Clinical implication of intra-amniotic sludge on ultrasound in patients with cervical cerclage

Amniotic fluid sludge is associated with earlier preterm delivery and raised cervicovaginal interleukin 8 concentrations

BACKGROUND

Preterm birth is the leading cause of global neonatal mortality. Amniotic fluid sludge, thought to indicate intra-amniotic infection, may have potential as a clinical biomarker of preterm birth risk.

OBJECTIVE

This study aimed to analyze whether the presence of amniotic fluid sludge in pregnant participants with a known short cervical length can help improve the understanding of the etiology and guide management choice.

STUDY DESIGN

This was a retrospective cohort study analyzing the effects of amniotic fluid sludge presence on the risk of preterm birth in high-risk asymptomatic pregnant participants with a short cervical length (<25 mm) at a large tertiary referral maternity center in London. Amniotic fluid sludge was detected on a routine transvaginal ultrasound scan.

RESULTS

Overall, 147 pregnant participants with a short cervical length were identified, 54 of whom had amniotic fluid sludge. Compared with pregnant participants without amniotic fluid sludge, pregnant participants with amniotic fluid sludge were more likely to have a short cervical length (19 vs 14 mm, respectively; P<.0001) and increased cervicovaginal fetal fibronectin concentrations at diagnosis (125 vs 45 ng/mL, respectively; P=.0006). Pregnant participants with amniotic fluid sludge were at increased risk of midtrimester loss and delivery before 24 weeks of gestation (relative risk, 3.4; 95% confidence interval, 1.2-10.3). Furthermore, this study showed that pregnant participants with amniotic fluid sludge have increased cervicovaginal interleukin 8 concentrations, supporting the concept of amniotic fluid sludge as an indicator of an inflammatory response to microbial invasion (P=.03). Neonatal outcomes were similar between the 2 groups.

CONCLUSION

In our cohort of high-risk asymptomatic pregnant participants with a short cervical length, the presence of amniotic fluid sludge is associated with an increased risk of delivery before 24 weeks of gestation. Moreover, pregnant participants with amniotic fluid sludge were more likely to have raised fetal fibronectin levels and inflammatory cytokines, particularly interleukin 8, in the cervicovaginal fluid, supporting the concept that amniotic fluid sludge is associated with an infective or inflammatory process. Future research should aim to further establish the clinical significance of amniotic fluid sludge presence and guide subsequent management.

Amniotic Sludge and Prematurity: Systematic Review and Meta-analysis

OBJECTIVE

 To perform a systematic review and meta-analysis of studies on maternal, fetal, and neonatal outcomes of women with singleton pregnancies, after spontaneous conception, and with the diagnosis of amniotic sludge before 37 weeks of gestational age.

DATA SOURCES

 We conducted a search on the PubMed, Cochrane, Bireme, and Theses databases until June 2022.

SELECTION OF STUDIES

 Using the keywords intra-amniotic sludge or fluid sludge or echogenic particles, we found 263 articles, 132 of which were duplicates, and 70 were discarded because they did not meet the inclusion criteria.

DATA COLLECTION

 The articles retrieved were analyzed by 2 reviewers; 61 were selected for full-text analysis, 18 were included for a qualitative analysis, and 14, for a quantitative analysis.

DATA SYNTHESIS

 Among the maternal outcomes analyzed, there was an increased risk of preterm labor (95% confidence interval [95%CI]: 1.45-2.03), premature rupture of ovular membranes (95%CI: 1.99-3.79), and clinical (95%CI: 1.41-6.19) and histological chorioamnionitis (95%CI: 1.75-3.12). Regarding the fetal outcomes, there was a significant increase in the risk of morbidity (95%CI: 1.80-3.17), mortality (95%CI: 1.14-18.57), admission to the Neonatal Intensive Care Unit (NICU; 95%CI: 1.17-1.95), and neonatal sepsis (95%CI: 2.29-7.55).

CONCLUSION

 The results of the present study indicate that the presence of amniotic sludge is a risk marker for preterm delivery. Despite the heterogeneity of the studies analyzed, even in patients with other risk factors for prematurity, such as short cervix and previous preterm delivery, the presence of amniotic sludge increases the risk of premature labor. Moreover, antibiotic therapy seems to be a treatment for amniotic sludge, and it may prolong pregnancy.

Relationship of Amniotic Fluid Sludge and Short Cervix With a High Rate of Preterm Birth in Women After Cervical Cerclage

OBJECTIVE

We aims to determine the relationship of amniotic fluid sludge (AFS) and/or short cervical length (CL, ≤25 mm) with a high rate of preterm birth in women after cervical cerclage.

