Cervical Consistency Index Research Articles

Performance of the First-Trimester Cervical Consistency Index to Predict Preterm Birth.

Background/Objectives: Preterm birth (PTB) remains a significant global health challenge. Previous attempts to predict preterm birth in the first trimester using cervical length have been contradictory. The cervical consistency index (CCI) was introduced to quantify early cervical changes and has shown promise across various clinical scenarios in the mid-trimester, though testing in the first trimester is lacking. This study aims to assess the cervical consistency index performance in predicting preterm birth during the first trimester of pregnancy. Methods: In this prospective cohort study, focused exclusively on research, women with singleton pregnancies, both with and without a history of spontaneous preterm birth (sPTB), were included. The primary outcome was sPTB before 37 weeks, with a secondary outcome of sPTB before 34 weeks. CCI measurements were taken between 11+0 to 13+6 weeks of gestation. Receiver operating characteristic (ROC) curves were generated, and sensitivity and specificity were calculated for the optimal cut-off and for the 5th, 10th, and 15th percentile. Intraobserver and interobserver agreements were assessed using the intraclass correlation coefficient (ICC). Results: Among the 667 patients analyzed, the rates of sPTB before 37 and 34 weeks were 9.2% (61/667) and 1.8% (12/667), respectively. The detection rates (DRs) for CCI predicting PTB before 37 and 34 weeks were 19.7% (12/61) and 33.3% (4/12). Negative predictive values were 91.8% (546/595) and 98.7% (588/596), while the areas under the curve (AUC) for sPTB before 37 and 34 weeks were 0.62 (95% CI: 0.54-0.69) and 0.80 (95% CI: 0.71-0.89), respectively. Of the 61 patients with preterm birth, 13 (21.3%) had a preterm birth history; in this group, the CCI percentile 10th identified 39% (5/13). Intraobserver ICC was 0.862 (95% CI: 0.769-0.920), and interobserver ICC was 0.833 (95% CI: 0.722-0.902). Conclusions: This study suggests that utilizing CCI in the first trimester of pregnancy could serve as a valuable tool for predicting preterm birth before 34 weeks of gestation, demonstrating robust intraobserver and interobserver reliability.

Study of Cervical Consistency Index and Cervical Length during Mid-trimester for the Prediction of Spontaneous Preterm Labor in Low-risk Pregnancies

Study of Cervical Consistency Index and Cervical Length during Mid-trimester for the Prediction of Spontaneous Preterm Labor in Low-risk Pregnancies

EP19.07: Patterns of cervical length and cervical consistency index in singleton gestations and the risk of preterm birth

EP19.07: Patterns of cervical length and cervical consistency index in singleton gestations and the risk of preterm birth

Causes and Consequences of Preterm Birth, A Systematic Review

To systematically review the potential causes and possible effects of preterm birth [<37 weeks gestational duration]. We searched PubMed, google scholar, clinicaltrials.gov and science direct for English language articles published from 2004 to march 2021. All kinds of study schemes were considered acceptable, comprising case –control, cohort studies, experimental and cross- sectional studies. Significant evidences indicate that social stress, elevated cadmium exposure, genomic variations, vitamin D deficiency, pre-conception hepatitis B infection, declined vaginal microbial community, intrauterine infection, reduction in cervical consistency index, strong exposure of creatinine corrected thallium, systemic autoimmune diseases, ozone, primary traffic air pollutants, road traffic noise, potential exposure of arsenic, HIV exposure, maternal thyroid dysfunction, maternal plasma protein level and COVID-19 exposure in pregnant females are the major risk factors for PTBs. Results of earlier investigations indicated prominent risk of insulin resistance, hypertension, neurological defects, heart failure, Chronic kidney disease, Lung function impairment, lower birth weight, thalamocortical system defects, cancer, altered cardiac phenotype and cardio metabolic diseases in survivors of preterm births. This review will help clinicians to isolate the fundamental etiology and to proactively identify, cope and improve outcomes of at-risk pregnancies.

Prediction of Preterm Birth with Serial Measurements of Ultrasound Markers.

