Should the diagnostic criteria for suspected clinical chorioamnionitis be changed?

The histologic fetal inflammatory response and neonatal outcomes: systematic review and meta-analysis

OBJECTIVE

This study aimed to investigate the prognostic role of concomitant histological fetal inflammatory response with chorioamnionitis on neonatal outcomes through a systematic review and meta-analysis of existing literature.

DATA SOURCES

The primary search was conducted on October 17, 2021, and it was updated on May 26, 2023, across 4 separate databases (MEDLINE, the Cochrane Central Register of Controlled Trials, Embase, and Scopus) without using any filters.

STUDY ELIGIBILITY CRITERIA

Observational studies reporting obstetrical and neonatal outcomes of infant-mother dyads with histological chorioamnionitis and histological fetal inflammatory response vs infant-mother dyads with histological chorioamnionitis alone were eligible. Studies that enrolled only preterm neonates, studies on neonates born before 37 weeks of gestation, or studies on neonates with very low birthweight (birthweight <1500 g) were included. The protocol was registered with the International Prospective Register of Systematic Reviews (registration number: CRD42021283448).

METHODS

The records were selected by title, abstract, and full text, and disagreements were resolved by consensus. Random-effect model-based pooled odds ratios with corresponding 95% confidence intervals were calculated for dichotomous outcomes.

RESULTS

Overall, 50 studies were identified. A quantitative analysis of 14 outcomes was performed. Subgroup analysis using the mean gestational age of the studies was performed, and a cutoff of 28 weeks of gestation was implemented. Among neonates with lower gestational ages, early-onset sepsis (pooled odds ratio, 2.23; 95% confidence interval, 1.76-2.84) and bronchopulmonary dysplasia (pooled odds ratio, 1.30; 95% confidence interval, 1.02-1.66) were associated with histological fetal inflammatory response. Our analysis showed that preterm neonates with a concomitant histological fetal inflammatory response are more likely to develop intraventricular hemorrhage (pooled odds ratio, 1.54; 95% confidence interval, 1.18-2.02) and retinopathy of prematurity (pooled odds ratio, 1.37; 95% confidence interval, 1.03-1.82). The odds of clinical chorioamnionitis were almost 3-fold higher among infant-mother dyads with histological fetal inflammatory response than among infant-mother dyads with histological chorioamnionitis alone (pooled odds ratio, 2.99; 95% confidence interval, 1.96-4.55).

CONCLUSION

This study investigated multiple neonatal outcomes and found association in the case of 4 major morbidities: early-onset sepsis, bronchopulmonary dysplasia, intraventricular hemorrhage, and retinopathy of prematurity.

Risk of adverse perinatal outcomes among women with clinical and subclinical histopathological chorioamnionitis

Introduction

Histologic chorioamnionitis (HCA) is a placental inflammatory condition associated with adverse perinatal outcomes (APOs). This historical cohort study explores the risk of APOs in pregnant women with HCA and compares the impact of clinical chorioamnionitis (CCA) with subclinical chorioamnionitis (SCCA).

Methodology

Placentas were evaluated by a perinatal pathologist tand all women with HCA were included. Two groups were integrated: (1) women with clinical chorioamnionitis (CCA) and (2) women with subclinical chorioamnionitis (SCCA). Additionally, we conducted a secondary analysis to compare the prevalence of APOs among stage 1, 2 and 3 of HCA and the risk of APOs between grades 1 and 2 of HCA. The APOs analyzed were preterm birth, stillbirth, neonatal weight < 1,500 g, neonatal sepsis. Relative risk with 95% confidence interval was calculated.

Results

The study included 41 cases of CCA and 270 cases of SCCA. The mean gestational age at diagnosis and birth was 30.2 ± 5.4 weeks and 32.5 ± 5.1 weeks, for group 1 and 2, respectively. The study also found that women with HCA stage 3 and grade 2 had a higher prevalence and risk of adverse perinatal outcomes.

Discussion

The findings of this study suggest the importance of placental histological study to excluded SCCA, which represents a significant risk to both maternal and neonatal health, contributing to high morbidity and mortality.

