Transvaginal Ultrasound Cervical Length Research Articles

Management, Utilization, and Outcomes of Preterm Labor in an Integrated Health Care System.

Fetal fibronectin (fFN) testing and transvaginal ultrasound (TVUS) are diagnostic tools used to predict impending spontaneous preterm birth (sPTB) among women presenting with preterm labor (PTL). We evaluated the association between fFN testing or TVUS cervical length (CL) measurement in predicting sPTB, respiratory distress syndrome (RDS), neonatal intensive care unit (NICU) admission, and sPTB-related costs. We conducted a retrospective cohort study using data from the Kaiser Permanente Southern California electronic health system (January 1, 2009-December 31, 2020) using diagnostic and procedure codes, along with a natural language processing algorithm to identify pregnancies with PTL evaluations. PTL evaluation was defined as having fFN and/or TVUS assessment. Outcomes were ascertained using diagnostic, procedural, and diagnosis-related group codes. Multivariable logistic regression assessed the association between fFN and/or TVUS results and perinatal outcomes. Compared with those without PTL evaluations, those with positive fFN tests had higher adjusted odds ratio (adj.OR) for sPTB (2.95, 95% confidence interval [CI]: 2.64, 3.29), RDS (2.34, 95% CI: 2.03, 2.69), and NICU admission (2.24, 95% CI: 2.01, 2.50). In contrast, those who tested negative had lower odds for sPTB (adj.OR: 0.75, 95% CI: 0.70, 0.79), RDS (adj.OR: 0.67, 95% CI: 0.61, 0.73), and NICU admission (adj.OR: 0.74, 95% CI: 0.70, 0.79). Among those with positive fFN results, the odds of sPTB was inversely associated with CL. Health care costs for mothers and neonates were lowest for those with fFN testing only. This study demonstrates that positive fFN results were associated with an increased odds of sPTB, RDS, and NICU admission and the association with sPTB was inversely proportional to CL. Additionally, negative fFN results were associated with decreased odds of sPTB, RDS, and NICU admissions. fFN testing may predict these and other sPTB-related adverse outcomes hence its utility should be explored further. Moreover, fFN testing has some cost savings over TVUS. · Patients with positive fFN tests had higher odds of sPTB, RDS, and NICU admission.. · Inverse relationship between sPTB and CL among those with positive fFN tests was observed.. · Health care costs for mothers and neonates were lowest for those with fFN testing only..

Cervical elastography using E-Cervix™ for prediction of preterm birth in twin pregnancies with threatened preterm labor

ObjectiveTo evaluate the prediction performance of E-Cervix™ for preterm birth in twin pregnancies with threatened preterm labor. MethodsThis was a single-center retrospective cohort study of twin pregnancies presenting to obstetrics triage for threatened preterm labor (PTL) between 23 0/7 – 33 6/7 weeks who received screening for PTL with transvaginal ultrasound cervical length (TVU CL) and cervical elastography with E-Cervix™ at the time of triage. Cervical elastography parameters were examined and compared between women who delivered preterm and those who did not. The quantification of cervical strain was calculated by a data analysis system that directly analyzes raw data from the region of interest (ROI) and described as hardness ratio (HR), mean strain level within 1 cm from internal (IOS) and external (EOS) os. Results63 twin gestations without prior preterm birth and with threatened PTL between 23 0/7 – 33 6/7 weeks of gestation were included in the study. 27 (42.9 %) had cervical length < 25 mm, and were admitted for true PLT. Out of the 36 women with cervical length ≥ 25 mm, 6 (16.7 %) were admitted. Women with threatened PTL had significantly higher HR compared to those with true PTL (p < 0.01), and significantly lower IOS and EOS. Women who delivered preterm had significantly higher HR compared to those who did not delivery preterm and significantly lower IOS and EOS, in overall cohort, and in the subset of women with true PTL. Incidences of HR < 50 % and < 35 % were statistically significantly higher in women who delivered preterm compared to those who did not (p < 0.01). ConclusionCervical elastography with E-Cervix™ may be useful for assessment of twin gestations presenting to obstetrics triage for threatened PTL.

Comparison of trans-vaginal ultrasound cervical length measurement and Bishop score in predicting successful labour induction in term pregnancies at Ahmadu Bello University Teaching Hospital Zaria

