Amniotic Fluid Matrix Metalloproteinase-8 Concentration Research Articles

Preterm labor with intact membranes: a simple noninvasive method to identify patients at risk for intra-amniotic infection and/or inflammation

Objective To develop a noninvasive scoring system to identify patients at high risk for intra-amniotic infection and/or inflammation, which would reduce the need for amniocentesis. Methods This prospective cohort study comprised patients admitted with preterm labor and intact membranes (20–34 weeks of gestation) who underwent a transabdominal amniocentesis and for whom concentrations of quantitative cervical fetal fibronectin and of maternal serum C-reactive protein (CRP) were determined. Intra-amniotic infection was defined as a positive amniotic fluid culture for microorganisms. Intra-amniotic inflammation was defined as an amniotic fluid matrix metalloproteinase-8 concentration >23 ng/mL. Multivariate logistic regression analysis was performed to identify intra-amniotic infection/inflammtion with noninvasive parameters that had a significant relationship with univariate analysis. With four parameters identified by multivariate analysis, we generated a noninvasive risk scoring system. Results Of the study population consisting of 138 singleton pregnant women, (1) the overall rate of intra-amniotic infection/inflammation was 28.3% (39/138); (2) four parameters were used to develop a noninvasive risk scoring system [i.e. cervical fetal fibronectin concentration (score 0–2), maternal serum CRP concentration (score 0–2), cervical dilatation (score 0-2), and gestational age at presentation (score 0–1)]; the total score ranges from 0 to 7; 3) the area under the curve of the risk score was 0.96 (95% confidence interval (CI), 0.92–0.99), significantly higher than that of each predictor in the identification of intra-amniotic infection/inflammation (p < .001, for all); 4) the risk score with a cutoff of 4 had a sensitivity of 94.9% (37/39), a specificity of 90.9% (90/99), a positive predictive value of 80.4% (37/46), a negative predictive value of 97.8% (90/92), a positive likelihood ratio of 10.4 (95% CI, 5.6–19.5), and a negative likelihood ratio of 0.06 (95% CI, 0.15–0.22) in the identification of intra-amniotic infection/inflammation. Conclusions (1) The combination of four parameters (concentrations of cervical fetal fibronectin and maternal serum CRP, cervical dilatation, and gestational age) was independently associated with intra-amniotic infection and/or inflammation; and (2) the risk scoring system comprised of the combination of 4 noninvasive parameters was sensitive and specific to identify the patients at risk for intra-amniotic infection and/or inflammation.

The Relationship Among Intra-Amniotic Inflammatory Response, The Progression of Inflammation in Chorionic Plate and Early-Onset Neonatal Sepsis.

Background: The chorionic plate (CP) has been denigrated by the well-known route of the extraplacental membranes from the decidua parietalis through the chorion to the amnion in the progression of ascending intrauterine infection among preterm births (PTBs). However, considering previous studies reporting the relationship among intra-amniotic inflammatory response (IAIR), the progression of inflammation in extraplacental membranes and early-onset neonatal sepsis (EONS), and the anatomic connection between extraplacental membranes and CP, there is a good chance that IAIR would be more likely and severe according to the progression of inflammation in CP, and this progression of inflammation in CP would be associated with a significant increase in EONS in neonates delivered due to either PTL or preterm-PROM. Unfortunately, there is no information about the relationship among IAIR, the progression of inflammation in CP, and EONS among spontaneous PTBs. The objective of the current study is to examine this issue.Method: The study population included 309 singleton pregnant women-delivered preterm neonates with the following conditions: (1) gestational age (GA) at delivery: 20.0~36.9 weeks; (2) spontaneous PTBs: PTL (151 cases) or preterm-PROM (158 cases); (3) available results of placental histologic examination; (4) without congenital anomaly; and (5) delivery within 60 h of amniocentesis. We examined IAIR, and the frequency of intra-amniotic inflammation (IAI) and EONS according to the progression of inflammation in CP [i.e., stage-0, inflammation-free CP; stage-1, inflammation restricted to subchorionic fibrin (SCF); stage-2, inflammation in connective tissue (CT) of CP but without chorionic vasculitis; and stage-3, chorionic vasculitis]. IAIR was determined by amniotic fluid (AF) matrix metalloproteinase-8 (MMP-8) concentration (ng/ml), and IAI was defined as an elevated AF MMP-8 concentration (≥23 ng/ml). EONS included either suspected or proven EONS.Results: (1) Each stage (stage-0 to stage-3) was present in 69.3% (214/309), 15.9% (49/309), 11.0% (34/309), and 3.9% (12/309) of the study population. (2) AF MMP-8 concentrations continuously elevated according to the progression of inflammation in CP [stage-0 vs. stage-1 vs. stage-2 vs. stage-3; median (ng/ml), range (ng/ml); 6.0 (0.3–4202.7) vs. 153.9 (0.3–6142.6) vs. 464.9 (5.8–3929.0) vs. 1,780.4 (35.1–5019.5); Kruskal–Wallis test, P < 0.001 and Spearman's rank-correlation test, P < 0.000001, r = 0.553]. (3) Moreover, the frequency of IAI and EONS gradually increased with the progression of inflammation in CP [stage-0 vs. stage-1 vs. stage-2 vs. stage-3; IAI, 30.5% (64/210) vs. 70.2% (33/47) vs. 96.7% (29/30) vs. 100% (12/12); EONS, 3.5% (7/200) vs. 25.5% (12/47) vs. 32.3% (10/31) vs. 40.0% (4/10); each for Pearson's chi-square test, P < 0.000001 and linear-by-linear association, P < 0.000001]. (4) Of note, multiple logistic regression analysis demonstrated that a more advanced stage in the progression of inflammation within CP was associated with a higher odds ratio (OR) for EONS [stage-1 vs. stage-2 vs. stage-3; OR, 7.215, 95% confidence-interval (CI) (2.177–23.908) vs. OR, 10.705, 95% CI (2.613–43.849) vs. OR, 27.189, 95% CI (2.557–289.124)] compared with stage-0 even after the adjustment for potential confounding variables.Conclusion: IAIR is more likely and severe according to the progression of inflammation in CP, and this progression of inflammation in CP is an independent risk factor for EONS in spontaneous PTBs. This finding suggests that CP may be another playground for the progression of ascending intrauterine infection in addition to extraplacental membranes, and the progression of inflammation in CP may be used for the prediction of EONS in spontaneous PTBs.

