Dynamic cervical change: is real-time sonographic cervical shortening predictive of preterm delivery in patients with symptoms of preterm labor?

Is real-time dynamic cervical shortening predictive of preterm birth?- A case control study

OBJECTIVES

We aimed to assess the risk of preterm birth in those with real-time dynamic cervical shortening.

METHODS

A retrospective matched case-control study. The study group comprised all women with dynamic cervical shortening (≥4 mm) noted from 24 to 34 weeks of gestation during 2010-2017 at a university hospital. Two control groups of women were established by matching the minimal and maximal cervical length measured, as well as age, parity, gestational age, history of spontaneous preterm birth, symptoms of preterm labor, and delivery year.

RESULTS

Data from 339 women were analyzed, 113 with dynamic cervical shortening comprised the study group, and two groups with 113 women each, matched for the minimal and maximal cervical lengths measured comprised the control groups. Rates of spontaneous preterm birth rate at <37 weeks (32.7% vs. 15.9%; OR [95% CI]: 2.60 (1.36, 4.87), p = .004) and <35 weeks (15.9% vs. 5.3%; OR [95% CI]: 3.38 (1.29, 8.86), p = .013) were significantly higher among those with dynamic cervix than among the control group matched for the maximal cervical length, and comparable to the control group matched for the minimal cervical length. The negative predictive values of cervical length for preterm birth occurrence at various cutoff values were lower in those with dynamic cervix.

CONCLUSIONS

The minimal cervical length measured should be used to guide patient management when dynamic cervix is noted. In the setting of dynamic cervical change, the value of cervical length as a negative predictor of preterm birth is limited.

Serial Change in Cervical Length for the Prediction of Emergency Cesarean Section in Placenta Previa

Purpose

To evaluate whether serial change in cervical length (CL) over time can be a predictor for emergency cesarean section (CS) in patients with placenta previa.

Methods

This was a retrospective cohort study of patients with placenta previa between January 2010 and November 2014. All women were offered serial measurement of CL by transvaginal ultrasound at 19 to 23 weeks (CL1), 24 to 28 weeks (CL2), 29 to 31 weeks (CL3), and 32 to 34 weeks (CL4). We compared clinical characteristics, serial change in CL, and outcomes between the emergency CS group (case group) and elective CS group (control group). The predictive value of change in CL for emergency CS was evaluated.

Results

A total of 93 women were evaluated; 31 had emergency CS due to massive vaginal bleeding. CL tended to decrease with advancing gestational age in each group. Until 29–31 weeks, CL showed no significant differences between the two groups, but after that, CL in the emergency CS group decreased abruptly, even though CL in the elective CS group continued to gradually decrease. On multivariate analysis to determine risk factors, only admissions for bleeding (odds ratio, 34.710; 95% CI, 5.239–229.973) and change in CL (odds ratio, 3.522; 95% CI, 1.210–10.253) were significantly associated with emergency CS. Analysis of the receiver operating characteristic curve showed that change in CL could be the predictor of emergency CS (area under the curve 0.734, p < 0.001), with optimal cutoff for predicting emergency cesarean delivery of 6.0 mm.

Conclusions

Previous admission for vaginal bleeding and change in CL are independent predictors of emergency CS in placenta previa. Women with change in CL more than 6 mm between the second and third trimester are at high risk of emergency CS in placenta previa. Single measurements of short CL at the second or third trimester do not seem to predict emergency CS.

Cervilenz assessment of cervical length compared to fetal fibronectin in the prediction of preterm delivery in women with threatened preterm labor

OBJECTIVE

To determine whether cervical length (CL) measured by the Cervilenz™ measuring device is an effective screening tool for the prediction of preterm delivery (PTD) compared to fetal fibronectin (fFN).

METHODS

We evaluated fFN and CL among women who enrolled into a randomized control trial (RCT) comparing management algorithms for threatened preterm labor between 24 and 34 weeks' gestation. In all subjects, fFN was collected, with CL determined in blinded fashion. The sensitivity, specificity, and positive and negative predictive values (NPV) for fFN or Cervilenz in prediction of PTD within 7 days or prior to 37 weeks were determined.

RESULTS

Fifty-two subjects were evaluated. CL <30 mm correlated with PTD <7 days (r = 0.31, p = 0.04) and fFN positivity (r = 0.43, p = 0.006). CL <30 mm and fFN had excellent NPV for PTD <7 days (97.1 vs. 97.3%), and the area under the receiver operator characteristic curves were similar for prediction of PTD <7 days (76.6 vs. 75.2%, p = 0.71) or <37 weeks (56.7 vs. 55.2%, p = 0.71).

CONCLUSIONS

Measurement of CL with Cervilenz appears to be equivalent to fFN in screening symptomatic women for PTD within 7 days or prior to 37 weeks. Given cost and turnaround time with fFN testing, Cervilenz represents a promising new tool for real time, clinically useful results in the management of women with threatened preterm labor.

Is dynamic cervical shortening during symptomatic contractions predictive of preterm delivery in patients with a normal baseline cervical length?

OBJECTIVE

The purpose of this study was to determine whether dynamic cervical change in symptomatic patients with a normal baseline cervical length (CL; >or=30 mm) is predictive of preterm delivery (PTD).

METHODS

A prospective observational study was performed in 120 symptomatic patients between 23 and 34 weeks' gestation. Patients underwent standardized CL sonography with contraction monitoring, and CL measurements were recorded each minute for approximately 10 minutes. Initial and minimum CLs as well as the presence of dynamic change were assessed for prediction of PTD.

