“Cervical length surveillance for predicting spontaneous preterm birth in women with congenital uterine anomalies: A systematic review and diagnostic accuracy meta-analysis”

“Cervical length surveillance for predicting spontaneous preterm birth in women with congenital uterine anomalies: A systematic review and diagnostic accuracy meta-analysis” | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 20 March 2026 V1 Latest version Share on “Cervical length surveillance for predicting spontaneous preterm birth in women with congenital uterine anomalies: A systematic review and diagnostic accuracy meta-analysis” Authors : Nikit Kadam 0009-0000-4206-8861 [email protected] , Sanaria Raouf , Nia Jones , and Kanna Mannadiar Jayaprakasan 0000-0002-1466-9376 Authors Info & Affiliations https://doi.org/10.22541/au.177399213.34622841/v1 137 views 71 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Background – The value of transvaginal cervical length surveillance for predicting spontaneous preterm birth (sPTB) in women with congenital uterine anomalies (CUA) is unclear. Objective - A systematic review and diagnostic accuracy meta-analysis of cervical length surveillance for predicting sPTB in women with CUA Search strategy – A literature review of MEDLINE, EMBASE, and the Cochrane Library from inception to December 2025. Selection criteria - Observational studies evaluating 2 nd trimester cervical length measurement in pregnant women with CUAs. Data collection and analysis - Review Manager and Meta-DiSc, with pooled odds ratios (ORs), sensitivity, specificity, likelihood ratios, and SROC curves generated using a random-effects model. Results – 5 studies including 624 women met the inclusion criteria. sPTB occurred in 52% with a short cervix versus 13.2% with normal cervical length (OR 8.05, [4.52–14.35]). A short cervix increased the risk of sPTB before 37 weeks (OR 6.68, [3.68–12.11]) and before 35 weeks (OR 28.16, [5.64–140.48]). The association was strongest for bicornuate uterus (OR 40.98, [4.27–393.10]), though estimates were imprecise. At a 25-mm cervical length threshold, sensitivity was low (0.35, [0.23 - 0.49]), specificity was high (0.94, [0.91 - 0.96]), with a LR+ ratio of 5.51. A 30 mm threshold improved sensitivity (1.00, [0 – 1.00]) but reduced specificity (0.84, [0.67 - 0.94]), reflecting sparse data. The SROC curve indicated moderate-to-good discriminatory performance. Conclusion – Cervical length measurement yields clinically useful risk stratification, especially when a short cervix is present. At the conventional 25-mm threshold, high specificity but limited sensitivity makes it better for confirming than excluding risk. Higher thresholds may improve detection, but the optimal cut-offs are still uncertain. “Cervical length surveillance for predicting spontaneous preterm birth in women with congenital uterine anomalies: A systematic review and diagnostic accuracy meta-analysis” Nikit Kadam 1,2 , Sanaria Raouf 1 , Nia Wyn Jones 2 , Kanna Jayaprakasan 1,2 . University Hospitals of Derby and Burton, Derby, United Kingdom University of Nottingham, Nottingham, United Kingdom. ABSTRACT Background – The value of transvaginal cervical length surveillance for predicting spontaneous preterm birth (sPTB) in women with congenital uterine anomalies (CUA) is unclear. Objective - A systematic review and diagnostic accuracy meta-analysis of cervical length surveillance for predicting sPTB in women with CUA Search strategy – A literature review of MEDLINE, EMBASE, and the Cochrane Library from inception to December 2025. Selection criteria - Observational studies evaluating 2 nd trimester cervical length measurement in pregnant women with CUAs. Data collection and analysis - Review Manager and Meta-DiSc, with pooled odds ratios (ORs), sensitivity, specificity, likelihood ratios, and SROC curves generated using a random-effects model. Results – 5 studies including 624 women met the inclusion criteria. sPTB occurred in 52% with a short cervix versus 13.2% with normal cervical length (OR 8.05, [4.52–14.35]). A short cervix increased the risk of sPTB before 37 weeks (OR 6.68, [3.68–12.11]) and before 35 weeks (OR 28.16, [5.64–140.48]). The association was strongest for bicornuate uterus (OR 40.98, [4.27–393.10]), though estimates were imprecise. At a 25-mm cervical length threshold, sensitivity was low (0.35, [0.23 - 0.49]), specificity was high (0.94, [0.91 - 0.96]), with a LR+ ratio of 5.51. A 30 mm threshold improved sensitivity (1.00, [0 – 1.00]) but reduced specificity (0.84, [0.67 - 0.94]), reflecting sparse data. The SROC curve indicated moderate-to-good discriminatory performance. Conclusion – Cervical length measurement yields clinically useful risk stratification, especially when a short cervix is present. At the conventional 25-mm threshold, high specificity