A comparison of rapid amniotic fluid markers in the prediction of microbial invasion of the uterine cavity and preterm delivery

The adenosine deaminase family acting on RNA 1 can be a useful diagnostic biomarker in chorioamnionitis

INTRODUCTION

Chorioamnionitis (CAM) involves infection and inflammation of the chorion and amniotic membrane, but there are still no effective diagnostic biomarkers for CAM.

METHODS

We investigated the correlation between RNA editing enzyme Adenosine deaminase family acting on RNA 1 (ADAR1) and CAM in chorion and amniotic membrane specimens derived from premature rupture of the membrane (PROM), CAM (pathologically diagnosed), and clinical CAM (clinically diagnosed) patients using reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

ADAR1 was upregulated in the chorion and amniotic membrane specimens of CAM and clinical CAM patients (p < 0.001 and p = 0.005). ADAR1 had a significantly higher area under the curve (AUC) (0.735 and 0.828) than markers of inflammation characteristics in diagnosing CAM and clinical CAM patients. ADAR1 also had significantly higher AUC (0.701 and 0.837) than clinical characteristics for CAM and clinical CAM patients.

DISCUSSION

ADAR1 can be a useful diagnostic biomarker in CAM patients.

Amniotic fluid interleukin-6 and neutrophil gelatinase-associated lipocalin for predicting fetal inflammatory response syndrome based on histological chorioamnionitis and funisitis

OBJECTIVE

We aimed to analyze the predictive efficacy of amniotic fluid interleukin-6 (IL-6) and neutrophil gelatinase-associated lipocalin (NGAL) for fetal inflammatory response syndrome (FIRS)-related infection.

MATERIALS AND METHODS

We included singleton pregnancies classified into FIRS and non-FIRS groups. FIRS was defined as histologic chorioamnionitis and funisitis. Amniotic fluid samples were collected during vaginal delivery (VD) or cesarean section (CS). We compared amniotic fluid IL-6 and NGAL levels between the groups.

RESULTS

Forty-six pregnancies were analyzed and classified into 20 (43.5%) FIRS and 26 (56.5%) non-FIRS pregnancies. We observed significant differences in amniotic fluid IL-6 and NGAL. Amniotic fluid collection significantly influenced NGAL levels (p < 0.001). The area under the concentration-time curve (AUC), with optimal cutoff values, for amniotic fluid IL-6 and NGAL (VD and CS) levels was 0.948 (11,344 pg/mL), 0.800 (1180 ng/mL), and 0.946 (708 ng/mL), respectively.

CONCLUSION

Amniotic fluid IL-6 and NGAL levels showed equivalent predictive ability for FIRS-related infection.

Antenatal N-acetylcysteine to improve outcomes of premature infants with intra-amniotic infection and inflammation (Triple I): randomized clinical trial

BACKGROUND

Intrauterine infection and/or inflammation (Triple I) is an important cause of preterm birth (PTB) and adverse newborn outcomes. N-acetylcysteine (NAC) is a Food and Drug Administration (FDA)-approved drug safely administered to pregnant women with acetaminophen toxicity.

METHODS

We conducted a single-center, quadruple-blind, placebo-controlled trial of pregnant women with impending PTB due to confirmed Triple I. Participants (n = 67) were randomized to an intravenous infusion of NAC or placebo mimicking the FDA-approved regimen. Outcomes included clinical measures and mechanistic biomarkers.

RESULTS

Newborns exposed to NAC (n = 33) had significantly improved status at birth and required less intensive resuscitation compared to placebo (n = 34). Fewer NAC-exposed newborns developed two or more prematurity-related severe morbidities [NAC: 21% vs. placebo: 47%, relative risk, 0.45; 95% confidence interval (CI) 0.21-0.95] with the strongest protection afforded against bronchopulmonary dysplasia (BPD, NAC: 3% vs. placebo: 32%, relative risk, 0.10; 95% CI: 0.01-0.73). These effects were independent of gestational age, birth weight, sex, or race. Umbilical cord plasma NAC concentration correlated directly with cysteine, but not with plasma or whole blood glutathione. NAC reduced the placental expression of histone deacetylase-2, suggesting that epigenetic mechanisms may be involved.

CONCLUSIONS

These data provide support for larger studies of intrapartum NAC to reduce prematurity-related morbidity.

IMPACT

In this randomized clinical trial of 65 women and their infants, maternal intravenous NAC employing the FDA-approved dosing protocol resulted in lower composite neonatal morbidity independent of gestational age, race, sex, and birthweight. Administration of NAC in amniocentesis-confirmed Triple I resulted in a remarkably lower incidence of BPD. As prior studies have not shown a benefit of postnatal NAC in ventilated infants, our trial highlights the critical antenatal timing of NAC administration. Repurposing of NAC for intrapartum administration should be explored in larger clinical trials as a strategy to improve prematurity-related outcomes and decrease the incidence of BPD.

Development and validation of a multivariable prediction model of spontaneous preterm delivery and microbial invasion of the amniotic cavity in women with preterm labor

BACKGROUND

Early spontaneous preterm delivery is often associated with microbial invasion of the amniotic cavity and/or intraamniotic inflammation.

OBJECTIVE

The objective of the study was to develop and validate clinically feasible multivariable prediction models of spontaneous delivery within 7 days and microbial invasion of the amniotic cavity in women admitted with diagnose of preterm labor and intact membranes below 34 weeks.

STUDY DESIGN

We used data from a cohort of women admitted from 2012 to 2018 with diagnosis of preterm labor below 34 weeks who had undergone amniocentesis to rule out microbial invasion of the amniotic cavity. The main outcome was spontaneous delivery within 7 days from admission. The secondary outcome was microbial invasion of the amniotic cavity, defined by a positive culture and/or 16S ribosomal RNA gene in the amniotic fluid. The sample (n = 358) was divided into derivation (2012-2016) and validation cohorts (2017-2018). Logistic regression models using a stepwise selection of variables were developed for the outcomes evaluated. We explored as predictive variables ultrasound cervical length measurement at admission, maternal C-reactive protein, gestational age, amniotic fluid glucose, and interleukin-6 (expressed as log units). Models were developed in the derivation cohort and applied to the validation cohort and diagnostic performance was calculated.

RESULTS

The derivation cohort included 263 women and the validation cohort 95 women. One hundred five of the women (39%, 105 of 268) spontaneously delivered in the following 7 days and 68 (19%, 68 of 358) had microbial invasion of the amniotic cavity. For spontaneous delivery within 7 days after admission, 4 predictors were identified: cervical length at admission, gestational age, amniotic fluid glucose, and interleukin-6. The diagnostic performance of the model was assessed in the validation cohort using the receiver operating characteristic curve and showed an area under curve of 0.86 (95% confidence interval, 0.77-0.95) with a detection rate of spontaneous delivery within 7 days of 87%, a false-positive rate of 33%, a negative predictive value of 80%, and a negative likelihood ratio of 0.1908. For microbial invasion of the amniotic cavity, 2 independent predictors of the amniotic cavity were identified: amniotic fluid glucose and maternal C-reactive protein. The receiver operating characteristic curve and an area under curve in the validation cohort was 0.83 (95% confidence interval, 0.70-0.96) with a detection rate of 76%, a false-positive rate of 8%, a negative predictive value of 93%, and a negative likelihood ratio of 0.2591.

CONCLUSION

In women with preterm labor, we propose 2 clinically feasible prediction models to classify as low vs high risk of spontaneous delivery within 7 days and of microbial invasion of the amniotic cavity. The models showed a high diagnostic performance and could be of value to optimize clinical management.

Evidence that antibiotic administration is effective in the treatment of a subset of patients with intra-amniotic infection/inflammation presenting with cervical insufficiency

BACKGROUND

Cervical insufficiency is a risk factor for spontaneous midtrimester abortion or early preterm birth. Intra-amniotic infection has been reported in 8-52% of such patients and intra-amniotic inflammation in 81%. Some professional organizations have recommended perioperative antibiotic treatment when emergency cervical cerclage is performed. The use of prophylactic antibiotics is predicated largely on the basis that they reduce the rate of complications during the course of vaginal surgery. However, it is possible that antibiotic administration can also eradicate intra-amniotic infection/inflammation and improve pregnancy outcome.

OBJECTIVE

To describe the outcome of antibiotic treatment in patients with cervical insufficiency and intra-amniotic infection/inflammation.

