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

A Review of the Literature: Amniotic Fluid "Sludge"-Clinical Significance and Perinatal Outcomes

Introduction: This paper seeks to report and emphasize the most important aspects from the scientific literature about the diagnostic accuracy of the amniotic fluid "sludge" (AFS), its characterization, its treatment, and its association with premature birth. AFS is defined as a floating freely hyperechogenic material within the amniotic cavity in the proximity of the internal os. Materials and Methods: We conducted a search on Pubmed and Google Scholar for relevant articles on the subject of amniotic fluid "sludge" published until January 2024. Searches were focused on articles about diagnosis, treatment, maternal and neonatal outcomes, risk of preterm birth, and case reports. The full-text reading stage resulted in the inclusion of 51 studies. Results: AFS is independently associated with chorioamnionitis, preterm delivery, short cervix, increased risk of neonatal morbidity, and cervical insufficiency. This hyperechogenic free-floating material is linked with preterm birth before 32 weeks of gestation, especially when it is associated with short cervical length. Discussion: Present studies identify some controversial benefits of antibiotics in reducing the incidence of preterm birth in women with AFS. Nevertheless, in this review, we can conclude that the presence of AFS in pregnancy is a marker for the microbial invasion of the amniotic cavity, as it is associated with preterm birth. Further studies on a larger group of patients are necessary to clarify and exactly define the terms of managing these cases.

The predictive value of hemogram parameters for early preterm delivery in pregnant women undergoing cervical cerclage

OBJECTIVE

This study aims to investigate the predictive value of hemogram parameters in early preterm delivery (32 gestational weeks and below) among pregnant women who have undergone cervical cerclage, based on cervical changes determined before the cerclage procedure.

METHODS

Between 2010 and 2020, a total of 161 patients underwent cervical cerclage. The participants were divided into three groups. Group 1 (n=92) consisted of pregnant women who underwent prophylactic cerclage. Group 2 (n=31) included those with cervical shortening (<5 mm) and/or dilation (≤3 cm). Group 3 (n=38) comprised pregnant women with cervical dilation >3 cm. Each group was further divided based on delivery weeks, with a cutoff at 32 weeks. Demographic parameters and laboratory parameters were assessed.

RESULTS

In Group 1, all hemogram parameters showed no significant differences between deliveries below and above 32 weeks. In Group 2, the neutrophil-to-lymphocyte ratio value before cerclage was higher in the early preterm delivery group (p=0.002), with a cutoff value of 4.75 in receiver operating characteristic analysis. In Group 3, the white blood cell value before cerclage was higher in the early preterm delivery group (p=0.005), with a cutoff value of 13.05×103/μL in receiver operating characteristic analysis.

CONCLUSION

The use of hemogram parameters to predict early preterm delivery in pregnant women undergoing prophylactic cerclage is not appropriate. However, neutrophil-to-lymphocyte ratio value can predict early preterm delivery when cervical dilation is 3 cm or less and/or cervical shortening is 5 mm or less. When cervical dilation exceeds 3 cm, the white blood cell value is more appropriate for predicting early preterm delivery.

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.

Which part of cervical length is predictive of preterm birth in women with cerclage?

OBJECTIVE

To evaluate the predictive value of transvaginal ultrasonography measures: total cervical length (TCL), length to internal OS (LIO) and external OS (LEO) from the cerclage following cerclage placement, for spontaneous preterm birth (PTB).

METHODS

A retrospective cohort at a single tertiary care center (2010-2020). Women with McDonald cerclage were evaluated during the 2nd and 3rd trimesters for cervical measurements: TCL, LIO, LEO. The primary outcome was PTB < 37 weeks. Demographic data, obstetric history, delivery information and serial cervical length measurements were collected. Subgroup analyses were performed to evaluate cervical length parameters (as described) and PTB rates prior to 34, 32 and 28 weeks of gestation.

RESULTS

Of 66 women enrolled, 36.4% (n = 24) had PTB. There were no differences in the obstetrical history and demographic information (p > .05) nor indication for cerclage (p = .369). Cervical length measurements at 20-24 weeks demonstrated a shorter TCL & LIO (22.69 vs. 33.86 mm, p = .001; 9.25 vs. 15.9 mm, p = .0042; respectively) in the preterm group. The LEO was similar in both groups. This pattern was also shown in a subgroup analysis (PTB < 34, 32 and 28 weeks).

CONCLUSION

Cervical length from internal OS to cerclage and total cervical length have a predictive value for PTB in women with a cervical cerclage, regardless of the indication for cerclage/previous pregnancy outcomes. Our data emphasize the importance of follow-up cervical length measurements of women with a cervical cerclage, and especially cervical length from internal OS to cerclage as those women may need additional care.