but limited sensitivity makes it better for confirming than excluding risk. Higher thresholds may improve detection, but the optimal cut-offs are still uncertain. INTRODUCTION – Congenital uterine anomalies (CUA) result from abnormal Mullerian duct development and are associated with an increased risk of adverse obstetric outcomes, particularly spontaneous preterm birth (sPTB), although many affected women experience uncomplicated pregnancies 1,2 . While the reported prevalence varies due to differences in diagnostic criteria and imaging modalities, CUAs represent an important high-risk group in whom preterm birth remains a major contributor to perinatal morbidity 2,3,4 . Transvaginal sonographic assessment of cervical length is a validated predictor of sPTB in both low and high-risk populations and underpins risk stratification and preventative strategies such as vaginal progesterone and cervical cerclage 5 . However, the diagnostic and prognostic accuracy of cervical length measurement in the context of CUA remains uncertain. Distorted uterine anatomy and altered uterocervical dynamics may influence cervical competence, raising questions about whether conventional cervical length thresholds are applicable in this population. In 2008, Crane et al. 6 highlighted the paucity of data in this area and called for further research. Since then, a few small observational studies have evaluated cervical length surveillance in women with CUAs, but findings are inconsistent and limited by heterogeneity in anomaly subtype, methods and clinical practice. Importantly, the diagnostic accuracy of cervical length measurement in this population has not been comprehensively synthesised using contemporary meta-analysis. Further, there is a lack of international consensus regarding cervical length thresholds used to define cervical shortening in CUA 7 further complicating the interpretation and application of the evidence. A rigorous, systematic synthesis of the literature is needed to establish whether cervical length surveillance meaningfully predicts sPTB in women with CUAs and whether conventional thresholds are appropriate in this population. Establishing the diagnostic performance of cervical length assessment may improve risk stratification, refine patient counselling, and guide decisions on preventative interventions, while also identifying key evidence gaps and priorities for future prospective studies. We conducted a systematic review and diagnostic accuracy meta-analysis to assess how well transvaginal cervical length predicts sPTB before 37 and 35 weeks of gestation in pregnant women with CUA. Secondary objectives were to examine its utility across different cervical length thresholds and by anomaly subtype. METHODS Registration – The protocol for this systematic review was prospectively registered in PROSPERO (CRD420251275567). The protocol delineates the rationale for the review, the comprehensive search strategy, predefined inclusion and exclusion criteria, the quality appraisal tool, and the procedures for data extraction and synthesis. The review was conducted and reported in accordance with the PRISMA 2020 guidance. We also adhered to the MOOSE checklist to improve the quality and transparency of our review. Search Strategy – A comprehensive and systematic search of MEDLINE, EMBASE, and the Cochrane Library was conducted from database inception to December 2025, using a combination of subject headings and keywords. The search terms employed included Müllerian anomalies, congenital uterine anomalies, premature birth, premature delivery, premature labour, preterm labour, preterm delivery, cervical length measurement, cervical length surveillance, and mid-trimester cervical length scan. The full search strategy is provided in an Appendix. No language restrictions were applied. Two reviewers (NK and KJ) independently screened titles, abstracts and full texts against predefined inclusion criteria. Selection criteria – We included prospective and retrospective observational studies evaluating transvaginal cervical length measurement during the second trimester in pregnant women with CUA. The main outcome of interest was sPTB before 37 weeks of gestation or earlier gestational thresholds as reported. We excluded case reports, conference abstracts, studies involving multiple gestations, studies using transabdominal cervical measurements, studies reporting cervical length only after cervical cerclage placement without baseline values, and studies that did not provide extractable sPTB outcomes specific to women with CUA. Risk of bias assessment – Methodological quality was assessed independently by two reviewers using the Newcastle-Ottawa scale (NOS), which evaluates the selection of participants, comparability of groups, and ascertainment of outcome. A study can be