Transvaginal Cervical Length Screening Research Articles

Assessing the multifaceted cervix: examining cervical gland area at cervical length screening to predict spontaneous preterm birth

BACKGROUNDBiologically active cervical glands provide a mucous barrier while influencing the composition and biomechanical strength of the cervical extracellular matrix. Cervical remodeling during ripening may be reflected as loss of the sonographic cervical gland area. As sonographic cervical length remains suboptimal for universal screening, adjunctive evaluation of other facets of the mid-trimester cervix may impart additional screening benefit. OBJECTIVETo sonographically assess the cervical gland area at universal cervical length screening for preterm birth. STUDY DESIGNWe performed a retrospective cohort study of singletons with transvaginal cervical length screening universally performed during anatomic survey between 18 0/7 and 23 6/7 weeks and subsequent live delivery at a single institution in 2018. Uterine anomalies, cerclage, suboptimal imaging, or medically indicated preterm birth were excluded. Ultrasound images were assessed for cervical length and cervical gland area (with quantitative measurements when present). The primary outcome was spontaneous preterm birth <37 weeks. Absent and present gland groups were compared using χ2, Fisher's exact, T-test, and multivariate logistic regression (adjusting for parity and progesterone use, as well as the gestational age, cervical length, and gland absence at screening ultrasound). Gland measurements were evaluated using the Mann-Whitney-U Test and Spearman's correlation. RESULTSAmong the cohort of 772 patients, absent and present CGA groups were overall similar. Patients were on average 33 years old, ∼20 weeks gestation at screening ultrasound, and overall, 2.5% had history of prior spontaneous preterm birth. The absent gland group was more likely to have been taking progesterone (17% vs 4%, P=.04). Overall rate of preterm birth was 2.6%. However, the 2.3% of patients with absent cervical gland area were significantly more likely to deliver <37 weeks (aOR 23.9, 95% CI 6.4–89, P<.001). Multivariate logistic regression demonstrated better performance of a cervical length screening model for preterm birth prediction with the addition of qualitative gland evaluation (P<.001). Qualitative gland assessment was reproducible (PABAK 0.89), but quantitative gland measurements did not correlate with preterm birth. CONCLUSIONQualitative gland absence at mid-gestation cervical length screening was associated with subsequent spontaneous preterm birth, whereas quantitative gland measurements were not. Multifaceted ultrasound screening may be needed to adequately evaluate the multiple biologic functions of the cervix.

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.

Cervical assessment certification and its impact on performance quality in the context of universal cervical screening.

To assess the impact of the introduction of universal transvaginal cervical screening and certification on the quality of cervical length ultrasound images. The present study included a retrospective cohort of singleton pregnancies that underwent transvaginal cervical length measurement at the anatomical scan (180/7 and 236/7 weeks) before (period A, 2015-2017) and after (period B, 2017-2019) the introduction of universal transvaginal cervical length screening. Independent observers blindly evaluated the images obtained for cervical length using a qualitative scoring method based on five criteria, according to the Fetal Medicine Foundation. In all, 6013 patients met the inclusion criteria, 3333 in period A and 2680 in period B. Maternal characteristics and risk factors for preterm birth were similar between the two periods. The acceptance of transvaginal cervical length measurement in period B was 95.5% in the overall cohort and 100% in the subgroup of high-risk patients. The quality score was significantly higher in period B than in period A. Among the image quality criteria, the anterior/posterior ratio, the correct magnification of the images, and the calipers' placement contributed significantly to the improved quality score in period B. Most of the sonographers performed better in period B, irrespective of the years of experience, but certificate holders obtained higher scores than non-certified sonographers, particularly those in mid-career. The identification of short cervix was significantly higher in period B than in period A. The implementation of universal transvaginal cervical length screening and the certification process are associated with improved quality of cervical length images, even among expert sonographers and in the presence of anatomical pitfalls.