The goal of induction of labour (IOL) is to achieve successful vaginal delivery and reduce caesarean section (CS). The gold standard method for assessing cervical status has been the use of the Bishop score (BS) which is not flawless leading to unnecessary intervention. Trans-vaginal ultrasound cervical length (CL) measurement has been compared with BS in predicting successful IOL. The objective of this study was to compare CL and BS in predicting successful IOL at Ahmadu Bello University Teaching Hospital. It was a cross sectional comparative study design conducted among pregnant women at 37-42 weeks of gestation slated for IOL between November 2017 to November 2018. Eighty-seven (87) women were recruited as participants. Each participant, had a trans-vaginal ultrasound (TVS) CL measured and each was followed by a digital cervical assessment using BS. Relevant data obtained was analysed using SPSS version 23. The significance level was considered at P&lt; 0.05 IOL was successful in 66.2% (47) of the participants, while 15% (13) had CS. The receiver operating characteristic curve (ROC) demonstrated a better performance of the BS (AUC= 0.556, P= 0.433, CI= 0.426-0.673, PPV=52.8%) in predicting successful IOL than the TVS-CL measurement (AUC= 0.446, P=0.391, CI= 0.317-0.574) PPV=60.2%). Results further showed that the best cut off values for favourability for IOL for TVS-CL and BS were ≤2.5 cm and ≥5 respectively. The most important component of the BS predictive of successful IOL was cervical dilatation (OR= 0.603, P=0.011). TVS-CL did not demonstrate a diagnostic accuracy in predicting successful IOL in term pregnancies compared to BS.

Randomized trial of screening for preterm birth in low-risk women - the preterm birth screening study

Preterm birth is a major cause of perinatal morbidity and mortality. It is unclear whether the introduction of a universal transvaginal ultrasound cervical length screening program in women at low risk for preterm delivery is associated with a reduction in the frequency of preterm birth. To test the hypothesis that the introduction of a midtrimester universal transvaginal ultrasound cervical length screening program in asymptomatic singleton pregnancies without prior preterm delivery would reduce the rate of preterm birth at <37 weeks of gestation. This study was a multicenter nonblinded randomized trial of screening of asymptomatic singleton pregnancies without prior spontaneous preterm birth, who were randomized to either cervical length screening program (ie, intervention group) or no screening (ie, control group). Participants were randomized at the time of their routine anatomy scan between 18 0/7 and 23 6/7 weeks of gestation. Women randomized in the screening group received cervical length measurement. Those who were found to have cervical length ≤25 mm were offered 200 mg vaginal progesterone daily along with cervical pessary. The primary outcome was preterm birth at <37 weeks. The risk of primary outcome was quantified by the relative risk with 95% confidence interval, and was based on the intention-to-screen principle. A total of 1334 asymptomatic women with singleton pregnancies and without prior preterm birth, were included in the trial. Out of the 675 women randomized in the transvaginal ultrasound cervical length screening group, 13 (1.9%) were found to have transvaginal ultrasound cervical length ≤25 mm during the screening. Preterm birth at <37 weeks of gestation occurred in 48 women in the transvaginal ultrasound cervical length screening group (7.5%), and 54 women in the control group (8.7%) (relative risk, 0.86; 95% confidence interval, 0.59-1.25). Women randomized in the transvaginal ultrasound cervical length screening group had no significant differences in the incidence of preterm birth at less than 34, 32, 30, 28, and 24 weeks of gestation. The introduction of a universal transvaginal ultrasound cervical length screening program at 18 0/6 to 23 6/7 weeks of gestation in singleton pregnancies without prior spontaneous preterm birth, with treatment for those with cervical length ≤25 mm, did not result in significant lower incidence of preterm delivery than the incidence without the screening program.

A new model based on artificial intelligence to screening preterm birth

Objective The objective of this study is to create a new screening for spontaneous preterm birth (sPTB) based on artificial intelligence (AI). Methods This study included 524 singleton pregnancies from 18th to 24th-week gestation after transvaginal ultrasound cervical length (CL) analyzes for screening sPTB < 35 weeks. AI model was created based on the stacking-based ensemble learning method (SBELM) by the neural network, gathering CL < 25 mm, multivariate unadjusted logistic regression (LR), and the best AI algorithm. Receiver Operating Characteristics (ROC) curve to predict sPTB < 35 weeks and area under the curve (AUC), sensitivity, specificity, accuracy, predictive positive and negative values were performed to evaluate CL < 25 mm, LR, the best algorithms of AI and SBELM. Results The most relevant variables presented by LR were cervical funneling, index straight CL/internal angle inside the cervix (≤ 0.200), previous PTB < 37 weeks, previous curettage, no antibiotic treatment during pregnancy, and weight (≤ 58 kg), no smoking, and CL < 30.9 mm. Fixing 10% of false positive rate, CL < 25 mm and SBELM present, respectively: AUC of 0.318 and 0.808; sensitivity of 33.3% and 47,3%; specificity of 91.8 and 92.8%; positive predictive value of 23.1 and 32.7%; negative predictive value of 94.9 and 96.0%. This machine learning presented high statistical significance when compared to CL < 25 mm after T-test (p < .00001). Conclusion AI applied to clinical and ultrasonographic variables could be a viable option for screening of sPTB < 35 weeks, improving the performance of short cervix, with a low false-positive rate.