STUDY DESIGN

The study population consisted of 22 women who met the following criteria: (1) singleton pregnancy; (2) painless cervical dilatation of >1 cm between 16.0 and 27.9 weeks of gestation; (3) intact membranes and absence of uterine contractions; (4) transabdominal amniocentesis performed for the evaluation of the microbiologic and inflammatory status of the amniotic cavity; (5) presence of intra-amniotic infection/inflammation; and (6) antibiotic treatment (regimen consisted of ceftriaxone, clarithromycin, and metronidazole). Amniotic fluid was cultured for aerobic and anaerobic bacteria and genital mycoplasmas, and polymerase chain reaction for Ureaplasma spp. was performed. Intra-amniotic infection was defined as a positive amniotic fluid culture for microorganisms or a positive polymerase chain reaction for Ureaplasma spp., and intra-amniotic inflammation was suspected when there was an elevated amniotic fluid white blood cell count (≥19 cells/mm³) or a positive rapid test for metalloproteinase-8 (sensitivity 10 ng/mL). For the purpose of this study, the "gold standard" for diagnosis of intra-amniotic inflammation was an elevated interleukin-6 concentration (>2.6 ng/mL) using an enzyme-linked immunosorbent assay. The results of amniotic fluid interleukin-6 were not available to managing clinicians. Follow-up amniocentesis was routinely offered to monitor the microbiologic and inflammatory status of the amniotic cavity and fetal lung maturity. Treatment success was defined as resolution of intra-amniotic infection/inflammation or delivery ≥34 weeks of gestation.

RESULTS

Of 22 patients with cervical insufficiency and intra-amniotic infection/inflammation, 3 (14%) had microorganisms in the amniotic fluid. Of the 22 patients, 6 (27%) delivered within 1 week of amniocentesis and the remaining 16 (73%) delivered more than 1 week after the diagnostic procedure. Among these, 12 had a repeat amniocentesis to assess the microbial and inflammatory status of the amniotic cavity; in 75% (9/12), there was objective evidence of resolution of intra-amniotic inflammation or intra-amniotic infection demonstrated by analysis of amniotic fluid at the time of the repeat amniocentesis. Of the 4 patients who did not have a follow-up amniocentesis, all delivered ≥34 weeks, 2 of them at term; thus, treatment success occurred in 59% (13/22) of cases.

CONCLUSION

In patients with cervical insufficiency and intra-amniotic infection/inflammation, administration of antibiotics (ceftriaxone, clarithromycin, and metronidazole) was followed by resolution of the intra-amniotic inflammatory process or intra-amniotic infection in 75% of patients and was associated with treatment success in about 60% of cases.

The combination of maternal blood and amniotic fluid biomarkers improves the predictive accuracy of histologic chorioamnionitis

INTRODUCTION

This study was performed to determine whether the combination of maternal blood and amniotic fluid biomarkers can improve the predictive accuracy of histologic chorioamnionitis (HC).

METHODS

This retrospective study included 80 singleton pregnant women who were suspected to have intrauterine infection and underwent measurement of two maternal blood biomarkers [maternal white blood cell count (mWBC) and maternal C-reactive protein level (mCRP)] and three amniotic fluid biomarkers [amniotic white blood cell count (aCell), amniotic glucose level (aGlucose), and amniotic lactate dehydrogenase level (aLDH)]. We divided the patients into two groups based on the presence or absence of HC and assessed the predictors of HC using logistic regression models: Model 1, combination of mWBC and mCRP; Model 2, combination of Model 1 and aGlucose; and Model 3, combination of Model 2, aCell, and aLDH.

RESULTS

The multivariable analysis showed that aCell was the only significant predictor of HC [odds ratio, 1.24; 95% confidence interval (CI), 1.06-1.68] independent of mWBC, mCRP, aGlucose, and aLDH. The c-statistics were higher in Model 3 (0.803; 95% CI, 0.701-0.905) than Model 1 (0.634; 95% CI, 0.511-0.758) and Model 2 (0.785; 95% CI, 0.684-0.887).

DISCUSSION

We found that the combination of maternal blood and amniotic fluid biomarkers can improve the predictive accuracy of HC. Therefore, our data provide relevant information to support counseling with regard to improving the predictive accuracy of HC in patients with suspected intrauterine infection.

Hepcidin, an Iron Regulatory Hormone of Innate Immunity, is Differentially Expressed in Premature Fetuses with Early-Onset Neonatal Sepsis

OBJECTIVE

Hepcidin, a mediator of innate immunity, binds the iron exporter ferroportin, leading to functional hypoferremia through intracellular iron sequestration. We explored hepcidin-ferroportin interactions in neonates clinically diagnosed with early-onset neonatal sepsis (EONS).

STUDY DESIGN

Hepcidin and interleukin (IL)-6 were quantified by enzyme-linked immunosorbent assay (ELISA) in 92 paired cord blood-maternal blood samples in the following groups: "Yes" EONS (n = 41, gestational age [GA] 29 ± 1 weeks) and "No" EONS (n = 51, GA 26 ± 1 weeks). Placental hepcidin and ferroportin expression were evaluated by immunohistochemistry and real-time-polymerase chain reaction (RT-PCR). Liver hepcidin and ferroportin expression patterns were ascertained in autopsy specimens of neonates (n = 8) who died secondary to culture-proven sepsis.

RESULTS

Cord blood hepcidin was significantly elevated (GA corrected, p = 0.018) and was positively correlated with IL-6 (r = 0.379, p = 0.001) in EONS. Hepcidin localized at syncytiotrophoblast and fetal vascular endothelium. Placental ferroportin, but not hepcidin mRNA correlated with cord blood hepcidin levels (r = 0.46, p = 0.039) and funisitis severity (r = 0.50, p = 0.018). Newborns who died from sepsis (n = 4) had higher hepatic hepcidin and iron sequestration, but lower ferroportin staining than those who died of nonsepsis causes (n = 4).

CONCLUSION

Premature fetuses with EONS have elevated circulating hepcidin, likely related to lower placenta and liver ferroportin expression. Fetal hepcidin-ferroportin interaction appears to play a role in EONS pathophysiology independent of maternal response to intrauterine inflammation.

Identification of haptoglobin switch-on status in archived placental specimens indicates antenatal exposure to inflammation and potential participation of the fetus in triggering preterm birth

OBJECTIVE

Haptoglobin (Hp) has key immunoregulatory roles that vary with phenotype (Hp1-1, Hp2-1, Hp2-2). Cord blood Hp expression is switched-off in the normal fetus. We hypothesized that in the setting of fetal inflammation placenta becomes inundated with Hp of fetal origin that in turn modulates the output of PGE₂ and MMP-9 in a phenotype dependent manner.

METHODS

Placentas from 40 pregnancies complicated by preterm birth (PTB) (<37 weeks), without (n = 15) or with (n = 25) intra-amniotic infection and histological chorioamnionitis (HCA) were scored for intensity of Hp immunostaining. Hp mRNA levels were evaluated by PCR. Cord blood Hp levels, switch-on status and phenotypes were determined by ELISA and Western blotting. Using a villous trophoblast explant system we investigated if Hp can modulate the release of PGE₂ and MMP-9 in the presence or absence of lipopolysaccharide (LPS).

RESULTS

All cases with HCA had positive Hp immunoreactivity within fetal vascular spaces. Hp staining intensity correlated with cord blood Hp levels and IL-6. Placentas with and without HCA had similar Hp mRNA levels suggesting Hp immunostaining in the fetal spaces is of fetal rather than placental origin. Both Hp1-1 and Hp2-2 up-regulated PGE₂ release in the presence of LPS (2-fold over the LPS level, P < .05), without affecting MMP-9 concentrations.

CONCLUSIONS

Fetal Hp switch-on status, a marker of antenatal exposure to intra-amniotic infection/inflammation, can be reliably established through evaluation of archived placental specimens. In the setting of infection/inflammation, Hp enhances placental PGE₂ output thereby supporting the role of the fetus in triggering parturition.

