Real-time ultrasound demonstration of uterine isthmus contractions during pregnancy.

BACKGROUND: Asymptomatic isthmic contractions are a frequent physiological phenomenon in pregnancy, sometimes triggered by bladder voiding. They can interfere with proper cervical length assessment and may lead to false images of placenta previa. However, there is limited research on the prevalence and characteristics of these contractions. OBJECTIVE: This study aimed to determine the prevalence and characteristics of isthmic contractions after bladder voiding in the second trimester of pregnancy, to evaluate their effect on cervical length assessment, and to propose a new method for the objective assessment of the presence and intensity of isthmic contractions. STUDY DESIGN: In this prospective observational study, long videos of the uterine cervix were recorded in 30 singleton pregnancies during the second trimester of pregnancy after bladder voiding. Isthmic length and cervicoisthmic length changes were assessed over time. The isthmic length was measured using a new approach, which involved calculating the distance from the base of the cervix to the internal os, including the isthmus. RESULTS: Isthmic contractions were observed in 43% of pregnant women (95% confidence interval, 26%-62%) after bladder voiding. The median time for complete isthmus relaxation was 19.7 minutes (95% confidence interval, 15.0 to not available). No substantial differences in maternal characteristics were found between individuals with and without contractions. The proposed method for measuring isthmic length provided an objective assessment of the presence and intensity of isthmic contractions. A cutoff of 18 mm in isthmic length allowed for the distinction of pregnant women presenting a contraction. In addition, the study identified a characteristic undulatory pattern in the relaxation of the isthmus in half of the cases with contractions. CONCLUSION: Isthmic contractions are a common occurrence after bladder voiding in the second trimester of pregnancy and may interfere with proper cervical length assessment. We recommend performing cervical assessment at least 20 minutes after bladder voiding to reduce the risk of bias in cervical length measurement and to avoid false images of placenta previa. The new method for measuring isthmic length provides an objective way to assess the presence and intensity of isthmic contractions. Further research is needed to understand the role of isthmic contractions in the physiology of pregnancy and birth.

SMFM Consult Series #70: Management of short cervix in individuals without a history of spontaneous preterm birth.

Most deliveries before 34 weeks of gestation occur in individuals with no previous history of preterm birth. Midtrimester cervical length assessment using transvaginal ultrasound is one of the best clinical predictors of spontaneous preterm birth. This Consult provides guides for the diagnosis and management of a short cervix in an individual without a history of preterm birth. The following are Society for Maternal-Fetal Medicine recommendations: (1) we recommend that all cervical length measurements used to guide therapeutic recommendations be performed using a transvaginal approach and in accordance with standardized procedures as described by organizations, such as the Perinatal Quality Foundation or the Fetal Medicine Foundation (GRADE 1C); (2) we recommend using a midtrimester cervical length of ≤25 mm to diagnose a short cervix in individuals with a singleton gestation and no previous history of spontaneous preterm birth (GRADE 1C); (3) we recommend that asymptomatic individuals with a singleton gestation and a transvaginal cervical length of ≤20 mm diagnosed before 24 weeks of gestation be prescribed vaginal progesterone to reduce the risk of preterm birth (GRADE 1A); (4) we recommend that treatment with vaginal progesterone be considered at a cervical length of 21 to 25 mm based on shared decision-making (GRADE 1B); (5) we recommend that 17-alpha hydroxyprogesterone caproate, including compounded formulations, not be prescribed for the treatment of a short cervix (GRADE 1B); (6) in individuals without a history of preterm birth who have a sonographic short cervix (10-25 mm), we recommend against cerclage placement in the absence of cervical dilation (GRADE 1B); (7) we recommend that cervical pessary not be placed for the prevention of preterm birth in individuals with a singleton gestation and a short cervix (GRADE 1B); and (8) we recommend against routine use of progesterone, pessary, or cerclage for the treatment of cervical shortening in twin gestations outside the context of a clinical trial (GRADE 1B).

Longitudinal evaluation of cervical length and shear wave elastography in women with spontaneous preterm birth.

