Transvaginal Ultrasound Cervical Length Screening Research Articles

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.

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.

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.

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.

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To compare the mean transvaginal ultrasound (TVU) cervical length (CL) at midtrimester screening for spontaneous preterm birth in asymptomatic monochorionic diamniotic versus dichorionic diamniotic twin pregnanciesThis was a multicenter retrospective cohort study. Study subjects were identified at the time of a routine second trimester fetal ultrasound exam at 18 0/7–23 6/7 weeks gestation. We excluded women that received progesterone, pessary, or cerclage. Distribution of CL was determined and normality was examined. Mean of TVU CL were compared between monochorionic diamniotic and dichorionic diamniotic pregnancies. The relationship of TVU CL with gestational age (GA) at delivery and incidence of spontaneous preterm birth (SPTB) at different TVU CL cut offs were assessed. Incidence of short TVU CL, defined as TVU CL ≤30 mm, was also calculated in the two groups.580 women with diamniotic twin pregnancies underwent TVU CL screening between 18 0/6 and 23 6/7 weeks. 175 (30.2%) were monochorionic diamniotic pregnancies, and 405 (69.8%) were dichorionic pregnancies. The demographic characteristics were similar on both groups. The mean GA at TVU CL was about 20 week in both groups. The mean TVU CL was significantly lower in the monochorionic diamniotic (32.8 ± 10.1) compared to the dichorionic (34.9 ± 8.6) group (MD −2.10 mm, 95% CI −3.91 to −0.29). TVU CL ≤30 mm was 16.6% (29/175) in the monochorionic group, and 11.9% (48/405) in the dichorionic group (aOR 1.48, 95% CI 1.03–2.43). Twins with a monochorionic diamniotic pregnancy had a significantly higher incidence of SPTB (53.1% vs 44.9%; aOR 1.22, 95% CI 1.22–1.79). For any given CL measured between 18 0–7 and 23 6/7 weeks, gestational age at delivery for monochorionic diamniotic pregnancies was about 2 weeks earlier compared to dichorionic pregnancies (MD -2.1 weeks; ANCOVA P < 0.001).Monochorionic diamniotic twin pregnancies had a higher rate of spontaneous preterm birth than dichorionic diamniotic pregnancies. The higher rate of spontaneous preterm delivery in monochorionic pregnancies is associated with lower midtrimester TVU CL when compared to dichorionic pregnancies.

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To compare the mean transvaginal ultrasound (TVU) cervical length (CL) at midtrimester screening for spontaneous preterm birth in asymptomatic monochorionic diamniotic versus dichorionic diamniotic twin pregnanciesThis was a multicenter retrospective cohort study. Study subjects were identified at the time of a routine second trimester fetal ultrasound exam at 18 0/7–23 6/7 weeks gestation. We excluded women that received progesterone, pessary, or cerclage. Distribution of CL was determined and normality was examined. Mean of TVU CL were compared between monochorionic diamniotic and dichorionic diamniotic pregnancies. The relationship of TVU CL with gestational age (GA) at delivery and incidence of spontaneous preterm birth (SPTB) at different TVU CL cut offs were assessed. Incidence of short TVU CL, defined as TVU CL ≤30 mm, was also calculated in the two groups.580 women with diamniotic twin pregnancies underwent TVU CL screening between 18 0/6 and 23 6/7 weeks. 175 (30.2%) were monochorionic diamniotic pregnancies, and 405 (69.8%) were dichorionic pregnancies. The demographic characteristics were similar on both groups. The mean GA at TVU CL was about 20 week in both groups. The mean TVU CL was significantly lower in the monochorionic diamniotic (32.8 ± 10.1) compared to the dichorionic (34.9 ± 8.6) group (MD −2.10 mm, 95% CI −3.91 to −0.29). TVU CL ≤30 mm was 16.6% (29/175) in the monochorionic group, and 11.9% (48/405) in the dichorionic group (aOR 1.48, 95% CI 1.03–2.43). Twins with a monochorionic diamniotic pregnancy had a significantly higher incidence of SPTB (53.1% vs 44.9%; aOR 1.22, 95% CI 1.22–1.79). For any given CL measured between 18 0–7 and 23 6/7 weeks, gestational age at delivery for monochorionic diamniotic pregnancies was about 2 weeks earlier compared to dichorionic pregnancies (MD -2.1 weeks; ANCOVA P < 0.001).Monochorionic diamniotic twin pregnancies had a higher rate of spontaneous preterm birth than dichorionic diamniotic pregnancies. The higher rate of spontaneous preterm delivery in monochorionic pregnancies is associated with lower midtrimester TVU CL when compared to dichorionic pregnancies.