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.

The earlier the gestational age, the greater the intensity of the intra-amniotic inflammatory response in women with preterm premature rupture of membranes and amniotic fluid infection by Ureaplasma species.

Objectives To determine the relationship between the intensity of the intra-amniotic inflammatory response and the gestational age at the time of diagnosis in cases with preterm premature rupture of membranes (PROM) and intra-amniotic infection caused by Ureaplasma spp. Methods A retrospective cohort study was conducted which included 71 women with preterm PROM and a positive amniotic fluid culture with Ureaplasma spp. Women with mixed intra-amniotic infections were excluded. The study population was classified into three groups according to gestational age: group 1, <26 weeks (extreme preterm PROM, n = 17); group 2, 26.0-33.9 weeks (moderate preterm PROM, n = 39); group 3, 34.0-36.9 weeks (late preterm PROM, n = 15). The intensity of the intra-amniotic and maternal inflammatory response was compared among the three groups. The intensity of the intra-amniotic inflammatory response was assessed by the concentration of amniotic fluid matrix metalloproteinase-8 (MMP-8) and white blood cell (WBC) count. The maternal inflammatory response was assessed by the concentration of C-reactive protein (CRP) and WBC count in maternal blood at the time of amniocentesis. Results (1) The median values of amniotic fluid MMP-8 concentration and WBC count were the highest in the extreme preterm PROM group and the lowest in the late preterm PROM group (P < 0.001 and P = 0.01, respectively); (2) the intensity of the maternal inflammatory response measured by maternal blood WBC count and CRP concentration was not significantly associated with gestational age at the time of diagnosis. Conclusion The earlier the gestational age at the time of PROM, the higher the intensity of the intra-amniotic inflammatory response in women with preterm PROM and intra-amniotic infection caused by Ureaplasma spp.

A high concentration of fetal fibronectin in cervical secretions increases the risk of intra-amniotic infection and inflammation in patients with preterm labor and intact membranes

Objective To determine whether the risk of intra-amniotic infection/inflammation and spontaneous preterm delivery (SPTD) varies as a function of the concentration of cervical fetal fibronectin (fFN) in patients with preterm labor and intact membranes. Methods This prospective study included 180 patients with preterm labor and intact membranes who had a sample collected for quantitative fFN measurement and underwent amniocentesis. Amniotic fluid was cultured for aerobic and anaerobic bacteria and genital mycoplasmas. Intra-amniotic inflammation was defined as an amniotic fluid matrix metalloproteinase-8 concentration >23 ng/mL. Results (1) The prevalence of intra-amniotic infection/inflammation and SPTD within 7 days was 32.2% (58/180) and 33.9% (61/178), respectively; (2) The higher the fFN concentration, the greater the risk of intra-amniotic infection/inflammation and SPTD within 7 days (P<0.001, respectively); (3) An fFN concentration 150 ng/mL had a better diagnostic performance than an fFN 50 ng/mL in the identification of intra-amniotic infection/inflammation and SPTD within 7 days; (4) Among the patients with an fFN <50 ng/mL, intra-amniotic infection/inflammation was identified in 7.6% (6/79) of patients and 66.7% (4/6) delivered within 7 days. Conclusion The higher the concentration of fFN, the greater the risk of intra-amniotic infection/inflammation and SPTD in patients with preterm labor and intact membranes.

