Introduction

Spontaneous preterm birth remains a leading cause of neonatal mortality and long-term morbidity worldwide. Cervical insufficiency, characterised clinically by painless cervical shortening and/or dilatation in the midtrimester, represents one mechanistic pathway to early birth. Cervical cerclage, the placement of a nonabsorbable suture or tape to reinforce the cervix, was introduced in the early twentieth century and popularised by Shirodkar and McDonald in the 1950s.^1,2 Despite its empirical origins, cerclage has persisted through a century of clinical refinement.

Over the past three decades, advances in imaging, trial methodology, and comparative effectiveness research have transformed cerclage from a history-based intervention into a targeted strategy guided by transvaginal ultrasound phenotyping and evidence-based risk stratification. This evolution reflects a broader shift in preterm birth prevention toward precision, phenotype-driven care.^1,3

Background

Cervical cerclage has been used for over a century to prevent midtrimester pregnancy loss and spontaneous preterm birth attributed to cervical insufficiency. Originally introduced as an empiric mechanical intervention, its role has evolved alongside improvements in imaging, surgical technique, and clinical trial design. Today, cerclage remains a core strategy for selected women at high risk of early spontaneous preterm birth, requiring careful patient selection, nuanced counselling and integration with surveillance, and adjunctive therapies.

Biological Rationale for Cervical Cerclage

The pathophysiology of cervical insufficiency is increasingly understood as a continuum of cervical integrity rather than a dichotomous diagnosis. Structural support may be only one mechanism through which cerclage confers benefit. Maintenance of cervical length, preservation of the endocervical mucus plug, and modification of the cervicovaginal microenvironment, including potential barrier effects against ascending infection, have all been proposed as contributory mechanisms.¹

This broader biological framing underpins contemporary practice, emphasising phenotype definition using obstetric history, cervical length trajectory, and physical examination findings, and supporting combined strategies in women at very high risk where mechanical reinforcement alone may be insufficient.^4,5

Fig. 1. Key milestones in the evolution of cervical cerclage from empiric intervention to precision prevention strategies.

Modern Role of Cervical Cerclage

Transvaginal Cerclage

Despite long-standing use, variation in surgical technique remains substantial. Available evidence suggests that outcomes are influenced more by indication, timing, and patient phenotype than by technical variation.

Cervical Length Assessment

The introduction of transvaginal ultrasound cervical length measurement represents the most important advance in cerclage practice, enabling refined risk stratification and avoidance of indiscriminate intervention.

Transabdominal Cerclage

Transabdominal cerclage offers an effective option for women with failed transvaginal cerclage or with significant cervical anatomical compromise. Minimally invasive laparoscopic and robotic approaches have reduced surgical morbidity while maintaining efficacy.

Combination Therapy

Emerging evidence suggests that combination therapy with vaginal progesterone and cervical cerclage may improve outcomes in selected high-risk women compared with either intervention alone.

An approach to decision-making regarding cervical cerclage is summarised in Figure 2.

Fig. 2. Decision tree for consideration of cervical cerclage in singleton pregnancies at risk of spontaneous preterm birth.

Clinical Implications and Current Controversies

Cervical cerclage was widely adopted before the advent of modern clinical trials, with early evidence largely observational. Subsequent randomised trials and individual patient data meta-analyses have refined indications, demonstrating that benefit from cerclage is concentrated within specific high-risk phenotypes defined by prior spontaneous preterm birth, cervical length shortening, and physical examination findings.

Fig. 3. Spectrum of cervical cerclage approaches aligned with increasing anatomical and obstetric risk.

The most consequential advances since the inception of cerclage include the objective risk stratified subtyping using transvaginal ultrasound cervical length, enabling more selective placement; the maturation of the evidence base for ultrasound indicated and emergency cerclage, including clearer recognition of subgroup effects; the expansion of transabdominal cerclage, particularly minimally invasive approaches for women with anatomical constraints or failed transvaginal cerclage; and increasing evidence for multimodal prevention, including combination therapy with vaginal progesterone in selected high-risk populations. Key advances include the transition from history-based to ultrasound-guided patient selection, the emergence of transabdominal cerclage for women with failed transvaginal approaches, and growing evidence supporting combination therapy with vaginal progesterone.

Despite these advances, some uncertainty remains regarding standardisation of surgical technique, optimal integration with adjunctive therapies, and the role of cerclage in women without prior spontaneous preterm birth. Future research must focus on phenotype-driven prevention strategies, mechanistic understanding, and global equity of access to advanced cerclage techniques.

For example, this presentation at 20 weeks gestation highlights the significance of clinical examination and scan findings in decision-making.

Fig 4. Presentation at 20 weeks gestation

Conclusion

Cervical cerclage exemplifies how an intervention introduced in the pre‑evidence era can remain relevant through refinement rather than replacement. Its contemporary role is defined by improved understanding of disease heterogeneity, careful patient selection, and integration into multimodal strategies for the prevention of spontaneous preterm birth. Ongoing priorities include standardisation of technique and training, clarification of optimal adjunctive therapies, and ensuring equitable access to advanced cerclage approaches within evolving precision prevention frameworks.