Decrease in the incidence of threatened preterm labor after implementation of transvaginal ultrasound cervical length universal screening

Background It is unknown if universal second-trimester transvaginal ultrasound (TVU) cervical length (CL) screening in asymptomatic women with singleton gestations and no prior spontaneous preterm birth (SPTB) affects the incidence of symptoms of preterm labor (PTL) later in pregnancy. Objective To evaluate the incidence of threatened PTL before and after the implementation of universal second trimester TVU CL screening. Study design This was a retrospective cohort study of all consecutive singleton gestations without prior SPTB presenting to obstetric triage for threatened PTL between 23 0/7 and 33 6/7 week in 2011 (1 January–31 December), and in 2014 (1 January–31 December) at Thomas Jefferson University Hospital (TJU) (Philadelphia, PA). These 2 years were chosen as a new protocol for universal TVU CL screening was started on 1 January 2012. This protocol involved one measurement of TVU CL in all singleton gestations without a prior SPTB at 18 0/7 − 23 6/7 week, the time of the “anatomy” scan. Women with prior SPTB were excluded from this study. The primary outcome included the incidence of threatened PTL, defined as the number of women with singleton gestations without prior SPTB who presented with threatened PTL to our labor and delivery (L&D) triage unit annually, divided by the total number of annual deliveries of women with singleton gestation without prior SPTB. Secondary outcomes were the incidence of PTL, defined as the number of women with singleton gestations without prior SPTB admitted for PTL annually divided by the total number of annual deliveries of women with singleton gestation and without prior SPTB; and length of stay in the hospital. We aimed to compare primary and secondary outcome in the “2011” versus the “2014” group. Results In 2011, there were a total of 1745 deliveries at TJU, of which 1550 (88.8%) were singletons without prior SPTB. In 2014, there were a total of 1924 deliveries at TJU, 1751 (91.0%) were singletons without prior SPTB who were offered universal TVU CL screening. One hundred and seventy-two women with singletons without prior SPTB presented in L&D triage unit in 2011; and 118 women with singletons without prior SPTB presented in L&D triage unit in 2014. There were significant decreases in the incidence of threatened PTL from 11.1% (172/1550) in 2011 to 6.7% (118/1751) in 2014 (p < .001), as well as in the rate of admission for PTL from 2.3% (35/1550) to 1.4% (24/1751), respectively (p = .04). Length of stay was not significantly different between the two groups. Conclusion The introduction of a universal TVU CL screening program in women with singleton gestations without a history of SPTB is associated with a reduction in the frequency of threatened PTL and admission for PTL. Key Message The introduction of a second trimester universal transvaginal ultrasound (TVU) cervical length (CL) screening program in women without a history of spontaneous preterm birth (SPTB) is associated with a reduction in the incidence of threatened preterm labor (PTL) and admission for PTL.

Risk of spontaneous preterm birth in IVF-conceived twin pregnancies

Objective: To compare the mean transvaginal ultrasound (TVU) cervical length (CL) at midtrimester in screening for preterm birth in in vitro (IVF)-conceived twin pregnancies versus spontaneously-conceived twin pregnancies. Methods: This was a retrospective cohort study. Potential study subjects were identified at the time of a routine second trimester fetal ultrasound exam at 18 0/7 to 23 6/7-week gestation. All women with twin diamniotic pregnancies screened with a single TVU CL for this trial were included. Mean TVU CLs were compared between IVF-conceived twin pregnancies and spontaneously-conceived twin pregnancies. The relationship of TVU CL with gestational age at delivery was assessed. Incidence of short TVU CL, defined as TVU CL ≤30 mm, was also calculated in the two groups. The primary outcome was the mean of TVU CL. Distribution of CL was determined and normality was examined in both groups Results: A total of 668 women with diamniotic twin pregnancies who underwent TVU CL screening between 18 0/6 and 23 6/7 weeks were included. 158 (23.7%) were IVF-conceived pregnancies, and 510 (76.3%) were spontaneously-conceived pregnancies. No women received progesterone, pessary, or cerclage for preterm birth prevention during pregnancy. The mean TVU CL was significantly lower in the IVF-conceived group (32.2 ± 10.5 mm) compared to the spontaneously-conceived group (34.1 ± 9.1 mm) (mean difference (MD) − 1.90 mm, 95%CI −3.72 to −0.08). The incidence of TVU CL ≤30 mm was 30.4% in the IVF-conceived group and 21.6% in the spontaneously-conceived group (adjusted odds ratio (aOR) 1.59, 95%CI 1.06–2.37). IVF-conceived twins had a significantly higher risk of spontaneous preterm birth <34 weeks (32.9 versus 21.2%; aOR 1.83, 95% confidence interval (CI) 1.23–2.71) and higher rate of delivery due to spontaneous onset of labor (64.5 versus 54.9%; aOR 1.50, 95%CI 1.03–2.17). For any given TVU CL measured between 18 0–7 and 23 6/7 weeks, gestational age at delivery for IVF-conceived twins was earlier by about 1 week on average compared with spontaneously-conceived twins. Conclusions: The higher rate of spontaneous preterm birth in IVF-conceived twin pregnancies is predicted by lower midtrimester TVU CL, as well as by the lower gestational age at birth per any given CL in the IVF-conceived compared to the spontaneously-conceived twin pregnancies.

