the presence of labor or rupture of membranes.Conclusion. Funisitis is present in 4% of women at term and is associated with microbial invasion of the amniotic cavity (MIAC) and inflammation as reflected by increased AF WBC count.

The relationship between amniotic fluid white blood cell count and funisitis at term

FUNISITIS AT TERM SI EUN LEE, ROBERTO ROMERO, SOON-SUP SHIM, KYUNG CHUL MOON, CHONG JAI KIM, BO HYUN YOON, Seoul National University College of Medicine, Department of Obstetrics and Gynecology, Seoul, South Korea, Wayne State University, Detroit, Michigan, Seoul National University College of Medicine, Department of Pathology, Seoul, South Korea OBJECTIVE: Funisitis is the histologic counterpart of the fetal inflammatory response syndrome, which is a multisystem disorder associated with impending preterm delivery and adverse shortand long-term neonatal outcome (i.e., cerebral palsy). However, this association was described in preterm gestation and there are questions whether this applies to term gestation, particularly in medico-legal cases of cerebral palsy at term. The objective of this study was to determine if there is a relationship between AF white blood cell (WBC) count and funisitis in term pregnancies. STUDY DESIGN: This study included 832 patients who delivered term singleton neonates within 72 hours of amniocentesis. AF was cultured for aerobic and anaerobic bacteria, as well as for mycoplasmas. Funisitis was diagnosed in the presence of neutrophil infiltration into the umbilical vessel walls or Wharton’s jelly. AF WBC count was determined with a hemocytometer chamber. RESULTS: 1) Funisitis was present in 3.6% (30/832) of patients; 2) A positive AF culture was more common in cases with funisitis than in those without funisitis (17% vs 5%; p!0.05); 3) Patients with funisitis had a higher median AF WBC count than those without funisitis (median, O1000 cells/mm; range, 0O1000 cells/mm; vs median, 2 cells/mm; range, 0-O1000 cells/mm; p!0.001); 4) The diagnostic indices of AF WBC (cutoff, 18 cells/mm) in the identification of funisitis were: a sensitivity of 70%, a specificity of 81%, a positive predictive value of 12%, and a negative predictive value of 99%. CONCLUSION: 1) An elevated AF WBC count is associated with funisitis in term gestations; 2) Funisitis is associated with AF infection. We propose that the diagnosis of funisitis in the placenta is evidence of prior exposure of the fetus to an inflammatory stimulus and can have medico-legal value in the defense of cases of cerebral palsy at term.

The relationship between amniotic fluid matrix metalloproteinase-8 and funisitis

Objective: The fetal inflammatory response syndrome is a multisystem disorder associated with impending preterm delivery and adverse neonatal outcome. Inflammation of the umbilical cord—funisitis— is the histologic counterpart of fetal inflammatory response syndrome and has been associated with an increased risk for the development of cerebral palsy. Neutrophils found in the amniotic cavity are of fetal origin. Therefore, neutrophil secretory products may be an index of the fetal inflammatory response syndrome. To test this hypothesis, we examined the relationship between levels of amniotic fluid matrix metalloproteinase-8 and funisitis. Study Design: The relationship between the presence of funisitis and concentrations of amniotic fluid matrix metalloproteinase-8 was examined in 255 consecutive patients who delivered preterm singleton neonates (gestational age, <36 weeks) within 72 hours of amniocentesis. Amniotic fluid was cultured for aerobic and anaerobic bacteria and for mycoplasmas. Funisitis was diagnosed in the presence of neutrophil infiltration into the umbilical vessel walls or Wharton jelly. Matrix metalloproteinase-8 was measured by use of a specific immunoassay. Nonparametric statistics were used for analysis. Results: Funisitis was present in 23% (59/255) of cases. Patients with funisitis had a significantly higher median concentration of amniotic fluid matrix metalloproteinase-8 than those without funisitis (median, 433.7 ng/mL [range, 1.5-3836.8 ng/mL] vs median, 1.9 ng/mL [range, <0.3-4202.7 ng/mL]; P <.001). The diagnostic indices of matrix metalloproteinase-8 (cutoff, 23 ng/mL) in the identification of funisitis were: sensitivity of 90% (53/59), specificity of 78% (153/196), positive predictive value of 55% (53/96), and negative predictive value of 96% (153/159). Conclusions: There is a strong association between increased levels of amniotic fluid matrix metalloproteinase-8 and funisitis. We propose that determination of amniotic fluid matrix metalloproteinase-8 concentrations may assist the assessment of the fetal inflammatory status, thereby eliminating the need for fetal blood sampling. (Am J Obstet Gynecol 2001;185:1156-61.)