awarded a maximum of 9 points/star. Studies were graded as low risk of bias (7-9 stars), medium risk of bias (5-6 stars), or high risk of bias (0-4 stars). Disagreements were resolved by consensus. Quality assessment of the included studies is shown in Table S1. Statistical analysis – Data were extracted independently by two reviewers (NK, KJ) to construct 2 × 2 contingency tables. The primary analysis quantified the association between short cervical length and sPTB before 37 weeks of gestation using pooled odds ratios (ORs). Pooled ORs with 95% confidence intervals (CIs) were estimated using a random-effects model. Between-study heterogeneity was assessed using the I² statistic and also by visual inspection of forest plots. The diagnostic performance of cervical length for predicting sPTB was evaluated by generating pooled sensitivity, specificity and summary receiver operating characteristic (SROC) curves using a random-effects model. The area under the SROC curve (AUC), positive and negative likelihood ratios and diagnostic odds ratios were calculated where data permitted. All statistical analyses were performed using Review Manager (RevMan 5.4) and Meta-DiSc software. RESULTS - The literature search yielded 502 records. Following the exclusion of 43 duplicates, 459 records were screened. Of these, 8 full‐text articles were retrieved as they met the predefined inclusion criteria. Ultimately, 5 of the 8 studies were deemed eligible and were included in the meta-analysis (Figure 1) Of the five included studies, four were retrospective (Crane 2012, Fox 2013, Rideout 2019, Hughes 2020) and one was prospective (Airoldi 2005). Only one study (Crane 2012) included a control group. Crane et al included 52 women in the study cohort, but relevant data could be extracted for 35 participants. As a result, the total number of women included in our analysis across five studies was 624. All five studies used various diagnostic modalities such as 3D ultrasonography, hysteroscopy, saline infusion sonography, CT, and MRI to identify congenital uterine anomalies (CUA). The characteristics of the included studies are summarised in the table below (Table S2) A total of five studies, comprising 624 women, were included in this meta-analysis (Figure 2). The pooled prevalence of spontaneous preterm birth was substantially higher in the short cervical length group than in the normal cervical length group, at 52% (38/73) versus 13.2% (73/551), corresponding to an odds ratio (OR) of 8.05 (95% CI 4.52–14.35; I 2 =4%; 5 studies; n=624). A meta-analysis of three studies reporting sPTB at <37 weeks demonstrated that short cervical length was strongly associated with spontaneous preterm birth at <37 weeks (OR 6.68, 95% CI 3.68–12.11; I 2 = 0%; 3 studies; n=525). Similarly, meta-analysis of two studies that reported sPTB at <35 weeks showed an increased likelihood of sPTB among women with a short cervix compared with those with a normal cervix (OR 28.16, 95% CI 5.64–140.48; I 2 =0%; 2 studies; n=99). We investigated the role of cervical length in predicting sPTB across different types of uterine anomaly (Figure 3). In a meta-analysis of two studies including pregnant women with a bicornuate uterus, a short cervical length was strongly associated with sPTB with OR 40.98 (95% CI 4.27–393.10; I 2 =0%; 2 studies; n=63). Although comparable effect estimates were observed for unicornuate and didelphys uteri (OR 17.00, 95% CI 0.60–483.50, and OR 10.20, 95% CI 0.31–336.93, respectively), these associations did not reach statistical significance. In the evaluation of diagnostic accuracy for cervical length measurement (Figure 4 & Table S3), a 25-mm cut-off demonstrated low sensitivity (0.35, 95% CI 0.23–0.49) but high specificity (0.94, 95% CI 0.91–0.96). The positive likelihood ratio (LR+) was 5.51 (95% CI 3.42–8.88), and the negative likelihood ratio (LR−) was 0.69 (95% CI 0.56–0.85), corresponding to a diagnostic odds ratio (DOR) of 7.96 (95% CI 4.16–15.23). The false positive rate was 0.06 (95% CI 0.05–0.09). At a higher threshold of 30 mm, sensitivity increased to 1.00 (95% CI 0–1.00), whereas specificity decreased to 0.84 (95% CI 0.67–0.94). The LR+ was 6.41 (95% CI 2.83–14.54). Due to complete separation in the included data, the LR− approached 0 and the DOR was unstable with very wide confidence intervals, reflecting sparse events and limited precision. The false positive rate at this threshold was 0.16 (95% CI 0.07–0.33). The area under the curve (AUC) of the summary receiver operating characteristic (ROC) curve was approximately 0.8–0.9 (Figure 5), indicating that cervical length demonstrates good overall discriminative performance for predicting sPTB, despite heterogeneity across studies. DISCUSSION – Main findings - In this systematic review and diagnostic accuracy meta-analysis, sPTB