Cervical Pessary for Prevention of Preterm Birth in Individuals With a Short Cervix

A short cervix as assessed by transvaginal ultrasound is an established risk factor for preterm birth. Study findings for a cervical pessary to prevent preterm delivery in singleton pregnancies with transvaginal ultrasound evidence of a short cervix have been conflicting. To determine if cervical pessary placement decreases the risk of preterm birth or fetal death prior to 37 weeks among individuals with a short cervix. We performed a multicenter, randomized, unmasked trial comparing a cervical pessary vs usual care from February 2017 through November 5, 2021, at 12 centers in the US. Study participants were nonlaboring individuals with a singleton pregnancy and a transvaginal ultrasound cervical length of 20 mm or less at gestations of 16 weeks 0 days through 23 weeks 6 days. Individuals with a prior spontaneous preterm birth were excluded. Participants were randomized 1:1 to receive either a cervical pessary placed by a trained clinician (n = 280) or usual care (n = 264). Use of vaginal progesterone was at the discretion of treating clinicians. The primary outcome was delivery or fetal death prior to 37 weeks. A total of 544 participants (64%) of a planned sample size of 850 were enrolled in the study (mean age, 29.5 years [SD, 6 years]). Following the third interim analysis, study recruitment was stopped due to concern for fetal or neonatal/infant death as well as for futility. Baseline characteristics were balanced between participants randomized to pessary and those randomized to usual care; 98.9% received vaginal progesterone. In an as-randomized analysis, the primary outcome occurred in 127 participants (45.5%) randomized to pessary and 127 (45.6%) randomized to usual care (relative risk, 1.00; 95% CI, 0.83-1.20). Fetal or neonatal/infant death occurred in 13.3% of those randomized to receive a pessary and in 6.8% of those randomized to receive usual care (relative risk, 1.94; 95% CI, 1.13-3.32). Cervical pessary in nonlaboring individuals with a singleton gestation and with a cervical length of 20 mm or less did not decrease the risk of preterm birth and was associated with a higher rate of fetal or neonatal/infant mortality. ClinicalTrials.gov Identifier: NCT02901626.

Cost-effectiveness of history-indicated cerclage vs cervical length assessment for prevention of preterm birth

Preterm birth is one of the major causes of neonatal morbidity and mortality. Preterm delivery is a large burden to our health care system, and a history of preterm birth is one of the most common risk factors for subsequent preterm birth. We sought to examine the cost-effectiveness of the history-indicated cerclage strategy compared with the transvaginal ultrasound cervical length assessment strategy in individuals with a history of preterm birth. We developed a decision analysis model to compare history-indicated cerclage and cervical length assessment. The primary outcome was the net monetary benefit from a maternal and neonatal perspective of both strategies, defined as the value of an intervention with a known willingness to pay threshold for a unit of benefit. The time horizon was set to be a lifetime. Costs (in 2022 USD) included those for the cerclage, serial transvaginal ultrasounds, maternal care for admission, neonatal care, and severe disability. Probabilities, utilities, and costs were derived from the literature. A cost-effectiveness threshold was set at $100,000 per QALY (quality-adjusted life year). We first conducted 1-way sensitivity analyses with associated variables as sensitivity analyses. We then performed a probabilistic sensitivity analysis using Monte Carlo simulation with 1000 trials to test the robustness of the results in the setting of simultaneous changes in probabilities, costs, and utilities. In our base-case analysis, the history-indicated cerclage strategy compared to transvaginal ultrasound cervical length assessment was associated with more cost ($85,038 vs $70,155), with slightly less effectiveness from the maternal perspective (26.74 QALY vs 26.78 QALY) and from the neonatal perspective (28.91 QALY vs 29.06 QALY), and with less maternal and neonatal net monetary benefit. Therefore, the history-indicated cerclage strategy was dominated. With the 1000 trials of Monte Carlo simulation, transvaginal ultrasound cervical length assessment was the preferred strategy 84% and 88% of the time from the maternal and neonatal perspectives, respectively. The history-indicated cerclage strategy was more expensive and slightly less effective than the transvaginal ultrasound cervical length assessment strategy with a lower net monetary benefit.

Longitudinal change in cervical length following vaginal or abdominal cervical cerclage: a randomized comparison