Amniotic Fluid Infection in Preterm Pregnancies with Intact Membranes

Introduction. Intra-amniotic infection (IAI) is a major cause of preterm labor and adverse neonatal outcome. We evaluated amniotic fluid (AF) proteolytic cascade forming biomarkers in relation to microbial invasion of the amniotic cavity (MIAC) and IAI in preterm pregnancies with intact membranes. Material and Methods. Amniocentesis was made to 73 women with singleton pregnancies; 27 with suspected IAI; and 46 controls. AF biomarkers were divided into three cascades: Cascade 1: matrix metalloproteinase-8 (MMP-8), MMP-9, myeloperoxidase (MPO), and interleukin-6; Cascade 2: neutrophil elastase (HNE), elafin, and MMP-9; Cascade 3: MMP-2, tissue inhibitor of matrix metalloproteinases-1 (TIMP-1), MMP-8/TIMP-1 molar ratio, and C-reactive protein (CRP). MMP-8 was measured by an immunoenzymometric assay and the others were measured by ELISA. Standard biochemical methods, molecular microbiology, and culture techniques were used. Results. MMP-8, MMP-9, MPO, elafin, and TIMP-1 concentrations were higher in IAI suspected cases compared to controls and also in IAI suspected cases with MIAC compared to those without MIAC when adjusted by gestational age at amniocentesis. All biomarkers except elafin and MMP-2 had the sensitivity of 100% with thresholds based on ROC-curve. Odd ratios of biomarkers for MIAC were 1.2-38 and 95% confidential intervals 1.0-353.6. Conclusions. Neutrophil based AF biomarkers were associated with IAI and MIAC.

Comparison of amniotic fluid matrix metalloproteinase-8 and cathelicidin in the diagnosis of intra-amniotic infection

OBJECTIVE

To evaluate the association of amniotic fluid (AF) matrix metalloproteinase-8 (MMP-8) and cathelicidin concentrations with microbial invasion of the amniotic cavity (MIAC) in pregnancies with preterm prelabor rupture of the membranes or intact membranes.

STUDY DESIGN

Amniocentesis was performed in 54 singleton pregnancies between 22⁺⁰ and 34⁺² gestational weeks with suspected intra-amniotic infection. AF-MMP-8 was analysed by immunoassay and AF-cathelicidin by commercial ELISA. Standard biochemical methods, molecular microbiology and culture techniques were used.

RESULTS

MIAC was present in 18 (33%) women. The cutoff value for the diagnosis of MIAC was 41.5 ng ml^-1 for AF-MMP-8, and 11.6 ng ml^-1 for AF-cathelicidin. With these cutoff values AF-MMP-8 had a sensitivity of 100%, specificity of 69%, positive predictive value of 62% and negative predictive value of 100% for MIAC. The corresponding values for AF-cathelicidin were 89, 81, 70 and 94%.

CONCLUSION

The performance of AF-cathelicidin in the prediction of MIAC is comparable to AF-MMP-8.

Amniotic fluid rapid biomarkers are associated with intra-amniotic infection in preterm pregnancies regardless of the membrane status

OBJECTIVE

The objective of this study was to evaluate the association of amniotic fluid lactate dehydrogenase and glucose concentrations with microbial invasion of amniotic cavity and histologic chorioamnionitis before 37 pregnancy weeks in women with or without preterm premature rupture of membranes.

STUDY DESIGN

Amniocentesis was performed on 70 women with suspected intra-amniotic infection. Standard biochemical methods, molecular microbiology and culture techniques were used. Histopathological examination of the placenta was performed.

RESULTS

Thirty (48%) women had microbial invasion of the amniotic cavity (MIAC), 53 (76%) women had histological chorioamnionitis and 28 women had both. The cutoff values for MIAC and histological chorioamnionitis were 429 IU l(-1) for lactate dehydrogenase and 0.7 mmol l(-1) for glucose. Both end points occurred equally often regardless of the membrane status.

CONCLUSION

Increased amniotic fluid lactate dehydrogenase and decreased glucose were associated with MIAC and histological chorioamnionitis. However, test performance was of limited value.

Compartmentalization of acute phase reactants Interleukin-6, C-Reactive Protein and Procalcitonin as biomarkers of intra-amniotic infection and chorioamnionitis

BACKGROUND

The arsenal of maternal and amniotic fluid (AF) immune response to local or systemic infection includes among others the acute-phase reactants IL-6, C-Reactive Protein (CRP) and Procalcitonin (PCT). If these molecules can be used as non-invasive biomarkers of intra-amniotic infection (IAI) in the subclinical phase of the disease remains incompletely known.

METHODS

We used time-matched maternal serum, urine and AF from 100 pregnant women who had an amniocentesis to rule out IAI in the setting of preterm labor, PPROM or systemic inflammatory response (SIR: pyelonephritis, appendicitis, pneumonia) to infection. Cord blood was analyzed in a subgroup of cases. We used sensitive immunoassays to quantify the levels of inflammatory markers in the maternal blood, urine and AF compartment. Microbiological testing and placental pathology was used to establish infection and histological chorioamnionitis.

RESULTS

PCT was not a useful biomarker of IAI in any of the studied compartments. Maternal blood IL-6 and CRP levels were elevated in women with subclinical IAI. Compared to clinically manifest chorioamnionitis group, women with SIR have higher maternal blood IL-6 levels rendering some marginal diagnostic benefit for this condition. Urine was not a useful biological sample for assessment of IAI using either of these three inflammatory biomarkers.

CONCLUSIONS

In women with subclinical IAI, the large overlapping confidence intervals and different cut-offs for the maternal blood levels of IL-6, CRP and PCT likely make interpretation of their absolute values difficult for clinical decision-making.

Sterile intra-amniotic inflammation in asymptomatic patients with a sonographic short cervix: prevalence and clinical significance

OBJECTIVE

To determine the frequency and clinical significance of sterile and microbial-associated intra-amniotic inflammation in asymptomatic patients with a sonographic short cervix.

METHODS

Amniotic fluid (AF) samples obtained by transabdominal amniocentesis from 231 asymptomatic women with a sonographic short cervix [cervical length (CL) ≤25 mm] were analyzed using cultivation techniques (for aerobic and anaerobic as well as genital mycoplasmas) and broad-range polymerase chain reaction (PCR) coupled with electrospray ionization mass spectrometry (PCR/ESI-MS). The frequency and magnitude of intra-amniotic inflammation [defined as an AF interleukin (IL)-6 concentration ≥2.6 ng/mL], acute histologic placental inflammation, spontaneous preterm delivery (sPTD), and the amniocentesis-to-delivery interval were examined according to the results of AF cultures, PCR/ESI-MS and AF IL-6 concentrations.

RESULTS

Ten percent (24/231) of patients with a sonographic short cervix had sterile intra-amniotic inflammation (an elevated AF IL-6 concentration without evidence of microorganisms using cultivation and molecular methods). Sterile intra-amniotic inflammation was significantly more frequent than microbial-associated intra-amniotic inflammation [10.4% (24/231) versus 2.2% (5/231); p < 0.001]. Patients with sterile intra-amniotic inflammation had a significantly higher rate of sPTD <34 weeks of gestation [70.8% (17/24) versus 31.6% (55/174); p < 0.001] and a significantly shorter amniocentesis-to-delivery interval than patients without intra-amniotic inflammation [median 35, (IQR: 10-70) versus median 71, (IQR: 47-98) days, (p < 0.0001)].

CONCLUSION

Sterile intra-amniotic inflammation is more common than microbial-associated intra-amniotic inflammation in asymptomatic women with a sonographic short cervix, and is associated with increased risk of sPTD (<34 weeks). Further investigation is required to determine the causes of sterile intra-amniotic inflammation and the mechanisms whereby this condition is associated with a short cervix and sPTD.

Mid-trimester maternal serum and amniotic fluid biomarkers for the prediction of preterm delivery and intrauterine growth retardation

AIM

Our purpose was to evaluate the predictive value of maternal serum and amniotic fluid biomarkers that were obtained at the time of genetic amniocentesis for preterm delivery and intrauterine growth retardation (IUGR).

METHODS

A prospective cohort analysis was conducted in 107 singleton pregnancies that underwent amniocentesis at 16-22 weeks according to standard genetic indications. Maternal blood and amniotic fluid obtained from genetic amniocentesis were tested for glucose, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), ceruloplasmin, ferritin, high-sensitivity C-reactive protein and interleukin-6 (IL-6). Ninety-four pregnancies were followed until delivery.

RESULTS

Of the 94 patients, 16 (18.1%) delivered before 37 weeks and seven (7.5%) delivered a baby below the 10th percentile for gestational age. Amniotic fluid glucose levels were significantly lower in patients with preterm delivery than term deliveries (P = 0.01). Median amniotic fluid ferritin and IL-6 levels and mean amniotic fluid ALP levels were higher in the preterm group but this difference did not reach statistical significance. Mean maternal ALP and LDH levels tended to be insignificantly higher. Only median maternal blood ferritin levels in the IUGR group were found to be higher than patients who were appropriate for gestational age (P = 0.03).