Maternal and obstetrical factors associated with short cervical length at midtrimester in women with no history of preterm delivery

Aim To evaluate associations between maternal characteristics and a short cervix in patients without history of preterm delivery, and to determine if these characteristics can predict the presence of a short cervix. Materials and methods This is a retrospective cohort study that included 18,592 women with singleton pregnancies without history of previous preterm deliveries who underwent universal transvaginal cervical length (TVCL) screening between 18 + 0 and 23 + 6 weeks/days of gestation. A short cervix was defined as a cervical length (CL) ≤25 mm, ≤20 mm, and ≤15 mm. Associations between maternal age, weight, height, body mass index (BMI), previous term deliveries, and history of previous miscarriages, with a short cervix were evaluated using logistic regression models. Results The prevalence of a short cervix in our population was: CL ≤25 mm, 2.2% (n = 403); CL ≤20 mm, 1.2% (n = 224); and CL ≤15 mm, 0.9% (n = 161). Women with BMI >30 and/or previous abortions constituted 45.5% of the total population (8463/18,582). Significant associations with short cervix were observed for women with BMI ≥30, and for women with at least one previous abortion (p < .001). Parous women had a significantly lower association with a short cervix than nulliparous women (p < .001). Maternal age or height were not associated with a short cervix. Prediction of short cervix based on presence of any of the following: BMI ≥ 30 or previous abortions showed sensitivities of 55.8% (≤25 mm), 61.6% (≤20 mm), and 63.4% (≤15 mm) with similar specificity (50.1–54.6%) and likelihood ratio positive (1.2–1.5); and prediction based on BMI ≥ 30 and previous abortions showed sensitivities of 11.1% (≤25 mm), 14.7% (≤20 mm), and 16.7% (≤15 mm) with specificity 93%. Conclusions Among low risk women for spontaneous preterm delivery, those with a BMI ≥30 and/or previous miscarriages had a significantly increased risk for a short cervix at 18 + 0 and 23 + 6 weeks/days of gestation. Despite these significant associations, screening by maternal risk factors in a low risk population of pregnant women should not be an alternative to mid-trimester universal CL measurement.

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.

VAGINAL PROGESTERONE IN RISK REDUCTION OF PRETERM BIRTH IN WOMEN WITH SHORT CERVIX IN MID TRIMESTER OF PREGNANCY

Background: Preterm labour is a major health challenge in obstetrics. Many risk factors being identified, the most common one is short cervical length, can be diagnosed by transvaginal ultrasound scan after 13 weeks of pregnancy. Vaginal progesterone is the most bioavailable form of progesterone that have effect on uterine and cervix. Progesterone is found to inhibit the production of proinflammatory cytokines and prostaglandins within the uterus and to inhibit myometrial contractility Aim:To evaluate the efficacy of vaginal progesterone administration for preventing preterm birth and decrease perinatal morbidity and mortality in asymptomatic women with a singleton gestation and a mid-trimester sonographic cervical length (CL) ≤ 25 mm. Materials And Methods:This is a prospective study of asymptomatic women with a singleton pregnancy and a sonographic short cervix (&lt;25mm) at 19 + 0 to 23 + 6 weeks of gestation. Women were allocated randomly to receive vaginal progesterone or placebo daily starting from 19 + 0 to 23 + 6 weeks until 36 + 6 weeks, rupture of membranes or delivery, whichever occurred first. Randomization sequence was stratified by centre and history of a previous preterm birth. The primary endpoint was preterm birth before 33 weeks of gestation. Analysis was by intention to treat. Results:Out of 100 patients for whom study was done, 20 lost to followup and remaining divided into two groups: 40 Singleton pregnant women with CL&lt;25mm between 19 + 0 to 23 + 6 weeks of gestation with no sign and symptoms were given daily vaginal progesterone for up to 36 + 6 weeks, rupture of membranes or delivery, whichever occurred first. The dose is 200 mg once daily and a group of 40 women with cervical length of &lt;25 mm between 19 + 0 to 23 + 6 weeks of pregnancy were given no treatment, Maximum distribution belongs to age of 19-24 years followed by 30-34 years. Most of women in this study have no history of preterm labour. In those who received vaginal progesterone 5 women had history of previous preterm labour and five women in no treatment group. It was found that there was statistically significant reduction in preterm labour in women with short cervix &lt;2.5cm with 200mg vaginal progesterone. Conclusions:This updated systematic review and meta-analysis reaffirms that vaginal progesterone reduces the risk of preterm birth and neonatal morbidity and mortality in women with a singleton gestation and a mid-trimester CL ≤ 25 mm, without any deleterious effects on neurodevelopmental outcome. Clinicians should continue to perform universal transvaginal CL screening at 19 + 0 to 23 + 6 weeks of gestation in women with a singleton gestation and to offer vaginal progesterone to those with a CL ≤ 25 mm.