Cervical cerclage has been shown to reduce the risk of recurrent spontaneous preterm birth in a high-risk patient population; however, the mechanism is not well understood. Transabdominal cerclage is superior to low and high vaginal cerclage in reducing early spontaneous preterm birth and fetal loss in women with previous failed vaginal cerclage. Cervical length measurements are commonly used to monitor high-risk women and may explain the mechanism of success. This study aimed to evaluate the rate of change in longitudinal cervical length after randomized placement of low transvaginal, high transvaginal, or transabdominal cerclage in women with a previous failed vaginal cerclage. This was a planned analysis of longitudinal transvaginal ultrasound cervical length measurements from patients enrolled in the Vaginal Randomised Intervention of Cerclage trial, a randomized controlled trial comparing transabdominal cerclage or high transvaginal cerclage with low transvaginal cerclage. Cervical length measurements at specific gestational ages were compared over time and between groups, using generalized estimating equations fitted using the maximum-likelihood random-effects estimator. In addition, cervical length measurements were compared in women with transabdominal cerclage placed before and during pregnancy. The diagnostic accuracy of cervical length as a predictor of spontaneous preterm birth at <32 weeks of gestation was explored. This study included 78 women who underwent longitudinal cervical length assessment (70% of the analyzed cohort) with a history of failed cerclage, of whom 25 (32%) were randomized to low transvaginal cerclage, 26 (33%) to high transvaginal cerclage, and 27 (35%) to transabdominal cerclage. Abdominal cerclage was superior to low (P=.008) and high (P=.001) vaginal cerclage at maintaining cervical length over the surveillance period (14 to 26 weeks of gestation) (+0.08 mm/week, 95% confidence interval, -0.40 to 0.22; P=.580). On average, the cervical length was 1.8 mm longer by the end of the 12-week surveillance period in women with transabdominal cerclage (+1.8 mm; 95% confidence interval, -7.89 to 4.30; P=.564). High vaginal cerclage was no better than low cervical cerclage in the prevention of cervical shortening; the cervix shortened by 13.2 mm over 12 weeks in those with low vaginal cerclage (95% confidence interval, -21.7 to -4.7; P=.002) and by 20 mm over 12 weeks in those with high vaginal cerclage (95% confidence interval, -33.1 to -7.4; P=.002). Preconception transabdominal cerclage resulted in a longer cervix than those performed during pregnancy; this difference was significant after 22 weeks of gestation (48.5 mm vs 39.6 mm; P=.039). Overall, cervical length was an excellent predictor of spontaneous preterm birth at <32 weeks of gestation (receiver operating characteristic curve, 0.92; 95% confidence interval, 0.82-1.00). In women with a previous failed cervical cerclage, in the next pregnancy, the cervical length in women treated with vaginal cerclage funneled and shortened over time, whereas there was preservation of cervical length in women who receive transabdominal cerclage. Cervical length remained longer in transabdominal procedures performed before pregnancy than in transabdominal procedures performed during pregnancy. Overall, cervical length was an excellent predictor of spontaneous preterm birth in our cohort. Our findings may explain the mechanism of benefit for transabdominal cerclage, with its high placement better maintaining the structural integrity of the cervix at the level of the internal os.

Is mid-trimester cervical length screening effective for reduction of threatened preterm labor?

ObjectiveTo assess the incidence of threatened preterm labor and preterm labor admissions and treatment of women with singleton gestations and no prior preterm birth before and after implementation of the universal mid-trimester transvaginal ultrasound cervical length screening. Materials and methodsA retrospective cohort study included of singleton gestations without a history of preterm birth presenting with threatened preterm labor between 24 0/7 and 36 6/7 gestational week in two study periods: before and after the implementation of the universal cervical length screening. Women with cervical length <25 mm were considered being at high risk for preterm birth and were prescribed a treatment with vaginal progesterone daily. The primary outcome was the incidence of threatened preterm labor. Secondary outcomes were the incidence of preterm labor. ResultsWe have found a significant increase in the incidence of threatened preterm labor from 6.42% (410/6378) in 2011 to 11.61% (483/4158) in 2018 (p < 0.0001). Gestational age at triage consult was lower in than in 2011, although the rate of admission for threatened preterm labor was similar in both periods. There was a significant decrease in the incidence of preterm delivery <37 weeks from 25.60% in 2011 to 15.94% in 2018 (p < 0.0004). Although there was a reduction in preterm delivery ≤34 weeks, this reduction was not significant. ConclusionThe universal mid-trimester cervical length screening in asymptomatic women is not associated with a reduction in the frequency of threatened preterm labor or the admission rate for preterm labor, but reduces the rate of preterm births.

Activity restriction for women with arrested preterm labor: a randomized controlled trial