OBJECTIVE: To evaluate longitudinal changes in cervical length (CL) and mean cervical shear wave elastography (CSWE) score in women with a singleton or twin pregnancy who undergo spontaneous preterm birth (sPTB) compared with those who deliver at term. METHODS: This was a prospective longitudinal study of unselected women with a singleton or twin pregnancy attending a dedicated research clinic for screening for sPTB at four timepoints during pregnancy: 11 + 0 to 15 + 6 weeks, 16 + 0 to 20 + 6 weeks, 21 + 0 to 24 + 6 weeks and 28 + 0 to 32 + 6 weeks. At each visit, a transvaginal ultrasound scan was conducted to measure the CL and the CSWE scores in six regions of interest (ROI) (inner, middle and external parts of anterior and posterior cervical lips). The mean CSWE score from the six ROIs was calculated for analysis. Log10 transformation was applied to data to produce a Gaussian distribution prior to statistical analysis. A multilevel mixed-effects analysis was performed to compare longitudinally CL and CSWE between the sPTB and term-delivery groups. RESULTS: The final cohort consisted of 1264 women, including 1143 singleton pregnancies, of which 57 (5.0%) were complicated by sPTB, and 121 twin pregnancies, of which 33 (27.3%) were complicated by sPTB. Compared to those who delivered at term, women with sPTB had a lower CL across gestation when controlling for history of cervical surgery, number of fetuses, gestational age (GA) at cervical assessment and the interaction between GA at cervical assessment and sPTB (P < 0.001). Specifically, CL in the sPTB group was significantly lower at 21 + 0 to 24 + 6 weeks (P = 0.039) and 28 + 0 to 32 + 6 weeks (P < 0.001). Twin pregnancies had significantly greater CL throughout pregnancy compared with singleton pregnancies (regression coefficient, 0.01864; P < 0.001). After adjusting for maternal age, weight, height, body mass index and GA at cervical assessment, CSWE score in the sPTB group was significantly lower compared with that in the term-delivery group across gestation (P = 0.013). However, on analysis of individual visits, CSWE score in the sPTB group was significantly lower than that in the term-delivery group only at 11 + 0 to 15 + 6 weeks (P = 0.036). There was no difference in CSWE score between singleton and twin pregnancies throughout gestation (regression coefficient, -0.00128; P = 0.937). CONCLUSIONS: Women with sPTB have a shorter and softer cervix across gestation compared with those who deliver at term. A shorter cervix in the sPTB group is observed from the late second trimester onwards, while lower cervical stiffness in the sPTB group is observed primarily in the first trimester. CL is significantly lower in singleton pregnancies compared with twin pregnancies, while cervical stiffness does not differ between the two. Our findings indicate that the cervix tends to undergo a softening process prior to shortening in sPTB cases. © 2024 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Cervical length screening among low-risk women; relationship of body mass index on cervical length and risk of preterm birth.

BACKGROUND: Preterm birth (PTB) contributes to nearly 11% of all deliveries in the world. The majority of spontaneous preterm birth (sPTB) remains unexplained. Risk factors include abnormal body mass index (BMI), short cervical length, comorbidities and many more. However, there is limited study on the association between body mass index, cervical length and preterm birth in Malaysia among low-risk women. Hence, we aim to examine the relationship between body mass index, cervical length and the risk of spontaneous preterm birth. METHOD: In this prospective cohort study, pregnant women between 16 and 24 weeks who fulfilled the criteria were recruited. Women with history of preterm birth were excluded. Demographic and clinical data (age, BMI, ethnicity, education level and parity) were obtained. Cervical length was measured using transvaginal scan. Patients were then followed up till delivery to determine their delivery gestation and outcome of delivery. RESULTS: Out of 153 women who participated in this study, 146 women had cervical length of more than 30 mm, six had cervical length between 25 mm and 30 mm and one had cervical length of 24 mm. There were nine (9) cases of sPTB, with all of them being late preterm with normal midtrimester cervical length. Almost half of them (44%) were overweight/obese. A significant association was found between age, cervical length, and parity compared to BMI. Nevertheless, no significant association was seen between the BMI and risk of sPTB. CONCLUSION: This study demonstrates a higher BMI is associated with longer cervical length, but it is not necessarily protective against sPTB. Hence, we concluded there is a limited role in cervical length screening among low-risk women regardless of their BMI in predicting sPTB.

Evaluation of Non-Compressive Transvaginal Cervical Elastography as a Quantitative Imaging Biomarker in Pregnancy: A Repeatability and Reliability Analysis.

