Cervilenz™ is an effective tool for screening cervical-length in comparison to transvaginal ultrasound

Universal cervical length screening with a cervicometer to prevent preterm birth <34 weeks: a decision and economic analysis

Background: Preterm birth is a leading cause of neonatal morbidity and mortality worldwide; evidence-based strategies to decrease preterm birth are desperately needed.Objective: The purpose of this study was to estimate which of three strategies for screening for shortened cervix in asymptomatic low-risk women is the most cost-effective in terms of prevention of preterm birth and associated morbidity.Study design: A decision analysis model was developed from available published evidence comparing three strategies in screening asymptomatic low-risk women for shortened cervix: (1) cervicometer with subsequent referral for transvaginal ultrasound, (2) transvaginal ultrasound screening, and (3) no screening. The cost and effectiveness of each strategy was assessed in terms of quality-adjusted life-years (QALYs), and cost in US dollars.Results: Screening with a cervicometer with referral was the most cost-effective strategy and represented a savings of $999.65 ($11,617.28 versus $12,616.93) over screening with ultrasound, and a savings of $15,601.62 ($11,617.28 versus $27,218.90) over no screening. Costs for outcomes ranged from $3528 for a healthy neonate ≥34 weeks to $717,467.5 for a neonate <34 weeks with severe morbidity. The cervicometer strategy avoided 11.68 neonatal deaths per 1000 deliveries (3.59 deaths versus 15.27 deaths) compared with no screening, and avoided 0.73 neonatal deaths per 1000 deliveries (3.59 deaths versus 4.32 deaths) compared with ultrasound strategy. The cervicometer strategy prevented 82.44 preterm births per 1000 deliveries (22.56 versus 105.00) compared with no screening, and 5.10 preterm births per 1000 deliveries (22.56 versus 27.66) compared with ultrasound strategy. Per QALY, cervicometer screening cost $386.57, transvaginal ultrasound cost $420.31, and no screening cost $922.73. Sensitivity analyses confirmed the robustness of these findings, including evaluation across the range of quoted transvaginal ultrasound costs ($43-$300).Conclusion: A simulation of universal screening of asymptomatic low-risk women with a cervicometer with subsequent referral for ultrasound for those with a cervix <25 mm is cost-effective and yields the greatest reduction in preterm births at <34 weeks. A risk simulation trial noted that a cervicometer strategy may be more expensive than a universal transvaginal ultrasound strategy, but both are less expensive than a no screening strategy.

Implementing universal cervical length screening in asymptomatic women with singleton pregnancies: challenges and opportunities

Cervical length (CL) screening has been successfully utilised to identify asymptomatic women, with a singleton pregnancy, at risk of preterm birth (PTB), thereby providing an opportunity to offer interventions that may reduce that risk. Cervical length screening with ultrasound is most effectively performed with a transvaginal approach. Universal cervical length screening, encompassing all singleton pregnancies rather than restricting screening to those considered at increased risk of PTB, is currently not widely used, despite a growing body of evidence in support of its utility for PTB prevention. There are a number of barriers that may prevent or restrict the implementation of a universal CL screening program. These include cost, availability of vaginal progesterone and other treatment options, reluctance of women to undergo transvaginal ultrasound and the perceptions and beliefs of medical practitioners. Given that mid-pregnancy CL measurement is a recognised predictor of spontaneous PTB, that most cases of PTB occur with no prior maternal history and that there are interventions available that may reduce the risk of PTB, we believe there is a clear role for routine CL screening to be adopted as a component of the fetal morphology ultrasound examination. As a strategy to reduce PTB rates, discussion and counselling about PTB prevention and CL screening should be adopted as a core element of prenatal care.

Assessment of a cervicometer compared to transvaginal ultrasound in identifying women with a short cervical length: a multicenter study

BACKGROUND

Preterm birth remains a major cause of neonatal morbidity and mortality worldwide. Short cervical length (CL) as measured by transvaginal ultrasound (TVU) in the second trimester represents the single most predictive risk factor for spontaneous preterm birth. Previous studies have addressed, in part, the limitations of TVU availability by utilizing a cervicometer to screen patients for short cervix, identifying those patients who may not benefit from TVU CL screening. In view of the prior studies indicating that a cervicometer measurement may have a high negative predictive value (NPV) for a sonographically short cervix, we sought to identify the ideal cervicometer threshold value in a prospective, multicenter study.

OBJECTIVE

The primary objective was to determine the cervicometer CL measurement threshold that provides a high NPV for the identification of patients who are highly unlikely to have a TVU CL measurement ≤20 and ≤25 mm and, therefore, may forego TVU.

STUDY DESIGN

This prospective study, executed in 5 US centers, included 401 women ≥18 years of age who provided written informed consent to undergo CL measurement in the mid trimester. All women underwent both cervicometer- and TVU-measured CLs by individuals blinded to results of the other measurement. Both measurements were performed at 17-23 weeks' gestation (visit 1) and repeated at 24-29 weeks' gestation (visit 2). All TVU measurement images were reviewed by a central reader. Test characteristics and receiver operating characteristic curves were created to determine and confirm the optimal cervicometer CL threshold, maximizing the NPV.

RESULTS

In all, 358 subjects were evaluable at visit 1 and 267 at visit 2. At visit 1, the average TVU CL was 38.7 ± 7.6 mm and the average cervicometer CL was 30.3 ± 8.8 mm. Similar measurements were seen at visit 2. Receiver operating characteristic curves were utilized to graphically identify a cervicometer CL threshold of 30 mm that maximized sensitivity while minimizing the false-positive rate. The 30-mm cervicometer CL threshold provided a 98-100% NPV and 0.0 negative likelihood ratio for identification of women who have a low likelihood to have a sonographic short cervix (ie, transvaginal CL ≤20 mm or ≤25 mm). The 17-23 weeks' gestation 30-mm cervicometer CL threshold has 100% sensitivity, 45-46% specificity, and 1.8 and 0.0 positive and negative likelihood ratios to predict sonographic CL ≤20 and ≤25 mm.

CONCLUSION

Cervicometer CL screening successfully identifies women at low risk for short transvaginal CL. Use of a 30-mm threshold by cervicometer CL measurement confers a 98-100% NPV, with high sensitivity and moderate specificity to predict a TVU short CL. Cervicometer measurement of CL may permit almost 50% of women to avoid TVU.