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

Short cervix, wide anterior cervical angle and low cervical consistency index as a predictor of preterm birth: a case-control study

Objective: To determine and compare either change in length, anterior angle, and consistency of cervix can be used as the predictors of preterm labor or not.Methods: This case-control study involved 54 pregnant women with gestational age 20 - 37 weeks, which the case group is women in preterm labor and the control group were not in labor at Sanglah General Hospital, Bali, Indonesia from November 2018 to October 2019. The samples were examined using Transvaginal Sonography (TVS) to collect Cervical Length (CL), Anterior Cervical Angle (ACA), and Cervical Consistency Index (CCI) data.Results: Short CL could increase the risk of preterm labor by 9 times (OR = 8.80, 95% CI = 2.50-30.97, p-value 0.001). Wide ACA could increase the risk by 10 times (OR = 10.45, CI 95% = 2.92-37.39, p = 0.001). Low CCI could increase the risk by 7 times (OR = 7.43, 95% CI = 1.80-30.67, p = 0.003). Anterior cervical angle has the greatest role in the occurrence of preterm labor, followed by CL and CCI, although statistically insignificant (p=0.138; p=0.212= p:0.203).Conclusion: Performing cervical examination using TVS as the antenatal care routine can help predict and prevent preterm delivery.

Minireview: Utility of predictive tests for preterm birth used in clinical practice

Preterm labor, defined as delivery before 37 weeks of gestation, is a serious obstetric condition that accounts for 11% of pregnancies worldwide. Predictive tests for preterm birth are important, given the personal, economic, and health impact of preterm birth. This review explores the utility of both, the current predictive tests used in clinical practice (maternal characteristics, cervical length and biochemical markers), as well as the new emerging tests. An electronic search was carried out in the scientific health databases: PUBMED, COCHRANE, SCIELO, national universities virtual repositories were also reviewed, using the following search items and their combinations: preterm delivery, cervical length, cervical shortening, cervicometry, fetal fibronectin, risk factors, and maternal characteristics. We included papers in English and Spanish published from 2006 to 2020, which responded to the aim of the review: the utility of predictive test for preterm delivery. A total of 30 articles were included in this review. There are multiple scientific criteria on the different current techniques to identify patients at risk and achieve adequate prevention of preterm birth. Measurement of cervical length by transvaginal ultrasound is the most cost-effective method in women with a history of preterm labor or symptoms of preterm labor; the current evidence allows us to affirm that it is also essential to perform routine cervicometry in all patients, even with low risk. There are promising ultrasound predictive methods such as cervical elastography and cervical consistency index, but there are limitations in their technical implementation, it is proposed that they could be a possible alternative in the future, that can be combined with cervical length measurement. Also, adding cervical length easurement to biochemical tests appears to improve predictive accuracy.

Normative Values of Mid Trimester Cervical Consistency Index in Women Delivering at Term

Abstract Aims and Objective Cervical Consistency Index (CCI) is a new technique to measure the consistency of Cervix (softening) and is expected to show changes before cervical shortening. The aim of this study was 1. To find out the normative values of mid-trimester Cervical Consistency Index in women delivering at term. 2. To compare the discriminative ability of cervical consistency index with cervical length for prediction of spontaneous preterm birth. Method A total of 144 antenatal patients undergoing mid-trimester anomaly scan were subjected to transvaginal cervical length measurement as per Fetal Medicine Foundation criteria. Cervical consistency index was measured as defined by Para et al. The anterior–posterior diameter of cervix was measured before compression (AP) and after compression (AP') in the same sitting. Cervical consistency index (CCI) was calculated by the formula:CCI = APⅹ/AP × 100;The result of CCI was not used in the clinical management of the patient. Women who delivered at 37 weeks and beyond were included to form the normative data. An attempt was made to study the ability of mid-trimester cervical consistency index to predict spontaneous preterm birth as compared to cervical length (CL). Results Range of CCI in our study was 41–100% and that of CL was 2–4 cm.Based on values of CCI and CL an ROC curve was made, AUC measured for CCI was 0.923 and for CL was 0.849. The cut off determined for CCI was 64.5%, above which all women delivered at ≥ 37 weeks. Only Two women who delivered preterm (&lt; 37) weeks had a CCI of less than 64.5% (64 and 47%), but cervical length was greater than 2.5 cms in both of them. The Sensitivity, Specificity, Positive Predictive Value, Negative Predictive Value and accuracy of CCI for predicting term delivery at a cutoff of 64.5% in our study was 83.8%, 100%, 100%, 8% and 93.8% respectively, whereas the corresponding figures for predicting preterm delivery were 100%, 83.8%, 8%, 100% and 93.8%. Discriminative ability of CCI in comparison to CL could not be determined because only two women delivered preterm in our study. Conclusion This was a pilot study to form the normative values of CCI for women delivering at term. At a cutoff value of 64.5% or more all women delivered at term. Two women who delivered preterm had a CCI of less than 64.5%. Further large studies are required before CCI can be incorporated as a routine to assess the antenatal cervix.