CONCLUSION

Low amniotic fluid glucose levels are associated with risk of preterm delivery, whereas high maternal blood ferritin levels increase the risk for IUGR. Although this result is significant and notable, there is not enough clinical evidence to recommend their use as a screening test for preterm delivery and IUGR in routine practice.

Amniotic Fluid Soluble Myeloid Differentiation-2 (sMD-2) as Regulator of Intra-amniotic Inflammation in Infection-induced Preterm Birth

PROBLEM

TLR4 mediates host responses to pathogens through a mechanism that involves protein myeloid differentiation-2 (MD-2) and its soluble form sMD-2. The role of sMD2 in intra-amniotic inflammation-induced preterm birth has not been previously explored.

METHOD OF STUDY

Human amniotic fluid (AF) sMD-2 was studied by Western blotting in 152 AF samples of patients who had an amniocentesis to rule-out infection (yes infection, n = 50; no infection, n = 50) or women with normal pregnancy outcome (second trimester genetic karyotyping, n = 26; third trimester lung maturity testing, n = 26). Histological localization and mRNA expression of MD2 in fetal membranes were studied by immunohistochemistry and RT-PCR. The ability of fetal membrane to release sMD-2 and inflammatory cytokines was studied in vitro.

RESULTS

Human AF contains three sMD-2 proteoforms whose levels of expression were lower at term. Intra-amniotic infection upregulated sMD-2. MD-2 mRNA and immunohistochemistry findings concurred. In vitro, LPS and monensin increased, while cycloheximide decreased sMD-2 production. Recombinant sMD-2 modulated TNF-α and IL-6 levels in a dose- and time-dependent fashion.

CONCLUSION

sMD2 proteoforms are constitutively present in human AF. The intensity of the intra-amniotic inflammatory response to bacteria or perhaps to other TLR4 ligands may be facilitated through synthesis and release of sMD2 by the amniochorion.

Interleukin 6 and fetal fibronectin as a predictors of preterm delivery in symptomatic patients

Preterm delivery is the leading cause of neonatal mortality and morbidity. The rate of preterm births has been estimated to be about 15 million, which accounts for 11.1% of all live births worldwide. The purpose of this study was to evaluate the cervico-vaginal (CVF) cytokine IL-6 and fetal fibronectin (fFN) status as predictors of preterm delivery in patients with symptoms of preterm labor. Patients with symptoms suggestive of preterm labor were recruited from September 2013 to March 2014. Vaginal swabs were taken for fetal fibronectin test (fFN) and CVF IL-6. Antibiotics, steroids and tocolytics were administered, where appropriate. The outcome was measured by the occurrence of preterm delivery within 14 days from the day of hospital admission. Cut-off value of 1305 pg/mL for the concentration of IL-6 in the CVF was the best predictor of preterm delivery, with the sensitivity of 69.4% and specificity of 68.2%. Patients with positive fFN test had the OR of 6.429 (95%CI 1.991-20.758) to deliver prematurely. The multivariate analysis of combined fFN and CVF IL-6 tests resulted in risk of 86.7% to deliver prematurely, if both tests were positive. The combination of both tests performed better than the individual tests and decreased the false positive rate, which in turn reduced the chances for inappropriate patient treatment, bringing down the costs.

Prevalence and clinical significance of sterile intra-amniotic inflammation in patients with preterm labor and intact membranes

PROBLEM

Inflammation and infection play a major role in preterm birth. The purpose of this study was to (i) determine the prevalence and clinical significance of sterile intra-amniotic inflammation and (ii) examine the relationship between amniotic fluid (AF) concentrations of high mobility group box-1 (HMGB1) and the interval from amniocentesis to delivery in patients with sterile intra-amniotic inflammation.

METHOD OF STUDY

AF samples obtained from 135 women with preterm labor and intact membranes were analyzed using cultivation techniques as well as broad-range PCR and mass spectrometry (PCR/ESI-MS). Sterile intra-amniotic inflammation was defined when patients with negative AF cultures and without evidence of microbial footprints had intra-amniotic inflammation (AF interleukin-6 ≥ 2.6 ng/mL).

RESULTS

(i) The frequency of sterile intra-amniotic inflammation was significantly greater than that of microbial-associated intra-amniotic inflammation [26% (35/135) versus 11% (15/135); (P = 0.005)], (ii) patients with sterile intra-amniotic inflammation delivered at comparable gestational ages had similar rates of acute placental inflammation and adverse neonatal outcomes as patients with microbial-associated intra-amniotic inflammation, and (iii) patients with sterile intra-amniotic inflammation and high AF concentrations of HMGB1 (≥8.55 ng/mL) delivered earlier than those with low AF concentrations of HMGB1 (P = 0.02).

CONCLUSION

(i) Sterile intra-amniotic inflammation is more frequent than microbial-associated intra-amniotic inflammation, and (ii) we propose that danger signals participate in sterile intra-amniotic inflammation in the setting of preterm labor.

The diagnostic performance of the Mass Restricted (MR) score in the identification of microbial invasion of the amniotic cavity or intra-amniotic inflammation is not superior to amniotic fluid interleukin-6

OBJECTIVE

Intra-amniotic infection/inflammation are major causes of spontaneous preterm labor and delivery. However, diagnosis of intra-amniotic infection is challenging because most are subclinical and amniotic fluid (AF) cultures take several days before results are available. Several tests have been proposed for the rapid diagnosis of microbial invasion of the amniotic cavity (MIAC) or intra-amniotic inflammation. The aim of this study was to examine the diagnostic performance of the AF Mass Restricted (MR) score in comparison with interleukin-6 (IL-6) and matrix metalloproteinase-8 (MMP-8) for the identification of MIAC or inflammation.

METHODS

AF samples were collected from patients with singleton gestations and symptoms of preterm labor (n = 100). Intra-amniotic inflammation was defined as >100 white blood cells/mm(3) (WBCs) in AF; MIAC was defined as a positive AF culture. AF IL-6 and MMP-8 were determined using ELISA. The MR score was obtained using the Surface-Enhanced Laser Desorption Ionization Time of Flight (SELDI-TOF) mass spectrometry. Sensitivity and specificity were calculated and logistic regression models were fit to construct receiver-operating characteristic (ROC) curves for the identification of each outcome. The McNemar's test and paired sample non-parametric statistical techniques were used to test for differences in diagnostic performance metrics.

RESULTS

(1) The prevalence of MIAC and intra-amniotic inflammation was 34% (34/100) and 40% (40/100), respectively; (2) there were no significant differences in sensitivity of the three tests under study (MR score, IL-6 or MMP-8) in the identification of either MIAC or intra-amniotic inflammation (using the following cutoffs: MR score >2, IL-6 >11.4 ng/mL, and MMP-8 >23 ng/mL); (3) there was no significant difference in the sensitivity among the three tests for the same outcomes when the false positive rate was fixed at 15%; (4) the specificity for IL-6 was not significantly different from that of the MR score in identifying either MIAC or intra-amniotic inflammation when using previously reported thresholds; and (5) there were no significant differences in the area under the ROC curve when comparing the MR score, IL-6 or MMP-8 in the identification of these outcomes.

CONCLUSIONS

IL-6 and the MR score have equivalent diagnostic performance in the identification of MIAC or intra-amniotic inflammation. Selection from among these three tests (MR score, IL-6 and MMP-8) for diagnostic purposes should be based on factors such as availability, reproducibility, and cost. The MR score requires a protein chip and a SELDI-TOF instrument which are not widely available or considered "state of the art". In contrast, immunoassays for IL-6 can be performed in the majority of clinical laboratories.

Low accuracy of manual white blood cell count in amniotic fluid

Intra-amniotic infection (IAI) is a common cause of pre-term labour. Manual WBC count on amniotic fluid (AF) has been suggested as a diagnostic test for IAI using a threshold of 50 cells/mm(3). However, no validation studies assessing the accuracy of this method have been performed. AF samples were selected for cell count analysis. WBCs were introduced to 47 AF samples. The results from two technologists' counts were compared with the calculated expected value for WBCs in these samples. Results showed that a comparison between the technologists' WBC count to the expected WBC count yielded R(2) coefficients of 0.62 and 0.78, indicating moderate accuracy. Percentage agreement between the technologists was 67%, indicating low reproducibility. It was concluded that there was moderate correlation between the manual and the expected WBC in the spiked AF samples. Clinicians should be aware of the inaccuracy and imprecision associated with this test when evaluating a patient for IAI.