In the past, some pregnant women have been recommended to be in activity restriction because of the presumed increased risk of preterm birth due to the increased release of catecholamines, which might stimulate myometrial activity, during exercise and aerobic activity. This study aimed to test the hypothesis that in women with singleton pregnancy and arrested preterm labor, activity restriction would reduce the rate of preterm birth at <37 weeks of gestation. This was a parallel-group nonblinded randomized trial conducted at a single center in Italy. Eligible patients were those with a diagnosis of arrested preterm labor, defined as not delivering after 48 hours of hospitalization for threatened preterm labor, with transvaginal ultrasound cervical length ≤25 mm, no other symptoms of possible uterine contractions, and cervical dilatation <3 cm at pelvic examination. Inclusion criteria were singleton pregnancies between 24 0/7 and 33 6/7 weeks of gestation. Participants were randomized in a 1:1 ratio to either activity restriction at the time of discharge or no activity restriction. Women in the intervention group were recommended activity restriction, defined as the following: pelvic rest, prohibition of sexual activity, and reduction of work and/or nonwork activity. The primary endpoint was preterm birth at <37 weeks of gestation. A total of 120 participants were included in the trial; 60 patients were enrolled in the activity restriction group and 60 in the control group. Preterm birth at <37 weeks of gestation occurred in 15 of 60 women (25.0%) in the activity restriction group and 23 of 60 women (38.3%) in the control group (relative risk, 0.65; 95% confidence interval, 0.38-1.12). There was no significant between-group difference in the incidence of preterm birth at <32 weeks and in neonatal outcomes, but the trial was not powered for these outcomes. In singleton gestations with arrested preterm labor, activity restriction, including pelvic rest, prohibition of sexual activity, and reduction of work and/or nonwork activity, does not result in a lower rate of preterm birth at <37 weeks. Given the evidence on the lack of benefits, use of activity restriction in this population should be discouraged.

Preterm Labor: A Comprehensive Review of Guidelines on Diagnosis, Management, Prediction and Prevention.

Preterm labor (PTL) is one of the most common and serious pregnancy complications associated with significant perinatal morbidity and mortality, as well as long-term neurologic impairment in the offspring. The aim of this study was to review and compare the most recently published major guidelines on diagnosis, management, prediction, and prevention of this severe complication of pregnancy. A descriptive review of guidelines from the National Institute for Health and Care Excellence (NICE), the World Health Organization, the American College of Obstetricians and Gynecologists, the New South Wales Government, and the European Association of Perinatal Medicine (EAPM) on PTL was carried out. There is a consensus among the reviewed guidelines that the diagnosis of PTL is based on clinical criteria, physical examination, measurement of cervical length (CL) with transvaginal ultrasound (TVUS) and use of biomarkers, although there is disagreement on the first-line diagnostic test. The NICE and the EAPM are in favor of TVUS CL measurement, whereas the New South Wales Government mentions that fetal fibronectin testing is the mainstay for PTL diagnosis. Moreover, there is consistency among the guidelines regarding the importance of treating PTL up to 34 weeks of gestation, to delay delivery for 48 hours, for the administration of antenatal corticosteroids, magnesium sulfate, and in utero transfer to higher care facility, although several discrepancies exist regarding the tocolytic drugs of choice and the administration of corticosteroids and magnesium sulfate after 34 and 30 gestational weeks, respectively. Routine cesarean delivery in case of PTL is unanimously not recommended. Finally, the NICE, the American College of Obstetricians and Gynecologists, and the EAPM highlight the significance of screening for PTL by TVUS CL measurement between 16 and 24 weeks of gestation and suggest the use of either vaginal progesterone or cervical cerclage for the prevention of PTL, based on specific indications. Cervical pessary is not recommended as a preventive measure. Preterm labor is a significant contributor of perinatal morbidity and mortality with a substantial impact on health care systems. Thus, it seems of paramount importance to develop consistent international practice protocols for timely diagnosis and effective management of this major obstetric complication and subsequently improve pregnancy outcomes.

VP46.14: Use of transvaginal ultrasound cervical length for prevention of spontaneous preterm delivery and its management

VP46.14: Use of transvaginal ultrasound cervical length for prevention of spontaneous preterm delivery and its management

Appalachian Women's perspectives on preterm birth and transvaginal ultrasound cervical length screening: Implications for addressing disparities in preterm birth

PurposePreterm birth (PTB), a pressing issue for US maternal-child health, disproportionately impacts women in Appalachia. Transvaginal ultrasound (TVU) cervical length (CL) screening is the most accurate PTB risk predictor but remains underutilized. This study characterizes the knowledge, attitudes and beliefs of patients with prior PTB concerning PTB prevention efforts and TVU CL screening. MethodsParticipants were recruited from community-based health centers in Appalachian Kentucky. Semi-structured interviews and likert-scale surveys were conducted with 22 pregnant women with a history of spontaneous PTB. Methods for data collection were guided by the Consolidated Framework for Implementation Research (CFIR). ResultsMost participants reported that TVU was uncomfortable, but none refused it. Most women were able to articulate the benefits of TVU, but several had concerns about its safety in pregnancy. Participants suggested that pregnant women receive more PTB education and self-advocate. They urged providers to take patient concerns seriously, and better educate patients on PTB risks and TVU safety. DiscussionOur study contributes crucial insights about the experience of a vulnerable population as it pertains to PTB prevention and the uptake of TVU CL screening. Our findings emphasize the need for increased efforts to better educate patients on the impact of prematurity and the safety and benefits of TVU CL screening as an evidence-based strategy for PTB prevention.