ASSESSMENT OF CERVICAL LENGTH, SHAPE AND CONSISTENCY BETWEEN 18-24 WEEKS GESTATIONAL AGE BY TRANSVAGINAL ULTRASOUND FOR PREDICTION OF PRETERM LABOR

Background: Preterm labor is the presence of uterine contractions of sufficient frequency and intensity to affect progressive effacement and dilation of the cervix prior to term gestation. Shortening and funneling of the cervix was first described to be associated with the diagnosis of cervical incompetence, Transvaginal sonographic measurement of cervical length could be used to predict a risk for preterm delivery for a significant proportion of preterm births. Cervical length is measured by transvaginal ultrasound from internal os to external os while the urinary bladder is empty. Objective: To determine the value of measurement of cervical parameters by transvaginal ultrasound between 18 and 24 weeks' gestation in the prediction of spontaneous preterm delivery. Patients and Methods: The study was carried out at Bab EL-Sha'aria University Hospital between 1/10/2018 and 31/12/2019 on 200 primigravida women with single pregnancy and intact membranes. Women with scarred uterus, women with chronic medical diseases or obstetric problems, women who underwent cerclage and fetal anomalies were excluded from the study. For all participants, transvaginal ultrasound was done between 18 and 24 weeks' gestation for measurement of cervical length, shape and consistency. Results: Infant means weight at delivery was 1589 g with SD 215 in preterm delivery, while Infant mean weight at delivery was 3024 g with SD 200 which was significant. 33.3% of preterm birth delivered vaginally, while 66.7% delivered by C.S. 62.6% of full term delivery delivered vaginally, while 37.4% delivered by C.S. No statistically significant difference was found regarding mode of delivery. Cervical length was significant in prediction of preterm labor with sensitivity 88.9%, specificity 91.2%, PPV 50.0% and NPV 98.8 %. Cervical consistency index was significant in prediction of preterm labor with sensitivity 88.9%, Specificity 93.4%, PPV 57.1% and NPV 98.8 %. Funneling was present in 33.3% of preterm delivery, and 4.4% of full term delivery which was significant. Measurement of cervical length, shape and consistency was a reliable method for prediction of preterm labor. Conclusion: Measurement of cervical length, shape and consistency by transvaginal ultrasound between 18 and 24 weeks' gestation was a reliable method for prediction of preterm labor.

ASSESSMENT OF CERVICAL LENGTH, SHAPE AND CONSISTENCY BETWEEN 18-24 WEEKS GESTATIONAL AGE BY TRANSVAGINAL ULTRASOUND FOR PREDICTION OF PRETERM LABOR

Background: Preterm labor is the presence of uterine contractions of sufficient frequency and intensity to affect progressive effacement and dilation of the cervix prior to term gestation. Shortening and funneling of the cervix was first described to be associated with the diagnosis of cervical incompetence, Transvaginal sonographic measurement of cervical length could be used to predict a risk for preterm delivery for a significant proportion of preterm births. Cervical length is measured by transvaginal ultrasound from internal os to external os while the urinary bladder is empty. Objective: To determine the value of measurement of cervical parameters by transvaginal ultrasound between 18 and 24 weeks' gestation in the prediction of spontaneous preterm delivery. Patients and Methods: The study was carried out at Bab EL-Sha'aria University Hospital between 1/10/2018 and 31/12/2019 on 200 primigravida women with single pregnancy and intact membranes. Women with scarred uterus, women with chronic medical diseases or obstetric problems, women who underwent cerclage and fetal anomalies were excluded from the study. For all participants, transvaginal ultrasound was done between 18 and 24 weeks' gestation for measurement of cervical length, shape and consistency. Results: Infant means weight at delivery was 1589 g with SD 215 in preterm delivery, while Infant mean weight at delivery was 3024 g with SD 200 which was significant. 33.3% of preterm birth delivered vaginally, while 66.7% delivered by C.S. 62.6% of full term delivery delivered vaginally, while 37.4% delivered by C.S. No statistically significant difference was found regarding mode of delivery. Cervical length was significant in prediction of preterm labor with sensitivity 88.9%, specificity 91.2%, PPV 50.0% and NPV 98.8 %. Cervical consistency index was significant in prediction of preterm labor with sensitivity 88.9%, Specificity 93.4%, PPV 57.1% and NPV 98.8 %. Funneling was present in 33.3% of preterm delivery, and 4.4% of full term delivery which was significant. Measurement of cervical length, shape and consistency was a reliable method for prediction of preterm labor. Conclusion: Measurement of cervical length, shape and consistency by transvaginal ultrasound between 18 and 24 weeks' gestation was a reliable method for prediction of preterm labor.