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

Midtrimester sonographic short cervix is a good predictor of preterm birth in singleton pregnancies. This study aimed to assess the impact of implementing a universal transvaginal cervical length screening program on preterm birth rate. 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. 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). 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.

The role of digital examination in the setting of a sonographically short cervix

Universal transvaginal cervical length screening has been associated with a reduction in the frequency of preterm birth. However, there is no clinically set standard to guide the performance of a digital cervical examination in the setting of a sonographically short cervix. To investigate the prevalence of cervical dilation at various midtrimester transvaginal cervical length thresholds. Furthermore, we sought to identify sonographic or clinical characteristics associated with cervical dilation that may inform who would benefit from a digital cervical examination in the setting of a sonographically short cervix. This retrospective cohort study was conducted at an academic institution and included women with a singleton gestation and an ultrasonographically detected short cervix (defined as a transvaginally obtained cervical length ≤25 mm) who had a documented digital cervical examination within 1 week of the ultrasonography. Bivariable analyses were used to determine the relationship between cervical length and the presence of cervical dilation. Multivariable logistic regression and receiver operating characteristic curve were used to evaluate the relationship between clinical and sonographic risk factors and cervical dilation. Of the 256 women who met eligibility criteria and had a sonographically detected short cervix, 103 (40.2%) were found to be dilated on digital cervical examination. The prevalence of cervical dilation increased as sonographic cervical length decreased; cervical dilation was identified in 15%, 39%, 53%, 64%, and 69% of women with a cervical length between 20.0 and 25.0 mm, 15.0 and 19.9 mm, 10.0 and 14.9 mm, 5.0 and 9.9 mm, and 0.0 and 4.9 mm, respectively. Maternal race or ethnicity (examined as a social construct), insurance status, nulliparity, previous cervical excisional procedure, funneling on ultrasonography, and sonographic cervical length were each associated with cervical dilation. However, including all of these variables into a regression yielded a model with only moderate predictive ability to identify cervical dilation, with receiver operating area under the curve of 0.77 (95% confidence interval, 0.71-0.83). Consideration should be given to performing a digital cervical examination in the setting of a sonographically short cervix (especially <20 mm) to detect cervical dilation.

The perceptions of obstetric care providers about cervical length screening for preterm birth prevention.

Routine cervical length (CL) measurement at the mid-pregnancy ultrasound is a central recommendation of the Western Australian Preterm Birth Prevention Initiative (Initiative). To evaluate the perceptions and changes in practice of Western Australian obstetric care providers regarding routine CL screening for preterm birth (PTB) prevention following the Initiative introduction. Two self-administered questionnaires were completed by providers from a range of practices. The first was during site visits with the Initiative Outreach team in 2015-2016. The questionnaire was re-issued in 2021 via online dissemination. Participant demographic data and opinions on CL screening for PTB prevention were collected. Two hundred and fourteen providers participated in 2015-2016 and 109 in 2021. In both surveys, providers were more likely to discuss transvaginal CL screening with high-risk women (48.1%, 76.1%; P<0.001) compared with low-risk (7.5%, 18.3%; P=0.002) and the importance of CL screening (13.5%, 40.4%; P<0.001), in 2015-2016 and 2021, respectively. Responses relating to CL screening, including what constitutes a short cervix on ultrasound were varied. A transabdominal CL <35mm was classified as short by 46.2% and 37.6% and <25mm on transvaginal ultrasound by 49.1% and 64.2%, in the respective surveys. Most providers ceased progesterone (68.6%, 75.2%) at >28weeks gestation. Providers focused on women with overt PTB risk factors, rather than a universal CL screening approach. Although there was improvement between the surveys, the definition of what constitutes a short cervix on ultrasound and how to treat and monitor women with a short CL remained varied.