Comparative microbial analysis of paired amniotic fluid and cord blood from pregnancies complicated by preterm birth and early-onset neonatal sepsis

BACKGROUND

16S rRNA-based genomic analyses have revolutionized our understanding of infectious diseases. Many cases which were recognized as "idiopathic" are now known to have an infectious etiology. Here, we present a proof-of-concept study to examine the microbial link between intra-amniotic infection (IAI) and early-onset neonatal sepsis (EONS).

RESULTS

Using culture independent methods, we analyzed paired amniotic fluid (AF) and cord blood (CB) samples from 36 singleton pregnancies complicated by preterm birth (PTB), IAI, and/or EONS. PTB cases were grouped as 1) Group 1- neonatal blood culture-positive EONS (n=6). 2) Group 2- neonatal blood culture-negative presumed EONS with positive IAI (n=16). 3) Group 3- neonatal blood culture-negative presumed EONS with no IAI (n=7); 4) Group 4- no EONS or IAI (n=7). In addition, samples from term healthy deliveries (n=8) served as technical controls. A total of 31 species (15 non-redundant) were identified in AF, of which only 1/3 were cultivated. Significantly fewer microorganisms were detected in CB, with a total of 18 species (7 non-redundant) identified, of which only 2 (Escherichia coli, Streptococcus agalactiae) were cultivated. Of those, Bergeyella, Fusobacterium nucleatum, and Sneathia sanguinegens had not been detected in EONS before. The novel species identified in AF by PCR include Peptoniphilus harei and Lachnospiraceae sp. The majority (72%) of CB species were also detected in the matching AF, with E. coli and F. nucleatum as the most prevalent. The 16S rRNA sequences of paired AF and CB were 99.9-100% identical, while no identical sequences were found between different pregnancies.

CONCLUSIONS

Previously unrecognized, uncultivated or difficult-to-cultivate species are implicated in EONS. Microbial species in paired AF and CB likely share the same infectious origin. Given its prevalence in EONS, F. nucleatum should be placed on the same importance scale as E. coli.

Advances in medical diagnosis of intra-amniotic infection

INTRODUCTION

Intrauterine infection is a global problem and a significant contributor to morbidity and perinatal death. The host response to infection causes an inflammatory state that acts synergistically with microbial insult to induce preterm birth and fetal damage. Prompt and accurate diagnosis of intra-amniotic infection in the asymptomatic stage of the disease is critical for improved maternal and neonatal outcomes.

AREAS COVERED

This article provides an overview of the most recent progress, challenges, and opportunities for discovery and clinical implementation of various maternal serum, cervicovaginal, and amniotic fluid biomarkers in pregnancies complicated by intra-amniotic infection.

EXPERT OPINION

Clinically relevant biomarkers are critical to the accurate diagnostic of intrauterine infection. Front-end implementation of such biomarkers will also translate in lower incidence of early-onset neonatal sepsis (EONS) which is an important determinant of neonatal morbidity and mortality associated with prematurity. However, of the hundreds of differentially expressed proteins, only few may have clinical utility and thus function as biomarkers. The small number of validation studies along with barriers to implementation of technological innovations in the clinical setting are current limitations.

Proteomics mapping of cord blood identifies haptoglobin "switch-on" pattern as biomarker of early-onset neonatal sepsis in preterm newborns

Background

Intra-amniotic infection and/or inflammation (IAI) are important causes of preterm birth and early-onset neonatal sepsis (EONS). A prompt and accurate diagnosis of EONS is critical for improved neonatal outcomes. We sought to explore the cord blood proteome and identify biomarkers and functional protein networks characterizing EONS in preterm newborns.

Methodology/Principal Findings

We studied a prospective cohort of 180 premature newborns delivered May 2004-September 2009. A proteomics discovery phase employing two-dimensional differential gel electrophoresis (2D-DIGE) and mass spectrometry identified 19 differentially-expressed proteins in cord blood of newborns with culture-confirmed EONS (n = 3) versus GA-matched controls (n = 3). Ontological classifications of the proteins included transfer/carrier, immunity/defense, protease/extracellular matrix. The 1^st-level external validation conducted in the remaining 174 samples confirmed elevated haptoglobin and haptoglobin-related protein immunoreactivity (Hp&HpRP) in newborns with EONS (presumed and culture-confirmed) independent of GA at birth and birthweight (P<0.001). Western blot concurred in determining that EONS babies had conspicuous Hp&HpRP bands in cord blood (“switch-on pattern”) as opposed to non-EONS newborns who had near-absent “switch-off pattern” (P<0.001). Fetal Hp phenotype independently impacted Hp&HpRP. A Bayesian latent-class analysis (LCA) was further used for unbiased classification of all 180 cases based on probability of “antenatal IAI exposure” as latent variable. This was then subjected to 2^nd-level validation against indicators of adverse short-term neonatal outcome. The optimal LCA algorithm combined Hp&HpRP switch pattern (most input), interleukin-6 and neonatal hematological indices yielding two non-overlapping newborn clusters with low (≤20%) versus high (≥70%) probability of IAI exposure. This approach reclassified ∼30% of clinical EONS diagnoses lowering the number needed to harm and increasing the odds ratios for several adverse outcomes including intra-ventricular hemorrhage.

Conclusions/Significance

Antenatal exposure to IAI results in precocious switch-on of Hp&HpRP expression. As EONS biomarker, cord blood Hp&HpRP has potential to improve the selection of newborns for prompt and targeted treatment at birth.

Cord blood erythropoietin and interleukin-6 for prediction of intraventricular hemorrhage in the preterm neonate

OBJECTIVE

To evaluate cord blood erythropoietin (EPO) and interleukin-6 (IL-6) levels to predict preterm infants at risk of developing intraventricular hemorrhage (IVH).

METHODS

Levels of umbilical cord EPO, acid-base status and IL-6 were analyzed in 116 consecutive, preterm newborns (GA at delivery: 29 [23-34 ] weeks) born to mothers who had a clinically indicated amniocentesis to rule out infection. Early-onset neonatal sepsis (EONS) was diagnosed using symptoms, hematological criteria and blood cultures.

RESULTS

IVH was diagnosed by cranial ultrasounds. The prevalence of IVH in our population was 25% (29/116). There was a direct relationship between cord blood EPO and cord blood IL-6 concentration (r = 0.225, p = 0.014), independent of GA at birth. Elevated cord blood EPO levels (r = 0.182, p = 0.016) and GA at birth (r =  -0.236, p = 0.004) remained significant independent factors associated with the risk of IVH, when evaluated with stepwise logistic regression analyses. Cord blood IL-6, pH, and EONS were not associated with IVH. These relationships remained following correction for GA at birth (p = 0.027).

CONCLUSIONS

Our results suggest that elevation in cord blood EPO may predict newborns at risk for IVH, independent of fetal inflammatory status. Further studies are warranted to confirm this association.

Interpretation of amniotic fluid white blood cell count in "bloody tap" amniocenteses in women with symptoms of preterm labor

OBJECTIVE

To estimate whether blood-contaminated amniotic fluid affects the performance of white blood cell (WBC) count in diagnosing intraamniotic inflammation and infection.

METHODS

Three hundred fifty-seven consecutive women pregnant with singletons undergoing amniocentesis to rule out infection were enrolled prospectively. A "bloody tap" was defined as a red blood cell (RBC) count of 1,000 cells/mm or more. Proteomics analysis of amniotic fluid was used in this study as the standard for diagnosing inflammation. Infection was confirmed by positive amniotic fluid culture. An amniotic fluid WBC count correction formula was computed using maternal WBC count, hematocrit, and mean corpuscular volume.

RESULTS

The prevalence of a bloody tap amniocentesis was 22% (77 of 357). In the absence of inflammation, the amniotic fluid WBC count was significantly higher in bloody tap (median [interquartile range] 18 [9-58] cells/mm) compared with non-bloody tap specimens (4 [1-10] cells/mm; P<.001). The correction formula reversed this difference to a nonsignificant level (bloody tap 0 [0-17] compared with non-bloody tap 3 [1-10] cells/mm; P=.273). In the setting of inflammation, the observed WBC count of bloody tap samples (778 [197-2,062 cells/mm]) was significantly elevated compared with that of the non-bloody tap specimens (616 [105-1,730] cells/mm; P=.023). Correction of the WBC count in bloody tap amniocenteses improved the test accuracy and positive likelihood ratios for inflammation and infection. A correction algorithm was not useful in amniotic fluid specimens with less than 1,000/RBCs/mm or WBC counts more than 1,100 cells/mm. Given the nonlinear relationship between amniotic fluid WBC and RBC, for a rapid correction of WBC count, the number of neutrophils that need to be subtracted from the observed WBC count is variable.