VP52.08: Mid‐trimester cervical consistency index, uterocervical angle and cervical texture analysis to predict spontaneous preterm birth in twins

VP52.08: Mid‐trimester cervical consistency index, uterocervical angle and cervical texture analysis to predict spontaneous preterm birth in twins

Evolving cervical imaging technologies to predict preterm birth.

Preterm birth, defined as delivery at less than 37weeks' gestation, increases maternal-fetal morbidity and mortality and places heavy financial and emotional burdens on families and society. Although premature cervical remodeling is a major factor in many preterm deliveries, how and why this occurs is poorly understood. This review describes existing and emerging imaging techniques and their advantages and disadvantages in assessing cervical remodeling. Brightness mode (B-mode) ultrasound is used to measure the cervical length, currently the gold standard for determining risk of preterm birth. Several new B-mode ultrasound techniques are being developed, including measuring attenuation, cervical gland area, and the cervical consistency index. Shear wave speed can differentiate between soft (ripe) and firm (unripe) cervices by measuring the speed of ultrasound through a tissue. Elastography provides qualitative information regarding cervical stiffness by compressing the tissue with the ultrasound probe. Raman spectroscopy uses a fiber optic probe to assess the biochemical composition of the cervix throughout pregnancy. Second harmonic generation microscopy uses light to quantify changes in collagen fiber structure and size during cervical maturation. Finally, photoacoustic endoscopy records light-induced sound to determine optical characteristics of cervical tissue. In the long term, a combination of several imaging approaches, combined with consideration of clinical epidemiologic characteristics, will likely be required to accurately predict preterm birth.

The Predictive Value of the Cervical Consistency Index to Predict Spontaneous Preterm Birth in Asymptomatic Twin Pregnancies at the Second-Trimester Ultrasound Scan: A Prospective Cohort Study.

Novel transvaginal ultrasound (TVU) markers have been proposed to improve spontaneous preterm birth (sPTB) prediction. Preliminary results of the cervical consistency index (CCI), uterocervical angle (UCA), and cervical texture (CTx) have been promising in singletons. However, in twin pregnancies, the results have been inconsistent. In this prospective cohort study of asymptomatic twin pregnancies assessed between 18+0–22+0 weeks, we evaluated TVU derived cervical length (CL), CCI, UCA, and the CTx to predict sPTB < 34+0 weeks. All iatrogenic PTB were excluded. In the final cohort of 63 pregnancies, the sPTB rate < 34+0 was 16.3%. The CCI, UCA, and CTx, including the CL was significantly different in the sPTB < 34+0 weeks group. The best area under the receiver operating characteristic curve (AUC) for sPTB < 34+0 weeks was achieved by the CCI 0.82 (95%CI, 0.72–0.93), followed by the UCA with AUC 0.72 (95%CI, 0.57–0.87). A logistic regression model incorporating parity, chorionicity, CCI, and UCA resulted in an AUC of 0.91 with a sensitivity of 55.3% and specificity of 88.1% for predicting sPTB < 34+0. The CCI performed better than other TVU markers to predict sPTB < 34+0 in twin gestations, and the best diagnostic accuracy was achieved by a combination of parity, chorionicity, CCI, and UCA.