Amniotic fluid matrix metalloproteinase-9 levels in women with preterm labor and suspected intra-amniotic infection

Objective: To determine the accuracy of amniotic fluid (AF) matrix metalloproteinase-9 measurements for diagnosing intra-amniotic infection in women with preterm labor. Methods: We performed amniocenteses in 44 women between 22 and 35 weeks’ gestation who presented to our center with preterm labor and clinical suspicion of intra-amniotic infection. Each sample was analyzed by glucose measurement, Gram stain, and culture for aerobes, anaerobes, and mycoplasmas. We tested the AF for matrix metalloproteinase-9 using gelatin zymography and a commercial enzyme-linked immunosorbent assay (ELISA) system. We calculated accuracy and confidence intervals (CIs) for AF matrix metalloproteinase-9, glucose, and Gram stain for diagnosing intra-amniotic infection, using culture as the criterion standard. Results: All patients who had matrix metalloproteinase-9 detectable by ELISA also demonstrated matrix metalloproteinase-9 by zymography. Six cases of intra-amniotic infection were confirmed by culture (prevalence 14%). The performance statistics of AF matrix metalloproteinase-9 for diagnosing intra-amniotic infection were: sensitivity 83% (95% CI 53, 99), specificity 95% (95% CI 88, 99), positive predictive value 71% (95% CI 37, 99), and negative predictive value 97% (95% CI 92, 99). Two women had false-positive results; one had gram-negative rods on the AF Gram stain and developed clinical signs and symptoms of chorioamnionitis several hours after amniocentesis and the other had a purulent vaginal discharge and an AF glucose level less than 15 mg/dL. Both delivered within 24 hours of amniocentesis. Conclusion: Measuring matrix metalloproteinase-9 in the AF appeared to be reliable for diagnosing intra-amniotic infection. An elevated matrix metalloproteinase-9 concentration in the AF at a preterm gestational age may portend imminent delivery regardless of microbiologic confirmation of intra-amniotic infection.

Is fluorescence polarization reliable and cost efficient in a fetal lung maturity cascade?