Cervical Length Screening in Asymptomatic Women at High Risk and Low Risk for Spontaneous Preterm Birth

Cervical length (CL) screening should be offered to singletons because there are interventions for those with a short CL. A transvaginal ultrasound (TVU) is the "gold standard" for CL. In singletons with prior spontaneous preterm birth, serial TVU CL screening is recommended between 16 and 23 6/7 weeks. Universal TVU CL screening between 18 and 24 weeks may be considered for low-risk singletons with the administration of vaginal progesterone for TVU CL≤20 mm; alternatively, transabdominal ultrasound CL screening may be considered with reflux to TVU CL screening for a transabdominal ultrasound CL<35 mm or inadequate visualization. CL screening is not recommended in multiples.

Current Implementation of Universal Cervical Length Screening for Preterm Birth Prevention in the United States [19

INTRODUCTION: To evaluate the incidence of implementation of universal cervical length (CL) screening for preterm birth (PTB) prevention among institutions with Maternal-Fetal Medicine (MFM) fellowship training in the United States. METHODS: In January 2015, we conducted a national survey of institutions with MFM Fellowship Programs regarding implementation of universal CL screening, defined as CL screening of women with singleton gestations without a prior spontaneous PTB. We also identified whether a transabdominal ultrasound (TAU) or transvaginal ultrasound (TVU) was used for screening. Results were compared by geographical regions. We also assessed if a low obstetrical volume (annual deliveries<3000) affected implementation of TVU CL screening program. RESULTS: We identified 78 MFM fellowship programs, of which 100% responded to the survey. Fifty-three programs (68%) had implemented a CL screening program, with 25 programs (32%) using TVU while the rest (36%) used TAU for CL screening. The Midwest had the highest percent of CL screening (94%), with the highest use of TVU (50%). The South had the lowest percent of CL screening (58%) (OR 0.52 [0.19–1.46]) and the lowest use of TVU (12.5%) (OR 0.22 [0.05–0.78]) compared to rest of the United States. Lower annual obstetrical volume did not affect the likelihood of implementing a program using TVU (7.6%) compared to programs having higher obstetrical volume (24.3%) (OR 0.73 [0.24–2.17]). CONCLUSION/IMPLICATIONS: Universal CL screening has been implemented by over two thirds of institutions with MFM Fellowship Programs. Of these programs, approximately half screen by TAU and half by TVU.

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

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. 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. 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. 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. 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.