Prediction of labour onset in women who present with symptoms of preterm labour using cervical length

BackgroundDiagnosis of preterm labour is difficult because initial symptoms and signs are often mild and may occur in continuing pregnancies. This study aims to investigate the utility of measuring cervical length, using transvaginal ultrasound, in women presenting to the delivery suite with symptoms of preterm labour.MethodsThis was a prospective cohort study performed in KK Women’s and Children’s Hospital, Singapore from September 2017 to July 2018. Women with singleton pregnancies, presenting with symptoms of contraction pain, between 24+ 0 to 36+ 6 weeks gestation, were included. Transvaginal ultrasound cervical length measurements were done at presentation to the labour ward, after four hours and in the following morning. The primary outcome of the study was delivery within 1 week. All statistical analyses were conducted with Microsoft Excel and Statistical Package for the Social Sciences.ResultsA total of 95 subjects were included. A one-millimeter increase in the 1st cervical length increases scan-to-delivery time by 0.802 days (p-value 0.003, CI 0.280–1.323). Receiver Operator Characteristic (ROC) curve analysis for prediction of delivery within 1 week showed an Area Under Curve (AUC) of 0.667, optimal cut-off value of 27.5mm (sensitivity 77.8 %, specificity 61.6 %). A one-millimetre increase in the 3rd cervical length increases scan-to-delivery time by 0.770 days (p-value 0.023, CI 0.108–1.432). ROC curve analysis for prediction of delivery within 1 week showed an AUC of 0.915, optimal cut-off value of 25.5mm (sensitivity 100 %, specificity 73.6 %). However, the change in cervical length over a period of 1 day was not significant in predicting delivery within 1 week.ConclusionsOur results indicate that by using a cervical length cut off of 27.5mm at presentation, we would have predicted 77.8 % of deliveries within 1 week. If we were to repeat the cervical length scan the next day, with the same cut-off of 27.5mm, we would have predicted 100 % of deliveries within 1 week. In our study, measuring the transvaginal ultrasound cervical length is a reliable diagnostic test for delivery within 1 week. However, the results are limited by the small sample size. Further studies should be conducted with a larger sample size.

Utility of follow-up cervical length screening in low-risk women with a cervical length of 26 to 29 mm

In women with a previous preterm birth, a protocol for serial cervical length screening has been studied and recommended for the identification and treatment of a short cervix. Cervical length screening along with vaginal progesterone has been suggested for low-risk women with singleton pregnancies to treat a short cervix and reduce preterm birth. However, specific protocols for single vs serial ultrasound measuring cervical length in this population are not established. Cost-effectiveness of universal cervical length screening depends on the cost of screening; follow-up of borderline measurements can contribute to increased costs with uncertain benefit. This study aimed to determine the utility of follow-up cervical length screening in otherwise low-risk women with singleton pregnancies with a midtrimester cervical length measurement of 26 to 29 mm through the assessment of the rate of short cervix (≤25 mm) on follow-up ultrasound and subsequent delivery outcomes. This was a 2-year retrospective cohort study at a single urban institution of women with singleton pregnancies with no previous spontaneous preterm birth and an initial transvaginal ultrasound cervical length measurement of 26 to 29 mm identified during universal cervical length screening at time of anatomy ultrasound (18 0/7 to 22 6/7 weeks' gestation). The primary outcome was the rate of short cervix (defined as ≤25 mm on transvaginal ultrasound) on follow-up ultrasound at <24 weeks' gestation. Secondary outcomes included the rate of spontaneous preterm birth (<37 and <34 weeks' gestation). During the study period, there were 2801 women with singleton pregnancies at 18 0/7 to 22 6/7 weeks' gestation with transvaginal ultrasound cervical length screening at time of anatomy scan. Among those women, 201 had a cervical length of 26 of 29 mm, and 184 (7%) had no previous spontaneous preterm birth and were included in the study. Furthermore, 144 women (78%) had a follow-up cervical length completed before 24 weeks' gestation. The mean follow-up interval was 1.5±0.6 weeks. Overall, the percentage of short cervix (≤25 mm) on follow-up was 15% (n=21). Baseline characteristics were similar, but the initial cervical length measurement was shorter in women who subsequently developed a short cervix (26.7±0.8 vs 27.8±1.0; P<.01). Delivery outcomes were available for 126 patients. The rate of spontaneous preterm birth at <37 weeks' gestation in women with an initial cervical length 26 to 29 mm and subsequent short cervix was significantly higher than the rate of spontaneous preterm birth in a historical cohort of low risk women with an initial cervical length >25 mm (16% vs 3%; P=.03). The rate of spontaneous preterm birth at <34 weeks' gestation in women with a subsequent short cervix was 11% (2 of 19). Here, approximately 15% of low-risk women with singleton pregnancies with a midtrimester cervical length measurement of 26 to 29 mm will experience cervical shortening of ≤25 mm before 24 weeks' gestation. Compared to women with singleton pregnancies without a history of preterm birth, the rate of spontaneous preterm birth (16%) in women with an initial cervical length of 26 to 29 mm and a subsequent cervical shortening of ≤25 mm is significantly higher. A total of 111 follow-up ultrasounds measuring cervical length would be required to prevent 1 early preterm birth at <34 weeks' gestation.

