Meconium staining of the amniotic fluid and the presence and severity of acute placental inflammation: a study of term deliveries in a predominantly African-American population.

OBJECTIVE: To determine frequency, stage and grade of placental histologic acute maternal inflammatory response (MIR) and fetal inflammatory response (FIR) in meconium-stained amniotic fluid (MSAF) in our predominantly African-American population. METHODS: Term placentas with MSAF (n = 310) were evaluated for MIR/FIR, including stage/grade, and compared with placentas with clear amniotic fluid (AF) (n = 250). MIR/FIR were also evaluated in thick compared to thin MSAF subgroups. Selected demographic and clinical features were compared. RESULTS: MIR and FIR were present in 57.7 and 40.3% of the MSAF compared to 44.0 and 29.2% of the clear AF group, respectively (p = .001 and .008). MIR with FIR was present in 35.8% of the MSAF compared to 25.2% of the clear AF group (p = .008); however, there was no significant difference in frequency of MIR without FIR between groups. There was no significant difference in frequency of MIR/FIR in thick compared to thin MSAF; however, thick MSAF was associated with higher FIR stage compared to thin MSAF (29.2 versus 5.4%, p = .004). This association was not seen with MIR stage or MIR/FIR grade. CONCLUSIONS: Histologic MIR and FIR are frequent findings in MSAF. Thick MSAF is associated with higher FIR stage when compared to thin MSAF.

Neonatal Morbidities Associated with Histologic Chorioamnionitis Defined Based on the Site and Extent of Inflammation in Very Low Birth Weight Infants.

Conflicting results on the influences of histologic chorioamnionitis (HC) on neonatal morbidities might be partly originated from using different definition of HC. The aim of this study was to determine the relationship between HC and neonatal morbidities using definition of HC that reflects the site and extent of inflammation. This was a retrospective cohort study of 261 very low birth weight (VLBW) infants admitted at a tertiary academic center. Based on the site of inflammation, HC was categorized: any HC; amnionitis; funisitis; amnionitis+funisitis. The extent of inflammation in each site was reflected by sub-defining high grade (HG). The incidences of morbidities in infants with and without HC were compared. The bronchopulmonary dysplasia (BPD) rate was significantly higher in infants with amnionitis and the severe retinopathy of prematurity (ROP) rate was significantly higher in infants with any HC and funisitis. After adjustment for both gestational age and birth weight, the respiratory distress syndrome (RDS) rate was significantly lower in infants with all categories of HC except for HG amnionitis and HG funisitis, which are not associated with lower RDS rate. HG amnionitis was significantly associated with increased BPD rate but the association of HC with severe ROP disappeared. In conclusion, HC is significantly associated with decreased RDS and HG amnionitis with increased BPD while lacking association with other neonatal morbidities in VLBW infants. The association with HC and neonatal morbidities differs by the site and extent of chorioamnionitis.

Neonatal Morbidities Associated with Histologic Chorioamnionitis Defined Based on the Site and Extent of Inflammation in Very Low Birth Weight Infants

Conflicting results on the influences of histologic chorioamnionitis (HC) on neonatal morbidities might be partly originated from using different definition of HC. The aim of this study was to determine the relationship between HC and neonatal morbidities using definition of HC that reflects the site and extent of inflammation. This was a retrospective cohort study of 261 very low birth weight (VLBW) infants admitted at a tertiary academic center. Based on the site of inflammation, HC was categorized: any HC; amnionitis; funisitis; amnionitis+funisitis. The extent of inflammation in each site was reflected by sub-defining high grade (HG). The incidences of morbidities in infants with and without HC were compared. The bronchopulmonary dysplasia (BPD) rate was significantly higher in infants with amnionitis and the severe retinopathy of prematurity (ROP) rate was significantly higher in infants with any HC and funisitis. After adjustment for both gestational age and birth weight, the respiratory distress syndrome (RDS) rate was significantly lower in infants with all categories of HC except for HG amnionitis and HG funisitis, which are not associated with lower RDS rate. HG amnionitis was significantly associated with increased BPD rate but the association of HC with severe ROP disappeared. In conclusion, HC is significantly associated with decreased RDS and HG amnionitis with increased BPD while lacking association with other neonatal morbidities in VLBW infants. The association with HC and neonatal morbidities differs by the site and extent of chorioamnionitis.

Accuracy of signs of clinical chorioamnionitis in the term parturient.