Prior Ultrasound-Indicated Cerclage

To evaluate outcomes of women with prior ultrasound-indicated cerclage, who in their subsequent pregnancy were either followed by transvaginal ultrasound cervical length screening or received a planned history-indicated cerclage. Multicenter cohort study of singleton gestations with a prior ultrasound-indicated cerclage performed from 1994 to 2014. We evaluated three pregnancies in the study participants: first pregnancy with prior spontaneous preterm birth at less than 37 weeks of gestation; second pregnancy with ultrasound-indicated cerclage for cervical length 25 mm or less; and the third index pregnancy managed with either transvaginal ultrasound cervical length screening with ultrasound-indicated cerclage for cervical length 25 mm or less or planned history-indicated cerclage. The primary outcome was incidence of spontaneous preterm birth at less than 37 weeks of gestation. We planned a subgroup analysis for women who delivered at less than 32 weeks of gestation compared with 32 weeks of gestation or greater in their prior ultrasound-indicated cerclage pregnancy. Of 102 singleton gestations included, 38 (37.3%) were followed with transvaginal ultrasound cervical length screening and 64 (62.7%) underwent history-indicated cerclage. Of 38 women in the transvaginal ultrasound group, 18 (47.4%) underwent ultrasound-indicated cerclage for cervical length 25 mm or less. After adjusting for confounders, the rate of spontaneous preterm birth at less than 37 weeks of gestation was similar between transvaginal ultrasound cervical length screening and history-indicated cerclage groups (36.8% compared with 43.8%; adjusted odds ratio 0.77, 95% confidence interval 0.47-1.45). Secondary outcomes were also similar in both groups. All women (n=7) who delivered at less than 32 weeks of gestation in their prior pregnancy and subsequently had transvaginal ultrasound screening received ultrasound-indicated cerclage in the index pregnancy compared with only 35.5% of women who delivered at 32 weeks of gestation or greater in their prior pregnancy. Women with prior ultrasound-indicated cerclage have similar outcomes if they receive either transvaginal ultrasound cervical length screening with ultrasound-indicated cerclage for cervical length 25 mm or less or planned history-indicated cerclage in the subsequent pregnancy. Less than 50% of the transvaginal ultrasound cervical length screening group require a repeat ultrasound-indicated cerclage in the subsequent pregnancy. II.

Cost-effectiveness of transvaginal ultrasound cervical length screening in singletons without a prior preterm birth: an update

We sought to reevaluate the cost-effectiveness of universal transvaginal ultrasound (TVU) cervical length (CL) screening in singleton pregnancies without prior spontaneous preterm birth. We developed a decision model to assess costs and effects of universal TVU CL screening at 18-23 weeks' gestation compared to routine care for singleton pregnancies without prior preterm birth. Based on recent data, the model contains the following updates: (1) reduced incidence of CL ≤20 mm at initial screening ultrasound (0.83%), (2) vaginal progesterone supplementation for women with CL ≤20 mm, (3) additional ultrasound(s) for women with CL 21-24.9 mm, and (4) the assumption that vaginal progesterone reduces the rate of preterm birth <34 weeks' gestation by 39% if a short CL is diagnosed. The primary outcome was incremental cost-effectiveness ratio. We assumed a willingness to pay of $100,000 per quality-adjusted life year (QALY) gained. Additional outcomes included incidence of offspring with long-term neurological deficits and neonatal death. Sensitivity analyses were performed to assess the robustness of the results. For every 100,000 women screened, universal TVU CL screening costs $9132 compared to routine care. Screening results in 215 QALYs gained and 10 fewer neonatal deaths or neonates with long-term neurologic deficits per 100,000 women screened. Based on the updated data, universal CL screening in low-risk women remains a cost-effective strategy (incremental cost-effectiveness ratio = $43/QALY), but is not cost saving as previously estimated. Sensitivity analyses reveal that when incidence of TVU CL ≤20 mm is <0.31%, universal TVU CL screening is no longer cost-effective. Additionally, when TVU CL costs >$314, progesterone reduces preterm delivery risk before 34 weeks <19%, or the incidence of a TVU CL 21-24.9 mm is >6.5%, CL screening is also no longer cost-effective. Despite the reduced incidence and efficacy used in this model, universal TVU CL continues to be cost-effective when compared to routine care in singletons without prior preterm birth.

148: Cost-effectiveness of transvaginal ultrasound cervical length screening in singletons without prior preterm birth: an update

148: Cost-effectiveness of transvaginal ultrasound cervical length screening in singletons without prior preterm birth: an update

Is universal cervical length screening indicated in women with prior term birth?