OBJECTIVES: Non-compressive strain elastography has been proposed as a novel quantitative imaging biomarker for assessing the structure and function of the cervix. The current study aims to assess the repeatability, and intra- and inter-observer reliability of transvaginal non-compressive cervical strain elastography in a clinical setting. METHODS: We conducted a dual-phase single-center prospective feasibility study of singleton gestations >16-weeks gestation that required a clinically-indicated transvaginal ultrasound. Each study participant, n = 43 in phase 1 and n = 13 in phase 2, had elastography performed by two trained observers that each performed multiple image acquisitions. We performed a multivariable regression to adjust for changes in clinical characteristics between study phases and calculated the repeatability coefficients, limits of agreement, and intraclass correlations for each quantitative elastography parameter. We compared quantitative elastography parameters to cervical length measurements, acquired from the same images. RESULTS: The repeatability coefficients and percent limits of agreement were wide for all of the quantitative elastography parameters, demonstrating poor repeatability. Intraclass correlation coefficients were poor-moderate for both intra-observer (0.31-0.77) and inter-observer reliability (0.35-0.77) in both study phases, while cervical length showed excellent reliability with intraclass correlations consistently >0.90. CONCLUSIONS: Non-compressive transvaginal strain cervical elastography did not demonstrate adequate repeatability or reliability. Our results highlight the importance of rigorously assessing novel quantitative imaging biomarkers before clinical application.

Cervical length as a screening tool for preterm birth in twin pregnancies: a systematic review and critical evaluation of quality clinical practice guidelines.

OBJECTIVES: Twin pregnancies are at increased risk of preterm birth (PTB) compared to singletons. Evaluation of cervical length (CL) represents the optimal tool to screen PTB in singleton. Conversely, there is less evidence on the use of CL in twins. Our aim was to evaluate the methodological quality and clinical heterogeneity of clinical practice guidelines (CPGs) on the CL application in twins using AGREE II methodology. METHODS: MEDLINE, Scopus, and websites of the main scientific societies were examined. The following aspects were evaluated: diagnostic accuracy of CL, optimal gestational age at assessment and interventions in twin pregnancies with reduced CL. The quality of the published CPGs was carried out using "The Appraisal of Guidelines for REsearch and Evaluation (AGREE II)" tool. The quality of guideline was rated using a scoring system. Each considered item was evaluated by the reviewers on a seven-point scale that ranges from 1 (strongly disagree) to 7 (strongly agree). A cut-off >60 % identifies a CPGs as recommended. RESULTS: The AGREE II standardized domain scores for the first overall assessment had a mean of 74 %. The score was more than 60 % in the 66.6 % of CPGs analyzed indicating an agreement between the reviewers on recommending the use of these CPGs. A significant heterogeneity was found; there was no specific recommendation on CL assessment in about half of the published CPGs. There was also significant heterogeneity on the CL cut-off to prompt intervention. CONCLUSIONS: Despite the fact that the AGREE II analysis showed that the majority of the included guidelines are of good quality, there was a significant heterogeneity among CPGs as regard as the indication, timing, and cut-off of CL in twins as well as in the indication of interventions.

Assessment of utero-cervical angle and cervical length as predictors for threatened preterm delivery in singleton pregnancies.

OBJECTIVES: The aim of this study was to evaluate the relationship between the cervix and the threat of preterm labor in singleton pregnancies between gestational weeks less than 37 and greater than 37 weeks in correlation with utero-cervical angle (UCA) and cervical length (CL) measurements. MATERIALS AND METHODS: We conducted a prospective cohort study with UCA and CL measurements in patients with threatened preterm labor (TPL). Primary outcome was differences in UCA and CL measurements in relationship to maternal characteristics and perinatal outcome between groups. Secondary outcome evaluated measurement results and influencing factors for delivery within 7 days, between 1 and 4 weeks and beyond 4 weeks. RESULTS: Overall 152 patients were divided into as study/preterm group (<37 weeks; n = 56) and the control/term group (≥37 weeks; n = 96). Mean gestational age at admission was similar in both groups (30.98 ± 2.83 vs. 30.36 ± 2.63 weeks, p = 0.149) with similar CL (33.9 ± 6.34 vs. 32.02 ± 8.88 mm, p = 0.132), but wider UCA in the preterm group (81.65 ± 16.81° vs. 99.21 ± 22.33°, p < 0.001). Multivariate logistic regression analysis for preterm delivery was significant for nulliparity and UCA measurement. The factor for delivering before 37 gestational weeks within 7 days was the gestational week at admission (p = 0.046). UCA and CL measurements were statistically significant for distinguishing patients for delivery within 7 days and beyond 4 weeks (p = 0.001 for CL and p = 0.0001 for UCA). NPV was found 92.5, 92.2, and 92.3 for UCA >105°, CL ≤30 mm, and Bishop score >3, respectively. CONCLUSION: Combined measurement of TV UCA and CL represents stronger predictors for sPTB ultrasonographically, demonstrating the uterocervical sub-segment maturation before the active onset of labor.