METHODS

A retrospective cohort study was conducted among singleton pregnancies after cervical cerclage between January 2018 and December 2021. A total of 296 patients who underwent transvaginal ultrasound to evaluate CL and the presence of AFS within 2 weeks after cerclage were included. Pregnancy outcome after cerclage was analyzed in accordance with the presence of AFS and CL ≤25 mm.

RESULTS

In patients with cerclage, AFS was an independent risk factor for preterm birth at <28 and <36 weeks but not for preterm birth at <32 weeks, and CL ≤25 mm was an independent risk factor for preterm birth at <28, <32, and <36 weeks. The Kaplan-Meier analysis showed that the association between the presence of AFS and short gestational age at delivery was statistically significant in women with CL ≤25 mm (log rank test, P = .000). The Cox regression analysis showed that these results remained significant after adjusting for confounding factors (P = .000). The negative linear relationships between AFS and CL (R = -0.454, P < .001) also explained the outcome.

CONCLUSIONS

AFS and short cervix have a direct effect on pregnancies after cerclage. Mid-trimester AFS can become a supplementary ultrasound index for detecting preterm birth after cerclage in pregnant women with a short cervix.

Guideline No. 401: Sonographic Cervical Length in Singleton Pregnancies: Techniques and Clinical Applications

OBJECTIVES

• To assess the association between sonography-derived cervical length measurement and preterm birth. • To describe the various techniques to measure cervical length using sonography. • To review the natural history of the short cervix. • To review the clinical uses, predictive ability, and utility of sonography-measured short cervix.

OUTCOMES

Reduction in rates of prematurity and/or better identification of those at risk, as well as possible prevention of unnecessary interventions.

INTENDED USERS

Clinicians involved in the obstetrical management or cervical imaging of patients at increased risk of a short cervix.

TARGET POPULATION

Women at increased risk of a short cervix or at risk of preterm birth.

EVIDENCE

Literature published up to June 2019 was retrieved through searches of PubMed and the Cochrane Library using appropriate controlled vocabulary and key words (preterm labour, ultrasound, cervix, cervical insufficiency, transvaginal, transperineal, cervical length, fibronectin). Results were restricted to general and systematic reviews, randomized controlled trials, controlled clinical trials, and observational studies. There were no date or language restrictions. Grey (unpublished) literature was identified through searching the websites of health technology assessment agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The evidence and this guideline were reviewed by the Diagnostic Imaging Committee of the Society of Obstetricians and Gynaecologists of Canada, and the recommendations were made and graded according to the rankings of the Canadian Task Force on Preventive Health Care (Online Appendix Table A1).

BENEFITS, HARMS, COSTS

Preterm birth is a leading cause of perinatal morbidity and mortality. Use of the sonographic technique reviewed in this guideline may help identify women at risk of preterm birth and, in some circumstances, lead to interventions that may reduce the rate of preterm birth. SUMMARY STATEMENTS (CANADIAN TASK FORCE ON PREVENTIVE HEALTH CARE GRADING IN PARENTHESES): RECOMMENDATIONS (CANADIAN TASK FORCE ON PREVENTIVE HEALTH CARE GRADING IN PARENTHESES).

Presence of amniotic fluid sludge and pregnancy outcomes: A systematic review

INTRODUCTION

Several studies acknowledge that the presence of amniotic fluid sludge (AFS) is an independent predictive factor for preterm birth. In the present systematic review, we summarize research that focuses on the comparison of pregnancy outcomes among women with and without AFS.

MATERIAL AND METHODS

Medline, Scopus, Clinicaltrials.gov, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar databases were systematically searched from inception. Both observational and randomized controlled studies were considered eligible provided that they reported data on pregnancy outcomes among women with and without AFS. Outcomes were not meta-analyzed because of the high heterogeneity in terms of selected population and outcome reporting.

RESULTS

Seventeen studies of 2432 women were included in this review. Six studies evaluated women at high risk for preterm birth. Pregnancies complicated by AFS had a lower gestational age at delivery and increased incidence of preterm delivery at <37 weeks. Neonatal death rates and admission to the Neonatal Intensive Care Unit were also increased. Evidence in low-risk women, those with signs of preterm labor, in those carrying twins, and in women with cervical cerclage or Arabin pessary was extremely limited.

CONCLUSIONS

Women with AFS seem to deliver at an earlier gestational age, and preterm birth rates are also increased. Limited data seem to point to neonatal morbidity and mortality being increased. However, the presence of a direct association should not be assumed because the evidence is not adjusted for the presence of confounders.

