Cervical cerclage for prevention of preterm birth and adverse perinatal outcome in twin pregnancies with short cervical length or cervical dilatation: A systematic review and meta-analysis

The role of cervical cerclage in preventing preterm birth

Cervical cerclage is an established intervention for the prevention of preterm birth in high-risk pregnancies. Although there is evidence to support the use of cervical cerclage in certain clinical situations, questions remain regarding its optimal application. As there are multiple underlying aetiologies of preterm birth, identifying the population of women who would benefit most from cerclage remains an ongoing clinical challenge. Moreover, establishing optimal surgical techniques and perioperative management strategies are areas of interest. This review explores the current role of cerclage in the prevention of preterm birth, while highlighting key areas for future research.

Prevention of preterm birth in twin pregnancy: international Delphi consensus

OBJECTIVE

To use the Delphi method to gain insight into approaches to prenatal diagnosis and management of preterm birth (PTB) in twin pregnancies, including complications such as twin-to-twin transfusion syndrome (TTTS) and a short and/or dilated cervix.

METHODS

A three-round Delphi process was conducted among an international panel of experts to assess their approach to prevention, monitoring and management strategies for PTB in twin pregnancies. Experts were selected based on their publication record or membership of related organizations. Response options were multiple-choice answers or a five-point Likert scale. A priori, a cut-off of ≥ 70% agreement was used to define consensus.

RESULTS

A total of 117 experts participated in the first round, of whom 94/117 (80.3%) completed all subsequent rounds. Representatives came from at least 22 countries (across five continents), most commonly the USA (50.4%) and the UK (12.0%). Over 70% of experts performed routine screening of cervical length (CL) using transvaginal ultrasound at 18-23 weeks' gestation, using CL ≤ 25 mm to diagnose short cervix in twin pregnancies, regardless of a history of PTB. In twin pregnancies with a short non-dilated cervix, most experts offered vaginal progesterone rather than pessary or cervical cerclage, regardless of a history of PTB. In twin pregnancies with asymptomatic dilated cervix, consensus was reached (88.3% agreement) for placement of cervical cerclage, performed up to 24 weeks' gestation (67.5% agreement; no consensus). Similarly, 96.1% of experts agreed that performing serial transvaginal ultrasound measurements of CL at 16-24 weeks' gestation was warranted in women with a current singleton pregnancy who had a previous twin pregnancy that required physical examination-indicated cerclage; these patients should be considered high risk for PTB (83.1% agreement). In twin pregnancies with TTTS, laser surgery is offered by most experts, regardless of preoperative CL. In patients with TTTS and short CL, most experts would recommend cervical cerclage (71.9%) or vaginal progesterone (65.6%) rather than pessary or expectant management. However, no consensus was reached on measures to prevent PTB in cases of TTTS with cervical dilation.

CONCLUSIONS

This Delphi consensus study highlights practice variations among healthcare providers worldwide in the evaluation and management of PTB in twin pregnancies, which often differ from recommendations given by national and international societies. © 2025 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Management of twin pregnancies: Remaining challenges and unanswered questions

Several professional societies have published guidelines on twin pregnancies over the past few years. These documents provide recommendations on antenatal surveillance and management of twin pregnancies. At the same time, these guidelines identify several key areas where evidence is limited and additional research is needed. In the present review, we summarize available evidence regarding some of these key areas, including the screening and prevention of preterm birth, the definition and management of fetal growth restriction, the diagnosis and management of gestational diabetes, the optimal maternal gestational weight gain, and the mode and timing of delivery. In addition, we describe several online tools related to these areas that can empower individuals with twin pregnancies and assist care providers in counseling these patients.

Cervical assessment

Transvaginal scan (TVS) of cervical length (CxL) at mid-trimester anomaly scan in asymptomatic pregnancy is useful for predicting the risk of preterm birth. In symptomatic women, measurement of CxL at presentation can help to distinguish between true and false preterm labor (PTL), and who might not deliver within 48 h and seven days. In both groups, the individualization of risk would lead to improvement of antenatal care, including frequency of visits, patient education to identify earlier symptoms, avoid excessive hospitalization, and unnecessary steroids. It is also possible that vaginal progesterone and/or cerclage reduce the PTB risk on those asymptomatic women with short cervix. The aim is to review the evidence that supports the use of TVS of CxL in both asymptomatic and symptomatic pregnant women for the prediction and management of PTL.

Cervical cerclage: An evolving evidence base

Cervical cerclage is an established intervention for the management of pregnancies at high risk of preterm birth. Although studies exist to support its use in certain situations, particularly in singleton pregnancies, many questions such as adjunct therapies and efficacy in specific subgroups of high-risk women have not been fully elucidated. This review will assess the current evidence as well as areas where there is currently a paucity of data and an urgent requirement for further research.