CONCLUSION

In the setting of an amniotic fluid sample contaminated with 1,000 RBCs/mm or more, WBC count is a less accurate indicator of inflammation and infection. In such samples, correction of WBC count enhances diagnostic performance for inflammation and infection.

LEVEL OF EVIDENCE

II.

Fetal renal artery impedance as assessed by Doppler ultrasound in pregnancies complicated by intraamniotic inflammation and preterm birth

OBJECTIVE

The objective of the study was to evaluate the fetal renal artery impedance in the context of inflammation-associated preterm birth.

STUDY DESIGN

We conducted a prospective Doppler assessment of the fetal renal artery impedance in 70 singleton fetuses. The study group consisted of 56 premature fetuses (median, 28.1 [interquartile range, 25.3-30.6] weeks at enrollment). Gestational age (GA) reference ranges were generated based on fetuses with uncomplicated pregnancies (n = 14). Doppler studies included renal artery pulsatility index (PI), resistance index (RI), systolic/diastolic (S/D) ratio, and presence or absence of end-diastolic blood flow. Proteomic profiling (surface-enhanced laser desorption ionization time-of-flight) was used for assessment of intraamniotic inflammation and biomarker peak corresponding to beta2-microglubin. Data were interpreted in relationship to amniotic fluid index (AFI), cord blood interleukin (IL)-6 and erythropoietin (EPO) levels. The cardiovascular and metabolic profiles of the neonates were investigated in the first 24 hours of life.

RESULTS

Fetuses delivered by mothers with intraamniotic inflammation had higher cord blood IL-6 but not EPO levels. Fetal inflammation did not affect either renal artery PI, RI, S/D ratio, or end-diastolic blood flow. Neonates delivered in the context of intraamniotic inflammation had higher serum blood urea nitrogen levels, which correlated significantly with AF IL-6 levels. The renal artery RI and SD ratio were inversely correlated with the AFI independent of GA, cord blood IL-6, and status of the membranes.

CONCLUSION

The fetus is capable of sustaining normal renal artery impedance despite inflammation. Resistance in the renal vascular bed affects urine output independent of inflammation.

Fetal inflammatory response in women with proteomic biomarkers characteristic of intra-amniotic inflammation and preterm birth

OBJECTIVE

To determine the relationship between presence of amniotic fluid (AF) biomarkers characteristic of inflammation (defensins 2 and 1 and calgranulins C and A) and fetal inflammatory status at birth.

DESIGN

Prospective observational cohort.

SETTING

Tertiary referral University hospital.

POPULATION

One hundred and thirty-two consecutive mothers (gestational age, median [interquartile range]: 29.6 [24.1-33.1] weeks) who had a clinically indicated amniocentesis to rule out infection and their newborns.

METHODS

Intra-amniotic inflammation was diagnosed by mass spectrometry surface-enhanced-laser-desorption-ionization time of flight (SELDI-TOF). The AF proteomic fingerprint (mass-restricted [MR] score) ranges from 0-4 (none to all biomarkers present). The intensity of intra-amniotic inflammation was graded based on the number of proteomic biomarkers: MR score 0: 'no' inflammation, MR score 1-2: 'minimal' inflammation and MR score 3-4: 'severe' inflammation. At birth, cord blood was obtained for all women. Severity of histological chorioamnionitis and early-onset neonatal sepsis (EONS) was based on established histological and haematological criteria. Interleukin-6 (IL-6) levels were measured by sensitive immunoassays. The cord blood-to-AF IL-6 ratio was used as an indicator of the differential inflammatory response in the fetal versus the AF compartment.

MAIN OUTCOME MEASURES

To relate proteomic biomarkers of intra-amniotic infection to cord blood IL-6 and to use the latter as the primary marker of fetal inflammatory response.

RESULTS

Women with intra-amniotic inflammation delivered at an earlier gestational age (analysis of variance, P<0.001) and had higher AF IL-6 levels (P<0.001). At birth, neonates of women with severe intra-amniotic inflammation had higher cord blood IL-6 levels (P=0.002) and a higher frequency of EONS (P=0.002). EONS was characterised by significantly elevated cord blood IL-6 levels (P<0.001). Of the 39 neonates delivered by mothers with minimal intra-amniotic inflammation, 15 (39%) neonates had umbilical cord blood IL-6 levels above the mean for the group and 2 neonates had confirmed sepsis. The severity of the neutrophilic infiltrate in the chorionic plate (P<0.001), choriodecidua (P=0.002), umbilical cord (P<0.001) but not in the amnion (P>0.05) was an independent predictor of the cord blood-to-AF IL-6 ratio. Relationships were maintained following correction for gestational age, birthweight, amniocentesis-to-delivery interval, caesarean delivery, status of the membranes, race, MR score and antibiotics and steroid exposure.

CONCLUSIONS

We provide evidence that presence of proteomic biomarkers characteristic of inflammation in the AF is associated with an increased inflammatory status of the fetus at birth. Neonates mount an increased inflammatory status and have positive blood cultures even in the context of minimal intra-amniotic inflammation.

Fetal heart rate monitoring patterns in women with amniotic fluid proteomic profiles indicative of inflammation

We hypothesized that abnormal fetal heart rate monitoring patterns (FHR-MPs) occur more often in pregnancies complicated by intra-amniotic inflammation. Therefore, our objective was to examine the relationships among FHR-MP abnormalities, intra-amniotic inflammation and/or infection, acute histological chorioamnionitis, and early-onset neonatal sepsis (EONS) in pregnancies complicated by preterm birth. Additionally, the ability of various FHR-MPs to predict EONS was investigated. FHR-MPs from 87 singleton premature neonates delivered within 48 hours from amniocentesis (gestational age, mean +/- SD: 28.9 +/- 3.3 weeks) were analyzed blindly using strict National Institute of Child Health and Human Development criteria. Strips were evaluated at three time points: at admission, at amniocentesis, and prior to delivery. Intra-amniotic inflammation was established based on a previously validated proteomic fingerprint (mass-restricted score). Diagnoses of histological chorioamnionitis and EONS were based on well-recognized pathological, clinical, and laboratory criteria. We determined that fetuses of women with severe intra-amniotic inflammation had a higher FHR baseline throughout the entire monitoring period and an increased frequency of a nonreactive FHR-MP at admission. Of all FHR-MPs, a nonreassuring test at admission had 32% sensitivity, 95% specificity, 73% positive predictive value, 77% negative predictive value, and 76% accuracy in predicting EONS. Although a nonreassuring FHR-MP at admission was significantly associated with EONS after correcting for gestational age (odds ratio, 5.6; 95% confidence interval, 1.2 to 26.2; P = 0.030), the majority of the neonates that developed EONS had an overall reassuring FHR-MP. Nonreassuring FHR-MPs at either amniocentesis or delivery had no association with EONS. We conclude that in cases complicated by preterm birth, a nonreassuring FHR-MP at the initial evaluation is a specific but not a sensitive predictor of EONS. An abnormal FHR-MP can thus raise the level of awareness that a fetus with EONS may be born, but it is not a useful clinical indicator of the need for antibiotic treatment of the neonate.

Using proteomic analysis of the human amniotic fluid to identify histologic chorioamnionitis

OBJECTIVE

To estimate the relationship between histologic chorioamnionitis and four amniotic fluid proteomic biomarkers characteristic of inflammation (defensins 2 and 1, calgranulins C and A).

METHODS

One hundred fifty-eight women with singleton pregnancies had a clinically indicated amniocentesis to rule out inflammation and infection in the context of preterm labor or preterm premature rupture of membranes. A proteomic fingerprint (Mass Restricted score) was generated from amniotic fluid using surface-enhanced laser desorption ionization time-of-flight mass spectrometry. The Mass Restricted score ranges from 0 to 4 (none to all four biomarkers present) in direct relationship with severity of intra-amniotic inflammation. Presence or absence of biomarkers was analyzed in relationship to placental pathology. Criteria for severity of histologic chorioamnionitis were 3 stages and 4 grades of inflammation of the amnion, choriodecidua and chorionic plate.

RESULTS

The prevalence of histologic chorioamnionitis was 64% (stage I 12%, stage II 16%, and stage III 37%). The Mass Restricted score significantly correlated with stages of histologic chorioamnionitis (r=0.539, P<.001), grades of choriodeciduitis (r=0.465, P<.001), and amnionitis (r=0.536, P<.001). African-American women were overrepresented in the group with severe inflammation (Mass Restricted score 3-4, P=.022). Of the four biomarkers of the Mass Restricted score, calgranulin C had the strongest relationship with presence of stage III chorioamnionitis, independent of race, amniocentesis-to-delivery interval, and gestational age.