Cervical and Amniotic Fluid Matrix Metalloproteinase-8 and Interleukin-6 Concentrations in Preterm Pregnancies with or without Preterm Premature Rupture of Membranes

Introduction: Intra-amniotic inflammation is defined by elevated inflammatory biomarkers in the amniotic fluid (AF), either due to microbial invasion of the amniotic cavity (MIAC) or sterile inflammation. Amniocentesis being an invasive procedure, we wanted to investigate whether elevated matrix metalloproteinase-8 (MMP-8) or interleukin-6 (IL-6) concentrations could be detected from cervical fluid samples. Materials and Methods: This prospective study included 67 women with singleton nondiabetic pregnancies with or without preterm premature rupture of membranes (PPROM) between 22⁺⁰ and 37⁺⁰ weeks of gestation. Simultaneous AF and cervical samples were obtained. Results: In women without PPROM, cervical MMP-8 concentrations correlated with AF MMP-8 concentrations (r_S = 0.466, p = 0.002), but cervical IL-6 did not correlate with AF IL-6 (r_S = 0.277, p = 0.076). In PPROM cases no correlations were found. Women with MIAC had higher concentrations of AF MMP-8 and AF IL-6 compared to women without MIAC regardless of membrane status. However, only women without PPROM had higher concentrations of cervical MMP-8 in proven MIAC. Conclusion: In women without PPROM, cervical MMP-8 concentration reflects the magnitude of AF MMP-8, thus potentially guiding the selection of patients benefitting from amniocentesis.

The frequency and clinical significance of intra-amniotic inflammation in twin pregnancies with preterm labor and intact membranes

Objective: The objective of this study is to evaluate the frequency and clinical significance of intra-amniotic inflammation in twin pregnancies with preterm labor and intact membranes.Study design: Amniotic fluid (AF) was retrieved from both sacs in 90 twin gestations with preterm labor and intact membranes (gestational age between 20 and 34 6/7 weeks). Preterm labor was defined as the presence of painful regular uterine contractions, with a frequency of at least 2 every 10 min, requiring hospitalization. Fluid was cultured and assayed for matrix metalloproteinase-8. Intra-amniotic inflammation was defined as an AF matrix metalloproteinase-8 concentration >23 ng/mL.Results: The prevalence of intra-amniotic inflammation for at least 1 amniotic sac was 39% (35/90), while that of proven intra-amniotic infection for at least one amniotic sac was 10% (9/90). Intra-amniotic inflammation without proven microbial invasion of the amniotic cavity was found in 29% (26/90) of the cases. Intra-amniotic inflammation was present in both amniotic sacs for 22 cases, in the presenting amniotic sac for 12 cases, and in the non-presenting amniotic sac for one case. Women with intra-amniotic inflammation observed in at least one amniotic sac and a negative AF culture for microorganisms had a significantly higher rate of adverse pregnancy outcome than those with a negative AF culture and without intra-amniotic inflammation (lower gestational age at birth, shorter amniocentesis-to-delivery interval, and significant neonatal morbidity). Importantly, there was no significant difference in pregnancy outcome between women with intra-amniotic inflammation and a negative AF culture and those with a positive AF culture.Conclusion: Intra-amniotic inflammation is present in 39% of twin pregnancies with preterm labor and intact membranes and is a risk factor for impending preterm delivery and adverse outcome, regardless of the presence or absence of bacteria detected using cultivation techniques.

The combined exposure to intra-amniotic inflammation and neonatal respiratory distress syndrome increases the risk of intraventricular hemorrhage in preterm neonates.

To evaluate the impact of combined exposure to intra-amniotic inflammation and neonatal respiratory distress syndrome (RDS) on the development of intraventricular hemorrhage (IVH) in preterm neonates. This retrospective cohort study includes 207 consecutive preterm births (24.0-33.0 weeks of gestation). Intra-amniotic inflammation was defined as an amniotic fluid matrix metalloproteinase-8 concentration >23 ng/mL. According to McMenamin's classification, IVH was defined as grade II or higher when detected by neurosonography within the first weeks of life. (1) IVH was diagnosed in 6.8% (14/207) of neonates in the study population; (2) IVH was frequent among newborns exposed to intra-amniotic inflammation when followed by postnatal RDS [33% (6/18)]. The frequency of IVH was 7% (8/115) among neonates exposed to either of these conditions - intra-amniotic inflammation or RDS - and 0% (0/64) among those who were not exposed to these conditions; and (3) Neonates exposed to intra-amniotic inflammation and postnatal RDS had a significantly higher risk of IVH than those with only intra-amniotic inflammation [odds ratio (OR) 4.6, 95% confidence interval (CI) 1.1-19.3] and those with RDS alone (OR 5.6, 95% CI 1.0-30.9), after adjusting for gestational age. The combined exposure to intra-amniotic inflammation and postnatal RDS markedly increased the risk of IVH in preterm neonates.