To determine whether universal transvaginal ultrasound (TVU) cervical length (CL) screening is indicated in women with prior term births. We conducted a prospective cohort study from Jan. 1, 2012, to June 30, 2013, of singleton gestations between 18 0/7-23 6/7 weeks undergoing TVU CL screening for prediction of spontaneous preterm birth (sPTB). Women with a prior sPTB, with cerclage, and without delivery data available were excluded. Primary outcomes were the incidence of a CL ≤20 mm, and rates of sPTB <37, <34, and <32 weeks gestation among women with prior term births vs nulliparous women. A total of 1569 women underwent TVU CL screening; 18 women with a prior iatrogenic preterm birth were excluded. Of those screened, 756 (48.7%) had a prior term delivery and 795 (51.3%) were nulliparous. Women with prior term births differed from nulliparous women with respect to age, body mass index, race, smoking status, and prior dilation and curettage. After adjustment for these confounders, there was no statistical difference in the incidence of CL ≤20 mm (0.8 vs 1.4%; adjusted odds ratio, 0.35; 95% confidence interval, 0.12-1.03) among women with prior term births compared with nulliparous women. Rates of sPTB <37, <34, <32 weeks were similar in women with a prior term birth compared with nulliparous women. The overall incidence of sPTB <37 weeks was 3.2% in women with a prior term birth and 5.0% in nulliparous women. When a CL ≤20 mm was identified, 3 of 6 women with prior term birth delivered at <37 weeks compared with 8 of 11 nulliparous women. There were no identified differences between the odds of sPTB between women with a CL ≤20 mm who had a prior term birth compared with nulliparous women. Women with prior term birth have a trend toward a lower incidence of CL ≤20 mm, compared with nulliparous women. Further studies are needed to determine whether women with prior term births should be included or excluded from TVU CL screening.

Prior Ultrasound-Indicated Cerclage

INTRODUCTION: To evaluate pregnancy outcomes of women with a history of ultrasound-indicated cerclage for a short cervix who in subsequent pregnancy either were followed by transvaginal ultrasound cervical length screening or received a history-indicated cerclage. METHODS: Retrospective cohort study was performed from 1993 to 2012 involving women with an index singleton pregnancy and history of ultrasound-indicated cerclage. Prior ultrasound-indicated cerclage was defined as cerclage placed for cervical length less than 25 mm before 24 weeks of gestation in women at high risk for preterm birth. At our institution, women with a history of ultrasound-indicated cerclage were managed in their subsequent pregnancy either by transvaginal ultrasound cervical length screening or by history-indicated cerclage, at the physician's discretion (Fig. 1). In the transvaginal ultrasound cervical length group, if cervical length became less than 25 mm before 24 weeks of gestation, an ultrasound-indicated cerclage was performed. In the history-indicated cerclage group, history-indicated cerclage was placed at approximately 12–15 weeks of gestation. Primary outcome was spontaneous preterm birth at less than 35 weeks (Table 1).RESULTS: Twenty-eight women met the inclusion criteria. Of these 28 women, 13 were in the transvaginal ultrasound cervical length group and 15 in the history-indicated cerclage group. Demographics were similar in both the groups, except earliest gestational age of prior spontaneous preterm birth (Table 1). The odds of spontaneous preterm birth at less than 35 weeks of gestation for the two groups was similar (odds ratio 0.54, 95% confidence interval 0.04–6.77). Secondary outcomes were also similar in two groups except birth weight (Table 1). CONCLUSION: Women with prior ultrasound-indicated cerclage have similar outcomes if they are managed in the next pregnancy by either transvaginal ultrasound cervical length screening and ultrasound-indicated cerclage placement if cervical length is less than 25 mm before 24 weeks of gestation or by history-indicated cerclage. Our study results are limited by small sample size. There are currently no other studies evaluating this clinical dilemma.

Does Second-Trimester Cervical Length Predict Prolonged Pregnancy?

INTRODUCTION: Third-trimester cervical length has been correlated with delivery timing. Given that second-trimester ultrasonography is routine practice, we sought to evaluate whether second-trimester cervical length is associated with prolonged pregnancy. METHODS: We performed a secondary analysis of data involving women with singleton gestations between 18 0/7 and 23 6/7 weeks of gestation undergoing universal transvaginal ultrasound cervical length screening for preterm birth prediction from January 1, 2012, to December 30, 2012. Women with prior spontaneous preterm births, cerclage in situ, and deliveries at outside institutions were excluded. Women were included if they had spontaneous labor, rupture of membranes, or reached 41 weeks of gestation. The primary outcome was the incidence of prolonged pregnancy (41 0/7 weeks of gestation and beyond). A receiver operating characteristic curve was calculated to identify the threshold cervical length predictive of a prolonged pregnancy. Statistical analysis was performed using SPSS 20.0. RESULTS: Of the 660 women who met inclusion criteria, 108 (16.4%) had prolonged pregnancies. Women with prolonged pregnancies had a higher mean body mass index and were less likely to have had a prior vaginal delivery compared with women without prolonged pregnancies. Women with prolonged pregnancies also had higher mean cervical length (43 compared with 42 mm, P=.057) and a higher incidence of cervical length greater than 30 mm (100% compared with 96%, P=.035; Table 1). The receiver operating characteristic curve demonstrated an area under the curve of 0.542 (standard error 0.027; Figure 1); no optimal cervical length was predictive of a prolonged pregnancy.CONCLUSIONS: Second-trimester cervical length is not predictive of prolonged pregnancy.

