Is midtrimester short cervix a sign of intraamniotic inflammation?

OBJECTIVE: We sought to determine the relationship between the degree of cervical shortening and intraamniotic inflammation in patients presenting with a midtrimester short cervix. STUDY DESIGN: Amniocentesis was performed on singleton pregnancies between 16-24 weeks' gestation with a sonographic cervical length (CL) <= 25 mm. The fluid was assayed for 25 cytokines. Spearman correlations were used to determine which cytokines correlate with CL. Stepwise regression identified the most significant cytokine and a receiver operating characteristic curve determined the CL cutoff predictive of intraamniotic inflammation. RESULTS: In all, 109 amniotic fluid samples were analyzed. Most (21 of 25) cytokines were inversely correlated to CL. Monocyte chemotactic protein (MCP)-1 was the most significant by stepwise regression. Using a cutoff of MCP-1 > 1500 pg/mL, CL of 5 mm had an 86% sensitivity, 85% specificity, 58% positive predictive value, and 96% negative predictive value to predict elevated MCP-1 levels. After excluding patients with intraamniotic infection or labor, findings were similar. CONCLUSION: CL <= 5 mm is associated with significant increases in amniotic fluid inflammatory cytokines, even in the absence of infection or labor. In the future, differentiation of those with and without inflammation may aid in choosing therapy directed at the cause of cervical shortening.