{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T11:11:31Z","timestamp":1788174691837,"version":"build-2803163510"},"reference-count":32,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2007,8,22]],"date-time":"2007-08-22T00:00:00Z","timestamp":1187740800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Ultrasound in Obstet &amp; Gyne"],"published-print":{"date-parts":[[2007,10]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Objectives<\/jats:title><jats:p>To determine the clinical significance of the presence of amniotic fluid (AF) \u2018sludge\u2019 among asymptomatic patients at high risk for spontaneous preterm delivery.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>This retrospective case\u2013control study included 281 patients with (<jats:italic>n<\/jats:italic> = 66) or without (<jats:italic>n<\/jats:italic> = 215) AF \u2018sludge\u2019, who underwent transvaginal ultrasound examination between 13 and 29 completed weeks of gestation. Patients with threatened preterm labor, multiple gestation, fetal anomalies, placenta previa or uterine contractions were excluded.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>The prevalence of AF \u2018sludge\u2019 in the study population was 23.5% (66\/281). The rates of spontaneous preterm delivery at &lt; 28 weeks, &lt; 32 weeks, &lt; 35 weeks and &lt; 37 weeks of gestation were 14.7% (29\/197), 21.3% (46\/216), 28.7% (62\/216) and 42.1% (91\/216), respectively. Patients with \u2018sludge\u2019 had: (1) a higher rate of spontaneous preterm delivery at &lt; 28 weeks (46.5% (20\/43) vs. 5.8% (9\/154); <jats:italic>P<\/jats:italic> &lt; 0.001), &lt; 32 weeks (55.6% (25\/45) vs. 12.3% (21\/171); <jats:italic>P<\/jats:italic> &lt; 0.001) and &lt; 35 weeks (62.2% (28\/45) vs. 19.9% (34\/171); <jats:italic>P<\/jats:italic> &lt; 0.001); (2) a higher frequency of clinical chorioamnionitis (15.2% (10\/66) vs. 5.1% (11\/215); <jats:italic>P<\/jats:italic> = 0.007), histologic chorioamnionitis (61.5% (40\/65) vs. 28% (54\/193); <jats:italic>P<\/jats:italic> &lt; 0.001) and funisitis (32.3% (21\/65) vs. 19.2% (37\/193); <jats:italic>P<\/jats:italic> = 0.03); (3) a higher frequency of preterm prelabor rupture of membranes (PROM) (39.4% (26\/66) vs. 13.5% (29\/215); <jats:italic>P<\/jats:italic> &lt; 0.001), lower gestational age at preterm PROM (median 24.7 (interquartile range (IQR), 22.3\u201328.1) weeks vs. 32.3 (IQR, 27.7\u201334.8) weeks; <jats:italic>P<\/jats:italic> &lt; 0.001); and (4) shorter median ultrasound\u2010to\u2010delivery interval (\u2018sludge\u2019 positive 127 days (95% CI, 120\u2013134 days) vs. \u2018sludge\u2019 negative 161 days (95% CI, 153\u2013169 days); <jats:italic>P<\/jats:italic> &lt; 0.001) and ultrasound\u2010to\u2010preterm PROM interval (\u2018sludge\u2019 positive 23 days (95% CI, 7\u201339 days) vs. \u2018sludge\u2019 negative 57 days (95% CI, 38\u201377 days); <jats:italic>P<\/jats:italic> = 0.003) than those without \u2018sludge\u2019. AF \u2018sludge\u2019 was an independent explanatory variable for the occurrence of spontaneous preterm delivery at &lt; 28 weeks, &lt; 32 weeks and &lt; 35 weeks, preterm PROM, microbial invasion of the amniotic cavity (MIAC) and histologic chorioamnionitis. Moreover, the combination of a cervical length &lt; 25 mm and \u2018sludge\u2019 conferred an odds ratio of 14.8 and 9.9 for spontaneous preterm delivery at &lt; 28 weeks and &lt; 32 weeks, respectively.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>AF \u2018sludge\u2019 is an independent risk factor for spontaneous preterm delivery, preterm PROM, MIAC and histologic chorioamnionitis in asymptomatic patients at high risk for spontaneous preterm delivery. Furthermore, the combination of \u2018sludge\u2019 and a short cervix confers a higher risk for spontaneous preterm delivery at &lt; 28 weeks and &lt; 32 weeks than a short cervix alone. Copyright \u00a9 2007 ISUOG. 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