Twenty-four percent of patients with clinical chorioamnionitis in preterm gestations have no evidence of either culture-proven intraamniotic infection or intraamniotic inflammation

Recent studies on clinical chorioamnionitis at term suggest that some patients with this diagnosis have neither intraamniotic infection nor intraamniotic inflammation. A false-positive diagnosis of clinical chorioamnionitis in preterm gestation may lead to unwarranted preterm delivery. We sought to determine the frequency of intraamniotic inflammation and microbiologically proven amniotic fluid infection in patients with preterm clinical chorioamnionitis. Amniocentesis was performed in singleton pregnant women with preterm clinical chorioamnionitis (<36 weeks of gestation). Amniotic fluid was cultured for aerobic and anaerobic bacteria and genital mycoplasmas and assayed for matrix metalloproteinase-8 concentration. Microbial invasion of the amniotic cavity was defined as a positive amniotic fluid culture; intraamniotic inflammation was defined as an elevated amniotic fluid matrix metalloproteinase-8 concentration of >23 ng/mL. Nonparametric and survival techniques were used for analysis. Among patients with preterm clinical chorioamnionitis, 24% (12/50) had neither microbiologic evidence of intraamniotic infection nor intraamniotic inflammation. Microbial invasion of the amniotic cavity was present in 34% (18/53) and intraamniotic inflammation in 76% (38/50) of patients. The most common microorganisms isolated from the amniotic cavity were the Ureaplasma species. Finally, patients without microbial invasion of the amniotic cavity or intraamniotic inflammation had significantly lower rates of adverse outcomes (including lower gestational age at delivery, a shorter amniocentesis-to-delivery interval, acute histologic chorioamnionitis, acute funisitis, and significant neonatal morbidity) than those with microbial invasion of the amniotic cavity and/or intraamniotic inflammation. Among patients with preterm clinical chorioamnionitis, 24% had no evidence of either intraamniotic infection or intraamniotic inflammation, and 66% had negative amniotic fluid cultures, using standard microbiologic techniques. These observations call for a reexamination of the criteria used to diagnose preterm clinical chorioamnionitis.

An elevated amniotic fluid prostaglandin F2α concentration is associated with intra-amniotic inflammation/infection, and clinical and histologic chorioamnionitis, as well as impending preterm delivery in patients with preterm labor and intact membranes

Objective: To determine whether an elevated amniotic fluid concentration of prostaglandin F2α (PGF2α) is associated with intra-amniotic inflammation/infection and adverse pregnancy outcomes in patients with preterm labor and intact membranes.Materials and methods: The retrospective cohort study included 132 patients who had singleton pregnancies with preterm labor (< 35 weeks of gestation) and intact membranes. Amniotic fluid was cultured for aerobic and anaerobic bacteria as well as for genital mycoplasmas. Intra-amniotic inflammation was defined by an elevated amniotic fluid matrix metalloproteinase-8 (MMP-8) concentration (>23 ng/mL). PGF2α was measured with a sensitive and specific immunoassay. The amniotic fluid PGF2α concentration was considered elevated when it was above the 95th percentile among pregnant women at 15–36 weeks of gestation who were not in labor (≥170 pg/mL).Results: (1) The prevalence of an elevated amniotic fluid PGF2α concentration was 40.2% (53/132) in patients with preterm labor and intact membranes; (2) patients with an elevated amniotic fluid PGF2α concentration had a significantly higher rate of positive amniotic fluid culture [19% (10/53) versus 5% (4/79); p = 0.019], intra-amniotic inflammation/infection [49% (26/53) versus 20% (16/79); p = 0.001], spontaneous preterm delivery, clinical and histologic chorioamnionitis, and funisitis, as well as a higher median amniotic fluid MMP-8 concentration and amniotic fluid white blood cell count and a shorter amniocentesis-to-delivery interval than those without an elevated concentration of amniotic fluid PGF2α (p < 0.05 for each); and (3) an elevated amniotic fluid PGF2α concentration was associated with a shorter amniocentesis-to-delivery interval after adjustment for the presence of intra-amniotic inflammation/infection [hazard ratio 2.1, 95% confidence interval (CI) 1.4–3.1; p = 0.001].Conclusion: The concentration of PGF2α was elevated in the amniotic fluid of 40.2% of patients with preterm labor and intact membranes and is an independent risk factor for intra-amniotic inflammation/infection, impending preterm delivery, chorioamnionitis, and funisitis.