Cervical funneling or intra-amniotic debris and preterm birth in nulliparous women with midtrimester cervical length less than 30 mm

OBJECTIVE

To evaluate whether the presence of cervical funneling or intra-amniotic debris identified in the second trimester is associated with a higher rate of preterm birth (PTB) in asymptomatic nulliparous pregnant women with a midtrimester cervical length (CL) less than 30 mm (i.e. below the 10th percentile).

METHODS

This was a secondary cohort analysis of data from a multicenter trial in nulliparous women between 16 and 22 weeks' gestation with a singleton gestation and CL less than 30 mm on transvaginal ultrasound, randomized to treatment with either 17-alpha-hydroxyprogesterone caproate or placebo. Sonographers were centrally certified in CL measurement, as well as in identification of intra-amniotic debris and cervical funneling. Univariable and multivariable analysis was performed to assess the associations of cervical funneling and intra-amniotic debris with PTB.

RESULTS

Of the 657 women randomized, 112 (17%) had cervical funneling only, 33 (5%) had intra-amniotic debris only and 45 (7%) had both on second-trimester ultrasound. Women with either of these findings had a shorter median CL than those without (21.0 mm vs 26.4 mm; P < 0.001). PTB prior to 37 weeks was more likely in women with cervical funneling (37% vs 21%; odds ratio (OR), 2.2 (95% CI, 1.5-3.3)) or intra-amniotic debris (35% vs 23%; OR, 1.7 (95% CI, 1.1-2.9)). Results were similar for PTB before 34 and before 32 weeks' gestation. After multivariable adjustment that included CL, PTB < 34 and < 32 weeks continued to be associated with the presence of intra-amniotic debris (adjusted OR (aOR), 1.85 (95% CI, 1.00-3.44) and aOR, 2.78 (95% CI, 1.42-5.45), respectively), but not cervical funneling (aOR, 1.17 (95% CI, 0.63-2.17) and aOR, 1.45 (95% CI, 0.71-2.96), respectively).

CONCLUSIONS

Among asymptomatic nulliparous women with midtrimester CL less than 30 mm, the presence of intra-amniotic debris, but not cervical funneling, is associated with an increased risk for PTB before 34 and 32 weeks' gestation, independently of CL. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Amniotic fluid "sludge" is an independent risk factor for preterm delivery

OBJECTIVE

To determine the prevalence and the clinical significance of amniotic fluid "sludge" (AFS) in asymptomatic patients at low and high risk for spontaneous preterm delivery.

METHOD

A prospective cohort study was conducted on 195 singleton pregnancies at low or high risk for preterm birth (PTB) between the 16th and 26th weeks. Cervical length (CL) <25 mm and the presence of AFS were evaluated. The risk for preterm delivery before 28, 32, 35 and 37 weeks were determined according to the presence of AFS, CL < 25 mm and history of high risk for PTB. Stepwise logistic regression was performed to compare variables.

RESULTS

AFS was an independent risk factor for PTB < 35 weeks (OR: 3.08, 95% CI: 1.13-8.34, p = 0.027) but not for PTB < 28, 32 and 37 weeks. CL < 25 mm was an independent risk factor for PTB < 28, 32 and 35 but not for PTB < 37 weeks. High risk for PTB was not found as an independent risk factor for PTB.

CONCLUSION

AFS is an independent risk factor for PTB before 35 weeks.

Impact of amniotic fluid "sludge" on the risk of preterm delivery

OBJECTIVE

To evaluate the impact of amniotic fluid "sludge" (AFS) on the risk of preterm delivery and to describe the effect of antibiotic treatment in that situation.

METHODS

Case-control study including singleton pregnancies with or without AFS, between 15-32 weeks of gestation. Factors associated with preterm delivery before 32 weeks, 34 weeks and 37 weeks were evaluated with univariate and multivariate logistic regression. Since all women with AFS in this study were treated with antibiotics, a historical comparison was performed with similar patients with AFS found before 2007 and not treated with antibiotics.

RESULTS

AFS was observed in 90/1220 patients (7.4%). AFS was associated with shorter cervical length, greater body mass index, cervical cerclage and preterm birth before 28 weeks. However, after adjustment, AFS did not remain associated with preterm delivery before 32 or 34 weeks. The historical comparison suggested that azithromycin could significantly reduce the risk of preterm delivery before 34 weeks (odds ratio: 0.2; 95% CI: 0.04-0.92).

CONCLUSIONS

AFS, treated with azithromycin, was associated with a higher risk of prematurity, but not independently after adjustment for cervical length and second trimester vaginal bleeding. Further studies need to evaluate the effect of antibiotics in pregnancies with AFS.