Assessment of Uterocervical Angle Width as a Predictive Factor of Preterm Birth: A Systematic Review of the Literature

Uterocervical angle and cervical length measurements for spontaneous preterm birth prediction in low-risk singleton pregnant women: a prospective cohort study

PURPOSE

Preterm birth is the leading cause of early neonatal morbidity and mortality. Strategies to predict preterm birth risk can help improve pregnancy outcomes. Even pregnant women without known risk factors for preterm birth can also experience it. This study aimed to evaluate the ability of the uterocervical angle and cervical length to predict spontaneous preterm birth in low-risk singleton pregnant women.

METHODS

A prospective study on 1107 singleton pregnant women between 16+0 and 23+6 weeks gestation at low risk for spontaneous preterm birth who were treated at the Haiphong Hospital of Obstetrics and Gynecology, Vietnam, between September 2020 and September 2021 was conducted. A single sonographer assessed the cervical length and the uterocervical angle using transvaginal ultrasonography. The patients were followed up until delivery to determine the main pregnancy outcome (spontaneous preterm birth before 37 weeks gestation). The cut-off points for the uterocervical angle and cervical length were established by analyzing the receiver operating characteristic curve. The sensitivity, specificity, likelihood ratio, positive and negative predictive values, and accuracy of the uterocervical angle and cervical length for predicting spontaneous preterm birth were determined.

RESULTS

A uterocervical angle ≥ 99° predicted spontaneous preterm birth at < 37 weeks, with a sensitivity and specificity of 91% and 76%, respectively. A cervical length ≤ 33.8 mm predicted preterm birth at < 37 weeks with a sensitivity and specificity of 25% and 66%, respectively. A uterocervical angle ≥ 99° combined with a cervical length ≤ 33.8 mm yielded the sensitivity, specificity, positive predictive value, likelihood ratio, and accuracy of spontaneous preterm birth prediction of 66%, 93%, 36%, 9, and 91%, respectively; thus provided a significant increase of specificity with an acceptable reduction of sensitivity as compared to cervical length alone.

CONCLUSION

Besides the cervical length, the uterocervical angle can be considered a valuable ultrasound parameter for predicting spontaneous preterm birth in low-risk singleton pregnant women. Combining the uterocervical angle and cervical length yielded stronger spontaneous preterm birth prediction values.

Utero-cervical angle to predict the risk of spontaneous preterm birth: a review of literature

BACKGROUND

The aim of this paper was to evaluate the predictive role of the uterocervical angle (UCA) in spontaneous preterm birth (sPTB).

METHODS

A systematic review of the literature was performed including all studies reporting the association between UCA and sPTB. Searches were performed with the use of a combination of keywords: "cervical length," "uterocervical angle," and "preterm birth" from inception of each database to March 2022. The statistical evaluations were carried out using the Comprehensive Meta-Analysis version 3 (Biostat Inc. USA).

RESULTS

Sixteen studies all conducted on the second trimester UCA as well as its association with sPTB were included in this study. In all studies the measurements of cervical length (CL) and UCA were performer in the second trimester, except in one that in the third trimester. In most studies the CL is greater than 30 mm and the UCA is greater than 110 °. In seven studies women with symptoms were considered while in 8 studies the women were asymptomatic.

CONCLUSIONS

It is too early for it to reach a firm conclusion on UCA utilization in clinical settings. A higher UCA measurement (greater than 150°) is an important risk factor for deliveries before 37 weeks' gestation. It provides a higher diagnostic performance in high risk patients than the CL measurement. However, the most relevant ultrasound parameter for the prediction of delivery within the next few data in women with preterm delivery remains the cervical length. There is a need to consider both markers and create protocols so that the values obtained with UCA and those with CL can make a real contribution to decisions to be made rather than using only CL.