OBJECTIVE: The objective of the study was to compare the accuracy of the TDxFLM test (Abbott Laboratories) with the fetal lung maturity cascade (shake, foam stability index, lecithin/sphingomyelin tests) and to determine whether the TDxFLM test could increase the efficiency and reduce the cost without decreasing the reliability of a cascade. STUDY DESIGN: A prospective, single-blinded study was conducted. Uncontaminated amniotic fluid obtained by transabdominal amniocentesis for fetal lung maturity assessment was evaluated with use of the fetal lung maturity cascade and the TDxFLM test. At study completion the results of the TDxFLM test were compared with those of the maturity cascade with regard to hyaline membrane disease, which was defined by strict clinical and radiographic parameters. A power analysis was performed requiring a sample size of 100 infants delivered within 72 hours of amniocentesis with use of the 95% confidence interval. RESULTS: A total of 115 cases had a full maturity cascade performed, of which 40 (35%) had a positive shake or foam stability index and 75 cases required progression to a lecithin/sphingomyelin ratio because of negative results. The TDxFLM test result was ≥70 mg/gm in 42 (37%) of these 115. One hundred eight newborns were delivered within 72 hours of the amniocentesis; 65% (71) of these were between 30 and 37 weeks of estimated gestational age. There were 7 cases of hyaline membrane disease in the 108 newborns. Of these 108, 87 had a mature original cascade versus 85 mature tests with use of a proposed TDxFLM test–lecithin/sphingomyelin ratio cascade with one case of respiratory distress syndrome and hyaline membrane disease. The sensitivity, specificity, and positive and negative predictive values for the original cascade were 86%, 84%, 27%, and 99%, respectively; for the proposed TDxFLM test–lecithin/sphingomyelin ratio cascade the values were 86%, 83%, 26%, and 99%, respectively. The TDxFLM test–lecithin/sphingomyelin ratio cascade would have resulted in a cost reduction of 24% with no significant delay in turnaround time. CONCLUSION: The TDxFLM test appears to be a reliable and accurate assessment of fetal lung maturity. Furthermore, by replacing the shake and foam stability index portion of the cascade with the TDxFLM test, a cost savings of 24% would occur without a decrease in safety. These results also reveal that it could enhance patient care and be cost efficient for institutions not currently doing fetal pulmonary maturity testing to undertake use of the TDxFLM test and to only send out specimens for a lecithin/sphingomyelin ratio that have an initial immature TDxFLM test result (<70 mg/gm). Likewise, institutions currently only performing a lecithin/sphingomyelin ratio may consider a TDxFLM test–lecithin sphingomyelin ratio cascade. Although direct costs would increase, they would be counterbalanced by a significant reduction in laboratory technician time. (Am J Obstet Gynecol 1997;177:835-41.)

Infection and labor: VI. Prevalence, microbiology, and clinical significance of intraamniotic infection in twin gestations with preterm labor

The purpose of this study was to establish the prevalence, microbiology, arid outcome of microbial invasion of the amniotic cavity in twin gestation presenting with preterm labor and intact membranes. Amniocenteses were performed on both sacs of 46 women with twin gestations, preterm labor, and intact membranes. Indigo carmine was injected to ensure sampling of both amniotic sacs. Amniotic fluid was cultured for aerobic and anaerobic bacteria, Mycoplasma hominis, and Ureaplasma urealyticum. A positive amniotic fluid culture of at least one sac was noted in 10.8% (5/46) of patients admitted in preterm labor and in 11.9% (5/42) of women delivered of preterm neonates. Of the five patients with microbial invasion of the amniotic cavity, three had microorganisms isolated from both sacs. The presenting sac was involved in all cases, supporting an ascending route for microbial invasion of the amniotic cavity in twin gestation. Polymicrobial infection was found in three of the eight amniotic sacs with positive cultures. In two cases different organisms were isolated from each sac. All patients with positive amniotic fluid cultures were delivered of preterm infants within 48 hours of amniocentesis. Patients with positive amniotic fluid cultures presented with preterm labor at an earlier gestational age and with more advanced cervical dilatation than did women with negative amniotic fluid cultures. Clinical evidence of chorioamnionitis subsequently developed in two of five women with positive amniotic fluid cultures. The interval between amniocentesis and delivery was shorter in women with positive amniotic fluid cultures than in women with negative amniotic fluid cultures (median: 3.5 vs 168 hours, p < 0.0001). Infants born to women with microbial invasion of the amniotic cavity had a lower median birth weight and a higher incidence of respiratory distress syndrome than those born to women with negative amniotic fluid cultures (birth weight: 1085 vs 1975 gm, p = 0.024; respiratory distress syndrome: 37.5% vs 8.3%, p = 0.04).