Gastric fluid versus amniotic fluid analysis for the identification of intra-amniotic infection due to Ureaplasma species

Objective: Early neonatal sepsis is often due to intra-amniotic infection. The stomach of the neonate contains fluid swallowed before and during delivery. The presence of bacteria as well as neutrophils detected by culture or Gram stain of the gastric fluid during the first day of life is suggestive of exposure to bacteria or inflammation. We undertook this study to determine the relationship between gastric fluid analysis and amniotic fluid obtained by transabdominal amniocentesis in the detection of Ureaplasma species, the most frequent microorganisms responsible for intra-amniotic infection.Materials and methods: The study population consisted of 100 singleton pregnant women who delivered preterm neonates (<35 weeks) within 7 days of amniocentesis. Gastric fluid of newborns was obtained by nasogastric intubation on the day of birth. Amniotic fluid and gastric fluid were cultured for genital Mycoplasmas, and polymerase chain reaction (PCR) for Ureaplasma species was performed. Intra-amniotic inflammation was defined as an elevated amniotic fluid matrix metalloproteinase-8 concentration (>23 ng/mL).Results: (1) Ureaplasma species were detected by culture or PCR in 18% (18/100) of amniotic fluid samples and in 5% (5/100) of gastric fluid samples; (2) among the amniotic fluid cases positive for Ureaplasma species, these microorganisms were identified in 27.8% (5/18) of gastric fluid samples; (3) none of the cases negative for Ureaplasma species in the amniotic fluid were found to be positive for these microorganisms in the gastric fluid; (4) patients with amniotic fluid positive for Ureaplasma species but with gastric fluid negative for these microorganisms had a significantly higher rate of intra-amniotic inflammation, acute histologic chorioamnionitis, and neonatal death than those with both amniotic fluid and gastric fluid negative for Ureaplasma species; and (5) no significant differences were observed in the rate of intra-amniotic inflammation, acute histologic chorioamnionitis, and neonatal death between patients with amniotic fluid positive for Ureaplasma species but with gastric fluid negative for these microorganisms and those with both amniotic fluid and gastric fluid positive for Ureaplasma species.Conclusions: Gastric fluid analysis has 100% specificity in the identification of intra-amniotic infection with Ureaplasma species. However, the detection of Ureaplasma species by culture or PCR in the gastric fluid of neonates at birth did not identify these microorganisms in two-thirds of cases with microbial invasion of the amniotic cavity. Thus, amniotic fluid analysis is superior to that of gastric fluid in the identification of intra-amniotic infection.

The frequency and clinical significance of intra-amniotic inflammation defined as an elevated amniotic fluid matrix metalloproteinase-8 in patients with preterm labor and low amniotic fluid white blood cell counts

ObjectiveTo determine the frequency and clinical significance of intra-amniotic inflammation (IAI) defined as an elevated amniotic fluid (AF) matrix metalloproteinase-8 (MMP-8) concentration in patients with preterm labor and intact membranes (PTL) and low AF white blood cell (WBC) counts.MethodsAdverse pregnancy outcomes were compared according to the presence or absence of IAI in 220 singleton gestations who underwent amniocentesis due to PTL (gestational age<35.7 weeks) and had low AF WBC counts (<19 cells/mm3). Adverse pregnancy outcomes included preterm birth within 5 days of amniocentesis, acute histologic chorioamnionitis (acute-HCA) and positive AF culture. IAI was defined as an elevated AF MMP-8 concentration (≥23 ng/mL).ResultsIAI was present in 19% of study population. Adverse pregnancy outcomes were significantly more frequent in patients with IAI than in those without IAI (preterm birth within 5 days of amniocentesis, 88% vs. 41%; acute-HCA, 47% vs. 11%; positive AF culture, 10% vs. 2%; each for P<0.05). Patients with IAI had a significantly shorter median amniocentesis-to-delivery interval than those without IAI (7.8 hours [0.01-3,307.3 hours] vs. 310.3 hours [0.01-2,973.8 hours]; P<0.001 from survival analysis). Multiple logistic regression analysis demonstrated that only an IAI (odds ratio, 3.3; 95% confidence interval, 1.5-7.3; P<0.005) retained a statistical significance in the prediction of acute-HCA after other confounding variables were adjusted.ConclusionApproximately one-fifth of patients with PTL and low AF WBC counts have an evidence of IAI and are at risk for impending preterm delivery and acute-HCA when AF MMP-8 concentration is used.