Recent Advances and Challenges in the Early Diagnosis and Treatment of Preterm Labor

Preterm birth (PTB) is the primary cause of neonatal mortality and long-term disabilities. The unknown mechanism behind PTB makes diagnosis difficult, yet early detection is necessary for controlling and averting related consequences. The primary focus of this work is to provide an overview of the known risk factors associated with preterm labor and the conventional and advanced procedures for early detection of PTB, including multi-omics and artificial intelligence/machine learning (AI/ML)- based approaches. It also discusses the principles of detecting various proteomic biomarkers based on lateral flow immunoassay and microfluidic chips, along with the commercially available point-of-care testing (POCT) devices and associated challenges. After briefing the therapeutic and preventive measures of PTB, this review summarizes with an outlook.

Uterocervical angle in predicting spontaneous preterm birth: a systematic review and meta-analysis

OBJECTIVE

This study aimed to compare the uterocervical angles in term and spontaneous preterm birth cohorts and to compare the test characteristics of the uterocervical angle and cervical length in the prediction of spontaneous preterm birth.

DATA SOURCES

A systematic search of published literature from January 1, 1945, to May 15, 2022, was performed using the following databases: PubMed, Cochrane Central Register of Controlled Trials, Embase, World Health Organization International Clinical Trials Registry Platform, Web of Science, and ClinicalTrials.gov. The search was not restricted. The references of all relevant articles were reviewed.

STUDY ELIGIBILITY CRITERIA

Randomized control trials, nonrandomized control trials, and observational studies were evaluated for primary comparisons. Included studies compared the uterocervical angles in term and spontaneous preterm birth cohorts and compared the uterocervical angle with cervical length in the prediction of spontaneous preterm birth.

METHODS

Of note, 2 researchers independently selected studies and evaluated the risk of bias with the Newcastle-Ottawa Scale for cohort and case-control studies. Mean differences and odds ratios were calculated using a random effects model for inclusion and methodological quality. The primary outcomes were uterocervical angle and successful prediction of spontaneous preterm birth. Moreover, posthoc analysis comparing the uterocervical angle and cervical length together was performed.

RESULTS

A total of 15 cohort studies with 6218 patients were included. The uterocervical angle was larger in the spontaneous preterm birth cohorts (mean difference, 13.76; 95% confidence interval, 10.61-16.91; P<.00001; I²=90%). Sensitivity and specificity analyses demonstrated lower sensitivities with cervical length alone and uterocervical angle plus cervical length than with uterocervical angle alone. Pooled sensitivities for uterocervical angle and cervical length alone were 0.70 (95% confidence interval, 0.66-0.73; I²=90%) and 0.46 (95% confidence interval, 0.42-0.49; I²=96%), respectively. Pooled specificities for uterocervical angle and cervical length were 0.67 (95% confidence interval, 0.66-0.68; I²=97%) and 0.90 (95% confidence interval, 0.89-0.91; I²=99%), respectively. The areas under the curve for uterocervical angle and cervical length were 0.77 and 0.82, respectively.

CONCLUSION

Uterocervical angle alone or with cervical length was not superior to cervical length alone in predicting spontaneous preterm birth.

Neutrophil-to-Lymphocyte Ratio (NLR) and Platelet-to-Lymphocyte Ratio (PLR) Can Predict Spontaneous Preterm Birth?

Purpose

To investigate the role of neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) in the prediction of spontaneous preterm birth.

Patients and Methods

Data was retrospectively collected from hospital record between February 2018 and November 2022. Pregnant women (n = 78) with a single pregnancy between 24 and 34 weeks of gestation, presented with labor pain, and had regular uterine contractions (threatened preterm labor - TPL) were included. Patients delivered within the first week after TPL were included in group 1 (n = 40) and who delivered after in group 2 (n = 38). Two groups were investigated for NLR and PLR values.