The effect of preinduction cervical length measurement with three different ultrasonographic methods on predicting delivery time.

AIM: This study aimed to evaluate the effect of preinduction cervical length (CL) measurement by transvaginal (TV), transperineal (TP), and transabdominal (TA) ultrasonography (USG) on the time of delivery and to compare these three sonographic methods in terms of superiority over one another. METHODS: This study included TV, TP, and TA CL measurements in pregnant women who were planned to undergo induction of labor at 37 weeks' gestation or later. The correlations between the said three methods and BISHOP scores were evaluated. These three methods were compared in terms of superiority in predicting the time of delivery. RESULTS: Pregnant women at 37-42 weeks' gestation undergoing labor induction were included, and all three methods were used for CL measurements. Three methods were correlated with each other (p < 0.001) and with BISHOP scores (p < 0.001). CONCLUSION: The correlation between all three methods and BISHOP scores indicates that TP and TA USG can be used instead of TV USG. On the other hand, while TA USG did not give a clear result in the accurate estimation of vaginal delivery time, TP, and TV USG gave both accurate and close results. When all these data are evaluated, it is concluded that TPU can be used safely instead of TVU, especially in patients receiving induction.

A pragmatic evaluation of the implementation and acceptance of a universal second trimester cervical length screening program in an un-selected population.

PURPOSE: To evaluate patients' acceptance of a universal transvaginal ultrasound cervical length (CL) screening program and the feasibility of initiating treatment with progesterone in a clinical setting in women found to have a short cervix. METHODS: An observational, pragmatic cohort study was conducted at one tertiary care facility from 2012-2015, involving eligible women with singleton pregnancies who accepted and underwent second-trimester CL screening. The primary outcomes were the percentage of women who were eligible and accepting of screening, compliance with progesterone treatment, and the screening value of TVCL in predicting SPTB. Secondary outcomes were the number of women who received progesterone treatment and the rates of SPTB. RESULTS: Overall cervical length screening acceptance rate was found to be 82.5%. Of the 797 women that underwent screening, 21 women (2.6%) had a TVCL < 25 mm, of whom nine had a TVCL < 20.0 mm. Nineteen of the 21 women with a TVCL < 25 mm were treated with progesterone, with a 94.7% compliance rate. Delivery outcomes were obtained for 767 women. Of those with a TVCL < 25 mm, there was a 35% rate of SPTB as opposed to a 6.3% SPTB rate in those with TVCL > 25 mm. The negative predictive value for SPTB with a TVCL 25 mm or greater was 94.0%. CONCLUSION: Universal cervical length screening was successfully implemented in 82.5% of the patient population with a high compliance rate with progesterone treatment. Furthermore, there was a higher rate of SPTB in those with a shorter cervix. Based on our outcomes obtained in an observational and pragmatic manner, we showed that incorporating second trimester transvaginal cervical length screening into routine clinical practice is readily accepted and, with the addition of vaginal progesterone treatment, may reduce the rate of prematurity.

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.

The utility of combined utero-cervical index in predicting preterm delivery in pregnant women with preterm uterine contractions.

PURPOSE: To evaluate the utility of a novel ultrasound index "combined utero-cervical index (CUCI)" in the prediction of preterm delivery. METHODS: The present prospective cohort study was conducted in Ankara Bilkent City Hospital Perinatology Clinic between January 1, 2023, and March 31, 2023. Pregnant women with uterine contractions between 24 and 36th gestational weeks but did not have dilatation or effacement were included. CUCI was calculated as: (utero-cervical angle)/(anterior cervical lip thickness + fundal thickness + lower uterine segment thickness + cervical length). In the presence of cervical funneling, one point was added to the final result. A ROC analysis was conducted to determine the potential of CUCI in predicting delivery <37 weeks of gestation, <34 weeks of gestation, and <4 weeks after the first admission to the hospital for uterine contractions, respectively. RESULTS: Optimal cut-off values of CUCI were found to be 1.4 (67.1% sensitivity, 67.2% specificity) for predicting delivery at <37th weeks, 1.7 (72.7% sensitivity, 65.7% specificity) for predicting delivery at <34th weeks, and 1.4 (62.5% sensitivity, 61.7% specificity) for predicting delivery at <4 weeks. CONCLUSION: CUCI may be used in the prediction of preterm delivery for pregnant women admitted to hospital with preterm uterine contractions.

Routine transabdominal cervical length screening in mid-pregnancy for the prevention of preterm birth: Is it good enough to use as a screening test?

