title: The prevalence and clinical significance of amniotic fluid 'sludge' in patients with preterm labor and intact membranes.
abstract: OBJECTIVE
  To determine the prevalence and clinical significance of amniotic fluid (AF) 'sludge' observed during transvaginal ultrasound examination of the cervix in patients with preterm labor and intact membranes, and in those with uncomplicated pregnancies.
  
  
  METHODS
  This retrospective study included patients with preterm labor and intact membranes (n = 84) and those with uncomplicated term pregnancies (n = 298). The outcome variables included the occurrence of documented microbial invasion of the amniotic cavity (MIAC), histological chorioamnionitis, examination-to-delivery interval, admission to the neonatal intensive care unit (NICU), a composite neonatal morbidity, perinatal death, and delivery within 48 h, 7 days, and < 35 weeks and < 32 weeks. Statistical analysis included Chi-square test, stepwise logistic regression analysis and survival analysis.
  
  
  RESULTS
  The prevalence of AF 'sludge' was 1% (3/298) in patients with uncomplicated term pregnancies and 22.6% (19/84) in those with preterm labor and intact membranes. Among patients with preterm labor and intact membranes: (1) cervical length < or = 15 mm was present in 58.3% (49/84) of the patients; (2) the prevalence of MIAC and histological chorioamnionitis was 12.1% (7/58) and 32.9% (25/76), respectively; (3) the rate of spontaneous preterm delivery within 48 h, 7 days, and < 32 weeks and < 35 weeks of gestation was 13.6% (8/59), 28.8% (17/59), 39.5% (17/43) and 50.8% (30/59), respectively; (4) patients with AF 'sludge' had a higher frequency of positive AF cultures [33.3% (6/18) vs. 2.5% (1/40), P = 0.003] and histological chorioamnionitis [77.8% (14/18) vs. 19% (11/58), P < 0.001] than those without AF 'sludge'; (5) a higher proportion of neonates born to patients with AF 'sludge' was admitted to the NICU [64.3% (9/14) vs. 12.9% (8/62), P < 0.01], had a composite neonatal morbidity [36.8% (7/19) vs. 13.8% (9/65), P = 0.04] and died in the perinatal period [36.8% (7/19) vs. 4.6% (3/65), P = 0.001] than those born to women without 'sludge'; (6) a higher proportion of patients with AF 'sludge' had spontaneous delivery within 48 h [42.9% (6/14) vs. 4.4% (2/45), P = 0.001], within 7 days [71.4% (10/14) vs. 15.6% (7/45), P < 0.001], < 32 weeks [75% (9/12) vs. 25.8% (8/31), P = 0.005] and < 35 weeks [92.9% (13/14) vs. 37.8% (17/45), P < 0.001] than those without AF 'sludge'; and (7) patients with AF 'sludge' had a shorter examination-to-delivery interval than those without AF 'sludge' [AF 'sludge' median, 1 (IQR, 1-5) days vs. no AF 'sludge' median, 33 (IQR, 18-58) days; P < 0.001].
  
  
  CONCLUSIONS
  The presence of AF 'sludge' in patients with preterm labor and intact membranes is a risk factor for MIAC, histological chorioamnionitis and impending preterm delivery.
authors.affiliation: Perinatology Research Branch, NICHD/NIH/DHHS, Detroit, MI 48201, USA.
authors.forename: J
authors.initials: J
authors.lastname: Espinoza
authors.forename: L F
authors.initials: LF
authors.lastname: Gonçalves
authors.forename: R
authors.initials: R
authors.lastname: Romero
authors.forename: J K
authors.initials: JK
authors.lastname: Nien
authors.forename: S
authors.initials: S
authors.lastname: Stites
authors.forename: Y M
authors.initials: YM
authors.lastname: Kim
authors.forename: S
authors.initials: S
authors.lastname: Hassan
authors.forename: R
authors.initials: R
authors.lastname: Gomez
authors.forename: B H
authors.initials: BH
authors.lastname: Yoon
authors.forename: T
authors.initials: T
authors.lastname: Chaiworapongsa
authors.forename: W
authors.initials: W
authors.lastname: Lee
authors.forename: M
authors.initials: M
authors.lastname: Mazor
mesh_terms: D000328:Adult; D000653:Amniotic Fluid / Q000000981:diagnostic imaging*; D002584:Cervix Uteri / Q000000981:diagnostic imaging; D002821:Chorioamnionitis / Q000000981:diagnostic imaging; D036861:Delivery, Obstetric; D005321:Extraembryonic Membranes / Q000000981:diagnostic imaging; D005260:Female; D005865:Gestational Age; D006801:Humans; D015931:Intensive Care, Neonatal; D007752:Obstetric Labor, Premature / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods