title: Clinical significance of the presence of amniotic fluid 'sludge' in asymptomatic patients at high risk for spontaneous preterm delivery.
abstract: OBJECTIVE
  To determine the clinical significance of the presence of amniotic fluid (AF) 'sludge' among asymptomatic patients at high risk for spontaneous preterm delivery.
  
  
  METHODS
  This retrospective case-control study included 281 patients with (n = 66) or without (n = 215) AF 'sludge', 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.
  
  
  RESULTS
  The prevalence of AF 'sludge' in the study population was 23.5% (66/281). The rates of spontaneous preterm delivery at < 28 weeks, < 32 weeks, < 35 weeks and < 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 'sludge' had: (1) a higher rate of spontaneous preterm delivery at < 28 weeks (46.5% (20/43) vs. 5.8% (9/154); P < 0.001), < 32 weeks (55.6% (25/45) vs. 12.3% (21/171); P < 0.001) and < 35 weeks (62.2% (28/45) vs. 19.9% (34/171); P < 0.001); (2) a higher frequency of clinical chorioamnionitis (15.2% (10/66) vs. 5.1% (11/215); P = 0.007), histologic chorioamnionitis (61.5% (40/65) vs. 28% (54/193); P < 0.001) and funisitis (32.3% (21/65) vs. 19.2% (37/193); P = 0.03); (3) a higher frequency of preterm prelabor rupture of membranes (PROM) (39.4% (26/66) vs. 13.5% (29/215); P < 0.001), lower gestational age at preterm PROM (median 24.7 (interquartile range (IQR), 22.3-28.1) weeks vs. 32.3 (IQR, 27.7-34.8) weeks; P < 0.001); and (4) shorter median ultrasound-to-delivery interval ('sludge' positive 127 days (95% CI, 120-134 days) vs. 'sludge' negative 161 days (95% CI, 153-169 days); P < 0.001) and ultrasound-to-preterm PROM interval ('sludge' positive 23 days (95% CI, 7-39 days) vs. 'sludge' negative 57 days (95% CI, 38-77 days); P = 0.003) than those without 'sludge'. AF 'sludge' was an independent explanatory variable for the occurrence of spontaneous preterm delivery at < 28 weeks, < 32 weeks and < 35 weeks, preterm PROM, microbial invasion of the amniotic cavity (MIAC) and histologic chorioamnionitis. Moreover, the combination of a cervical length < 25 mm and 'sludge' conferred an odds ratio of 14.8 and 9.9 for spontaneous preterm delivery at < 28 weeks and < 32 weeks, respectively.
  
  
  CONCLUSIONS
  AF 'sludge' 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 'sludge' and a short cervix confers a higher risk for spontaneous preterm delivery at < 28 weeks and < 32 weeks than a short cervix alone.
authors: Perinatology Research Branch, National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Department of Health and Human Services, Bethesda, MD, USA.
authors: J P
authors: JP
authors: Kusanovic
authors: J
authors: J
authors: Espinoza
authors: R
authors: R
authors: Romero
authors: L F
authors: LF
authors: Gonçalves
authors: J K
authors: JK
authors: Nien
authors: E
authors: E
authors: Soto
authors: N
authors: N
authors: Khalek
authors: N
authors: N
authors: Camacho
authors: I
authors: I
authors: Hendler
authors: P
authors: P
authors: Mittal
authors: L A
authors: LA
authors: Friel
authors: F
authors: F
authors: Gotsch
authors: O
authors: O
authors: Erez
authors: N G
authors: NG
authors: Than
authors: S
authors: S
authors: Mazaki-Tovi
authors: M L
authors: ML
authors: Schoen
authors: S S
authors: SS
authors: Hassan
mesh_terms: D000328:Adult; D000653:Amniotic Fluid / Q000000981:diagnostic imaging* / Q000382:microbiology; D016022:Case-Control Studies; D002584:Cervix Uteri / Q000002:abnormalities; D005260:Female; D005865:Gestational Age; D006801:Humans; D007752:Obstetric Labor, Premature / Q000209:etiology*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000000981:diagnostic imaging* / Q000517:prevention & control; D012189:Retrospective Studies; D012307:Risk Factors; D014463:Ultrasonography
references: Ment Retard Dev Disabil Res Rev. 2002;8(1):3-13
references: 11921380
references: J Matern Fetal Neonatal Med. 2002 Jan;11(1):18-25
references: 12380603
references: J Infect Dis. 1982 Jan;145(1):1-8
references: 7033397
references: Sex Transm Dis. 1983 Oct-Dec;10(4 Suppl):294-302
references: 6665671
references: Am J Obstet Gynecol. 1988 Jul;159(1):114-9
references: 2456013
references: Am J Obstet Gynecol. 1990 Sep;163(3):968-74
references: 1698338
references: J Clin Ultrasound. 1991 Feb;19(2):77-83
references: 1847952
references: Am J Obstet Gynecol. 1991 Oct;165(4 Pt 1):821-30
references: 1951538
references: Am J Obstet Gynecol. 1991 Oct;165(4 Pt 1):955-61
references: 1951562
references: Prenat Diagn. 1992 Feb;12(2):111-7
references: 1553356
references: Am J Obstet Gynecol. 1992 May;166(5):1382-8
references: 1595794
references: Obstet Gynecol. 1993 Jun;81(6):941-8
references: 8497360
references: Am J Obstet Gynecol. 2001 Nov;185(5):1130-6
references: 11717646
references: JAMA. 2001 Sep 19;286(11):1340-8
references: 11560539
references: Ultrasound Obstet Gynecol. 2001 Sep;18(3):204-10
references: 11555447
references: Am J Obstet Gynecol. 2000 Nov;183(5):1124-9
references: 11084553
references: Am J Obstet Gynecol. 2000 Jun;182(6):1458-67
references: 10871466
references: Ultrasound Obstet Gynecol. 2000 Feb;15(2):109-13
references: 10775991
references: J Obstet Gynaecol Can. 2006 Mar;28(3):198-202
references: 16650357
references: J Perinat Med. 2006;34(1):13-9
references: 16489881
references: Obstet Gynecol. 2005 Sep;106(3):553-6
references: 16135586
references: J Matern Fetal Neonatal Med. 2005 Jul;18(1):31-7
references: 16105789
references: Ultrasound Obstet Gynecol. 2005 Apr;25(4):346-52
references: 15789375
references: Am J Obstet Gynecol. 1999 Oct;181(4):809-15
references: 10521734
references: J Reprod Med. 1995 May;40(5):375-9
references: 7608879
references: Obstet Gynecol. 1998 Dec;92(6):902-7
references: 9840546
references: Ultrasound Obstet Gynecol. 1998 Nov;12(5):312-7
references: 9819868
references: Am J Obstet Gynecol. 1998 Jul;179(1):194-202
references: 9704787
references: Obstet Gynecol. 1998 Jul;92(1):77-82
references: 9649098
references: Obstet Gynecol. 1998 Jul;92(1):31-7
references: 9649088
references: N Engl J Med. 1996 Feb 29;334(9):567-72
references: 8569824
references: Am J Obstet Gynecol. 1999 Oct;181(4):793-7
references: 10521731