BACKGROUND: Preterm birth (PTB) is a major pregnancy complication. There is evidence that a short cervical length in mid-pregnancy may predict women at increased risk of PTB. AIMS: To evaluate the utility of population-based, transabdominal cervical length (TACL) measurement screening in mid-pregnancy for PTB prediction in women. MATERIALS AND METHODS: A transabdominal approach was initially performed, with a transvaginal (TVCL) approach offered when the TACL was <35 mm, could not be accurately measured, or the pregnancy had risk factors for PTB. TACL was compared to the directly related TVCL, when both were performed at the same assessment. Women with risk factors of PTB were included when they had both TACL and TVCL measurements performed at the same visit. RESULTS: Data were provided for 9355 singleton pregnancies from 13 participating imaging centres. A transabdominal approach was used in 9006 (96.3%), including 682 (7.3%) TVCL combined with TACL. There were 349 (3.7%) women who had TVCL only. The median TACL was longer (40 mm) than the TVCL (38 mm). In 682 paired TACL and TVCL measurements, TACL <35 mm correctly identified 96.2% of pregnancies with TVCL <25 mm, compared with 65.4% of cases when using a TACL <30 mm. A TVCL <25 mm occurred in 59 (0.6%) women. A TACL <35 mm was associated with birth <37 weeks of gestation in 12.1% of women and birth <32 weeks of gestation in 3.9%. CONCLUSIONS: Universal TACL is a feasible option for population screening of cervical length in a low-risk population, progressing to TVCL if the TACL is <35 mm or the cervix cannot be transabdominally accurately measured.

Cervical length measurement between 11 and 13 + 6 weeks of pregnancy: Comparison of maternal and ultrasonographic characteristics between term and preterm deliveries.

OBJECTIVE: The aim of this study was to evaluate the maternal and ultrasonographic characteristics of pregnant women who underwent cervical length (CL) measurement by transvaginal ultrasound between 11 and 13 + 6 weeks of gestation and who delivered at term or preterm. METHODS: A retrospective cohort study was carried out between March 2013 and December 2018 by analyzing ultrasound data of singleton pregnant women who underwent CL measurement by transvaginal ultrasound during the first trimester scan. CL was compared between the two groups (full-term and preterm birth [PB]) using Student's t-test. RESULTS: A total of 5097 pregnant women were enrolled, of whom 5061 (99.3%) had term and 36 (0.7%) had PB < 34 weeks. CL measurements did not differ between the term and preterm groups (36.62 vs. 37.83 mm, p = 0.08). Maternal age showed a significant and linear association with CL (r = 0.034, p = 0.012) and CRL (r = 0.086, p < 0.001). Smoking status was associated with shorter CL (36.64 vs. 35.09 mm, p = 0.003). When we analyzed the CL of the pregnant women in the term and preterm groups, according to the gestational age cut-offs for prematurity (28, 30, 32, and 34 weeks), we found that there was no significant difference between the measurements in all groups (p > 0.05). CONCLUSION: We observed no significant differences between CL measurements between 11 and 13 + 6 weeks in pregnant women who had preterm and term deliveries. Gestational age and CRL showed a significant and linear association with CL measurement.

Placental Area in the Lower Uterine Segment, Cervical Length, and Clinical Outcome in Pregnancies With Complete Placenta Previa.

BACKGROUND: Complete placenta previa is associated with a higher percentage of adverse clinical outcomes and magnetic resonance imaging (MRI) is widely used in the preoperative examination of patients with placenta previa. PURPOSE: To evaluate the effectiveness of the placental area in the lower uterine segment and cervical length in identifying the adverse maternal-fetal outcomes in women with complete placenta previa. STUDY TYPE: Retrospective. POPULATION: A total of 141 pregnant women (median age, 32; age range, 24-40 years) with complete placenta previa were examined by MRI to evaluate the uteroplacental condition. FIELD STRENGTH/SEQUENCE: A 3 T with T1 -weighted imaging (T1 WI), T2 -weighted imaging (T2 WI), and half-Fourier acquisition single-shot turbo spin echo (HASTE) sequence. ASSESSMENT: The association of the placental area in the lower uterine segment and cervical length measured using MRI with the risk of massive intraoperative hemorrhage (MIH) and maternal-fetal perinatal outcomes were determined. The adverse neonatal outcomes (preterm delivery, respiratory distress syndrome [RDS], admission to neonatal intensive care unit [NICU]) were analyzed in different groups. STATISTICAL TESTS: The t-test, Mann-Whitney U test, Chi-square, Fisher's exact test, and receiver operating characteristic (ROC) curve were used, and a P < 0.05 indicated a statistically significant difference. RESULTS: The mean operation time, intraoperative blood loss, and intraoperative blood transfusing were significantly higher in patients with large placental area and short cervix than in patients with the small placental area and long cervix, respectively. The incidence of adverse neonatal outcomes was significantly higher in the large placenta area group and short cervix group than in the small placenta group area and long cervix group, respectively, such as preterm delivery, RDS, and NICU. By combining placental area with cervical length sensitivity and specificity increased to 93% and 92%, respectively, for the identification of MIH > 2000 mL with area under the receiver operating curve (AUC) 0.941. DATA CONCLUSION: Large placental area and short cervical length may be associated with a high risk of MIH and adverse maternal-fetal perinatal outcomes in patients with complete placenta previa. TECHNICAL EFFICACY STAGE: 2.