Correlation between intrapartum CTG findings and interleukin-6 levels in the umbilical cord arterial blood: A prospective cohort study

OBJECTIVE

to investigate the correlation between the intrapartum CardioTocoGraphic (CTG) findings "suggestive of fetal inflammation" ("SOFI") and the interleukin (IL)-6 level in the umbilical arterial blood.

STUDY DESIGN

prospective cohort study conducted at a tertiary maternity unit and including 447 neonates born at term.

METHODS

IL-6 levels were systematically measured at birth from a sample of blood taken from the umbilical artery. The intrapartum CTG traces were retrospectively reviewed by two experts who were blinded to the postnatal umbilical arterial IL-6 values as well as to the neonatal outcomes. The CTG traces were classified into "suggestive of fetal inflammation (SOFI)" and "no evidence of fetal inflammation (NEFI) according to the principles of physiologic interpretation the CTG traces. The CTG was classified as "SOFI" if there was a persistent fetal heart rate (FHR) increase > 10 % compared with the observed baseline FHR observed at the admission or at the onset of labor without any preceding repetitive decelerations. The occurrence of Composite Adverse Outcome (CAO) was defined as Neonatal Intensive Care Unit (NICU) or Special Care Baby Unit (SCBU) admission due to one or more of the following: metabolic acidaemia, Apgar score at 5 min ≤ 7, need of neonatal resuscitation, respiratory distress, tachypnoea/polypnea, jaundice requiring phototherapy, hypotension, body temperature instability, poor perinatal adaptation, suspected or confirmed early neonatal sepsis.

MAIN OUTCOME MEASURES

To compare the umbilical IL-6 values between the cases with intrapartum CTG traces classified as "SOFI" and those classified as "NEFI"; to assess the correlation of umbilical IL-6 values with the neonatal outcome.

RESULTS

43 (9.6 %) CTG traces were categorized as "SOFI"; IL-6 levels were significantly higher in this group compared with the "NEFI" group (82.0[43.4-325.0] pg/ml vs. 14.5[6.8-32.6] pg/mL; p <.001). The mean FHR baseline assessed 1 h before delivery and the total labor length showed an independent and direct association with the IL-6 levels in the umbilical arterial blood (p <.001 and p = 0.005, respectively). CAO occurred in 33(7.4 %) cases; IL-6 yielded a good prediction of the occurrence of the CAO with an AUC of 0.72 (95 % CI 0.61-0.81).

CONCLUSION

Intrapartum CTG findings classified as "SOFI" are associated with higher levels of IL-6 in the umbilical arterial blood.

Validation of diagnosis codes for chorioamnionitis in medical encounter data, 2013-2018

PURPOSE

Chorioamnionitis refers to intrauterine infection/inflammation that can be diagnosed clinically or from laboratory testing. This study aimed to validate chorioamnionitis International Classification of Diseases (ICD) codes using reference standards for clinical and histologic cases.

METHODS

Department of Defense Birth and Infant Health Research program data identified a cohort of live deliveries at two United States military hospitals from 2013 to 2018. Deliveries were screened for chorioamnionitis using ICD codes from maternal delivery records; a sample of screen positive and negative deliveries was selected for chart review. Primary analyses validated deliveries using a reference standard for clinical chorioamnionitis; secondary analyses employed a reference standard that also included histologic cases, but were limited by temporal differences in availability of laboratory data. Sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values were calculated with 95% confidence intervals (CIs).

RESULTS

Overall, 1857 deliveries (465 screen positive, 1392 screen negative) were eligible for analysis and 336 met the reference standard for clinical chorioamnionitis, yielding a PPV of 0.68 (95% CI 0.63, 0.72) and sensitivity of 0.76 (95% CI 0.72, 0.81). In secondary analyses, 390 deliveries met the reference standard for clinical or histologic chorioamnionitis, resulting in an overall PPV of 0.75 (95% CI 0.71, 0.79); in 2018, when more laboratory results were available, the PPV was 0.91 (95% CI 0.84, 0.97). NPV and specificity were ≥0.97 across reference standards.

CONCLUSIONS

Chorioamnionitis ICD codes exhibited moderate correlation with clinical disease, suggesting challenges in using medical encounter data to isolate clinical cases from those only identified through laboratory testing.

