Cervical length screening: a randomized trial assessing the impact on visit length and patient attitudes

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.

The acceptability of cervical electrical impedance spectroscopy within a multi-modal preterm birth screening package: a mixed methods study

BACKGROUND

Reducing the rate of preterm birth is a cornerstone of global efforts to address child mortality, however existing screening tests offer imperfect prediction. Cervical electrical impedance spectroscopy (EIS) is a novel technique to quantify the ripening changes which precede labour. Mid-trimester EIS measurements have been shown to accurately predict preterm birth in asymptomatic women. This study aimed to comprehensively evaluate the acceptability of cervical EIS to low and high-risk women as part of a package of screening tests performed during a larger prospective trial.

METHODS

In this parallel convergent mixed methods study, 40 women completed questionnaires before and after screening tests (EIS, cervical length measurement and fetal fibronectin quantification). Quantitative outcomes were anxiety levels before and after screening (Spielberger State Trait Anxiety Inventory, STAI-6), pain (Short Form McGill Pain Questionnaire) and ratings of EIS device appearance and test acceptability (visual analogue scales). Twenty-one women (11 high-risk, 10 low-risk) also attended a semi-structured qualitative interview. Interviews were recorded and transcribed, then thematic analysis was performed. A convergence coding matrix was constructed to enable triangulation of quantitative and qualitative results.

RESULTS

High risk women demonstrated a significant reduction in anxiety following screening (mean STAI-6 score 34.5 vs. 29.0, p = 0.002). A similar trend was observed among low-risk participants. Ratings of pain, EIS device appearance and procedural acceptability did not differ between groups. Mean pain ratings were low (visual analogue scale 0.97 and 1.01), comparing favourably to published evaluations of conventional screening tests. Qualitative analysis provided insight into both the physical consequences and emotional experiences of screening. Additional determinants of the screening experience included device design, pre-existing perspectives on intimate examination, attitudes to knowledge in pregnancy and interaction with clinical staff. Finally, a range of practical considerations regarding wider use of EIS were identified, with valuable complementary detail regarding acceptability for use in antenatal care.

CONCLUSIONS

Cervical EIS is well tolerated and acceptable to both low and high-risk women when performed as part of a multi-modal screening package. These results provide useful insights to inform the design of future study and screening protocols.

Implementing a Universal Cervical Length Screening Program in a Large Hospital System, it Takes Some Time to Achieve Consistent Results

OBJECTIVE

To describe changes in the acceptance of transvaginal (TV) cervical length (CL) measurements, and in the variance of CL measurements among operators, after implementation of universal TV-CL measurements at 18+0-23+6 weeks/days of gestation.

STUDY DESIGN

Retrospective cohort study Participants/Materials, Setting, Methods This study was performed after universal TV-CL screening was implemented at the University of Texas Health Science Center in Houston, Texas, for all women undergoing an anatomy ultrasound (US) between 18 0/6 and 23 6/7 weeks of gestation. Pregnant women carrying singletons without prior history of preterm delivery who underwent anatomy ultrasound evaluation between September 2017 and March 2020 (30 months) were included. The complete study period was divided in five epochs of six months each. Changes in patient's acceptance for the TV scan, in CL distribution, in the prevalence of short cervix defined as ≤15, ≤20, or ≤25 mm, and in the performance of ultrasound operators across the five epochs were evaluated. For this analysis, success rate was defined as the percentage of TV-CL measurements obtained in relation to the number of second trimester anatomy scans.

RESULTS

A total of 22,207 low risk pregnant women evaluated by 36 trained sonographers were analyzed. Overall, the acceptance for TV-CL measurement was 82.3% (18,289/22,207), increasing from 76.7% in the first epoch to 82.8% (p<0.0001) in the last epoch. The mean CL did not significantly change from 38.6 mm in the first epoch to 38.5 mm in the last epoch (p=0.7); however, the standard deviation decreased from 7.9 mm in the first epoch to 7.04 mm in the last epoch (p=<0.01). The prevalence of a short cervix ≤25 mm was 2.2% (n=399/18,289), ≤20 mm was 1.2% (224/18,289), and ≤15 mm was 0.9% (162/18,289). This prevalence varied only for CL ≤25 mm from 3.02% (88/2,907) in the first epoch to 1.77% (64/3,615) in the last epoch (p=0.0009). There was a variation in CL measurements among operators (mean 3.3 mm). Sonographers with less than one year of experience had a lower success rate for completing TV-CL examinations than more experienced sonographers (80.8% vs. 85.8%; p <0.03). In general 77% (27/35) of operators had a success rate ≥80% for completing TV-SL scans.