Patient Acceptability of Universal Transvaginal Cervical Length Screening Program Implementation at HRH Princess Maha Chakri Sirindhorn Medical Center, Thailand

Background: Preterm birth is a significant problem. It is a leading cause of early neonatal death. Transvaginal ultrasonography for cervical length measurement during second trimester could predict preterm labor. Vaginal progesterone reduced preterm birth incidence in pregnant women with short cervical length. Objective: To evaluate the acceptance rate of a universal transvaginal cervical length (TCL) screening program implementation. Materials and Methods: A retrospective cohort study of universal TCL before 24 weeks of gestation at the time of anatomical scan between 18 to 23+6 weeks from single center from July, 2017 through July, 2018. Pregnant woman with cervical length (CL) &lt;20 millimeters (mm) were diagnosed cervical shortening and were offered treatment as protocol. Incidence of cervical shortening was assessed. Acceptance rates and factors for declining TCL screening were analyzed. The incidence of preterm birth before 34 weeks and 37 weeks were reported. Results: Three hundred forty-one Thai pregnant women were enrolled. Of those, 294 (86.2%) accepted TCL screening. Three pregnant woman (1.1%) had a CL &lt;20 mm. Employed women and women who had income &gt;10,000 Baht per month were likely to accept TCL screening (OR, 2.13; 95% CI, 1.14 to 3.98 and OR, 2.85; 95% CI, 1.37 to 5.95, respectively). The incidence of preterm birth was accounted for 8.9 percent in the acceptance and 2.1 percent in denial group. Conclusion: The universal transvaginal cervical length screening program at HRH Princess Maha Chakri Sirindhorn Medical Center was successfully implemented at 86.2% of acceptance rate. Keywords: Cervical length; Universal screening; Acceptability; Preterm birth; Prevention

Ultrasound indicated cerclage in women with previous late preterm birth

It is unclear whether women with a history of late preterm birth (34 to 36+6 weeks’ gestation) should undergo serial transvaginal cervical length screening. We sought to compare the rates of ultrasound indicated cerclage between women with a history of preterm birth prior to 34 weeks and those with previous late preterm birth.

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.

The perceptions of pregnant women about cervical length screening for preterm birth prevention.

The Western Australian Preterm Birth Prevention Initiative was officially launched in November 2014. It demonstrated an initial decrease in the preterm birth rate in Western Australia. One of the key points of this initiative is the routine ultrasound measurement of the cervical length in mid-pregnancy. The aim of this study was to evaluate the perceptions and attitudes of Western Australian women regarding transvaginal cervical length (TVCL) screening for preterm birth prevention. Self-administered questionnaires were completed by pregnant women before and after their mid-trimester obstetric ultrasound. Maternal demographical and medical data were collected in addition to opinions of TVCL screening. A total of 598 women participated with the maternal age range representative of the Western Australian obstetric population. There was a high rate of acceptance of TVCL imaging, with 2% of the 149 women declining a transvaginal ultrasound (TVU) offered in this study, 1.5% refusing a TVU in the past and 5.7% reporting that they would have a concern in having a TVU in the future. Women stated that they either had declined TVCL in the past (11%) or would decline in the future (30.7%) as they wanted to discuss the procedure with their clinician first, had been advised not to have a TVU by their clinician (11% in the past and 47.7% in the future) or felt uncomfortable with the operator (22% at a previous TVU and 34.4% in the future). Pregnant women participating in this study had a high acceptance of TVCL screening for preterm birth prevention.

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.

749 Performance of cervical length screening in obese women

Universal cervical length (CL) screening is recommended in all singleton pregnancies to identify patients at risk of spontaneous preterm birth (sPTB) with treatments available to decrease this risk. Since the prevalence of obesity in pregnancy is rising, we aimed to characterize midtrimester CL and evaluate the association of CL and sPTB in nulliparous obese women. This is a retrospective cohort study of 5502 nulliparous women undergoing universal transvaginal CL screening at 17-23 weeks gestation age between 2011-2016. Women with CL ≤20mm were offered intervention for short cervix. The distribution of cervical length in obese (BMI ≥30) women was plotted. The incidence of CL ≤15mm, ≤20mm, and ≤25mm was compared between obese and nonobese women. The rate of preterm birth was compared between the two groups. Receiver operating characteristic curves were used to compare the performance of CL screening in prediction of sPTB <34 weeks. Of the 5502 patients in the cohort, 1427 (25.9%) were obese. Although the mean cervical length increased with increasing BMI class (nonobese 39.9 + 6.9mm, class 1 obesity 40.9 + 7.0mm, class 2 obesity 41.1 + 7.8mm, class 3 obesity 40.0 + 7.6mm, p <0.01), obese and nonobese women had similar rates of short cervix at all examined cutoffs. Compared to nonobese patients, obese patients had a higher likelihood of sPTB prior to 34, 28, and 24 weeks. The rate of sPTB <37 weeks was similar between obese and nonobese women (Table) and occurred in 50% of patients with CL <20mm in both groups. CL performed equally well as a predictor for sPTB <34 weeks in obese and nonobese women (Figure). The sensitivity and specificity of CL <20mm for sPTB <34 weeks did not differ between groups. Obese women are at higher risk for sPTB prior to 34, 28, and 24 weeks. This risk appears to be independent of midtrimester CL, suggesting that the etiology of PTB in obese patients may not be cervical insufficiency.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