Postpartum cervical length as a predictor of subsequent preterm birth-novel insights on an old enigma.

BACKGROUND: Preterm birth poses one of the biggest challenge in modern obstetrics. Prediction of preterm birth has previously been based on patient history of preterm birth, short cervical length around midtrimester, and additional maternal risk factors. Little is known about cervical length and physiology during the postpartum period and any associations between postpartum cervical features and subsequent preterm birth. OBJECTIVE: This study aimed to determine the feasibility and utility of postpartum cervical length measurements in prediction of subsequent spontaneous preterm birth. STUDY DESIGN: This was a prospective cohort study in a single tertiary center, conducted during a 5-year period (2017-2021). We evaluated the mean postpartum cervical length in patients after both preterm birth and term deliveries at 4 time periods: 8, 24, and 48 hours, and 6 weeks postpartum, with follow-up in their subsequent pregnancies to evaluate gestational age at delivery. The mean postpartum cervical length in different populations stratified by gestational age at delivery was assessed in phase 1 of the study, and the gestational age at subsequent delivery was assessed in phase 2. RESULTS: A total of 1384 patients participated in phase 1. Mean postpartum cervical length was significantly shorter in the preterm birth (<34 weeks' gestation) group than in the term group at 8 hours (8.4±4.2 vs 22.3±3.5 mm; P<.0001), 24 hours (13.2±3.8 vs 33.2±3.1 mm; P<.0001), and 48 hours (17.9±4.4 vs 40.2±4.2 mm; P<.0001) postpartum. There was no significant difference in mean postpartum cervical length between the preterm birth group and the term group at 8, 24, and 48 hours postpartum. Cervical length was similar between the groups at 6 weeks postpartum. A total of 891 patients participated in phase 2. The area under the curve was higher for preterm birth screening based on a history of a short postpartum cervix alone than for a history of spontaneous preterm birth alone (0.66 [95% confidence interval, 0.63-0.69] vs 0.57 [95% confidence interval, 0.54-0.61]; P<.0001). Combining both a history of spontaneous preterm birth and a short postpartum cervix resulted in additional benefit, with an area under the curve of 0.74 (95% confidence interval, 0.73-0.84; P<.0001). CONCLUSION: Postpartum cervical length measurements may assist in detecting the group of patients at higher risk of subsequent spontaneous preterm birth. It may be beneficial to consider an increased follow-up regimen and earlier interventions in this group to reduce adverse perinatal outcomes.

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

BACKGROUND: 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. OBJECTIVE: 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. STUDY DESIGN: 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. RESULTS: 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. CONCLUSION: 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.

The introduction of a universal transvaginal cervical length screening program is associated with a reduced preterm birth rate.