Results

The median cervical length among women who gave birth within a week was significantly lower (24.5 versus 30.0 p < 0.001). The median neutrophil-to-lymphocyte ratio among women who gave birth within a week was significantly higher (6.4 versus 4.5 p < 0.001). The median platelet-to-lymphocyte ratio among women who gave birth within a week was significantly higher (151 versus 131 p < 0.001). The cut-off values to predict preterm birth were >5 for NLR (sensitivity: 90%, specificity: 92.1%), >139 for PLR (sensitivity: 97.5%, specificity: 100%).

Conclusion

NLR and PLR values predict spontaneous preterm birth with high sensitivity and specificity. By predicting preterm birth, the pregnancy process can be managed sensitively and smoothly.

Distribution of uterocervical angles of pregnant women at 16+ 0 to 23+ 6 weeks gestation with low risk for preterm birth: first vietnamese cohort of women with singleton pregnancies

BACKGROUND

Cervical length (CL) measured by ultrasound in the second trimester is a predictor of spontaneous preterm birth (sPTB). The uterocervical angle (UCA) has recently been suggested as a predictor to identify women at risk of sPTB. The aim of this study was to investigate the UCAs' distribution in singleton pregnant women at 16^+ 0 - 23^+ 6 weeks of gestation with low risk for sPTB.

METHODS

This was a prospective cohort study of 1,051 pregnant women with singleton pregnancies at low risk for preterm delivery. Pregnant women with a viable singleton fetus at 16^+ 0 - 23^+ 6 weeks of gestation were enrolled in the study conducted at the Haiphong Hospital of Obstetrics and Gynecology, Vietnam, from 09/2019 to 09/2020. CL and the UCA were assessed using transvaginal ultrasonography (TVS) by a single sonographer. Subjects were followed-up until the end of pregnancy, and maternal and neonatal outcomes were recorded. The UCAs' range and their relationship with gestational age were evaluated using regression analysis. P < 0.05 was considered statistically significant.

RESULTS

The normal range of the UCA (5^th - 95^th percentiles) was 46.47° (95% CI, 40.27°-51.81°) to 127.06° (95% CI, 123.02° - 130.71°). The UCAs in the preterm birth (< 37 weeks) and full-term groups were 117.86° ± 20.25° and 83.80° ± 24.18°, respectively (p < 0.001). Linear regression analysis showed a significant change in the UCA range from 16^+ 0 to 23^+ 6 weeks of gestation (2.51 degrees per week, p < 0.001). The linear function yielded the highest correlation coefficient in the variation rule of the UCA values (r = 0.22). A total of 42/63 (66.7%) patients with preterm birth < 37 weeks had a UCA above the 75^th percentile. The majority of women with preterm birth had a UCA ≥ 95° compared with those with full-term delivery (88.9% vs. 31.3%, p < 0.001).

CONCLUSIONS

The results of this study present background information about the normal range of UCA values in singleton pregnant women at 16^+ 0 to 23^+ 6 weeks at low risk for sPTB in this Vietnamese cohort. In this study population at low risk for sPTB, pregnant women with a UCA value ≥ 95^o were also considered at risk for preterm birth.

The effect of anterior uterocervical angle (aUCA) and cervical length on the development of pelvic inflammatory disease

This study aims to compare the uterine body longitudinal axis, uterine body transverse axis, uterine cervix longitudinal axis and anterior cervical axis angle measured ultrasonographically between women with pelvic inflammatory disease (PID) and healthy controls. Women aged 18-45 years with PID and healthy controls were included in the study. Demographic characteristics, uterine body long axis, uterine body transverse axis, uterine cervix long axis and anterior cervical axis angle of PID patients and healthy controls were evaluated. Gravida, parity, history of smoking were significantly higher in the PID group (n = 75) than the control group (n = 74). The uterine body longitudinal axis (p = 0.001) and transverse axis (p = 0.005) were significantly lower, and the cervix longitudinal axis (p < 0.001) and the anterior uterocervical angle (p < 0.001) were significantly higher in the PID group than the control group. Binary logistic regression analysis showed that uterine body (UTX) longitudinal axis (p = 0.005), uterine cervix longitudinal axis (p < 0.001) and UCA (p < 0.001) were significant predictors of PID. Uterine body longitudinal axis, uterine cervix longitudinal axis, and UCA can be associated to PID. This article is protected by copyright. All rights reserved.