947 Recurrence risk of short cervix in women with history of short cervix and term delivery

Little is known about the recurrence risk for short cervix in women with an obstetric history of short cervix with term delivery. The objective of our study was to determine the recurrence risk of short cervix in this population of women. We performed a cross-sectional study of women who delivered at a single tertiary care center from 1/1/2015–12/31/2019 with an obstetric history of short cervix - defined as a cervical length <2.5cm - who delivered at term in an index pregnancy. At our institution, universal transvaginal cervical length screening is performed at the anatomical survey between 16 and 24 weeks. Measurements were performed in compliance with the Cervical Length Education and Review program. Women were included if the index and subsequent pregnancies and deliveries were within our institution during the study period. Women with a history of preterm birth, multiple gestations, fetal anomalies, stillbirth and missing data were excluded. Data were collected via chart abstraction and compared between women with and without recurrent short cervix. 54 women met our inclusion criteria. 21 (39%) women had recurrent short cervix in the subsequent pregnancy. In unadjusted univariate analysis, women with short cervix diagnosed at ≥20 weeks in the index pregnancy were at increased risk of recurrent short cervix in the subsequent pregnancy (Table 1). This persisted after controlling for age, race, body mass index, and vaginal progesterone use during the index pregnancy (aOR 7.86, 95% CI 1.30-47.38) (Table 2). There was no difference in the overall and spontaneous preterm birth (PTB) rates between women with and without recurrent short cervix (overall PTB 9.52% vs 9.09%, p=0.99; spontaneous PTB 4.76% vs 3.03%, p=0.99). In women with an obstetric history of short cervix with a term birth, gestational age at diagnosis of short cervix in the index pregnancy was associated with an increased risk of recurrent short cervix in the subsequent pregnancy. However, there was no increased risk of preterm birth based on recurrent short cervix.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Mid-Trimester Cervical Length Screening: Effect of Poorly Developed Lower Uterine Segment on Pregnancy Outcome.

To identify whether a poorly developed lower uterine segment (PDLUS) observed during cervical length (CL) screening affects the duration of gestation in women with no prior spontaneous preterm birth (sPTB). A retrospective cohort study of women with a singleton gestation and no prior sPTB, who underwent transvaginal CL screening at our institution. We excluded women with progesterone exposure, major anomalies, and women delivering elsewhere. Women with PDLUS were compared to those with a measured (normal) CL ≥25 mm. birth gestational age (GA). sPTB <35 and 37 weeks, hospital evaluation for preterm labor without delivery, delivery indication, and mode. A Cox proportional-hazards survival model considered time from CL scan to delivery. We powered the study to detect a one-half week difference in birth GA. We included 270 women with PDLUS and 985 women with normal CL. Mean birth GA was 38.9 ± 2.0 weeks with PDLUS versus 38.7 ± 2.4 weeks with normal CL (p=.10). Women with PDLUS were less likely to experience sPTB <37 weeks (1.1% vs 3.6%; p=0.04). There was no difference in sPTB <35 weeks (0.8% vs 1.7%; p=.25). Hospital evaluation for preterm labor (17% vs 19%; p=.54), delivery indication, and mode were not different. The hazard ratio for earlier birth in women with PDLUS was 0.67 (95% CI 0.46, 0.98; p=.04). We observed no difference in mean GA at birth; however, PDLUS was protective against sPTB <37 weeks and was associated with a lower hazard ratio for earlier birth.