The frequency and clinical significance of intra-amniotic inflammation in women with preterm uterine contractility but without cervical change: do the diagnostic criteria for preterm labor need to be changed?

Objective: The objective of this study was to determine the frequency and clinical significance of intra-amniotic inflammation in patients with preterm increased uterine contractility with intact membranes but without cervical change. Methods: Amniocentesis was performed in 132 patients with regular uterine contractions and intact membranes without cervical change. Amniotic fluid was cultured for bacteria and mycoplasmas and assayed for matrix metalloproteinase-8 (MMP-8). Intra-amniotic inflammation was defined as an elevated amniotic fluid MMP-8 concentration (>23 ng/mL). Results: (1) Intra-amniotic inflammation was present in 12.1% (16/132); (2) Culture-proven intra-amniotic infection was diagnosed in 3% (4/132) of patients without demonstrable cervical change on admission or during the period of observation; and (3) Patients with intra-amniotic inflammation had significantly higher rates of preterm delivery and adverse outcomes, and shorter amniocentesis-to-delivery intervals than those without intra-amniotic inflammation (P < 0.05 for each). Adverse outcomes included chorioamnionitis, funisitis, and neonatal death. Conclusion: Intra-amniotic inflammation was present in 12% of patients with regular uterine contractions without cervical change, while culture-proven intra-amniotic infection was present in 3%. The presence of intra-amniotic inflammation was a significant risk factor for adverse neonatal outcomes. These observations question whether cervical changes should be required for the diagnosis of preterm labor, because patients without modifications in cervical status on admission or during a period of observation are at risk for adverse pregnancy outcomes.

The Frequency and Clinical Significance of Intra-Uterine Infection and Inflammation in Patients with Placenta Previa and Preterm Labor and Intact Membranes

Objective Histologic placental and/or intra-amniotic inflammation is frequently documented during ascending intra-uterine infections in patients with preterm labor and intact membranes. Placenta previa can be a clinical situation that shows the successive schema of histologic placental and intra-amniotic inflammation during the process of ascending intra-uterine infections. However, a paucity of information exists about the frequency and clinical significance of intra-uterine infections and inflammation in patients with placenta previa and preterm labor and intact membranes. The purpose of this study was to examine this issue. Study design Amniocentesis was performed on 42 patients with placenta previa and preterm labor and intact membranes (gestational age < 37 weeks). Amniotic fluid (AF) was cultured for aerobic and anaerobic bacteria and genital mycoplasmas, and AF white blood cell (WBC) count and matrix metalloproteinase-8 (MMP-8) concentrations were determined. The diagnosis of intra-amniotic inflammation was made in patients with an elevated AF MMP-8 (≥23 ng/ml). Non-parametric statistics were used for analysis. Results 1) Intra-amniotic inflammation was present in 16.7% (7/42), proven AF infection in 4.9% (2/41), and histologic chorioamnionitis in 19.0% (8/42) of patients with placenta previa and preterm labor; 2) Patients with intra-amniotic inflammation had significantly higher rates of a positive AF culture, histologic chorioamnionitis, funisitis, and a shorter interval-to-delivery than those without intra-amniotic inflammation ( p < 0.05 for each); 3) Among patients with histologic chorioamnionitis, inflammation of the choriodecidua, which was exposed to the cervical canal, existed in all cases (8/8), but inflammation of the chorionic plate existed in 63% of patients (5/8); 4) Patients with inflammation of the chorionic plate had significantly higher median AF MMP-8 concentrations and WBC counts, and higher rates of intra-amniotic inflammation than those in whom inflammation was restricted to choriodecidua ( p < 0.05 for each). Conclusions Placental inflammation was present in 19.0% and intra-amniotic inflammation was present in 16.7% of patients with placenta previa and preterm labor and intact membranes. The intra-amniotic inflammatory response was stronger when inflammation was present in the chorionic plate and choriodecidua, than when it was restricted to the choriodecidua only, which was exposed to the cervical canal in placenta previa.

The importance of intra-amniotic inflammation in the subsequent development of atypical chronic lung disease

Objective. To examine whether the intra-amniotic inflammation is a risk factor for the development of atypical chronic lung disease (CLD).Study design. A retrospective cohort study was undertaken in 72 patients who delivered preterm neonates (gestational age: 24–32 weeks) within 5 days of amniocentesis and whose neonates subsequently developed CLD. Atypical CLD was defined as CLD without respiratory distress syndrome (RDS). Intra-amniotic inflammation was defined as an elevated amniotic fluid (AF) concentration of matrix metalloproteinase-8 (MMP-8) (>23 ng/ml).Results. (1) Atypical CLD was identified in 54.2% (39/72) of cases with CLD; (2) there were no significant differences in the median gestational age at birth and the rate of antenatal corticosteroid use between infants with atypical CLD and CLD with RDS; (3) preterm newborns with atypical CLD had a significantly higher median AF MMP-8 concentration (median 373.1 ng/ml vs. 8.6 ng/ml, p = 0.003) and median AF white blood cell count (median 450.0/mm3vs. 5.5/mm3, p = 0.009), and a higher rate of intra-amniotic inflammation (74.4%vs. 45.5%, p = 0.012) than those with CLD with RDS.Conclusion. Intra-amniotic inflammation confers a greater risk for atypical CLD than for typical CLD with initial RDS. This novel observation strengthens the importance of prenatal inflammation as a mechanism of lung injury.