BACKGROUND: Midtrimester sonographic short cervix is a good predictor of preterm birth in singleton pregnancies. OBJECTIVE: This study aimed to assess the impact of implementing a universal transvaginal cervical length screening program on preterm birth rate. STUDY DESIGN: This study consisted of 2 parts: a before-and-after multicenter study and a study on the ECHOCOL ("echo"="ultrasound" and "col"="cervix" in French) prospective cohort. We compared the rate of preterm birth before and after the introduction of universal cervical length screening at the time of midtrimester anatomy ultrasound. The multicenter before-and-after regional study included all women with a singleton pregnancy who gave birth after 24 weeks' gestation in the South East of France from January 1, 2012 to April 30, 2018. In parallel, the ECHOCOL cohort study was prospectively conducted from May 2015 to July 2018, including 17 maternity hospitals in the South East region of France. In case of asymptomatic short cervix <25 mm, treatments offered included 200 mg of vaginal progesterone, or cerclage, or a pessary until 34 weeks' gestation. RESULTS: We observed a significant decrease rate of preterm birth between periods A and B after multivariate analysis. (respectively, 5.8% vs 5.6%; adjusted odds ratio, 0.92; 95% confidence interval, 0.89-0.95; P<.0001). In parallel, the percentage of cervical length screening significantly increased from 28.9% in period A to 52.9% in period B (odds ratio, 2.76; 95% confidence interval, 2.71-2.80; P<.0001). Among the 3468 patients of the ECHOCOL prospective cohort, 38 (1.1%) asymptomatic short cervices were detected, and 192 patients gave birth prematurely (11 with an asymptomatic short cervix and 181 without). In the ECHOCOL cohort, a marked but statistically insignificant tendency toward a reduced rate of preterm birth before 37 weeks of gestation was observed (from 5.8% to 5.5%; adjusted odds ratio, 0.72; 95% confidence interval, 0.51-1.03; P=.068). CONCLUSION: This study showed a significantly lower rate of preterm birth after the implementation of a universal cervical length screening and treating policy during the second trimester of pregnancy. The clinical trial was registered under NCT02598323.

Vaginal progesterone for preventing preterm birth and adverse perinatal outcomes in twin gestations: a systematic review and meta-analysis.

OBJECTIVE: To evaluate the efficacy of vaginal progesterone for the prevention of preterm birth and adverse perinatal outcomes in twin gestations. DATA SOURCES: MEDLINE, Embase, LILACS, and CINAHL (from their inception to January 31, 2023), Cochrane databases, Google Scholar, bibliographies, and conference proceedings. STUDY ELIGIBILITY CRITERIA: Randomized controlled trials that compared vaginal progesterone to placebo or no treatment in asymptomatic women with a twin gestation. METHODS: The systematic review was conducted according to the Cochrane Handbook for Systematic Reviews of Interventions. The primary outcome was preterm birth <34 weeks of gestation. Secondary outcomes included adverse perinatal outcomes. Pooled relative risks with 95% confidence intervals were calculated. We assessed the risk of bias in each included study, heterogeneity, publication bias, and quality of evidence, and performed subgroup and sensitivity analyses. RESULTS: Eleven studies (3401 women and 6802 fetuses/infants) fulfilled the inclusion criteria. Among all twin gestations, there were no significant differences between the vaginal progesterone and placebo or no treatment groups in the risk of preterm birth <34 weeks (relative risk, 0.99; 95% confidence interval, 0.84-1.17; high-quality evidence), <37 weeks (relative risk, 0.99; 95% confidence interval, 0.92-1.06; high-quality evidence), and <28 weeks (relative risk, 1.00; 95% confidence interval, 0.64-1.55; moderate-quality evidence), and spontaneous preterm birth <34 weeks of gestation (relative risk, 0.97; 95% confidence interval, 0.80-1.18; high-quality evidence). Vaginal progesterone had no significant effect on any of the perinatal outcomes evaluated. Subgroup analyses showed that there was no evidence of a different effect of vaginal progesterone on preterm birth <34 weeks of gestation related to chorionicity, type of conception, history of spontaneous preterm birth, daily dose of vaginal progesterone, and gestational age at initiation of treatment. The frequencies of preterm birth <37, <34, <32, <30, and <28 weeks of gestation and adverse perinatal outcomes did not significantly differ between the vaginal progesterone and placebo or no treatment groups in unselected twin gestations (8 studies; 3274 women and 6548 fetuses/infants). Among twin gestations with a transvaginal sonographic cervical length <30 mm (6 studies; 306 women and 612 fetuses/infants), vaginal progesterone was associated with a significant decrease in the risk of preterm birth occurring at <28 to <32 gestational weeks (relative risks, 0.48-0.65; moderate- to high-quality evidence), neonatal death (relative risk, 0.32; 95% confidence interval, 0.11-0.92; moderate-quality evidence), and birthweight <1500 g (relative risk, 0.60; 95% confidence interval, 0.39-0.88; high-quality evidence). Vaginal progesterone significantly reduced the risk of preterm birth occurring at <28 to <34 gestational weeks (relative risks, 0.41-0.68), composite neonatal morbidity and mortality (relative risk, 0.59; 95% confidence interval, 0.33-0.98), and birthweight <1500 g (relative risk, 0.55; 95% confidence interval, 0.33-0.94) in twin gestations with a transvaginal sonographic cervical length ≤25 mm (6 studies; 95 women and 190 fetuses/infants). The quality of evidence was moderate for all these outcomes. CONCLUSION: Vaginal progesterone does not prevent preterm birth, nor does it improve perinatal outcomes in unselected twin gestations, but it appears to reduce the risk of preterm birth occurring at early gestational ages and of neonatal morbidity and mortality in twin gestations with a sonographic short cervix. However, more evidence is needed before recommending this intervention to this subset of patients.