LIMITATIONS

Characteristics of individuals who accepted versus those who declined TV-CL were not compared; CL values were not correlated with clinical outcomes.

CONCLUSIONS

During the first six months after implementation of a universal cervical length screening program, there was greater variation in CL measurements, lower acceptance for a TV ultrasound, and a higher number of women diagnosed with a CL ≤25 mm, as compared to subsequent epochs. After the first six months, these metrics improved and remained stable. Most operators improved their performance over time; however, there were a few with a low success rate for TV-CL, and others who systematically over or under estimate CL measurements.

It is about time. The advantage of transabdominal cervical length screening

PURPOSE

Sonographic cervical length (CL) measurement has become a standard practice for identifying women at increased risk for preterm birth. We aimed to assess the time needed for CL measurement during fetal anatomy scan using either transabdominal or transvaginal ultrasound, and to provide a predictive value of the transabdominal CL measurements for reassuring transvaginal CL measurements of more than 25 mm.

METHODS

In a prospective study we measured CL transabdominally, and transvaginally in all the anatomy scans performed at 18-25 weeks' gestation, from January 2017 until January 2018. CL and the duration of the examination were compared between the two approaches. Adjustments were made for, body mass index, previous cesarean sections and parity.

RESULTS

Four hundred sixty-eight patients participated in the study. The time needed for the transabdominal CL measurement was significantly lower compare with the transvaginal CL measurement (0.46 ± 0.3 min versus 6.9 ± 1.38 min, p < 0.001). The CL measured transabdominally was significantly shorter than the CL measured transvaginally (36.7 ± 6.7 mm versus 41.9 ± 7.3 mm, respectively p < 0.001). All women with transabdominal CL measurements above 36 mm (64.2% of patients) had a transvaginal CL of more than 25 mm.

CONCLUSION

Transvaginal measurement of CL is a time-consuming procedure that prolong fetal anomaly scan by 25%. Transabdominal CL measurement of 36 mm is reassuring CL above 25 mm. Transabdominal ultrasound should be used as an initial tool for CL screening. Transvaginal measurements of CL should be reserved for high-risk women, for women with difficulties in demonstrating the cervix abdominally, and for women with transabdominal measurements of less than 36 mm.

Cervical assessment by ultrasound for preventing preterm delivery

BACKGROUND

Measurement of cervical length by ultrasound is predictive of preterm birth (PTB). There are three methods of ultrasound cervical assessment: transvaginal (TVU), transabdominal (TAU), and transperineal (TPU, also called translabial). Cervical length measured by TVU is a relatively new screening test, and has been associated with better prediction of PTB than previously available tests. It is unclear if cervical length measured by ultrasound is effective for preventing PTB. This is an update of a review last published in 2013.

OBJECTIVES

To assess the effectiveness of antenatal management based on transvaginal, transabdominal, and transperineal (also called translabial) ultrasound screening of cervical length for preventing preterm birth.

SEARCH METHODS

For this update, we searched the Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, and the WHO International Clinical Trials Registry Platform (ICTRP) to 30 August 2018; reviewed the reference lists of all articles, and contacted experts in the field for additional and ongoing trials.

SELECTION CRITERIA

We included published and unpublished randomised controlled trials (RCT) including pregnant women between the gestational ages of 14 to 32 weeks, for whom the cervical length was screened for risk of PTB with TVU, TAU, or TPU. This review focused on studies based on knowledge versus no knowledge of cervical length results, or ultrasound versus no ultrasound for cervical length. We excluded studies based on interventions (e.g. progesterone, cerclage) for short cervical length.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods.