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.

C-reactive protein concentration in vaginal fluid as a marker for intra-amniotic inflammation/infection in preterm premature rupture of membranes

Objective. The purpose of this study was to determine whether C-reactive protein (CRP) concentrations in vaginal fluid can identify patients with intra-amniotic inflammation/infection (IAI) and predict adverse outcome in preterm premature rupture of membranes (PROM).Methods. The study population consisted of 121 singleton pregnant women with preterm PROM (⩽36 weeks of gestation) who had an amniocentesis and vaginal fluid collection. A Dacron polyester-tipped applicator was soaked with vaginal fluid for 10 seconds and diluted with 1 mL buffer solution. Amniotic fluid was cultured for aerobic and anaerobic bacteria, as well as mycoplasmas. Vaginal fluid CRP and amniotic fluid matrix metalloproteinase-8 (MMP-8) were determined by specific immunoassays. IAI was defined as an amniotic fluid MMP-8 concentration >23 ng/mL and/or a positive amniotic fluid culture. Nonparametric tests and survival techniques were used for statistical analysis.Results. Patients with IAI had a significantly higher median vaginal fluid CRP concentration than those without IAI (median (range), 7.8 (0.1–1310.1) ng/mL vs. 1.0 (0.1–319.4) ng/mL, p < 0.005). The median amniotic fluid white blood cell (WBC) count was significantly higher in patients with a vaginal fluid CRP concentration of >10 ng/mL than in those with a lower concentration (median (range), 82.5 (0–8640) cells/mm3 vs. 2 (0–>1000) cells/mm3, p < 0.001). Patients with vaginal fluid CRP concentration of >10 ng/mL had a significantly shorter sampling-to-delivery interval and higher rates of preterm delivery within five days, funisitis, and histologic chorioamnionitis than did those with a vaginal fluid CRP concentration below this cut-off. A vaginal fluid CRP cut-off of 10 ng/mL had a specificity of 89% and a sensitivity of 45% in the identification of IAI.Conclusion. An elevated CRP concentration in vaginal fluid collected by polyester-tipped applicator is a risk factor for intra-amniotic inflammation/infection and impending preterm delivery in preterm PROM.

Clinical significance of intra-amniotic inflammation in patients with preterm premature rupture of membranes

This study was conducted to determine the frequency and clinical significance of intra-amniotic inflammation in patients with preterm premature rupture of the membranes. Amniotic fluid was retrieved from 219 patients with preterm premature rupture of the membranes; the fluid was cultured for aerobic and anaerobic bacteria and mycoplasmas and assayed for neutrophil collagenase, which is also known as matrix metalloproteinase-8. Matrix metalloproteinase-8 was used because previous studies indicated that this was a sensitive and specific index of inflammation and that is correlated with the amniotic fluid white blood cell count. Intra-amniotic inflammation was defined as an elevated amniotic fluid matrix metalloproteinase-8 concentration (>23 ng/mL). Nonparametric and survival techniques were used for statistical analysis. The overall rate of intra-amniotic inflammation was 42% (93/219 samples); proven intra-amniotic infection was detected only in 23% (50/219 samples). Intra-amniotic inflammation with a negative amniotic fluid culture for micro-organisms was found in 23% (51/219 samples) and was as common as proven intra-amniotic infection. Pregnancy outcome was worse in patients with intra-amniotic inflammation and a negative culture than in those patients with a negative culture and without inflammation. There were no differences in the interval-to-delivery or rate of complications between patients with intra-amniotic inflammation and a negative culture and patients with proven amniotic fluid infection. We conclude that intra-amniotic inflammation, regardless of culture result, is present in 42% of patients with preterm premature rupture of the membranes and that it is a risk factor for impending preterm delivery and adverse outcome. We propose that intra-amniotic inflammation, rather than infection, be used to classify and treat patients with preterm premature rupture of the membranes.

