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Poster Session 3

(864) Preterm labor with intact membranes: the differential diagnosis between intraamniotic infection and sterile intraamniotic inflammation

Friday, January 31, 2025
10:30 AM – 12:30 PM  

    Submitting Author and Presenting Author(s)

  • Mousa Eissa, MD (he/him/his)

    MFM Fellow
    Detroit Medical Center
    Detroit, Michigan, United States

    • Coauthor(s)

  • Roberto Romero, MD

    Chief
    Pregnancy Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research, Eunice Kennedy Shriver NICHD, NIH, DHHS, Bethesda, Maryland, USA
    Bethesda, Maryland, United States

  • DB

    David R. Bryant, MD

    Wayne State University School of Medicine
    Detroit, Michigan, United States

  • Fatima Ali, DO (she/her/hers)

    Fellow
    Detroit Medical Center/Wayne State University
    Detroit, Michigan, United States

  • AM

    Arun Mezzayhagan, PhD

    Wayne State University School of Medicine
    Detroit, Michigan, United States

  • TC

    Tinnakorn Chaiworapongsa, MD

    Professor
    Wayne State University School of Medicine
    Detroit, Michigan, United States

Objective: Preterm labor (PTL) is a syndrome caused by multiple pathologic processes. Intraamniotic inflammation is a major cause of preterm birth and neonatal morbidity/mortality. The two causes of intraamniotic inflammation [intraamniotic infection (IAI) and sterile intraamniotic inflammation (S-IAI)] can be treated in humans. The optimal test to identify intraamniotic inflammation is amniotic fluid (AF) interleukin (IL)-6. This study was designed to determine if AF IL-6 concentration can be used in the differential diagnosis between IAI and S-IAI.

Study Design: The value of AF IL-6 was tested in two independent cohorts of patients with PTL (20–35 weeks of gestation). AF was analyzed for microorganisms using culture and PCR. IL-6 concentration was determined by ELISA. IAI was diagnosed by the combination of bacteria and inflammation (AF IL-6 ≥ 2.6 ng/ml). S-IAI was diagnosed if inflammation was present without microorganisms. ROC analysis was used from the first cohort (n=142) to identify patients with IAI. The results were tested in a second cohort (n=166).

Results: 1) Patients with IAI had the highest AF IL-6 concentrations among the groups (Figure); 2) an AF IL-6 ≥ 28.9 ng/ml had a sensitivity of 87% and a specificity of 97% to identify patients with IAI [AUC 0.97 (95% CI, 0.94–1.00)]; 3) an AF IL-6 ≥ 9 ng/ml identified all patients with IAI with a false-positive rate of 19%; 4) all patients with an AF IL-6 concentration between 2.6 and 9 ng/mL were diagnosed with S-IAI, and this IL-6 interval identified 38.5% (15/39) of patients with S-IAI; and 5) results were replicated in the second cohort. AF IL-6 ≥ 28.9 ng/ml had a sensitivity of 83% and a specificity of 83% for IAI. AF IL-6 ≥ 9 ng/ml identified all patients with IAI, and IL-6 between 2.6 and 9 ng/ml identified 39.5% with sterile intraamniotic inflammation.

Conclusion: AF IL-6 concentration can be used for the rapid assessment and diagnosis of IAI and S-IAI.