RESULTS

Forty-seven patients (39.2%) had dynamic cervical change and delivered at a mean gestational age +/- SD of 37.1 +/- 2.7 weeks compared to 38.7 +/- 1.5 weeks for those without dynamic change (P < .01). A larger proportion of those with dynamic change delivered before 37 weeks (43% versus 15%; P < .01) and before 35 weeks (19% versus 0%; P < .01). Multivariable logistic regression analysis showed that dynamic cervical change was predictive of PTD, but not independently of the minimum CL. Statistical analyses were completed using the Student t test, chi(2) test, Fisher exact test, Wilcoxon rank sum test. and logistic regression as appropriate.

CONCLUSIONS

Although symptomatic patients with a normal baseline CL who have dynamic shortening generally deliver at term, they appear to be at increased risk of PTD.

The value of serial cervical length measurements for the prediction of threatened preterm labour

OBJECTIVES

To assess the predictive performance of cervical length measurement at presentation and 24h later in women with symptoms of preterm labour.

STUDY DESIGN

Cervical length was measured transvaginally at presentation and 24 hours later in 122 women presenting with threatened preterm labour between 23 and 33+6 gestational weeks.

RESULTS

Six women delivered within 1 week of presentation. The sensitivity and specificity of a cervical length <15 mm at admission for delivery within one week was 83.3 and 95.8%, respectively. A reduction of >20% in cervical length 24h after admission predicted 50% of preterm deliveries within 1 week, with a specificity of 92.7%; in combination with cervical length at presentation it did not improve the prediction. The same was observed for birth before 32 weeks (N=9) and birth before 35 weeks (N=15).

CONCLUSIONS

Women with threatened preterm labour and a cervical length of <15 mm at presentation are at high risk of delivering preterm. Cervical change in the following 24 hours does not seem to improve the prediction.

Transvaginal cervical length measurement for prediction of preterm birth in women with threatened preterm labor: a meta-analysis

OBJECTIVES

To integrate data on the performance of cervical length measurement for the prediction of preterm birth in symptomatic women.

METHODS

MEDLINE, SCOPUS and manual searches for studies with transvaginal ultrasound measurement of the cervical length in symptomatic women were carried out. Random effects models were used for data integration, and pooled test estimates of sensitivity, specificity, and positive and negative likelihood ratios (LR+ and LR-) were calculated along with their 95% CIs.

RESULTS

Twenty-eight studies fulfilled the selection criteria. For birth within 1 week from presentation, the pooled sensitivity, specificity, LR+ and LR- of cervical length < 15 mm were 59.9% (95% CI, 52.7-66.8%), 90.5% (95% CI, 89.0-91.9%), 5.71 (95% CI, 3.77-8.65) and 0.51 (95% CI, 0.33-0.80), respectively. The same estimates for studies with presentation at or before 34 + 0 weeks were 71.0% (95% CI, 60.6-79.9%), 89.8% (95% CI, 87.4-91.9%), 5.19 (95% CI, 2.29-11.74) and 0.38 (95% CI, 0.11-1.34), respectively. For prediction of birth before 34 weeks, the pooled sensitivity, specificity, LR+ and LR- of cervical length < 15 mm were 46.2% (95% CI, 34.8-57.8%), 93.7% (95% CI, 90.7-96.0%), 4.31 (95% CI, 2.73-6.82) and 0.63 (95% CI, 0.38-1.04), respectively. There was considerable heterogeneity across studies in most estimates.

CONCLUSIONS

Measurement of cervical length in symptomatic women can detect a significant proportion of those who will deliver within 1 week and help to rationalize their management. The considerable heterogeneity across studies may be indicative of methodological flaws, which either were not reported at all or were under-reported.

Diagnosis of early preterm labour

While preterm contractions occur almost as often extremely preterm as they do closer to term, birth due to spontaneous preterm labour before 27 weeks of gestation is rare, accounting for 0.05-0.7% of all births in different populations. Although the likelihood that uterine contractions before 27 weeks of gestation represent true preterm labour is low, the risk of adverse outcome in such cases is high. A correct diagnosis is important, and a useful diagnostic test should have a high sensitivity. In most reports, only 30-40% of women hospitalised for spontaneous preterm labour experience a preterm birth, suggesting a low positive predictive value of clinical diagnosis based on uterine contractions and vaginal examination. Transvaginal ultrasonographic scanning (TVUSS) of cervical length has shown a high sensitivity for preterm birth, 90-100% for preterm birth before 33-35 weeks, using a liberal cutoff at 30 mm. Assessment of cervicovaginal fetal fibronectin (FFN) levels has shown a sensitivity of about 80%. Adding FFN assessment to TVUSS might contribute insignificantly to the prediction of preterm birth. In a retrospective study of 147 women with spontaneous preterm labour and intact membranes before 27 weeks in our department, 61% of hospitalised women and 77% of women receiving tocolytic infusion therapy delivered before 32 weeks. Among 66 singleton pregnancies delivered before 32 weeks, at admission, 94% either had an effaced cervix or cervix with >/=2 cm dilation (74%), vaginal bleeding (61%) or serum C-reactive protein level >20 mg/l (40%), whereas one of these findings only was present in 18% of women who delivered at later gestations. Among 132 women with symptoms of spontaneous preterm contractions before 27 weeks not admitted for hospital care, only 2 (1.5%) delivered before 32 weeks, not significantly higher than for all other women (0.6%). Although TVUSS may be useful when the diagnosis of spontaneous preterm labour is in doubt, the main predicament in early spontaneous preterm labour may not be to predict preterm birth but to prevent it, since many women appear in advanced labour or with manifest chorioamnionitis.