Clinical significance of the presence of amniotic fluid 'sludge' in asymptomatic patients at high risk for spontaneous preterm delivery.
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.
Kusanovic
J P
JP
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.
Espinoza
J
J
Romero
R
R
Gonçalves
L F
LF
Nien
J K
JK
Soto
E
E
Khalek
N
N
Camacho
N
N
Hendler
I
I
Mittal
P
P
Friel
L A
LA
Gotsch
F
F
Erez
O
O
Than
N G
NG
Mazaki-Tovi
S
S
Schoen
M L
ML
Hassan
S S
SS
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
Ment Retard Dev Disabil Res Rev. 2002;8(1):3-13
11921380
J Matern Fetal Neonatal Med. 2002 Jan;11(1):18-25
12380603
J Infect Dis. 1982 Jan;145(1):1-8
7033397
Sex Transm Dis. 1983 Oct-Dec;10(4 Suppl):294-302
6665671
Am J Obstet Gynecol. 1988 Jul;159(1):114-9
2456013
Am J Obstet Gynecol. 1990 Sep;163(3):968-74
1698338
J Clin Ultrasound. 1991 Feb;19(2):77-83
1847952
Am J Obstet Gynecol. 1991 Oct;165(4 Pt 1):821-30
1951538
Am J Obstet Gynecol. 1991 Oct;165(4 Pt 1):955-61
1951562
Prenat Diagn. 1992 Feb;12(2):111-7
1553356
Am J Obstet Gynecol. 1992 May;166(5):1382-8
1595794
Obstet Gynecol. 1993 Jun;81(6):941-8
8497360
Am J Obstet Gynecol. 2001 Nov;185(5):1130-6
11717646
JAMA. 2001 Sep 19;286(11):1340-8
11560539
Ultrasound Obstet Gynecol. 2001 Sep;18(3):204-10
11555447
Am J Obstet Gynecol. 2000 Nov;183(5):1124-9
11084553
Am J Obstet Gynecol. 2000 Jun;182(6):1458-67
10871466
Ultrasound Obstet Gynecol. 2000 Feb;15(2):109-13
10775991
J Obstet Gynaecol Can. 2006 Mar;28(3):198-202
16650357
J Perinat Med. 2006;34(1):13-9
16489881
Obstet Gynecol. 2005 Sep;106(3):553-6
16135586
J Matern Fetal Neonatal Med. 2005 Jul;18(1):31-7
16105789
Ultrasound Obstet Gynecol. 2005 Apr;25(4):346-52
15789375
Am J Obstet Gynecol. 1999 Oct;181(4):809-15
10521734
J Reprod Med. 1995 May;40(5):375-9
7608879
Obstet Gynecol. 1998 Dec;92(6):902-7
9840546
Ultrasound Obstet Gynecol. 1998 Nov;12(5):312-7
9819868
Am J Obstet Gynecol. 1998 Jul;179(1):194-202
9704787
Obstet Gynecol. 1998 Jul;92(1):77-82
9649098
Obstet Gynecol. 1998 Jul;92(1):31-7
9649088
N Engl J Med. 1996 Feb 29;334(9):567-72
8569824
Am J Obstet Gynecol. 1999 Oct;181(4):793-7
10521731