Diagnosis or prognosis? An umbrella review of mid-trimester cervical length and spontaneous preterm birth.

BACKGROUND: Cervical length is widely used to assess a woman's risk of spontaneous preterm birth (SPTB). OBJECTIVES: To summarise and critically appraise the evidence from systematic reviews on the prognostic capacity of transvaginal sonographic cervical length in the second trimester in asymptomatic women with singleton or twin pregnancy. SEARCH STRATEGY: Searches were performed in Medline, Embase, CINAHL and grey literature from 1 January 1995 to 6 July 2021, including keywords 'cervical length', 'preterm birth', 'obstetric labour, premature', 'review' and others, without language restriction. SELECTION CRITERIA: We included systematic reviews including women who did not receive treatments to reduce SPTB risk. DATA COLLECTION AND ANALYSIS: From 2472 articles, 14 systematic reviews were included. Summary statistics were independently extracted by two reviewers, tabulated and analysed descriptively. The ROBIS tool was used to evaluate risk of bias of included systematic reviews. MAIN RESULTS: Twelve reviews performed meta-analyses: two were reported as systematic reviews of prognostic factor studies, ten used diagnostic test accuracy methodology. Ten systematic reviews were at high or unclear risk of bias. Meta-analyses reported up to 80 combinations of cervical length, gestational age at measurement and definition of preterm birth. Cervical length was consistently associated with SPTB, with a likelihood ratio for a positive test of 1.70-142. CONCLUSIONS: The ability of cervical length to predict SPTB is a prognostic research question; systematic reviews typically analysed diagnostic test accuracy. Individual participant data meta-analysis using prognostic factor research methods is recommended to better quantify how well transvaginal ultrasonographic cervical length can predict SPTB.

Predicting spontaneous preterm birth in asymptomatic high-risk women with cervical cerclage.

OBJECTIVE: To determine the performance of the predictive markers of spontaneous preterm birth, cervicovaginal quantitative fetal fibronectin (fFN) and cervical length, in asymptomatic high-risk women with transabdominal, history-indicated or ultrasound-indicated cervical cerclage. METHODS: This was a secondary analysis of a prospective cohort of asymptomatic high-risk women with cervical cerclage and no other prophylactic intervention (including progesterone), who attended the preterm birth clinic at a central London teaching hospital between October 2010 and September 2016. Women had either transabdominal cerclage, placed prior to conception, history-indicated cerclage, placed before 14 weeks' gestation, or ultrasound-indicated cerclage for a short cervix (< 25 mm), placed before 24 weeks. All women underwent serial cervical length assessment on transvaginal ultrasound in the second trimester (16-28 weeks), and quantitative fFN testing from 18 weeks onward. Test performance was analyzed for the prediction of spontaneous preterm birth before 30 weeks (cerclage failure), 34 weeks and 37 weeks, using receiver-operating-characteristics (ROC)-curve analysis. RESULTS: Overall, 181 women were included in the analysis. Cervical length and fFN were strong predictors of spontaneous preterm birth before 30 weeks in women with cerclage, with areas under the ROC curve (AUC) of 0.86 (95% CI, 0.79-0.94) and 0.84 (95% CI, 0.75-0.92), respectively. Cervical length was a better predictor of preterm birth before 30 weeks in women with history-indicated compared to those with ultrasound-indicated cerclage, although both showed clinical utility (AUC, 0.96 (95% CI, 0.91-1.00) vs 0.79 (95% CI, 0.66-0.91); P = 0.01). Quantitative fFN was a strong predictor of spontaneous preterm birth before 30 weeks in women with history-indicated cerclage (AUC, 0.91 (95% CI, 0.75-1.00)) and retained clinical utility in those with ultrasound-indicated cerclage (AUC, 0.76 (95% CI, 0.64-0.89)). There were no spontaneous deliveries before 34 weeks in women with a transabdominal cerclage, so AUC was not calculated. Delivery was delayed significantly in this group (P < 0.01). CONCLUSIONS: Cervical length and quantitative fFN retain clinical utility for the prediction of spontaneous preterm birth in women with cervical cerclage, and prediction is best in women with a history-indicated stitch. These tests can be relied upon to discriminate risk and have utility when planning clinical management with regard to treatment failure. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.