Contribution of cervical incompetence to occurrence of second trimester abortion in patients with polycystic ovary syndrome during the frozen embryo transfer cycle

Background

Second-trimester abortion is a critical issue in infertile women with polycystic ovary syndrome (PCOS) treated with assisted reproductive technology (ART), cervical incompetence (CI) may play a role. Although previous studies have revealed an association between PCOS and CI in women undergoing ART with fresh embryo transfer, the associated risk factors in frozen embryo transfer cycles are still unknown. The primary objective of this study is to examine the impact of CI on the occurrence of second-trimester abortion in women with PCOS undergoing frozen embryo transfer.

Methods

This retrospective cohort study included patients who underwent frozen-thawed embryo transfer and experienced second-trimester abortion between January 2012 and January 2020 from the Reproductive Medical Center of the First Affiliated Hospital of Zhengzhou University. Logit-transformed propensity score matching (PSM) was used to assess covariates. Patients were classified into the PCOS and non-PCOS groups. The PCOS group was further divided into two subgroups: the CI group and non-CI group.

Results

After case matching with PSM, 278 patients were included: 139 each in the PCOS group and non-PCOS groups. More miscarriages were attributed to CI in the PCOS group compared with the control group (20.14% vs. 10.07%). Subsequently, in the PCOS group, CI and non-CI subgroup analyses revealed a higher transfer cleavage-stage embryo incidence in the CI group than in the blastocysts group (p=0.001). Moreover, the between-group miscarriage-related gestational age varied significantly (p=0.039). Binary logistic regression analysis revealed that cleavage embryo transfer (p= 0.047) was associated with increased CI risk in the PCOS group, besides, increasing the number of transferred embryos did not impact the occurrence of CI in patients with PCOS.

Conclusion

CI independently predicted a higher risk of second-trimester abortion in patients with PCOS during the frozen embryo transfer cycle. What's more, increasing the number of transferred embryos did not affect the incidence of CI in the PCOS group.

Interventions for women with premature cervical dilatation and exposed fetal membranes to prevent pregnancy loss and preterm birth - A systematic review and meta-analysis

INTRODUCTION

The management of women with premature cervical dilatation and exposed unruptured fetal membranes remains uncertain and controversial. Treatment options may include expectant management or emergency cervical cerclage (ECC). Little is known regarding the effectiveness of individual interventions, or additional therapies. This systematic review aims to summarise all existing evidence to improve understanding of the treatment options and pregnancy outcomes for women presenting with premature cervical dilatation.

METHODS

Databases were searched using a prospective protocol (CRD42021286275). Studies were eligible for inclusion across five distinct comparison groups if they included women with premature cervical dilatation and reported clinical outcomes. Primary outcome was pregnancy loss (miscarriage, stillbirth, neonatal death and termination of pregnancy). Planned subgroups included singletons and twins, and low-cervical or high-cervical suture. Pairwise random effects meta-analysis calculated in RevMan5.4, single arm random effects proportional meta-analysis calculated using RevMan and R studio. Risk of bias was assessed using Cochrane Risk of Bias tool and Joanna Briggs Institute checklists.

RESULTS

6781 abstracts were screened, and 177 (four randomised controlled trials) studies included in the five analysis groups. Women receiving ECC were significantly less likely to experience pregnancy loss (combined RR 0.48 95 %CI 0.39-0.59 singleton RR 0.48 95 %CI 0.34-0.67 twin only RR 0.39 95 %CI 0.26-0.58) compared to expectant management. Adjuvant amnioreduction with ECC was not found to reduce pregnancy loss (RR 1.12 (95 % CI 0.73-1.72) or any other outcomes compared to ECC without amnioreduction. Women were significantly more likely to experience pregnancy loss (RR3.85 95 %CI 3.13-4.74) after ECC compared to planned cerclage. The probability of intra-operative rupture of membranes at ECC insertion was 3.3 % (95 %CI 1.8-5.1) and the probability of an ECC attempt being abandoned was 2.6 % (95 %CI 1.1-4.6 %).

DISCUSSION

ECC appears to reduce the risk of pregnancy loss for both singletons and twins although the overall quality of evidence is poor. It is important that women are counselled regarding the outcomes following cerclage according to indication. Pregnancy complications are common after ECC although the rates of intra-operative complications are lower than may be anticipated. Randomised trials remain imperative for understanding the role of ECC and adjunctive treatments in preventing pregnancy loss in this condition.

Study protocol for two randomised controlled trials evaluating the effects of Cerclage in the reduction of extreme preterm birth and perinatal mortality in twin pregnancies with a short cervix or dilatation: the TWIN Cerclage studies

INTRODUCTION

Twin pregnancies have a high risk of extreme preterm birth (PTB) at less than 28 weeks of gestation, which is associated with increased risk of neonatal morbidity and mortality. Currently there is a lack of effective treatments for women with a twin pregnancy and a short cervix or cervical dilatation. A possible effective surgical method to reduce extreme PTB in twin pregnancies with an asymptomatic short cervix or dilatation at midpregnancy is the placement of a vaginal cerclage.