Prediction of duration of labor based on biomechanical measurements of the cervix: A preliminary study

ObjectiveInduction of labor is a common procedure in obstetrics. Predictability of duration of labor could facilitate planning as well as patient’s satisfaction. The primary purpose of this study was to evaluate the usefulness of a new biomechanical measurement of the cervix based on the aspiration technique for predicting the duration of labor after induction. Study designThis was a prospective single centre study. Inclusion criteria were term nulliparous pregnant women with an unfavourable cervix who needed an induction of labor. Digital (Bishop score), sonographic (cervical length and cervical consistency index (CCI)) as well as aspiration measurements (closure pressure) of the cervix were performed and compared to duration of labor. The technical feasibility and the acceptability of the measurements were explored. ResultsThere were no technical complications of the sonographic or aspiration measurements. Measuring the Bishop score was reported as most painful examination. Both the time to active phase of labor and the time to delivery is significantly correlated with the Bishop score, but not with the cervical length, CCI or closure pressure. ConclusionThe new biomechanical measurement of the cervix, based on the aspiration technique, is technically feasible and acceptable. In our small cohort no correlation was found between the closure pressure and the duration of labor.

Prediction of preterm birth and adverse perinatal outcomes after cervical pessary placement in singleton pregnancies with short cervical length

Objectives To identify ultrasound-assessed cervical characteristics, modified after pessary placement, which could be predictive of spontaneous preterm birth (sPTB) at < 34 weeks of gestation (WG) or severe adverse perinatal outcomes (APO). Study design This prospective observational study conducted at Vall d’Hebron Universitary Hospital assessed multiple cervical characteristics in women with short cervical length (CL). All participants were examined by transvaginal ultrasound before and immediately after a cervical pessary was placed. Cervical assessment included CL, uterocervical angles (UCA), and cervical consistency indexes (cervical consistency index (CCI) and cervical length consistency index (CLCI)). Pregnancy outcomes were recorded to determine the capacity of these variables for predicting sPTB at < 34 WG and severe APO. Results Thirty-one women with short CL, 17 (54.8%) with asymptomatic midtrimester short CL, and 14 (45.2%) after arrested threatened preterm labor were enrolled. After pessary placement, transvaginal ultrasound detected four participants in whom the pessary was not correctly placed around the cervix (12.9%); additionally, significant changes were observed in most cervical baseline characteristics, with CL, anterior UCA (A-UCA), CLCI, and intersegmentary angle (ISA) being predictive of sPTB at <34 WG and severe APO. Receiver operator curves were calculated to compare the predictive capacity of these variables, with CL and A-UCA after pessary placement being the best predictive parameters with an area under the curve of 0.88 and 0.87, respectively. Conclusions Transvaginal ultrasound after pessary placement detects incorrect pessary placement after pessary insertion and during follow-up. APO and sPTB can be predicted by measuring CL, A-UCA, CLCI, and ISA immediately after pessary placement, being CL and A-UCA more accurate and easier to be measured. Our results help to better identify women in whom the pessary is more likely to fail. Further research is required to assess the effectiveness of applying alternative, sequential or additional treatments to reduce prematurity and our results could be considered when designing such studies.

EP01.03: Mid‐trimester cervical consistency index and cervical length to predict spontaneous preterm birth in twins

EP01.03: Mid‐trimester cervical consistency index and cervical length to predict spontaneous preterm birth in twins

Cervical modifications after pessary placement in singleton pregnancies with maternal short cervical length: 2D and 3D ultrasound evaluation.

The use of a pessary proved to prevent preterm birth in asymptomatic women with mid-trimester short cervical length (CL); however, the precise mechanisms by which the pessary confers its benefit remain unclear. The aim of this study was to evaluate multiple cervical characteristics assessed by 2-dimensional and 3-dimensional ultrasound before and after placement of a cervical pessary to ascertain its mechanism of action. In this prospective cohort study, we assessed the cervical characteristics in singleton pregnancies with maternal short CL and compared them with matched reference women with normal CL. The variables evaluated were: CL, uterocervical angles, cervical consistency indices (cervical consistency index and CL consistency index), cervical volume and vascular indices. All variables were re-assessed immediately after pessary placement and 4-6weeks later in all participants. Mann-Whitney U test was used to assess differences between groups and paired samples t test for comparisons in two different examinations in the same women. The aim of this study was to evaluate multiple cervical ultrasound variables before and after the placement of a cervical pessary and compare the evolution of these variables with a reference group with normal CL to better understand the device's mechanism of action. Thirty-three women with short CL and 24 reference women with normal CL were enrolled. At the time of enrollment, gestational age and maternal baseline characteristics did not differ between groups. Immediately after pessary placement, CL increased, uterocervical angles were narrower and cervical consistency increased significantly. When the magnitude of change in cervical variables was compared over time between the reference group and the study group, median CL had increased in the study group (1.47mm) but it had shortened in the reference group (-2.56mm). These inverse trends were statistically significant (P=0.006). Cervical pessary reduces both uterocervical angles and corrects cervical angulation by pushing the cervix up toward the uterus. Maintaining the cervix aligned to the uterine axis leads to reduced cervical tissue stretch, so avoiding further cervical shortening. All these changes were present after pessary placement; however, the clinical implications of these findings remain unknown.