Tdap vaccination during pregnancy and risk of chorioamnionitis and related infant outcomes

INTRODUCTION

An increased risk of chorioamnionitis in people receiving tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine during pregnancy has been reported. The importance of this association is unclear as additional study has not demonstrated increased adverse infant outcomes associated with Tdap vaccination in pregnancy.

METHODS

We conducted a retrospective observational cohort study of pregnant people ages 15-49 years with singleton pregnancies ending in live birth who were members of 8 Vaccine Safety Datalink (VSD) sites during October 2016-September 2018. We used a time-dependent covariate Cox model with stabilized inverse probability weights applied to evaluate associations between Tdap vaccination during pregnancy and chorioamnionitis and preterm birth outcomes. We used Poisson regression with robust variance with stabilized inverse probability weights applied to evaluate the association of Tdap vaccination with adverse infant outcomes. We performed medical record reviews on a random sample of patients with ICD-10-CM-diagnosed chorioamnionitis to determine positive predictive values (PPV) of coded chorioamnionitisfor "probable clinical chorioamnionitis," "possible clinical chorioamnionitis," or "histologic chorioamnionitis."

RESULTS

We included 118,211 pregnant people; 103,258 (87%) received Tdap vaccine during pregnancy; 8098 (7%) were diagnosed with chorioamnionitis. The adjusted hazard ratio for chorioamnionitis in the Tdap vaccine-exposed group compared to unexposed was 0.96 (95% CI 0.90-1.03). There was no association between Tdap vaccine and preterm birth or adverse infant outcomes associated with chorioamnionitis. Chart reviews were performed for 528 pregnant people with chorioamnionitis. The PPV for clinical (probable or possible clinical chorioamnionitis) was 48% and 59% for histologic chorioamnionitis. The PPV for the combined outcome of clinical or histologic chorioamnionitis was 81%.

CONCLUSIONS AND RELEVANCE

Tdap vaccine exposure during pregnancy was not associated with chorioamnionitis, preterm birth, or adverse infant outcomes. ICD-10 codes for chorioamnionitis lack specificity for clinical chorioamnionitis and should be a recognized limitation when interpreting results.

Clinical characteristics, complications, and predictive model of histological chorioamnionitis in women with preterm premature rupture of membranes

We aimed to analyze the impact of histological chorioamnionitis (HCA) in the presence of preterm premature rupture of the membranes (PPROM) on obstetric and neonatal outcomes, and its possible predictability. A retrospective cohort analysis of PPROM cases (20-37 weeks) was conducted comparing the patients with and without HCA, seeking a predictive model of HCA using logistic regression. A total of 295 cases of PPROM were selected, of which 72 (24.4%) had HCA. The group with HCA had a shorter latency period and a greater number of clinical and laboratory criteria in the evolution. The group with HCA had a worse comparative result and presented: lower gestational age at delivery, lower average birth weight, lower Apgar scores, longer neonatal hospitalization, worse maternal clinical conditions and, higher rates of stillbirth, low birth weight (LBW), very low birth weight (VLBW), complications in pregnancy and childbirth, and cesarean delivery due to fetal distress or chorioamnionitis. A predictive model for HCA was developed, with the following independent variables: abdominal pain (odds ratio [OR] = 11.61), uterine activity (noticeable contractions on physical exam) (OR = 5.97), fever (OR = 5.77), latency > 3 days (OR = 2.13), and C-reactive protein (OR = 1.01). With this model, an adequate receiver operating characteristic curve was found, with an area under the curve of 0.726, and some HCA probability curves were constructed for different clinical situations. In this novel study, we present a non-invasive predictive model, with clinical and laboratory variables, which may help in decision-making in a patient with PPROM.

Association of clinical signs of chorioamnionitis with histological chorioamnionitis and neonatal outcomes

BACKGROUND

Chorioamnionitis is a risk factor for fetal and neonatal outcomes. Therefore, predicting histological chorioamnionitis (HCA) and neonatal outcomes using clinical parameters could be helpful in management and preventing morbidities.