OBJECTIVE: Uniform histopathologic guidelines were applied to diagnose chorioamnionitis and estimate the accuracy of clinical signs in term parturients. STUDY DESIGN: A retrospective cohort study utilized slides from term parturient placentas with Amniotic Fluid Infection Nosology Committee guidelines as the gold standard. Sensitivity, specificity and accuracy for fever, maternal tachycardia and fetal tachycardia were calculated. RESULT: Of 641 placentas, 367 (57.3%) had histologic chorioamnionitis and 274 (42.7%) were negative. Fever had a sensitivity of 42%, specificity of 86.5% and accuracy of 61%. Fever, maternal tachycardia and fetal tachycardia had a sensitivity of 18.3%, specificity of 98.2% and accuracy of 52.4%. CONCLUSION: Histologic chorioamnionitis, frequently asymptomatic, is a common finding in placentas examined from term parturients. Clinical signs are not accurate in the diagnosis. Adoption of uniform pathologic guidelines will facilitate research into the clinical significance of these lesions in the future.

Funisitis and chorionic vasculitis: relation to chorioamnionitis, timing and scoring.

Five hundred consecutive cases with histologic chorioamnionitis and umbilical cord inflammation were analyzed to develop a staging system for funisitis and to correlate stage of funisitis with stage of chorioamnionitis in order to estimate the timing of various stages of funisitis. Funisitis progresses through venous involvement (with or without Wharton's jelly inflammation) to arterial involvement without Wharton's jelly and then full involvement of all three vessels and surrounding Wharton's jelly. Arterial involvement and full funisitis are strongly associated with stage III/IV chorioamnionitis, and imply a significant time interval following the onset of amniotic cavity inflammation.

Amniotic infection syndrome: nosology and reproducibility of placental reaction patterns.

Clinically responsive placental examination seeks to provide useful information regarding the etiology, prognosis, and recurrence risk of pregnancy disorders. The purpose of this study was to assemble and validate a complete set of the placental reaction patterns seen with amniotic fluid infection in the hope that this might provide a standardized diagnostic framework useful for practicing pathologists. Study cases (14 with amniotic fluid infection, 6 controls) were reviewed blindly by six pathologists after agreement on a standard set of diagnostic criteria. After analysis of initial results, criteria were refined and a second, overlapping set of cases were reviewed. Majority vote served as the gold standard. Grading and staging of maternal and fetal inflammatory responses was found to be more reproducible using a two- versus three-tiered grading system than a three- versus five-tiered staging system (overall agreement 81% vs. 71%). Sensitivity, specificity, and efficiency for individual observations ranged from 67-100% (24/30 > 90%). Reproducibility was measured by unweighted kappa values and interpreted as follows: < 0.2, poor; 0.2-0.6, fair/moderate; > 0.6, substantial. Kappa values for the 12 lesions evaluated in 20 cases by the six pathologists were: acute chorioamnionitis/maternal inflammatory response (any, 0.93; severe 0.76; advanced stage, 0.49); chronic (subacute) chorioamnionitis (0.25); acute chorioamnionitis/fetal inflammatory response (any, 0.90; severe, 0.55; advanced stage, 0.52); chorionic vessel thrombi (0.37); peripheral funisitis (0.84); acute villitis (0.90); acute intervillositis/intervillous abscesses (0.65), and decidual plasma cells (0.30). Adoption of this clearly defined, clinically relevant, and pathologically reproducible terminology could enhance clinicopathologic correlation and provide a framework for future clinical research.

The relationship between amniotic fluid interleukin-6 concentration and histologic evidence of chorioamnionitis.

BACKGROUND: Chorioamnionitis is considered to be one of the important causes of preterm labor. To investigate the relationship between inflammatory cytokines in amniotic fluid and the histologic evidence of chorioamnionitis, we studied amniotic fluid interleukin-6 (IL-6) levels in patients with preterm labor. METHODS: Between 1993 and 1996, we obtained amniotic fluid by amniocentesis from 110 patients before 32 weeks of gestation who had preterm labor on admission. We measured IL-6 levels in the amniotic fluid with an ELISA method. Histologic examination of placentae and fetal membranes after delivery was evaluated. As controls, we measured IL-6 levels in the amniotic fluid of 37 patients without preterm labor. Seventy-eight patients delivered after 35 weeks of gestation, and 32 patients delivered before 34 weeks of gestation. Analysis was conducted using Mann-Whitney U test and Scheffe's multiple comparison test. RESULTS: Amniotic fluid IL-6 levels in patients delivering before 34 weeks were significantly higher than those in patients delivering after 35 weeks (p<0.01). IL-6 levels in the amniotic fluid were significantly different among control patients, patients without chorioamnionitis and those with histologic stages I, II and III which means subchorionic intervillositis, chorionitis and amnionitis, respectively (controls vs patients with stage I, II, III: p<0.001, patients without chorioamnionitis vs those with stage II, III, stage I vs II, stage II vs III: p<0.01). The IL-6 concentration in the amniotic fluid associated with histologic stages II or III was above 3500 pg/ml (sensitivity: 87.5%, specificity: 89.5%). CONCLUSIONS: Our findings indicate that amniotic fluid IL-6 may have a sensitive diagnostic and prognostic value in the management of preterm labor and is an index of the severity of chorioamnionitis during pregnancy.