1074 Cervical length nomogram in hispanic patients

Most of the studies have been done on the general population and none targeted special populations. The studies on transvaginal ultrasound cervical length (TVUCL) included patients with various ethnicities. There are reports that CL differs by race and ethnicity. The aim of this study was to develop a TVUCL normogram in low risk pregnant Hispanic women. All TVUCL measurements performed between December 2016 and December 2018 at a single tertiary care institution were reviewed. We included all patients who self-identified as Hispanic, were between the ages of 18 to 45 years, had singleton pregnancies, and underwent universal TVUCL between 16-24 weeks of gestation. We excluded patients with twin or higher order pregnancies, uterine anomalies or cerclage placement at time of screening or with history of preterm birth. We collected demographic data, gravidity, parity, gestational age at time of cervical length screen and cervical length. Cervical length across gestation was analyzed by the LMS method. A thousand patients were included in the analysis (Table 1). Nomogram is shown in Figure 1A. The 50th, 10th and 5th percentiles TVUCLs were 4.01 cm, 3.23 cm, and 3 cm, respectively (Table 2). Compared with those who delivered at term (>37 weeks), patients who had spontaneous preterm birth (sPTB) had shorter TVUCL (mean difference (MD): 0.57cm, 95%CI 0.25-0.89; Figure 1B), but those with medically indicated preterm delivery did not (MD: -0.06cm, 95%CI -0.25-0.13; Figure 1C). Among preterm deliveries, only deliveries below 28 weeks had significantly shorter cervix (MD: 0.99cm, 95%CI (0.21- 1.77)) compared to patients who delivered more than 28 weeks. Receiver operating characteristic curve analysis revealed that for a clinically relevant positive likelihood ratio, a TVUCL cutoff of 3.08cm was best in predicting sPTB (Table 3). The nomogram for TVUCL in Hispanic low risk pregnant women shows longer CL than previously reported. If validated in other studies, a higher cutoff may need to be used to define short cervix in Hispanics.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

331 Correlation between MRI and transvaginal-ultrasound cervical length measurements in pregnancies complicated by twin-twin transfusion syndrome

Twin pregnancies are at high risk of preterm birth, especially when complicated by twin-twin transfusion syndrome (TTS). Pregnancies with TTTS that are candidates for selective fetoscopic laser photocoagulation (SFLP) at our institution undergo transvaginal ultrasound (TVUS) and MRI evaluation of cervical length (CL) to assess preterm birth risk during the perioperative period. There is a paucity of data on accuracy of MRI for cervical length screening in high-risk pregnancies. We sought to investigate the correlation of CL between the two imaging modalities Retrospective cohort study comparing TVUS to MRI measures of CL in pregnancies that underwent SFLP for TTTS at a single center, 4/2010-6/2019. Among 626 pregnancies, data on pre-operative TVUS (n=579), MRI (n=424), and post-op TVUS (n=596) CL measures were available for analysis. Correlation was estimated using Pearson’s coefficient, mean CL measurements were compared with two-tailed paired T-test, and frequency of short cervix detection by the two imaging modalities was compared with chi-square The mean pre-op CL by MRI was an average of 3 mm shorter than the TVUS CL, 39 vs 42mm, respectively (p=0.002). The frequency of short CL ≤25 mm was 39(6.7%) by TVUS and 47(10.8%) by MRI, p=0.0001. CL measures by MRI correlate with TVUS overall (r=0.64); however, the correlation is poor at the shortest cervical lengths (r<0.20), see figure. MRI missed n=2(40%), 3(18.8%), 9(32.1%), and 13(28.9%) of CL cases detected as short by TV US at cut-offs of ≤15, 20, 25 and 28 mm, respectively. Sensitivity analyses excluding or adjusting for cerclage and pessary did not alter these findings Although MRI measurement of CL correlates well with TVUS overall, it performs poorly to accurately detect short cervix. Although prenatal MRI has some fetal anatomic diagnostic advantages over ultrasound, TVUS remains the optimal screening modality for cervical length in pregnancies at high-risk of preterm birthView Large Image Figure ViewerDownload Hi-res image Download (PPT)

