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271: Patients undergoing physical exam-indicated cerclage: What are the predictors of microbial invasion of the amniotic cavity?

      Objective

      Some have advocated amniocentesis prior to physical exam (PE)-indicated cerclage due to high rates of microbial infection of the amniotic cavity (MIAC). The objective of this study was to ascertain the rate of MIAC in a cohort of patients presenting with cervical insufficiency (CI) and identify its predictors.

      Study Design

      All patients presenting from 2003-2008 for PE-indicated cerclage at 16-25 weeks underwent amniocentesis to exclude MIAC (N=48). Exclusion criteria were bleeding, contractions, premature rupture of membranes (PROM), fever or uterine tenderness. Logistic regression analysis was performed to identify clinical and laboratory predictors of positive amniotic fluid (AF) culture results.

      Results

      6/48 (12.5%, 95% CI 5-25%) patients had MIAC. Patients with MIAC were similar to those without it in terms of maternal age, race, previous D&C, cervical surgery, gestational age, serum or AF WBC, AF segmented neutrophils, glucose and gram stain. Logistic regression analysis identified only AF lymphocyte count as predictor for positive AF culture results (P=0.03). ROC curve analysis indicated AF lymphocyte count of 4 as optimal predictor of MIAC (sensitivity=67%, specificity=88%). In addition, there was a trend towards prediction of positive AF culture for positive genital culture (P=0.058).

      Conclusion

      Patients presenting with CI have lower rates of MIAC than reported in earlier non-cohort series. Unlike in the settings of premature labor or PROM, AF WBC, glucose and gram stain are not predictive of MIAC, whereas AF lymphocyte count and, to a lesser extent, genital cultures, are predictors of MIAC.