OBJECTIVE

To determine if parameters of clinical chorioamnionitis (CCA) would be associated with HCA and neonatal outcomes.

STUDY DESIGN

In this cohort study using a retrospective design, we analyzed the performance of signs of CCA in predicting HCA, and neonatal outcomes. Data were extracted from the electronic health record for all neonates with documented CCA delivered at our institution from 2011 to 2016. We compared our findings based on the old ACOG definition of CCA and the new definition released in 2017 - maternal fever plus any of fetal tachycardia, maternal leukocytosis, and purulent vaginal discharge. Maternal tachycardia and uterine tenderness were removed from the new criteria. Neonatal laboratory samples on admission, 12 h and 24 h were used to define the three time points of neonatal suspected sepsis.

RESULTS

There were 530 mothers-infant dyads with chorioamnionitis. Seventy-three were preterm, and 457 were term. Eighty-eight percent of the preterm mothers had CCA, and HCA was present in 62.5% of 72 preterm placentas. Preterm infants with placental HCA significantly had lower birth weight, gestational age, placental weight, and more infants with lower 5-minute Apgar scores, compared to those with no HCA. In preterm infants, maternal urinary tract infection was significantly associated with decreased odds for HCA (OR 0.22, CI 0.10 - 0.71). More preterm babies with suspected sepsis criteria at the 3 time points had HCA (all p ≤ .01). In the term cohort, 95.4% and 65.6% had CCA and HCA, respectively. In term infants (n = 457), maternal leukocytosis (p = .002) and prolonged rupture of membranes (PROM; p = 002) were associated with HCA. Suspected sepsis was associated with PROM (p = .04), HCA (p = .0001), and maternal leukocytosis (p ≤ .05) in at least 1 of the 3 time points.

CONCLUSION

Though maternal leukocytosis was significantly associated with the presence of HCA in the term cohort, there were no CCA criteria that accurately predicted presence of HCA in either the preterm or the term infants.

Histological severity of maternal and fetal inflammation is correlated with the prevalence of maternal clinical signs

AIM

To evaluate whether there is a stepwise increase in the prevalence of maternal clinical signs according to the severity of histological inflammation in the chorioamniotic membranes, placenta, and umbilical cord in preterm deliveries.

METHODS

This retrospective study, conducted between January 2007 and May 2017, included patients with preterm delivery between 22 and 33 weeks. The histological findings of maternal/fetal inflammatory responses were staged and graded according to the Amsterdam Placental Workshop Group consensus statement. Correlations between the histological severity of maternal/fetal inflammatory responses and the prevalence of clinical chorioamnionitis and clinical signs were evaluated using the Cochran-Armitage trend test.

RESULTS

A total of 138 patients were included. The stage and grade of the maternal inflammatory response were correlated with earlier gestational weeks at delivery and lighter birth weight. The prevalence of clinical chorioamnionitis was significantly correlated with a higher stage and grade of the maternal inflammatory response (Gibbs/Lencki criteria: 15.8%/15.8% in Stage 3, 16.3%/14% in Grade 2). No significant correlations were observed between gestational weeks at delivery and birth weight and stage/grade of fetal inflammatory response. The prevalence of clinical chorioamnionitis was significantly correlated with higher stage and grade of fetal inflammatory response (Gibbs/Lencki criteria: 25%/25% in Stage 3 and 29.4%/29.4% in Grade 2).

CONCLUSION

Correlations exist between the severity of histological maternal/fetal inflammatory responses and the prevalence of clinical chorioamnionitis and positive maternal clinical signs in preterm deliveries. However, the prevalence of clinical chorioamnionitis was 20%-30% even in the most severe fetal inflammatory responses.

Expression of S100A Alarmins in Cord Blood Monocytes Is Highly Associated With Chorioamnionitis and Fetal Inflammation in Preterm Infants

Background: Preterm infants exposed to chorioamnionitis and with a fetal inflammatory response are at risk for neonatal morbidity and adverse outcome. Alarmins S100A8, S100A9, and S100A12 are expressed by myeloid cells and have been associated with inflammatory activation and monocyte modulation.

