Clinical implication of intra-amniotic sludge on ultrasound in patients with cervical cerclage

Objective The aim of this study was to determine whether intra-amniotic (IA) sludge, a sonographic finding of hyperechoic matter in the amniotic fluid close to the internal cervical os, is associated with preterm delivery in patients with cervical cerclage. Methods A retrospective cohort study of patients who had undergone McDonald cerclage between January 1997 and December 2004 was conducted. Transvaginal ultrasound examinations had been performed at 14-28 weeks of gestation, and the ultrasound images were assessed by three reviewers (blinded to patient outcome) to determine the presence or absence of IA sludge. The primary outcome studied was the gestational age at delivery. Results A total of 177 patients who had undergone cervical cerclage, and for whom adequate records were available, were identified. Sixty had sonographic evidence of IA sludge (Group 1) and 117 had absence of IA sludge (Group 2). There was no significant difference in the mean gestational age at delivery between the two groups (36.4 +/- 4.0 vs. 36.8 +/- 2.9 weeks, P = 0.53), and no statistical difference in the rate of preterm delivery at < 28 (6.7% vs. 1.7%, P = 0.18), < 30 (6.7% vs. 3.4%, P = 0.45), < 32 (8.3% vs. 6.8%, P = 0.77) or < 36 (16.7% vs. 19.7%, P = 0.69) weeks of gestation. Conclusion Intra-amniotic sludge on ultrasound is not associated with an increased risk of preterm delivery in patients with cervical cerclage. Copyright (C) 2010 ISUOG. Published by John Wiley & Sons, Ltd.