occurred in 52% of women with CUA and a short cervix compared with 13% of women with CUA and a normal cervical length (pooled OR 8.05). Subgroup analyses demonstrated that a short cervix was associated with an increased risk of sPTB before both 37 weeks (54% vs 15%; OR 6.68) and 35 weeks of gestation (44% vs 2%; OR 28.16). The association appeared particularly strong in women with a bicornuate uterus (OR 40.98), although these estimates were imprecise and based on small numbers. From a diagnostic perspective, transvaginal cervical length measurement demonstrated moderate to good overall discriminative ability for predicting sPTB in women with CUA, although test performance varied according to threshold. At the conventional 25 mm cutoff, cervical length showed low sensitivity but high specificity with a positive likelihood ratio consistent with clinically meaningful ‘rule-in’ utility. In contrast, the negative likelihood ratio indicated limited ability to exclude sPTB risk when the cervix was not shortened. At a 30 mm threshold, sensitivity increased, but estimates were imprecise and likely influenced by small sample size and sparse events limiting confidence in this cut-off and underscoring the need for prospective validation. Interpretation - Cervical length measurement is an established predictor of sPTB in both low- and high-risk obstetric populations and underpins contemporary preterm birth prevention strategies. However, evidence specific to women with CUA has remained limited since earlier reviews highlighted the paucity of robust data 6 . Our findings extend the literature by providing pooled diagnostic estimates and suggest that, although cervical shortening remains strongly associated with sPTB in this population, its predictive performance differs from that observed in structurally normal uteri. In particular, the low sensitivity at the conventional 25-mm threshold suggests that a substantial proportion of women with CUA who deliver preterm may not exhibit marked mid-trimester cervical shortening. The available evidence regarding the utility of cervical length assessment in women with CUA is limited, and our review confirms this gap. The modest sensitivity observed is biologically plausible, as preterm birth in this population may result not only from classical cervical insufficiency but also from altered uterine geometry, reduced uterine cavity volume, abnormal myometrial contractility, or impaired uteroplacental adaptation. These mechanisms may precipitate preterm labour independently of progressive cervical shortening. Furthermore, CUAs represent a heterogeneous group encompassing fusion (e.g. bicornuate and didelphys) and resorption (e.g. septate) defects, which may differ in biomechanical behaviour and obstetric risk. The particularly strong association observed in bicornuate uterus, although imprecise, raises the possibility that predictive performance varies by subtype and warrants further subtype-specific evaluation. We observed a significant association between short cervical length and spontaneous preterm birth in women with bicornuate uterus, with directionally similar but statistically non-significant trends in unicornuate and didelphys uteri. While several studies 13,14 have addressed adverse reproductive outcomes in women with CUAs, the small number of studies and limited subtype-specific data highlight the need for adequately powered, subtype-stratified research. From a clinical perspective, our findings suggest that transvaginal cervical length surveillance in women with congenital uterine anomalies (CUA) functions primarily as a risk stratification tool. At the conventional 25-mm threshold—consistent with NICE guidance defining cervical shortening 15 —high specificity supports its utility in identifying a subgroup at particularly high risk who may benefit from intensified surveillance within established preterm birth pathways. However, the limited sensitivity observed indicates that a normal cervical length should not be used to de-escalate care in this population. Although a 30-mm threshold improved sensitivity, reduced specificity and imprecision, together with the fact that only one included study utilised this cut-off, limits immediate clinical adoption. More broadly, there remains considerable international heterogeneity in cervical length thresholds applied in practice 15,16 , and Hughes et al. 7 have emphasised the need for high-quality studies to establish consensus regarding optimal cut-offs in women with CUA. Importantly, given the multifactorial pathophysiology of spontaneous preterm birth in this cohort—including non-cervical mechanisms—extrapolation of intervention strategies such as progesterone or cerclage from general preterm birth populations should be undertaken cautiously. Future research should prioritise