Aim: To study S100A alarmin expression in cord blood monocytes from term healthy and preterm infants and relate results to clinical findings, inflammatory biomarkers and alarmin protein levels, as well as pathways identified by differentially regulated monocyte genes.

Methods: Cord blood CD14+ monocytes were isolated from healthy term (n = 10) and preterm infants (<30 weeks gestational age, n = 33) by MACS technology. Monocyte RNA was sequenced and gene expression was analyzed by Principal Component Analysis and hierarchical clustering. Pathways were identified by Ingenuity Pathway Analysis. Inflammatory proteins were measured by Multiplex ELISA, and plasma S100A proteins by mass spectrometry. Histological chorioamnionitis (HCA) and fetal inflammatory response syndrome (FIRS) were diagnosed by placenta histological examination.

Results: S100A8, S100A9, and S100A12 gene expression was significantly increased and with a wider range in preterm vs. term infants. High S100A8 and S100A9 gene expression (n = 17) within the preterm group was strongly associated with spontaneous onset of delivery, HCA, FIRS and elevated inflammatory proteins in cord blood, while low expression (n = 16) was associated with impaired fetal growth and physician-initiated delivery. S100A8 and S100A9 protein levels were significantly lower in preterm vs. term infants, but within the preterm group high S100A gene expression, spontaneous onset of labor, HCA and FIRS were associated with elevated protein levels. One thousand nine hundred genes were differentially expressed in preterm infants with high vs. low S100A alarmin expression. Analysis of 124 genes differentially expressed in S100A high as well as FIRS and HCA groups identified 18 common pathways and S100A alarmins represented major hubs in network analyses.

Conclusion: High expression of S100A alarmins in cord blood monocytes identifies a distinct clinical risk group of preterm infants exposed to chorioamnionitis and with a fetal inflammatory response. Gene and pathway analyses suggest that high S100A alarmin expression also affects monocyte function. The connection with monocyte phenotype and inflammation-stimulated S100A expression in other cell types (e.g., neutrophils) warrants further investigation.

Clinical chorioamnionitis criteria are not sufficient for predicting intra-amniotic infection

Aim: To evaluate the diagnostic performance of three conventional clinical chorioamnionitis criteria; including Gibbs, Lencki, and suspected triple I; for the prediction of intra-amniotic infection.Methods: A retrospective cohort study was conducted using data from three perinatal centers from 2014 to 2018. Patients with preterm labor or premature prelabor rupture of membranes between 22 and 33 weeks of gestation and those who underwent transabdominal amniocentesis to detect intra-amniotic infection were selected. Intra-amniotic infection was defined as a positive amniotic fluid culture for microorganisms, including genital mycoplasmas, plus low glucose level or leukocytosis in amniotic fluid. Sensitivity, specificity, and positive and negative likelihood ratios were calculated to determine the diagnostic performance of each criterion in predicting intra-amniotic infection.Results: Of 99 pregnant women who met the study inclusion criteria, 13 (13.1%) had intra-amniotic infection confirmed by amniocentesis and 86 (86.9%) had no intra-amniotic infection. Maternal characteristics were not significantly different between groups, except for the higher incidence of preterm, prelabor rupture of membranes in pregnant women with intra-amniotic infection (53.8 versus 14%, p < .01). The incidences of clinical chorioamnionitis in the non-IAI and IAI groups were 1 of 86 (1.2%), 1 of 86 (1.2%), 0 of 86 (0%) and 2 of 13 (15.4%), 2 of 13 (15.4%), 2 of 13 (15.4%) according to Gibbs, Lenki, and suspected triple I criteria, respectively. The specificity of the three criteria ranged from 98.8 to 100%; however, the sensitivity was low (15.4%). The positive likelihood ratio was significant for three criteria from 13.2 (95% confidence interval [CI], 1.29-135) to infinite. However, the negative likelihood ratio was not low enough and not significant for the three criteria (0.85 [95% CI, 0.67-1.07] to 0.86 [95% CI, 0.68-1.08]).Conclusion: The conventional clinical chorioamnionitis criteria are not sensitive for the prediction of intra-amniotic infection in pregnant women with preterm labor and/or preterm prelabor rupture of membranes.