Laboratory and clinical evaluation of a rapid slide agglutination test for phosphatidylglycerol

Amniostat-FLM is a recently developed rapid slide agglutination test for amniotic fluid phosphatidylglycerol. We compared phosphatidylglycerol quantitated by two-dimensional thin-layer chromatography with phosphatidylglycerol determined by Amniostat-FLM in 180 amniotic fluid samples. If any level of phosphatidylglycerol by thin-layer chromatography, including a trace, was considered positive, then phosphatidylglycerol by thin-layer chromatography and Amniostat-FLM were concordant in 171 of 180 samples (95%). Both were positive in 123 and both negative in 48 samples. The nine amniotic fluid samples with discrepant results were as follows: Five negative Amniostat-FLM results were associated with trace phosphatidylglycerol by thin-layer chromatography (1% to 2% of total phospholipids), one negative Amniostat-FLM result was associated with 3% phosphatidylglycerol by thin-layer chromatography, and three positive Amniostat-FLM results were associated with negative phosphatidylglycerol by thin-layer chromatography results. There were 14 samples with trace phosphatidylglycerol by thin-layer chromatography; of these, there were nine positive and five negative Amniostat-FLM results. If >2% phosphatidylglycerol by thin-layer chromatography was considered positive, concordance between the two tests was 93% (167 of 180). From these samples, 119 infants were delivered within 72 hours of amniocentesis. There were 100 positive Amniostat-FLM results and all were associated with the absence of respiratory distress syndrome; of the 19 negative Amniostat-FLM results, five were associated with infants who developed respiratory distress syndrome. The present study confirms that Amniostat-FLM is a sample, rapid, and accurate test for determining the presence of phosphatidylglycerol in amniotic fluid.

Amniotic fluid absorbance at 650 nm: Its relationship to the lecithin/sphingomyelin ratio and neonatal pulmonary sufficiency

In the present study, we sought to assess the clinical efficacy of the optical density of amniotic fluid at 650 nm (A650) to predict lung maturity in the human fetus. The A650 of 113 samples of amniotic fluid obtained from 16 to 45 weeks' gestation was determined. Mature values (A650 ≥ 0.11) were not observed until 35 weeks' gestation but were always present after 39 weeks' gestation. In those infants delivered within 48 hours of amniocentesis, the absence rates of respiratory distress syndrome were the same with a mature lecithin/sphingomyelin (L/S) ratio (97.9%) and a mature A650 (97.3%). However, immature values in both tests were poor prognosticators of respiratory distress syndrome, with a rate of 37.5% with the immature L/S ratio and 15.8% with the immature A650. A mature A650 may be substituted for the L/S ratio, but an immature A650 is less reliable. In addition, we found that differences in centrifugation altered the A650 value, whereas exposure to light and cold storage did not.

A new rapid slide agglutination test for amniotic fluid phosphatidylglycerol: Laboratory and clinical correlation

A new rapid slide agglutination test (Amniostat-FLM/AFLM) for amniotic fluid phosphatidylglycerol has been developed. One hundred ninety-three samples of amniotic fluid were tested for lecithin/sphingomyelin (L/S) ratio and phosphatidylglycerol by thin-layer chromatography and fluorescence polarization and compared with the AFLM. All four tests agreed in 123/193 cases. Phosphatidylglycerol and AFLM were concordant in 176/193 cases. From these samples, data were available on 105 neonates, of whom 74 were delivered within 72 hours of amniocentesis. All positive AFLM tests were associated with absence of hyaline membrane disease, of 22 negative tests, eight babies had hyaline membrane disease. Thus, preliminarily, it appears that this is a useful, rapid test for assessing fetal lung maturity, which like other tests is reliable when indicating maturity but has a high incidence of falsely immature results.