Prediction of Preterm Birth with Serial Measurements of Ultrasound Markers

To compare the ability of cervical length (CL), anterior cervical angle (ACA), and cervical consistency index (CCI) to predict premature birth.

METHODS

This prospective study involved 85 pregnant women who gave birth prematurely and a control group of 31 pregnant women who gave birth at term. The study was performed in the Obstetrics and Gynecology Clinic of the Municipal Clinical Hospital Filanthropia Craiova between January 1, 2019, and January 1, 2022. Cases were examined using transvaginal ultrasonography (TVU) in the second and third trimesters of pregnancy, and cervical length (CL), Anterior Cervical Angle (ACA), and Cervical Consistency Index (CCI) were measured.

RESULTS

The mean value from the three measurements at all three parameters was statistically significant with preterm birth (p<0.05). Cervical length <25mm, was highly significant in the prediction of preterm labor with a sensitivity of 99%, specificity of 61%, positive predictive value (PPV) of 78%, negative predictive value (NPV) of 97 %, and a positive likelihood ratio (LR+) of 2.54 and negative likelihood ratio (LR-) of 0.02. CCI also remains, despite low specificity and PPV values, a potential predictive parameter in the prediction of preterm birth, with a sensitivity of 73%, NPV of 92% and a LR+of 1.32 and LR- of 0.6 also correlated with CL, CCI being more difficult to interpret as an independent predictive parameter.

CONCLUSIONS

CL remains the standard parameter for predicting the preterm birth, but in combination with other parameters, the prediction rate can increase significantly.

The Value of Posterior Cervical Angle as a Predictor of Vaginal Delivery: A Preliminary Study

Accurate prediction of failure to progress and rapid decision making regarding the mode of delivery can improve pregnancy outcomes. We examined the value of sonographic cervical markers in the prediction of successful vaginal delivery beyond 34 weeks of gestation. A retrospective chart review was carried out. Medical information of singleton gestations delivered at a single center from 1 July 2019 to 30 August 2020 was collected. Transvaginal sonographic records of cervical length, anterior and posterior cervical angles, and cervical dilatation were obtained and re-measured. The value of these markers and clinical characteristics of mother and baby on vaginal delivery were investigated and compared to women who underwent cesarean section. A total of 90 women met the inclusion criteria. The rate of vaginal delivery was 75.6%. There were no differences found in terms of maternal age, rate of abortion, induction of labor, premature rupture of membranes, preterm labor, hypertension, diabetes, cervical length, and neonatal sex and weight. The prediction of vaginal delivery was provided by parity, maternal body mass index, and posterior cervical angle. The area under the receiver operating characteristic curve for prediction of vaginal delivery was 0.667 (95% CI 0.581–0.864, p = 0.017) for the posterior cervical angle, with a cutoff of 96.5°. Regression analysis revealed a posterior cervical angle ≥96.5° in the prediction of vaginal delivery (adjusted odds ratio: 6.24; 95% confidence interval: 1.925–20.230, p = 0.002). Posterior cervical angle ≥96.5° is associated with successful vaginal delivery. It is simple and easy to measure and can be useful in determining the mode of delivery.

Measurement of the Uterocervical Angle for Predicting the Latent Period in Pregnancy Exhibiting Premature Membrane Rupture

OBJECTIVES

The duration of the latent period is uncertain in preterm premature rupture of membranes (PPROM). This time estimate provides information on the time of the corticosteroid to be applied and the time of delivery of the pregnant women. Here, we used transvaginal sonography to determine the relationship between the uterocervical angle (UCA) and PPROM latency and the risk for neonatal complications.