An elevated amniotic fluid matrix metalloproteinase-8 level at the time of mid-trimester genetic amniocentesis is a risk factor for spontaneous preterm delivery

Objective: Strong evidence implicates chronic intra-amniotic inflammation in the etiology of mid-trimester abortion and spontaneous preterm delivery. The purpose of this study was to determine if concentrations of amniotic fluid matrix metalloproteinase-8, and cytokines such as interleukin-6 and angiogenin can identify patients at risk for spontaneous preterm delivery in patients undergoing mid-trimester amniocentesis. Study Design: A case-control study was conducted to compare mid-trimester concentrations of amniotic fluid matrix metalloproteinase-8, interleukin-6, and angiogenin in patients who delivered at term and in those who delivered before term. The study included 19 cases with spontaneous preterm delivery and 95 matched controls with normal outcomes. Patients with abnormal fetal karyotypes or major anomalies were excluded. Matrix metalloproteinase-8, interleukin-6, and angiogenin were measured by using specific immunoassays. Mann-Whitney U tests, Fisher exact tests, and receiver-operating characteristic curves were used for statistical analysis. Results: The median amniotic fluid matrix metalloproteinase-8, interleukin-6, and angiogenin concentrations of patients with spontaneous preterm delivery were significantly higher than those of control cases (matrix metalloproteinase-8: median, 3.1 ng/mL [range, 0.3-1954.9 ng/mL] vs median, 1.3 ng/mL [range, <0.3-45.2 ng/mL], P <.01; interleukin-6: median, 0.32 ng/mL [range, 0.04-2.52 ng/mL] vs median, 0.18 ng/mL [range, 0.01-1.81 ng/mL], P <.01; angiogenin: median, 11.1 ng/mL [range, 4.5-30.7 ng/mL] vs median, 6.7 ng/mL [range, 1.3-21.9 ng/mL], P <.001). Amniotic fluid matrix metalloproteinase-8 concentrations higher than 23 ng/mL had the highest specificity and odds ratio (sensitivity, 42% [8/19]; specificity, 99% [94/95]; OR, 68.4 [95% CI, 7.8-599.1]) in the identification of the patients with preterm delivery after genetic amniocentesis. Conclusions: Elevated mid-trimester concentrations of amniotic fluid matrix metalloproteinase-8, interleukin-6, and angiogenin are a risk factor for early spontaneous preterm delivery (<32 weeks). An elevated matrix metalloproteinase-8 level of >23 ng/mL is a powerful predictor of spontaneous preterm delivery (<32 weeks) with an odds ratio of 68.4. Amniotic fluid studies can be used to improve the risk assessment for preterm delivery in women who undergo mid-trimester amniocentesis for genetic indications. (Am J Obstet Gynecol 2001;185:1162-7.)

Value of amniotic fluid neutrophil collagenase concentrations in preterm premature rupture of membranes

Objective: Neutrophils in amniotic fluid are thought to be of fetal origin, and therefore the detection of these cells and/or their products in amniotic fluid may reflect the fetal inflammatory status. We propose that amniotic fluid neutrophil collagenase (matrix metalloproteinase-8) is a useful parameter to predict adverse neonatal outcome, impending preterm labor/delivery, and intrauterine infection in the setting of preterm premature rupture of the membranes. Study Design: Amniotic fluid was obtained by transabdominal amniocentesis from 101 patients with preterm premature rupture of the membranes (gestational age, 24-36 weeks). Fluid was cultured for aerobic and anaerobic bacteria and Mycoplasmas. Amniotic fluid analysis included Gram stain, white blood cell count, and determination of interleukin-6 and matrix metalloproteinase-8 concentrations (enzyme-linked immunosorbent assay). Results: Neonates with adverse neonatal outcome were born to mothers with a significantly higher median amniotic fluid matrix metalloproteinase-8 concentration than those without adverse neonatal outcome (median, 54.4 ng/mL; range, 0.82-14,500 ng/mL vs median, 28.9 ng/mL; range, 0.78-2451.8 ng/mL; P <.05, respectively). The higher the amniotic fluid matrix metalloproteinase-8 concentrations, the shorter the interval to delivery (Cox proportional hazards model adjusting for gestational age at delivery; hazard ratio, 1.9; 95% CI, 1.1-3.5; P <.03). Amniotic fluid matrix metalloproteinase-8 concentration was more sensitive than an amniotic fluid white blood cell count and interleukin-6 in the detection of microbiologically proven intra-amniotic infection. Conclusion: Increased concentrations of neutrophil collagenase (matrix metalloproteinase-8) in amniotic fluid are associated with intra-amniotic infection, impending preterm delivery, and adverse neonatal outcome in patients with preterm premature rupture of the membranes. Moreover, matrix metalloproteinase-8 in amniotic fluid is a stronger predictor for the duration of pregnancy and intra-amniotic inflammation than interleukin-6 and an amniotic fluid white blood cell count. (Am J Obstet Gynecol 2001;185:1143-8.)