Antenatal Diagnosis of Defects of Ureagenesis

The approach usually taken to the intrauterine diagnosis of inborn errors of metabolism is to assay a particular enzyme in cultured amniotic cells, the rationale being that if the enzyme is normally present, its absence can be used to indicate fetal disease. Of the five inborn errors of ureagenesis, however, only two, ie citrullinemia and argininosuccinic aciduria, can be diagnosed in this manner because argininosuccinic acid synthetase and argininosuccinic acid lyase are the only urea cycle enzymes normally found in these cells. Both of these disorders have now been detected in utero,87,88 (S. D. Cederbaum and C. R. Scott, unpublished observations, 1980), and several other fetuses at risk have been correctly diagnosed as unaffected88-90 (S. I. Goodman, unpublished observations, 1980). Enzyme deficiency in cultured amniotic cells can be demonstrated directly21,22,91 or by examining the incorporation of 14C into arginine or cell protein.21,73,88,89,92 Further, fetuses with argininosuccinic aciduria have shown increased concentrations of argininosuccinic acid in amniotic fluid at amniocentesis87,88 (S. D. Cederbaum, unpublished observations, 1980) and delivery,93 with its amount remaining undetected when the fetus was not affected88 (S. I. Goodman, unpublished observations, 1980). Argininosuccinic acid is accumulated by the affected fetus, eg it is the most prominent free amino acid in its liver87,94 and, as it is poorly reabsorbed from the glomerular filtrate by cells of the proximal tubule,71 it probably enters the amniotic fluid in fetal urine.95 Thus, provided that a fetus has an intact urinary tract, whether or not it has argininosuccinic aciduria can probably be established within hours of amniocentesis merely by examining the fluid for the acid and/or its anhydrides by ion-exchange chromatography.

Amniotic fluid infection as determined by transabdominal amniocentesis in patients with intact membranes in premature labor

The rate of microbial infection of amniotic fluid among patients in premature labor with intact membranes and the effect of this condition on perinatal morbidity and mortality are not known. To study this question, specimens of amniotic fluid were collected by transabdominal amniocentesis from 31 patients in premature labor with intact membranes. Microorganisms were isolated from 25% (8/31) of the specimens; 87% (7/8) of these mothers underwent delivery within 48 hours of amniocentesis, and 75% (6/8) of positive cultures were from mothers who never febrile. Perinatal morbidity was significantly greater among mothers with positive amniotic fluid cultures, as evidenced by earlier gestational age at delivery (31 vs. 36 weeks), lower newborn weight (1,704 vs. 2,613 grams), and longer hospitalization (39 vs. 9 days). A few simple, commonly available laboratory tests (amniotic fluid Gram stain, lactic dehydrogenase levels, and white blood cell count) appear to be useful in making a rapid diagnosis. The data suggest that the presence of microorganisms in the amniotic fluid of afebrile patients in premature labor with intact membranes represents an infectious process rather than an innocuous condition and raises questions with regard to current obstetric trends in the management of premature labor. The routine evaluation of similar patients by transabdominal amniocentesis is not recommended unless prospective studies can demonstrate a decrease in perinatal morbidity and mortality with this approach.

FETAL SERUM LYSOSOMAL ENZYMES

The difficulties and hazards of prolonged tissue culture (3-6 wks.) needed to establish the prenatal diagnoses of the hereditary biochemical disorders of metabolism are well recognized. Direct fetal blood sampling for study of lysosomal enzymes should allow the prenatal diagnosis of many ‘storage’ disorders within 24 hours of amniocentesis. The normal range of specific activity (SA) for these enzymes in fetal serum need be established. The minimum volume of fetal serum required for, assay was 2.5-100 μl. Assays using 4-methylumbilliferyl glycosides as substrates, for hexosaminidase, glucuronidase, arylsulfatase, and mannosidase, were performed on 5 fetal sera (12-20 wks. gestation), 3 second trimester pregnancy sera, and 4 healthy adult sera. The total fetal serum protein (mean 40.7 mg/ml) was less than half the level of normal adult serum (91.0 mg/ml) and lower than mid-trimester pregnancy serum (74.7 mg/ml). The SA's of hexosaminidase in fetal serum (mean 38.4) was more than 3 times the adult control SA (11.4) and significantly more than the pregnancy sera (23.5). similar observations of increased SA for mannosidase were made in fetal serum. The SA of arylsulfatase was similar in fetal and pregnancy serum which were each almost 4 times the SA of normal adult serum. No difference was observed in the SA of glucuronidase in the 3 groups studied.