Universal transvaginal cervical length screening during pregnancy increases the diagnostic incidence of low-lying placenta and placenta previa

Universal transvaginal cervical length screening has been increasingly implemented with both positive and negative consequences. In this study, we described the diagnostic incidence of low-lying placenta and placenta previa with the implementation of universal transvaginal cervical length screening. This is a retrospective cohort study of women undergoing midtrimester universal transvaginal cervical length screening. The primary outcome was the rate of transvaginal diagnosis of low-lying placenta or placenta previa using midtrimester universal transvaginal cervical length screening. This study included 1982 midtrimester ultrasounds, of which 211 indicated a low-lying placenta or placenta previa on either transabdominal or transvaginal ultrasound. With transvaginal ultrasound, a low-lying placenta or placenta previa was diagnosed in 211 women (10.6% of the study population). Of the 211 patients with a low-lying placenta or placenta previa, 90 (42.6%) had a false-negative result, diagnosed using only transvaginal ultrasound; 112 (53.1%) had a true-positive result; and 9 (4.3%) had a false-positive result. The relative risk of having an abnormal finding on ultrasound with the addition of universal transvaginal cervical length screening was 9.2 (95% confidence interval, 4.6-18.1). Of the low-lying placenta or placenta previa diagnosed using midtrimester universal transvaginal cervical length screening, 98.9% resolved (95% confidence interval, 93.7-99.97). Implementation of universal transvaginal cervical length screening increases the diagnostic incidence of low-lying placenta or placenta previa without an increase in the diagnoses that persist to term, which comes at the cost of increased follow-up ultrasounds and potentially increased anxiety for the patient.

Time required to complete transvaginal cervical length in women receiving universal cervical length screening for preterm birth prevention

Background Preterm birth contributes to over one-third of infant deaths, and although there are several risk factors for preterm birth few tests predict this obstetric complication. Midtrimester transvaginal cervical length (TVCL) screening is currently the best clinical predictor of spontaneous preterm birth and has been suggested to be applied universally. Although several studies have examined the cost-efficacy of universal screening, the time consumption and resultant time management has not been examined. Objective We aim to quantitate the time requirement for transvaginal cervical length (TVCL) screening with the implementation of universal TVCL screening. Study design : This is a retrospective cohort study of women undergoing cervical length screening after implementation of universal Transvaginal Cervical Length (TVCL) screening at a university setting over a 1-year period. The primary outcome was time in minutes for TVCL screening from completion of transabdominal to completion of transvaginal ultrasound. Results This study included 2803 ultrasounds, 1673 of which involved completion of a TVCL after completion of abdominal imaging between 16 0/7 and 23 6/7 weeks of gestation. The mean duration of cervical length screening was 9.8 min (standard deviation [SD], 4.0 min). The time range was less than 1 min to 48 min. For women obtaining cervical lengths, 4.2% required less than 5 additional minutes to perform cervical length screening, 52.1% (872), required less than 10 additional minutes. The majority, 91.8%, of ultrasounds required less than 15 min to complete. Ultrasounds performed in private practice sites required less time compared to those at teaching sites (8.2 ± 3.1 min versus 10.2 ± 4.1 min, p < .001). No significant time improvement occurred after 6 months of universal TVCL screening, with the first 6 months average of 10.1 min versus 9.6 min in the later half, p = .61. Conclusion Implementation of a universal TVCL program adds an average of 10 min to each ultrasound exam. This additional time does diminish with increasing experience with TVCL, but not to a significant degree.

Cervical Assessment by Transvaginal Ultrasound for Predicting Preterm Birth in Asymptomatic Women

Abstract Preterm birth (PTB) is defined as delivery before completing 37 weeks of gestation. It is the main cause of neonatal morbidity and mortality in the most countries. The inherent cervical length and strength are two main features of the cervix that determine whether or not a pregnant woman is at risk for PTB. Routine transvaginal cervical length screening was recommended for women with singleton pregnancy and history of prior spontaneous PTB, while the issue of universal cervical length screening and the screening in multiple gestations remain an object of debate. Strain sonoelastography and shear-wave sonoelastography have been used to evaluate the cervical stiffness in pregnant women, but the predictive value for PTB still requires further investigations. In this review, we will discuss the measurement methods of cervical length and cervical stiffness, and compare the value of cervical assessment by transvaginal ultrasound for predicting PTB in asymptomatic women.