MAIN RESULTS

We included seven RCTs (N = 923): one examined asymptomatic women with twin pregnancies; four included women with singleton pregnancies and symptoms of preterm labour (PTL); one included women with singleton pregnancies and symptoms of preterm premature rupture of membranes (PPROM); and one included asymptomatic singletons. All trials used TVU for screening.We assessed the risk of bias of the included studies as mixed, and the quality of the evidence for primary outcomes as very low for all populations.For asymptomatic women with twin pregnancies, it is uncertain whether knowledge of TVU-measured cervical length compared to no knowledge reduces PTB at less than 34 weeks (risk ratio (RR) 0.62, 95% confidence intervals (CI) 0.30 to 1.25; 1 study, 125 participants) because the quality of the evidence is very low. The results were also inconclusive for preterm birth at 36, 32, or 30 weeks; gestational age at birth, and other maternal and perinatal outcomes.Four trials examined knowledge of TVU-measured cervical length of singletons with symptoms of PTL versus no knowledge. We are uncertain of the effects because of inconclusive results and very low-quality evidence for: preterm births at less than 37 weeks (average RR 0.59, 95% CI 0.26 to 1.32; 2 studies, 242 participants; I² = 66%; Tau² = 0.23). Birth occurred about four days later in the knowledge groups (mean difference (MD) 0.64 weeks, 95% CI 0.03 to 1.25; 3 trials, 290 women). The results were inconclusive for the other outcomes for which there were available data: PTB at less than 34 or 28 weeks; birthweight less than 2500 g; perinatal death; maternal hospitalisation; tocolysis; and steroids for fetal lung maturity.The trial of singletons with PPROM (N = 92) evaluated safety of using TVU to measure cervical length in this population as its primary outcome, not its effect on management. The results were inconclusive for incidence of maternal and neonatal infections between the TVU and no ultrasound groups.In the trial of asymptomatic singletons (N = 296), in which women either received TVU or not, the results were inconclusive for preterm birth at less than 37 weeks (RR 1.27, 95% CI 0.61 to 2.61; I² = 0%), gestational age at birth, and other perinatal and maternal outcomes.We downgraded evidence for limitations in study design, inconsistency between the trials, and imprecision, due to small sample size and wide confidence intervals crossing the line of no effect.No trial compared the effect of knowledge of the CL with no knowledge of CL in other populations, such as asymptomatic women with singleton pregnancies, or symptomatic women with twin pregnancies.

AUTHORS' CONCLUSIONS

There are limited data on the effects of knowing the cervical length, measured by ultrasound, for preventing preterm births, which preclude us from drawing any conclusions for women with asymptomatic twin or singleton pregnancies, singleton pregnancies with PPROM, or other populations and clinical scenarios.Limited evidence suggests that knowledge of transvaginal ultrasound-measured cervical length, used to inform the management of women with singleton pregnancies and symptoms of preterm labour, appears to prolong pregnancy by about four days over women in the no knowledge groups.Future studies could look at specific populations separately (e.g. singleton versus twins; symptoms versus no symptoms of PTL), report on all pertinent maternal and perinatal outcomes, and include cost-effectiveness analyses. Most importantly, future studies should include a clear protocol for management of women based on TVU-measured cervical length.

A Quality Study to Explore Rationale for Pregnant Women to Decline Transvaginal Cervical Length Screening

OBJECTIVES

To identify patient rationale for pregnant women to decline transvaginal cervical length screening.

METHODS

Survey data from 511 women presenting for second-trimester anatomy and transvaginal cervical length sonography were collected during a 4-month period from September 2016 to January 2017. Each patient completed a medical questionnaire that includes demographic and obstetric history data and a survey to document their acceptance or declination of transvaginal cervical length screening.

RESULTS

Of the 511 women included in the study, 5.9% (n = 30) declined transvaginal cervical length screening. Demographic characteristics and risk factors for prematurity were similar between those who accepted and declined. The sonographer performing the study was significantly associated with declination of transvaginal cervical length screening (P < .001), with 4 of 13 sonographers accounting for 83.3% of all declinations. The most frequently reported reasons for declining the transvaginal cervical length screening were feeling that it was not needed (47%; n = 14) and not feeling prepared for the transvaginal sonography (27%; n = 8).

CONCLUSION

The findings of this study indicate that the sonographer performing transvaginal cervical length screening may be associated with declination. The most common reasons patients cited for declining included not feeling that the study was needed and not feeling prepared for the procedure. Increased sonographer education and sonographer use of a scripted approach when discussing the procedure with patients may improve patient acceptance.

Universal cervical length screening in singleton gestations without a previous preterm birth: ten reasons why it should be implemented

A short cervix is associated strongly with preterm birth. Pharmacologic intervention with vaginal progesterone in women with a singleton pregnancy and a short cervix in the second trimester decreases the incidence of preterm birth. We explore the evidence that universal cervical length screening in women with a singleton pregnancy meets the criteria for an effective screening test for preterm birth prevention, driving it towards becoming routinely offered in prenatal care.