CONCLUSION

Proteomic analysis of amniotic fluid provides an opportunity for early recognition of histologic chorioamnionitis. This methodology may in the future identify candidates for antenatal therapeutic interventions.

LEVEL OF EVIDENCE

II.

Recurrent preterm birth

Recurrent preterm birth is frequently defined as two or more deliveries before 37 completed weeks of gestation. The recurrence rate varies as a function of the antecedent for preterm birth: spontaneous versus indicated. Spontaneous preterm birth is the result of either preterm labor with intact membranes or preterm prelabor rupture of the membranes. This article reviews the body of literature describing the risk of recurrence of spontaneous and indicated preterm birth. Also discussed are the factors which modify the risk for recurrent spontaneous preterm birth (a short sonographic cervical length and a positive cervicovaginal fetal fibronectin test). Patients with a history of an indicated preterm birth are at risk not only for recurrence of this subtype, but also for spontaneous preterm birth. Individuals of black origin have a higher rate of recurrent preterm birth.

Value of placental microbial evaluation in diagnosing intra-amniotic infection

OBJECTIVE

To evaluate the ability of microbiologic and pathologic examination of the placenta to accurately diagnose intraamniotic infection and inflammation.

METHODS

One hundred eighty-three women with a clinically indicated amniocentesis were enrolled prospectively. We applied our analysis to 56 women with evidence of preterm labor or preterm premature rupture of membranes who delivered within 48 hours of amniotic fluid testing results. Twenty-three patients, assessed for fetal lung maturity in the third trimester, served as controls. Amniotic fluid was cultured for aerobic, anaerobic, Ureaplasma, and Mycoplasma species. We used mass spectrometry to assess the degree of intraamniotic inflammation (Mass Restricted scoring). After delivery, microbiologic and histologic studies of the placenta were performed. These results were interpreted in comparison with the direct microbiologic and inflammatory analysis of the amniotic fluid. A sample size of 45 patients was required to show a test accuracy of 80% or more.

RESULTS

Ninety-two percent of women with positive amniotic fluid cultures tested with at least one positive placenta culture. Eighty percent of women who had negative amniotic fluid cultures also tested with a positive placenta culture. The accuracy of placental cultures in predicting amniotic fluid infection varied from 44% to 57%. Placental pathology showed an accuracy of only 58% in diagnosing intraamniotic inflammation.

CONCLUSION

Placental microbiologic and histologic studies poorly reflect the infectious and inflammatory status of the amniotic fluid. Results of such studies should be interpreted with caution in the management and future counseling of women with preterm labor or preterm premature rupture of membranes.

LEVEL OF EVIDENCE

II.

Proteomic biomarkers of intra-amniotic inflammation: relationship with funisitis and early-onset sepsis in the premature neonate

Our goal was to determine the relationship between 4 amniotic fluid (AF) proteomic biomarkers (human neutrophil defensins 2 and 1, calgranulins C and A) characteristic of intra-amniotic inflammation, and funisitis and early-onset sepsis in premature neonates. The mass restricted (MR) score was generated from AF obtained from women in preterm labor (n = 123). The MR score ranged from 0-4 (none to all biomarkers present). Funisitis was graded histologically and interpreted in relation to the MR scores. Neonates (n = 97) were evaluated for early-onset sepsis. There was significant correlation between the severity of AF inflammation and the presence (53/123) and grades of funisitis (p < 0.001). Funisitis occurred independently of the amniocentesis-to-delivery interval or status of the membranes and was best predicted by an MR score 3-4 and an earlier gestational age (GA) at delivery. Neonates born to women with an MR score 3-4 had an increased incidence of suspected/confirmed sepsis, even after adjusting for GA at birth. Calgranulin C had the highest association with clinically significant funisitis, while calgranulin A had the strongest association with early-onset sepsis. To conclude, AF proteomic analysis shows that women with MR scores 3-4 are more likely to have histologic funisitis, and deliver neonates with early-onset sepsis.

Amniocentesis results and novel proteomic analysis in a case of occult candidal chorioamnionitis

We report a case of subclinical Candida albicans chorioamnionitis with mid-trimester cervical dilation diagnosed by amniotic fluid culture and Gram stain. Proteomic analysis of amniotic fluid demonstrated protein biomarkers previously associated only with bacterial intra-amniotic infections. We hypothesize that since amniotic fluid culture of yeast may take days, novel tests such as proteomic profiling may lead to the development of rapid diagnostic tests for fungal intra-amniotic infections.

Interleukin-8 and glucose in amniotic fluid, fetal fibronectin in vaginal secretions and preterm labor index based on clinical variables are optimal predictive markers for preterm delivery in patients with intact membranes

AIM

Various predictive markers for preterm delivery have been proposed in previous studies. We investigated which marker is most reliable.

METHODS

In 126 patients with preterm labor before 32 weeks of gestation and intact membranes, who had regular uterine contractions with cervical changes effaced > or =50%, we evaluated seven markers: interleukin (IL)-8, glucose, and granulocyte count in amniotic fluid (AF); fetal fibronectin (fFN) in vaginal secretions; IL-8 in cervical mucus; cervical length; and preterm labor index (PLI) based on clinical variables. The relationships of these variables to the occurrence of preterm delivery before 34 weeks were examined by logistic regression analysis.

RESULTS

Values for AF IL-8, AF granulocyte count, fFN in vaginal secretions, and PLI were significantly higher, while the value for AF glucose was significantly lower, in patients delivering before 34 weeks than those in patients delivering at or following 34 weeks (P < 0.0001 for all). The most sensitive marker for predicting delivery before 34 weeks was AF IL-8 (sensitivity, 67.8%). The most specific markers were AF IL-8 (specificity, 95.5%) and PLI (specificity, 95.5%). By the logistic regression analysis, AF IL-8, AF glucose, fFN in vaginal secretions and PLI showed independent relationships with delivery before 34 weeks (P = 0.0009, P = 0.0032, P = 0.0131 and P = 0.0038, respectively).

CONCLUSIONS

In preterm labor with intact membranes, AF IL-8, AF glucose, fFN in vaginal secretions and PLI were highly predictive markers for detecting preterm delivery before 34 weeks.

Proteomic profiling of the amniotic fluid to detect inflammation, infection, and neonatal sepsis

BACKGROUND

Proteomic analysis of amniotic fluid shows the presence of biomarkers characteristic of intrauterine inflammation. We sought to validate prospectively the clinical utility of one such proteomic profile, the Mass Restricted (MR) score.

METHODS AND FINDINGS

We enrolled 169 consecutive women with singleton pregnancies admitted with preterm labor or preterm premature rupture of membranes. All women had a clinically indicated amniocentesis to rule out intra-amniotic infection. A proteomic fingerprint (MR score) was generated from fresh samples of amniotic fluid using surface-enhanced laser desorption ionization (SELDI) mass spectrometry. Presence or absence of the biomarkers of the MR score was interpreted in relationship to the amniocentesis-to-delivery interval, placental inflammation, and early-onset neonatal sepsis for all neonates admitted to the Newborn Special Care Unit (n = 104). Women with "severe" amniotic fluid inflammation (MR score of 3 or 4) had shorter amniocentesis-to-delivery intervals than women with "no" (MR score of 0) inflammation or even "minimal" (MR score of 1 or 2) inflammation (median [range] MR 3-4: 0.4 d [0.0-49.6 d] versus MR 1-2: 3.8 d [0.0-151.2 d] versus MR 0: 17.0 d [0.1-94.3 d], p < 0.001). Nonetheless, a "minimal" degree of inflammation was also associated with preterm birth regardless of membrane status. There was a significant association between the MR score and severity of histological chorioamnionitis (r = 0.599, p < 0.001). Furthermore, neonatal hematological indices and early-onset sepsis significantly correlated with the MR score even after adjusting for gestational age at birth (OR for MR 3-4: 3.3 [95% CI, 1.1 to 9.2], p = 0.03). When compared with other laboratory tests routinely used to diagnose amniotic fluid inflammation and infection, the MR score had the highest accuracy to detect inflammation (white blood cell count > 100 cells/mm3), whereas the combination of Gram stain and MR score was best for rapid prediction of intra-amniotic infection (positive amniotic fluid culture).

CONCLUSIONS

High MR scores are associated with preterm delivery, histological chorioamnionitis, and early-onset neonatal sepsis. In this study, proteomic analysis of amniotic fluid was shown to be the most accurate test for diagnosis of intra-amniotic inflammation, whereas addition of the MR score to the Gram stain provides the best combination of tests to rapidly predict infection.