334 Influence of cervical length change after laser surgery for twin-twin transfusion syndrome on pregnancy outcomes

Twin pregnancies complicated by twin-twin transfusion syndrome (TTTS) are at especially high risk of preterm birth. Cases that have selective fetoscopic laser photocoagulation (SFLP) at our institution undergo transvaginal ultrasound (TVUS) measurement of cervical length (CL) before and after SFLP to assess preterm birth risk during the perioperative period Retrospective cohort study comparing pre- and post-op TVUS CL in pregnancies that underwent SFLP at a single center from 4/2010-6/2019. Among 626 SFLP cases, 476 had data on both pre- and post-op CL and comprised the study cohort. Pre-op TVUS CL was obtained <30 days prior to SFLP, and post-op measure was obtained 0 to 5 days after SFLP. Change in cervical length was defined as pre-op CL minus post-op CL. No change in pre- to post-op CL was defined as a change of <0.5 mm Among 476 patients, n=309(64.9%) experienced net decrease in CL, 54(11.3%) had no change and 113(23.7%) had net increase in CL following SFLP. The mean pre-op CL was significantly longer in cases that had net increase in CL after SFLP compared to those that decreased, 4.59cm vs 3.53cm, p=0.0001. There was no difference in mean DVP of the recipient or latency to delivery among groups (mean 10 wks, p=0.606), Table 1. Cases with a net increase in CL after SFLP had lower rates of preterm birth (PTB) <28 and <32 wks. Decrease or no change in CL after SFLP had no significant influence on PTB rates even when accounting for short pre-op CL, Table 2. Short cervix pre-op in combination with CL change was not significantly associated with PTB Increase in cervical length after SFLP is associated with reduced risk of early preterm birth. It has previously been hypothesized that intraoperative amnioreduction of recipient polyhydramnios may decrease PTB by decreasing uterine stretch, however our data did not show differences in mean DVP with respect to CL change. The mechanisms that influence CL changes in the SFLP perioperative period and influence preterm parturition warrant further investigationView Large Image Figure ViewerDownload Hi-res image Download (PPT)

916 The association between preterm birth and ultrasound visualization of the cervical gland area

Preterm birth (PTB) is a leading cause of neonatal morbidity and mortality. Yet, transvaginal ultrasound (TVUS) cervical length (CL) screening suboptimally predicts spontaneous PTB (SPTB). Abnormal remodeling of glandular crypts along the cervical canal may contribute to increased PTB risk via premature cervical ripening, which may correspond to no visualizable cervical gland area (CGA) on TVUS (Figure 1). This study aims to determine if no visualizable (“absent”) CGA at CL screening is predictive of PTB. We performed a retrospective cohort study of pregnant women carrying a singleton gestation who had CL screening between 180/7 – 236/7 weeks gestation and delivered a live neonate at a single academic institution between 1/1/18 and 12/31/18. 1000 of the most recent deliveries in 2018 were screened for inclusion. Patients with uterine anomalies, cerclage, suboptimal imaging, or with indicated preterm delivery were excluded. TVUS images were assessed for CL, CGA visualization, and if present, quantitative CGA measurements were performed. The primary outcome was SPTB prior to 37 weeks. Absent and present CGA groups were compared using χ2, Fischer’s exact, T-test, and logistic regression with significance at p<0.05. 784 women were included. Demographic and medical characteristics of the sonographically absent and present CGA groups were similar. The absent CGA group was more likely parous and to receive progesterone supplementation (77 vs 40% and 17 vs 4% respectively, p=0.03). Overall PTB rate was 2.7% and rate of absent CGA was 2.3%. Absent CGA was significantly associated with delivery <37, <34, and <32 weeks (p<0.005) (Table 1). Quantitative CGA width, length, and area did not individually correlate with PTB. A multiple logistic regression model demonstrated 8% improvement for prediction of PTB <37 weeks with the addition of CGA evaluation compared to CL alone (p<0.001). Patients with no visualizable CGA were more likely to experience spontaneous preterm delivery. Assessment of CGA visualization may improve the performance of CL screening for predicting SPTB.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Transvaginal Ultrasound Cervical Length as an Indicator for Successful Induction of Labor

Background: Induction of labour is a common obstetric practice which refers to the process where the uterine contractions are initiated by medical and surgical means before the onset of spontaneous labour. The aim of this work was to evaluate the role of Preinduction transvaginal ultrasonographic measurement of cervical length as an indicator of a successful induction of labor. Methods: A cross-sectional study was carried out in Zagazig University Maternity Hospital during the period from May 2017 till November 2018. Included 171 pregnant women admitted for induction of labour.40 women delivered by Cesarean section (positive group) and 131 women delivered vaginally (negative group). All patients were subjected to full history taking, general, abdominal and pelvic examinations and investigations (including CBC, Rh, transvaginal ultrasound and non-stress test). All patients had vaginal examination for assessing the Bishop score before induction of labour and transvaginal ultrasound for assessment of cervical length. Results: Our study showed that the cervical length was significantly higher (31 ± 5.93 mm versus 22.61 ±3.67, p-value =0.00) and the Bishop Score significantly lower (5.95 ± 1.13 versus 7.87 ± 1, p-value = 0.00, respectively) in patients undergoing cesarean delivery compared with those delivering vaginally. Conclusions: Transvaginal ultrasonography proved to be better in predicting the success of induction of labor by having higher sensitivity, specificity, higher predictive value and better tolerability and less inter and intra observer variation.