Patients with an asymptomatic short cervix (<or=15 mm) have a high rate of subclinical intraamniotic inflammation: implications for patient counseling.

OBJECTIVE: The objective of the study was to determine the frequency and clinical significance of intraamniotic inflammation in asymptomatic women with a sonographic short cervix (SCX) in the midtrimester.

STUDY DESIGN: This cohort study included 47 asymptomatic women (14-24 weeks) with an SCX (<or=15 mm) who underwent amniocentesis. Women with multiple gestation, cerclage, or cervical dilatation greater than 2 cm were excluded. Intraamniotic inflammation was defined as an elevated amniotic fluid (AF) matrix metalloproteinase-8 concentration (>23 ng/mL).

RESULTS: (1) intraamniotic infection was found in 4.3% of patients; (2) among patients with a negative AF culture, the prevalence of intraamniotic inflammation was 22.2%; and (3) patients with a negative AF culture, but with intraamniotic inflammation, had a higher rate of delivery within 7 days (40% vs 5.7%; P=.016) and a shorter median diagnosis-to-delivery interval than those without intraamniotic inflammation (18 vs 42 days; P=.01).

CONCLUSION: Twenty-two percent of patients with a midtrimester SCX have intraamniotic inflammation. The risk of preterm delivery within 7 days for these patients is 40%.