Lactate dehydrogenase isoform activity mapping in patients with intra-amniotic infection

OBJECTIVE

Five distinct lactate dehydrogenase isoenzymes have been described. We sought to illustrate the specific amniotic fluid lactate dehydrogenase isoenzyme activity profiles in women with intra-amniotic infection.

STUDY DESIGN

Amniotic fluid was retrieved from 82 women who were stratified in the following groups: (1) positive amniotic fluid cultures (n = 23 women; gestational age, 26 weeks [range, 21-32 weeks]); (2) negative amniotic fluid cultures (n = 22 women; gestational age, 30 weeks [range, 16-36 weeks]); (3) second trimester control (normal genetic karyotype; n = 17 women; gestational age, 18 weeks [range, 16-22 weeks]); and (4) third trimester control (fetal lung maturity testing; n = 20 women; gestational age, 36 weeks [range, 31-38 weeks]). The optical density of each isoform was determined relative to a standard with 5 known lactate dehydrogenase isoenzyme activities. Total lactate dehydrogenase activity was measured by the clinical laboratory immediately after retrieval and by a kinetic UV spectrophotometric assay at the time of the isoelectric focusing.

RESULTS

Infection increased total lactate dehydrogenase activity: positive amniotic fluid cultures (median, 762.4 [range, 169.3-3374.8]) vs negative amniotic fluid cultures (median, 203.7 [range, 57.8-1939.3]; U/L; P < .001]). Lactate dehydrogenase isoform profiling identified significant and specific increases in lactate dehydrogenase isoforms 3, 4 (P < .01), and 5 (P < .05) in positive amniotic fluid cultures compared to the negative amniotic fluid cultures group. A selective up-regulation in lactate dehydrogenase isoform 5 was identified at term in healthy subjects.

CONCLUSION

Intra-amniotic infection is characterized by an increase in the activities of lactate dehydrogenase isoforms 3, 4, and 5; advancing gestational age demonstrates an up-regulation of isoform 5 only.

Evaluation of amniotic fluid cytokines in preterm labor and intact membranes

OBJECTIVE

To compare the amniotic fluid (AF) concentration of pro-inflammatory cytokines between women with preterm labor and intact membranes that delivered within 7 days, with those that delivered after 7 days of the amniocentesis according to the result of the AF culture.

METHODS

Fifty-two women with preterm labor and intact membranes between 21 and 35 weeks of gestation were included in the study. Transabdominal amniocentesis was performed to rule out intra-amniotic infection, and AF concentrations of interleukin-1alpha (IL-1alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor (TNF) were determined with sensitive and specific enzyme-linked immunosorbent assays. Amniotic fluid was cultured for aerobic and anaerobic bacteria, Ureaplasma urealyticum, and Mycoplasma hominis. Exclusion criteria included preterm premature rupture of membranes, vaginal bleeding, multiple gestations, uterine anomalies, fetal congenital anomalies, ominous fetal heart rate tracings and fetal deaths. Proportions were compared using chi2 or Fisher's exact test. Receiver operator characteristic (ROC) curve analysis was performed for each cytokine for the prediction of delivery within 7 days.

RESULTS

Sixty-two percent (32/52) of women delivered within 7 days and 38% (20/52) delivered after 7 days of amniocentesis. All women that delivered after 7 days of the procedure had negative AF cultures. In contrast, 28% (9/32) of women that delivered within 7 days had positive AF cultures and 72% (23/32) had negative AF cultures. Women that delivered within 7 days regardless of AF cultures had a lower birth weight and a shorter amniocentesis-to-delivery interval than those that delivered after 7 days of amniocentesis. Among women that delivered within 7 days, those with positive AF cultures had a lower gestational age at delivery and a higher frequency of histologic chorioamnionitis than those with negative AF cultures. The AF concentrations of all cytokines were significantly higher in women that delivered within 7 days with positive AF cultures than in those with negative AF cultures. Similarly, the AF concentrations of IL-1alpha, IL-6, and IL-8 were significantly higher in women that delivered within 7 days than those that delivered after 7 days of the amniocentesis, regardless of the AF culture results. Diagnostic indexes were calculated for all cytokines using critical values derived from ROC curve analysis for the prediction of delivery within 7 days.

CONCLUSIONS

Women with preterm labor and intact membranes that delivered within 7 days had higher AF concentrations of pro-inflammatory cytokines than those who delivered after 7 days of the amniocentesis regardless of the AF culture results.

Mid-trimester amniotic fluid angiogenin, lactate dehydrogenase and fibronectin in the prediction of preterm delivery

OBJECTIVE

Our purpose was to compare angiogenin, lactate dehydrogenase (LDH) and fibronectin levels in mid-trimester amniotic fluid of patients with preterm and term deliveries and to find out their predictive values for preterm birth.

STUDY DESIGN

A prospective cohort study was conducted in 55 pregnancies with singleton gestations that underwent amniocentesis at 15-20 weeks for standard genetic indications. Amniotic fluid angiogenin, lactate dehydrogenase and fibronectin levels were measured by enzyme-linked immunosorbent assay (ELISA), radial immundiffusion technic and automated analyzer, respectively.

RESULTS

Five patients delivered preterm, five developed signs or symptoms of threatened preterm labor and 45 had term delivery after an uneventful pregnancy. Demographic data were not significantly different. Amniotic fluid angiogenin and lactate dehydrogenase levels were significantly higher in patients with preterm than term deliveries (P<0.001 and 0.02, respectively). Receiver-operator characteristic curve analysis showed that the amniotic fluid angiogenin had the best screening efficiency in predicting preterm delivery. An angiogenin level of 35ng/ml was the optimal cut-off value for the prediction of preterm delivery, with a sensitivity of 100% and specificity of 91%.

CONCLUSION

Second-trimester angiogenin is found to be quite effective in the prediction of preterm delivery. Preexisting intrauterine ischemia may be an important risk factor for preterm delivery and already be present in the early mid-trimester.

Maternal serum interleukin 6 levels in preterm labor: prediction of admission-to-delivery interval

OBJECTIVE

To evaluate the diagnostic value of maternal serum interleukin 6 (IL-6), C-reactive protein (CRP) levels and white blood cell (WBC) count for the prediction of preterm labor and length of admission-to-delivery interval in patients with preterm labor.

METHODS

Maternal serum IL-6, CRP and WBC count were prospectively determined in eighty-two patients in preterm labor and 21 controls. Data was analyzed in study and control groups, and for the assessment of clinical and laboratory risk factors in the prediction of admission-to-delivery interval in the study group.

RESULTS

Maternal serum IL-6 levels were significantly higher in the study group than controls. The IL-6 value associated with the highest percent of true positives and true negatives for the prediction of preterm labor was 5 pg/ml. The area under curve of maternal IL-6 was significantly higher than the area under curve of of CRP and WBC count. In the study group maternal serum IL-6 levels were significantly higher in patients delivered within 2 and 7 days than the nondelivering ones and a cut off value of 8.3 pg/ml was determined for estimation of preterm delivery.

CONCLUSION

Maternal serum IL-6 is a reliable marker in the prediction and management of preterm labor and delivery.

Amniotic fluid glucose and cytokines values in the early diagnosis of amniotic infection in patients with preterm labor and intact membranes

OBJECTIVE

Our goal was to compare sensitivity, specificity, and predictive values of glucose and cytokines [interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor (TNF)] in amniotic fluid (AF) to detect an AF-positive culture.

METHODS

Amniocentesis was performed on 113 patients with preterm labour (PTL) and intact membranes. Fluid was cultured for aerobic and anaerobic bacteria, and for mycoplasmas. AF analysis included cytokines and glucose determinations.

RESULTS

The prevalence of positive AF cultures was 11.5% (13/113). Anaerobic bacteria were isolated in 9 patients (69.2%). The glucose <16 mg/dl and cytokines values; IL-1 >640 pg/ml, IL-6 >55,000 pg/ml, IL-8 >1,000 pg/ml, TNF >672 pg/ml, were significantly correlated (P < 0.01) with AF culture result. Glucose had a sensitivity of 69.2% and a specificity of 96% for the prediction of positive AF culture. The sensitivity and specificity of the cytokines ranged from 61.5-53.4% and 79.8-8.99%, respectively.

CONCLUSIONS

In the diagnosis of the AF-positive culture, glucose <16 mg/dl is more sensitive than cytokines.