Cervical Length Screening With Ultrasound-Indicated Cerclage Compared With History-Indicated Cerclage for Prevention of Preterm Birth

To compare pregnancy outcomes in singleton gestations with prior preterm birth that were managed either by cervical length screening with cerclage for short cervical length or history-indicated cerclage. DATA SOURCES AND METHODS OF STUDY SELECTION: Medline, Scopus, and the Cochrane Central Register of Controlled Trials were searched for the terms "cerclage," "randomized trial," and "clinical trial" from 1966 until January 2011. No restrictions for language were applied. We performed a meta-analysis of randomized trials of singleton gestations with prior preterm birth. Management by policy of transvaginal ultrasonography cervical length screening with cerclage placement for cervical shortening was compared with history-indicated cerclage. Four randomized trials met inclusion criteria, including 467 women. In women with a singleton gestation and prior preterm birth, cervical length screening with cerclage for short cervical length was associated with similar incidences of preterm birth before 37 weeks (31% compared with 32%, relative risk 0.97, 95% confidence interval [CI] 0.73-1.29), preterm birth before 34 weeks (17% compared with 23%, relative risk 0.76, 95% CI 0.48-1.20), and perinatal mortality (5% compared with 3%, relative risk 1.77, 95% CI 0.58-5.35) compared with history-indicated cerclage. In the transvaginal ultrasound cervical length screening group, 42% developed a short cervical length and received cerclage. Singleton gestations in women with prior preterm birth may be monitored safely with a policy of transvaginal ultrasound cervical length screening as compared with a policy of routine history-indicated cerclage. Cerclage can be reserved for the minority of women who develop a short cervical length.

Cervical assessment by ultrasound for preventing preterm delivery.

Measurement of cervical length (CL) by transvaginal ultrasound (TVU) is predictive of preterm birth (PTB). It is unclear if this screening test is effective for prevention of PTB. To assess the effectiveness of antenatal management based on TVU CL screening for preventing PTB. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (September 2008), MEDLINE (1966 to September 2008), and reviewed the reference list of all articles. Published and unpublished randomized controlled trials including pregnant women between the gestational ages of 14 to 32 weeks screened with TVU CL for risk of PTB. This review focuses exclusively on studies based on knowledge versus no knowledge of TVU CL results. All potential studies identified as in the search were assessed for inclusion by three independent review authors. We also analyzed studies for quality measures and extracted data. Of 12 trials identified, five were eligible for inclusion (n = 507). Three included singleton gestations with preterm labor (PTL); one included singleton gestations with preterm prelabour rupture of membranes (PPROM); and one included twin gestations without or with PTL.In the three trials of singleton gestations with PTL, 290 women were randomized; 147 to knowledge and 143 to no knowledge of TVU CL. Knowledge of TVU CL results was associated with a non-significant decrease in PTB at less than 37 weeks (22.3% versus 34.7%, respectively; risk ratio 0.59, 95% confidence interval (CI) 0.26 to 1.32). Delivery occurred at a later gestational age in the knowledge versus no knowlege groups (mean difference 0.64 weeks (CI 0.03 to 1.25)). All other outcomes for which there were available data (PTB at less than 34 or 28 weeks; birthweight less than 2500 grams; perinatal death; maternal hospitalization; tocolysis; and steroids for fetal lung maturity) were similar in the two groups.The trial of singleton gestations with PPROM (n = 92) evaluated as its primary outcome safety of TVU CL in this population, and not its effect on management. The incidence of maternal and neonatal infections was similar in the TVU CL and no TVU CL groups.In the trial of twin gestations with or without PTL (n = 125), PTB at less than 36, 34, or 30 weeks, gestational age at delivery, and other perinatal and maternal outcomes were similar in the TVU CL and the no TVU CL groups. Life table analysis revealed significantly less preterm birth at less than 35 weeks in the TVU CL group compared to the no TVU CL group (P = 0.02). Currently there is insufficient evidence to recommend routine screening of asymptomatic or symptomatic pregnant women with TVU CL. Since there is a non-significant association between knowledge of TVU CL results and a lower incidence of PTB at less than 37 weeks in symptomatic women, we encourage further research. Future studies should look at specific populations separately (eg singleton versus twins; symptoms of PTL or no such symptoms), 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 CL results, so that it can be easily evaluated and replicated.