Cervical consistency index and risk of Cesarean delivery after induction of labor at term.

To evaluate the association between the cervical consistency index (CCI) and the risk of Cesarean delivery after planned induction of labor (IOL) at term. This was a prospective observational study of women with a term singleton pregnancy admitted for IOL due to maternal or fetal indication. Ultrasonographic images were obtained before IOL and CCI was calculated offline once recruitment was completed. The main outcome was defined as Cesarean delivery due to failed IOL or arrest of labor. Cesarean deliveries indicated due to maternal or fetal compromise (Van Dillen's grade 1 or 2) were excluded from analysis. Univariate statistical analysis was performed using Fisher's exact test and Student's t-test for categorical and continuous variables, respectively. Multivariate analysis was performed using logistic regression, including CCI and other variables related to the main outcome. Intraclass correlation coefficients were used to estimate intra- and interobserver agreement. Of 510 women admitted for IOL during the study period and for whom image quality was adequate, 46 were excluded due to emergency Cesarean delivery leaving 464 pregnancies for analysis. Cesarean section due to failed IOL or arrest of labor was performed in 100/464 (21.6%) pregnancies. The mean CCI of women who underwent Cesarean delivery was not significantly different from that in those who had vaginal delivery after IOL (70.1 ± 12.3% vs 70.0 ± 13.1%; P = 0.94). Multivariate analysis also showed absence of statistical association between CCI and Cesarean delivery for failed IOL or arrest of labor. Intraclass correlation coefficients for intra- and interobserver agreement were 0.81 (95% CI, 0.66-0.89) and 0.86 (95% CI, 0.75-0.92), respectively. CCI does not seem to be associated with the risk of Cesarean delivery after IOL. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

463: Second trimester normal cervical length in asymptomatic high-risk women: Role of the cervical consistency index

463: Second trimester normal cervical length in asymptomatic high-risk women: Role of the cervical consistency index

Cervical consistency index is a valid predictor of preterm birth in low-risk pregnant women

Background Preterm birth (PTB) remains a global problem associated with perinatal morbidity, including low birth weight, growth retardation and irreversible damage to the nervous system. The objective of this study was to determine the predictive value of cervical consistency index (CCI) to indicate the occurrence of PTB in mid trimester screening of low risk pregnant women. MethodsThis was a prospective study conducted on low-risk pregnant women at 14-28 weeks of pregnancy. The cervical length (CL) and AP cervical diameter were measured and the CCI determined according to the formula AP2/AP1*100. The ROC curves were drawn according to gestational age and the sensitivity and the specificity were calculated for optimal cut-off for 1st, 5th, 10th, 21th, and 24th centiles of CCI. The inter-observer agreement was validated by interclass correlation coefficients (ICC).ResultsA total of 149 participants were enrolled in this study. Among them, 12.08% had PTB (&lt;37weeks) and 87.92% had normal birth. Mean CCI for all subjects was 68.60%, but was lower in PTB (48.9%). The best cutoff for predicting PTB based on CCI was 59.46% with 99.18% sensitivity and 85% specificity. The AUC for CCI for prediction of PTB &lt;37weeks was 0.936. There was no inter-observer difference in measurement of CCI and CL (ICC values for CCI and CL were 0.997 and 0.990 respectively).ConclusionIn women with normal CL the CCI could predict PTB in the second trimester in low risk women. So, CCI is a valid predictor of PTB in low risk women.