Transactions of the Twenty-Fourth Annual Meeting of the Society for Maternal-Fetal Medicine
Clinical significance of intra-amniotic inflammation in patients with preterm premature rupture of membranes

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Objective

This study was conducted to determine the frequency and clinical significance of intra-amniotic inflammation in patients with preterm premature rupture of the membranes.

Study design

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.

Results

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.

Conclusion

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.

Section snippets

Study design

The study population consisted of consecutive patients who were admitted to Seoul National University Hospital with the diagnosis of PPROM (<35 weeks of gestation) and singleton gestation who underwent amniocentesis for assessment of microbiologic status of the amniotic cavity and fetal lung maturity between May 1993 and August 2002. At our institution, amniocentesis is offered routinely to all patients who are admitted with the diagnosis of PPROM. After delivery of all patients, MMP-8 was

AF inflammation and culture

Amniocentesis was performed in 224 patients with PPROM. AF was not available in 5 patients for MMP-8 determinations (3 patients with a negative AF culture and 2 patients with a positive culture); therefore, these patients were excluded from the further analysis, because they could not be evaluated with respect to the presence or absence of intra-amniotic inflammation.

The overall rate of intra-amniotic inflammation was 42% (93/219 samples); proven intra-amniotic infection was detected in 23%

Comment

Our data indicate that intra-amniotic inflammation, regardless of AF culture result, is present in 42% of patients with PPROM and that it is a risk factor for impending preterm delivery and adverse maternal and neonatal outcome. The magnitude of intra-amniotic inflammatory response and the maternal and neonatal outcome of patients with intra-amniotic inflammation without demonstrable intra-amniotic infection were similar to that of patients with microbiologically proven intra-amniotic infection.

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    • Cited by (0)

    Supported by grant 2000-N-NL-01-C-078 from the Korea Institute of Science and Technology Evaluation and Planning (KISTEP), Republic of Korea.

    Presented at the Twenty-Fourth Annual Meeting of the Society for Maternal-Fetal Medicine, February 2-7, 2004, New Orleans, La.

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