DESIGN

This is a prospective cohort study of 80 singleton pregnancies with PPROM. Participants/Materials, Setting, and Methods: This prospective cohort study was conducted at a tertiary center with a total of 80 singleton pregnancies with PPROM. The UCA and cervical length were measured in the first evaluation of PPROM in patients between 24 and 34 weeks of age. The study population was subdivided into 2 groups: group 1 (n = 27) included women who gave birth within 10 days after a PPROM diagnosis and group 2 (n = 53) included women who gave birth later than this. Our aim was latency prediction (more or less than 10 days) in PPROM patients undergoing regular UCA monitoring.

RESULTS

Of the women in group 1, 74.1% (n = 20) had spontaneous births and 7.4% (n = 2) had induced births because of clinical chorioamnionitis. Of the women in group 2, 71.6% (n = 38) had spontaneous births and 7.6% (n = 4) had induced births because of clinical chorioamnionitis (n = 3) or poor fetal condition (n = 1). We drew receiver operating characteristic curves to explore whether the UCA predicted birth within 10 days of PPROM. The area under the curve was 0.894 (p < 0.001). The optimal UCA cutoff was 108°, with 93% sensitivity and 85% specificity.

LIMITATIONS

First, the sample size was small; it would have been better to have more patients. Second, we measured the UCA only once. Third, patients were not categorized by parity.

CONCLUSIONS

The UCA, measured by the transvaginal route, can successfully predict latent period in PPROM. Measuring the UCA can be useful to determine the time of corticosteroid administration and to inform patients about the time of birth.

Measurement of the uterocervical angle for the prediction of preterm birth in symptomatic women

Purpose

To examine if the uterocervical angle (UCA) can be used to predict preterm delivery in women with painful and regular uterine contractions and a cervical length of 25 mm or less.

Methods

Retrospective study at the perinatal unit of the University Hospital of Tuebingen, Germany. Women with singleton gestation and preterm contractions between 24 + 0 and 33 + 6 weeks’ gestation were included. For the UCA measurement, a line is placed from the internal os to the external os irrespective of whether the cervix is straight or curved. A second line is drawn to delineate the lower uterine segment. The angle between the two lines is the UCA measurement. The measurements were taken on stored images from our database.

Results

The study consisted of 213 singleton pregnancies. At the time of UCA measurement, median maternal and gestational age was 31.4 years and 29.7 weeks’ gestation. Median gestational age at delivery was 35.3 weeks and the corresponding birth weight 2480 g, respectively. The UCA measurement in women who delivered within 2 days, between 3–7 days and after 7 days was not helpful to distinguish between these three groups [median UCA measurements: 108.5°, 108.0° and 107.3° (Kruskal–Wallis test p = 0.576)]. Uni- and multivariate logistic multiple regression analysis demonstrated that the delivery within 2 days was only dependent on the gestational age and the cervical length at the time of presentation.

Conclusion

The measurement of UCA is not useful in predicting preterm birth in the subsequent 7 days after an episode of preterm contractions.

Uterocervical Angle and Cervical Length as a Tool to Predict Preterm Birth in Threatened Preterm Labor

Objective

To evaluate the diagnostic performance of uterocervical angle (UCA) and UCA with cervical length (CL) in predicting preterm delivery in threatened preterm labor.

Methods

A multicenter prospective observational cohort study was conducted in 160 pregnant women having threatened preterm labor at Srinagarind and Udonthani Hospitals in Thailand between March 2019 and June 2020. Researchers measured UCA and CL by transvaginal ultrasonography. Medical records were reviewed for patient characteristics, and patients were followed up until the date of delivery to assess for the outcome of preterm birth. The cut-off point of UCA was determined from receiver operating characteristic curve analysis. The sensitivity, specificity, likelihood ratio, positive and negative predictive values (PPV and NPV) of UCA and of UCA with CL for predicting preterm birth were determined.