METHODS AND ANALYSIS

We designed two multicentre randomised trials involving eight hospitals in the Netherlands (sites in other countries may be added at a later date). Women older than 16 years with a twin pregnancy at <24 weeks of gestation and an asymptomatic short cervix of ≤25 mm or cervical dilatation will be randomly allocated (1:1) to both trials on vaginal cerclage and standard treatment according to the current Dutch Society of Obstetrics and Gynaecology guideline (no cerclage). Permuted blocks sized 2 and 4 will be used to minimise the risk of disbalance. The primary outcome measure is PTB of <28 weeks. Analyses will be by intention to treat. The first trial is to demonstrate a risk reduction from 25% to 10% in the short cervix group, for which 194 patients need to be recruited. The second trial is to demonstrate a risk reduction from 80% to 35% in the dilatation group and will recruit 44 women. A cost-effectiveness analysis will be performed from a societal perspective.

ETHICS AND DISSEMINATION

This study has been approved by the Research Ethics Committees in the Netherlands on 3/30/2023. Participants will be required to sign an informed consent form. The results will be presented at conferences and published in a peer-reviewed journal. Participants will be informed about the results.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, NCT05968794.

Randomized controlled trials: not always the "gold standard" for evidence in obstetrics and gynecology

Randomized controlled trials are considered the "gold standard" for therapeutic interventions, and it is not uncommon for sweeping changes in medical practice to follow positive results from such trials. However, randomized controlled trials are not without their limitations. Physicians frequently view randomized controlled trials as infallible, whereas they tend to dismiss evidence derived from sources other than randomized controlled trials as less credible or reliable. In several situations in obstetrics and gynecology, there are no randomized controlled trials to help guide the clinician. In these circumstances, it is important to evaluate the entire body of evidence including observational studies, rather than dismiss interventions altogether simply because no randomized controlled trials exist. Randomized controlled trials and observational studies should be viewed as complementary rather than at odds with each other. Some reversals in widely adopted clinical practice have recently been implemented following subsequent studies that contradicted the outcomes of major randomized controlled trials. The most notable of these was the withdrawal from the market of 17-hydroxyprogesterone caproate for preterm birth prevention. Such reversals could potentially have been averted if the inherent limitations of randomized controlled trials were carefully considered before implementing these universal practice changes. This Clinical Opinion underscores the limitations of an exclusive reliance on randomized controlled trials while disregarding other evidence in determining how best to care for patients. Solutions are proposed that advocate that clinicians adopt a more balanced perspective that considers the entirety of the available medical evidence and the individual patient characteristics, needs, and wishes.

Development and validation of a prediction model on spontaneous preterm birth in twin pregnancy: a retrospective cohort study

BACKGROUND

This study was conducted to develop and validate an individualized prediction model for spontaneous preterm birth (sPTB) in twin pregnancies.

METHODS

This a retrospective cohort study included 3845 patients who gave birth at the Chongqing Maternal and Child Health Hospital from January 2017 to December 2022. Both univariable and multivariable logistic regression analyses were performed to find factors associated with sPTB. The associations were estimated using the odds ratio (OR) and the 95% confidence interval (CI). Model performance was estimated using sensitivity, specificity, accuracy, area under the receiver operating characteristic curve (AUC) and decision curve analysis (DCA).

RESULTS

A total of 1313 and 564 cases were included in the training and testing sets, respectively. In the training set, univariate and multivariate logistic regression analysis indicated that age ≥ 35 years (OR, 2.28; 95% CI 1.67-3.13), pre-pregnancy underweight (OR, 2.36; 95% CI 1.60-3.47), pre-pregnancy overweight (OR, 1.67; 95% CI 1.09-2.56), and obesity (OR, 10.45; 95% CI, 3.91-27.87), nulliparity (OR, 0.58; 95% CI 0.41-0.82), pre-pregnancy diabetes (OR, 5.81; 95% CI 3.24-10.39), pre-pregnancy hypertension (OR, 2.79; 95% CI 1.44-5.41), and cervical incompetence (OR, 5.12; 95% CI 3.08-8.48) are independent risk factors for sPTB in twin pregnancies. The AUC of the training and validation set was 0.71 (95% CI 0.68-0.74) and 0.68 (95% CI 0.64-0.73), respectively. And then we integrated those risk factors to construct the nomogram.

CONCLUSIONS

The nomogram developed for predicting the risk of sPTB in pregnant women with twins demonstrated good performance. The prediction nomogram serves as a practical tool by including all necessary predictors that are readily accessible to practitioners.