adequately powered prospective cohort studies with standardised classification of uterine anomaly subtype and clear differentiation of spontaneous preterm birth phenotypes. Comparative evaluation of alternative cervical length thresholds, serial cervical length trajectories, and multimodal risk assessment strategies may help improve predictive accuracy. In addition, interventional studies evaluating progesterone, cerclage, or other preventive approaches specifically in women with CUAs are required to determine whether cervical length–guided management translates into improved obstetric outcomes in this distinct population. Strengths - This study represents, to our knowledge, the first diagnostic accuracy meta-analysis synthesising cervical length surveillance data specifically in women with CUA. Strengths include prospective protocol registration, systematic literature search without language restriction, and structured diagnostic performance analyses. The studies included in this review generally exhibited a medium risk of bias according to the Newcastle–Ottawa Scale (NOS), and all employed highly sensitive diagnostic modalities to identify CUA. Limitations - The number of eligible studies was small, sample sizes were limited, and heterogeneity existed in anomaly classification, cervical thresholds and outcome definitions. Some subgroup estimates were imprecise with wide confidence intervals, reflecting sparse data. Further, all included studies were observational with some of the participants may have presented with additional established risk factors for preterm labour, which may have introduced residual confounding. These limitations underscore the need for cautious interpretation. Conclusion - this systematic review demonstrates that cervical length surveillance in women with congenital uterine anomalies (CUA) provides clinically meaningful risk stratification, particularly when a short cervix is identified. However, limited sensitivity at conventional thresholds restricts its ability to exclude risk, and optimal cut-offs remain uncertain. By synthesising the available evidence, this review supports informed counselling and structured surveillance within preterm birth pathways, while highlighting important gaps in knowledge. Larger, well-designed prospective studies are required to refine threshold selection, standardise cervical length measurement protocols, and clarify the role of targeted preventive strategies in improving pregnancy outcomes for women with CUA. Funding – This study received no funding. REFERENCES. 1. Chan YY, Jayaprakasan K, Tan A, Thornton JG, Coomarasamy A, Raine-Fenning NJ. Reproductive outcomes in women with congenital uterine anomalies: a systematic review. Ultrasound Obstet Gynecol. Oct 2011;38(4):371-82. doi:10.1002/uog.10056. 2. Akhtar MA, Saravelos SH, Li TC, Jayaprakasan K. Reproductive Implications and Management of Congenital Uterine Anomalies (2024 Second Edition) : Scientific Impact Paper No. 62. BJOG : an international journal of obstetrics and gynaecology. 2025;132(5):e86-e97. doi:10.1111/1471-0528.18054. 3. Kim M-A, Kim HS, Kim Y-H. Reproductive, Obstetric and Neonatal Outcomes in Women with Congenital Uterine Anomalies: A Systematic Review and Meta-Analysis. 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Giouleka S, Tsakiridis I, Kostakis N, et al. Preterm Labor: A Comprehensive Review of Guidelines on Diagnosis, Management, Prediction and Prevention. Obstet Gynecol Surv. May 2022;77(5):302-317. doi:10.1097/OGX.0000000000001023. Supplementary Material File (figures.pptx) Download 872.96 KB File (tables - bjog.docx) Download 180.52 KB Information & Authors Information Version history V1 Version 1 20 March 2026 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords diagnostic meta-analysis general obstetrics preterm labour: basic science preterm labour: clinical research radiological imaging: ultrasound reproductive science: cervical function systematic reviews Authors Affiliations Nikit Kadam 0009-0000-4206-8861 [email protected] University Hospitals of Derby and Burton NHS Foundation Trust View all articles by this author Sanaria Raouf University Hospitals of Derby and Burton NHS Foundation Trust View all articles by this author Nia Jones University of Nottingham View all articles by this author Kanna Mannadiar Jayaprakasan 0000-0002-1466-9376 University Hospitals of Derby and Burton NHS Foundation Trust View all articles by this author Metrics & Citations Metrics Article Usage 137 views 71 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Nikit Kadam, Sanaria Raouf, Nia Jones, et al. “Cervical length surveillance for predicting spontaneous preterm birth in women with congenital uterine anomalies: A systematic review and diagnostic accuracy meta-analysis”. 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