The prevalence and clinical significance of amniotic fluid ‘sludge’ in patients with preterm labor and intact membranes

Abstract

K E Y W O R D S:amniotic fluid 'sludge'; chorioamnionitis; intrauterine inflammation; microbial invasion of the amniotic cavity; preterm delivery; preterm labor; ultrasound ' [AF 'sludge' median, 1 (IQR,[1][2][3][4][5] 33 (IQR, ABSTRACT

Risk of Impending Preterm Delivery Associated with the Presence of Amniotic Fluid Sludge in Women in Preterm Labor with Intact Membranes

“…Owing to the study design, we were not able to determine the prevalence of amniotic fluid sludge in women in preterm labor with intact membranes. A prevalence of 22.6% has been reported in a similar cohort [8] . Similarly to previous studies, our observations reveal that the presence of amniotic fluid sludge is associated with shorter cervical length.…”

“…In the third trimester of pregnancy, free-floating particulate matter has been attributed to the presence of vernix and meconium [15][16][17][18] and is present in about 88% by 35 weeks [19] . However, the sonographic appearance of what has been termed 'intra-amniotic fluid sludge' seen at cervical ultrasound is different [8,20,21] . Amniotic fluid sludge appears as a free-floating hyperechogenic material within the amniotic fluid and always in close proximity to the internal os or within the cervical funneling when the latter Fig.…”

“…Thus, amniotic fluid sludge may represent a sign that microbial invasion of the amniotic cavity and an inflammatory process are in progress and therefore, these patients are at increased risk for preterm delivery [21,22] . The prevalence of amniotic fluid sludge at 20-35 weeks in patients with uncomplicated term pregnancies is about 1% [8] , whereas in high-risk pregnancies at 13-29 weeks it is 23.5% [23] . Owing to the study design, we were not able to determine the prevalence of amniotic fluid sludge in women in preterm labor with intact membranes.…”

“…The material resembles pus when collected and examined at first glance and under the microscope [21] . It has been suggested that progressive infection induces an intense inflammatory response and that the combination of microorganisms and the inflammatory cell leads to the formation of this particular material observed by sonographic examination [8] . Additionally, it has been suggested that this sludge could potentially be a bacterial biofilm, a matrix of polymeric compounds that microorganisms may produce to protect themselves from host defense mechanisms [21] .…”

“…Short cervical length, usually defined as below the 10th percentile or ^ 25 mm as measured by transvaginal ultrasound, has been strongly related to the risk of preterm birth among asymptomatic pregnant women [6] and also in those in preterm labor with intact membranes [7] . It has been suggested that the presence of amniotic fluid sludge, a cluster of free-floating hyperechogenic material sitting close to the internal cervical os, is associated with impending preterm delivery, microbial infection of the amniotic cavity and histological Association between Amniotic Fluid Sludge and Impending Preterm Delivery chorioamnionitis in women in preterm labor with intact membranes [8] .…”