Amniotic fluid complement C3 as a marker of intra-amniotic infection

Area of Science:

• Obstetrics and Gynecology
• Infectious Diseases
• Clinical Chemistry

Background:

• Intra-amniotic infection (IAI) is a significant complication in preterm labor.
• Early and accurate diagnosis of IAI is crucial for timely intervention.
• Existing rapid markers for IAI have limitations in sensitivity and specificity.

Purpose of the Study:

• To evaluate amniotic fluid (AF) complement C3 as a diagnostic marker for IAI.
• To compare the diagnostic performance of AF complement C3 with other rapid markers of IAI.

Main Methods:

• Transabdominal amniocentesis was performed on 104 women in preterm labor with intact membranes.
• AF was analyzed for complement C3, white blood cell (WBC) count, lactate dehydrogenase (LDH), glucose, and Gram stain.
• AF cultures were performed to confirm IAI, and diagnostic marker performance was statistically analyzed.

Main Results:

• The prevalence of positive AF cultures was 11.5%.
• Significantly higher median AF complement C3 levels were observed in culture-positive cases compared to culture-negative cases (7.0 vs. 3.0 mg/dL, P < .001).
• Complement C3 demonstrated sensitivity, specificity, and predictive values comparable or superior to WBC count, LDH, glucose, and Gram stain for IAI detection.

Conclusions:

• AF complement C3 is a valuable and readily available marker for diagnosing IAI in preterm labor with intact membranes.
• Complement C3 offers a favorable alternative to existing rapid markers for IAI.
• The study supports the concept of a fetal inflammatory response to microbial invasion of AF.