Results

The incidence of preterm birth in women having threatened preterm labor was 27%. The sensitivity, specificity, PPV and NPV of UCA ≥110.97 degrees for predicting preterm birth were 65.1%, 43.6%, 29.8% and 77.3%, respectively. The sensitivity, specificity, PPV and NPV of UCA ≥110.97 degrees with CL <3.4 centimeters for predicting preterm birth were 48.8%, 68.4%, 36.2% and 78.4%. The specificity and NPV of UCA with CL were higher than for UCA alone.

Conclusion

With adequate sensitivity and high NPV, UCA by TVS can be supplemented with CL measurement in threatened preterm labor management to increase the diagnostic performance for predicting preterm birth.

The Novel Ultrasonographic Marker of Uterocervical Angle for Prediction of Spontaneous Preterm Birth in Singleton and Twin Pregnancies: A Systematic Review and Meta-Analysis

The alteration of the uterocervical angle (UCA) has been proposed to play an important role in spontaneous preterm birth (sPTB). The aim of this systematic review and meta-analysis was to evaluate the evidence on the UCA predictive role in sPTB. In this study, PubMed, Web of Science, Scopus, and Google scholar were systematically searched from inception up to June 2020. Inter-study heterogeneity was also assessed using Cochrane's Q test and the I2 statistic. Afterward, the random-effects model was used to pool the weighted mean differences (WMDs) and the corresponding 95% confidence intervals (CIs). Eleven articles that reported second-trimester UCA of 5,061 pregnancies were included in this study. Our meta-analysis results indicate that a wider UCA significantly increases the risk of sPTB in following cases: all pregnancies (WMD = 15.25, 95% CI: 11.78-18.72, p < 0.001; I2 = 75.9%, p < 0.001), singleton (WMD = 14.43, 95% CI: 8.79-20.06, p < 0.001; I2 = 82.4%, p < 0.001), and twin pregnancies (WMD = 15.14, 95% CI: 13.42-16.87, p < 0.001; I2 = 0.0%, p = 0.464). A wider ultrasound-measured UCA in the second trimester seems to be associated with the increased risk of sPTB in both singleton and twin pregnancies, which reinforces the clinical evidence that UCA has the potential to be used as a predictive marker of sPTB.

Uterocervical angle measurement for preterm birth prediction in singleton pregnant women with no history of preterm birth and normal cervical length: A prospective cohort study

OBJECTIVE

To evaluate the ability of second trimester uterocervical angle (UCA) to predict spontaneous preterm birth (sPTB) in low-risk singleton pregnant women.

STUDY DESIGN

Transvaginal sonographies were performed in the second trimester of 450 singleton pregnant women with no history of sPTB and no history of second trimester miscarriage with normal cervical length (CL) who attended antenatal care at Songklanagarind Hospital, a tertiary teaching hospital in southern Thailand. Gestational ages at delivery were recorded then the UCA values were evaluated according to sPTB occurrence. The differences in mean values of UCA between sPTB and full-term groups were evaluated using t-test. A receiver operating characteristics (ROC) curve was used to assess the ability of UCA to predict sPTB.

RESULTS

After excluding women with unknown pregnancy outcomes or missing UCA images, the sPTB rate was 34/421 (8.1 %). In women with anteflexed uterus, the mean UCA value was wider in the sPTB group compared to those with term birth if the measurements were performed at GA 19.5-24 weeks (sPTB group, 123.4°vs controls, 104.3°; P = 0.017). The ROC curve showed an area under the curve (AUC) of 0.7045. The optimal UCA cut-off value was ≥110 degrees, which gave a sensitivity of 83.3 % and a specificity of 61.2 %. The positive predictive value (PPV) was 16.7 %, negative predictive value (NPV) 97.5 %, positive likelihood ratio (LR+) 2.2 and negative likelihood ratio (LR-) 0.3.

CONCLUSION

The UCA in the second trimester is not a good predictor of sPTB in low risk pregnant women.

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.