Cerclage for Short Cervix on Ultrasonography

Prevention of preterm delivery in twin pregnancy

The incidence of twin gestation has increased markedly over the past decades, mostly because of increased use of assisted reproductive technologies. Twin pregnancies are at increased risk of preterm delivery (i.e. birth before 37 weeks of gestation). Multiple gestations therefore account for 2-3% of all pregnancies but constitute at least 10% of cases of preterm delivery. Complications from preterm birth are not limited to the neonatal period, such as in retinopathy of prematurity, intraventricular haemorrhage, necrotising enterocolitis, respiratory disorder and sepsis; they can also constitute sequelae such as abnormal neurophysiological development in early childhood and underachievement in school. Several treatment modalities have been proposed in singleton high-risk pregnancies. The mechanism of initiating labour may, however, be different in singleton and twin gestations. Therefore, it is mandatory to evaluate the proposed treatments in randomised trials of multiple gestations. In this chapter, we describe the results of trials to prevent preterm delivery in twin pregnancies.

Do placental histologic findings of chorion-decidual hemorrhage or inflammation in spontaneous preterm birth influence outcomes in the subsequent pregnancy?

INTRODUCTION

Spontaneous preterm birth (SPTB) is the common endpoint of different underlying etiologies, including chorion-decidual bleeding and inflammation. However, specific histologic findings from a prior pregnancy do not always inform clinical management in subsequent pregnancies secondary to few prior studies having evaluated the relationship between prior pregnancy pathology and subsequent outcomes in patients with SPTB.

METHODS

Included subjects had: 1) a SPTB with available placental pathology and 2) a subsequent consecutive delivery at >20 weeks gestational age at our institution. For included subjects archived placenta and membrane paraffin blocks from the index SPTB were cut, stained with Prussian Blue and evaluated by a perinatal pathologist for the presence of hemosiderin. The association between histologic findings and subsequent pregnancy outcomes were evaluated through logistic and linear regression.

RESULTS

A total of 131 subjects were included, of whom 39.7% had a recurrent SPTB. Funisitis at the time of preterm delivery significantly increased the risk of early (<34 weeks) recurrent preterm birth (OR 3.38, p = 0.016), though this may have been confounded by gestational age at delivery. Several histologic features were significantly associated with reductions in birth weight in the subsequent pregnancies, even if they did not increase the risk of recurrent preterm birth.

DISCUSSION

The presence of chorion-decidual bleeding or inflammation in a prior pregnancy can signal an increased risk in a future pregnancy beyond the recurrent risk of SPTB itself.

CONCLUSIONS

Placental histologic findings after SPTB maybe associated with differences in birth weight in a subsequent pregnancy.

Cervical pessaries for prevention of spontaneous preterm birth: past, present and future

This Review describes the rationale for the use of cervical pessaries to prevent spontaneous preterm birth and their gradual introduction into clinical practice, discusses technical aspects of the more commonly used designs and provides guidance for their use and future evaluation. Possible advantages of cervical pessaries include the easy, 'one-off' application, good side-effect profile, good patient tolerance and relatively low cost compared with current alternatives. Use of transvaginal sonography to assess cervical length in the second trimester allows much better selection of patients who may benefit from the use of a cervical pessary, but future clinical trials are needed to establish clearly the role of pessaries as a preterm birth prevention strategy worldwide.

Transvaginal cervical cerclage: evidence for perioperative management strategies

The objective was to review the evidence supporting various perioperative technical and management strategies for transvaginal cervical cerclage. We performed MEDLINE, PubMed, EMBASE, and COCHRANE searches with the terms, cerclage, cervical cerclage, cervical insufficiency, and randomized trials, plus each technical aspect (eg, suture, amniocentesis, etc) considered. The search spanned 1966 through September 2012 and was not restricted by language. Each retrieved manuscript was carefully evaluated, and any pertinent references from the reports were also obtained and reviewed. All randomized trials covering surgical and selected perioperative, nonsurgical aspects of cerclage were included in the review. The evidence was assessed separately for history-, ultrasound-, and physical examination-indicated cerclage. Evidence levels according to the new method outlined by the US Preventive Services Task Force were assigned based on the evidence. There are no grade A high-certainty recommendations regarding technical aspects of transvaginal cervical cerclage. Grade B moderate-certainty recommendations include performing a fetal ultrasound before cerclage to ensure fetal viability, confirm gestational age, and assess fetal anatomy to rule out clinically significant structural abnormalities; administering spinal, and not general, anesthesia; performing a McDonald cerclage, with 1 stitch, placed as high as possible; and outpatient setting. Unfortunately, no other recommendations can be made regarding the other technical aspects of cerclage.

What is predictive of preterm delivery in the first trimester: isthmus or cervical length?

OBJECTIVE

This study aims to evaluate the utility of first trimester cervical ultrasonography in predicting preterm delivery by separate analysis of measurements of cervical and isthmus length.

METHODS

This is a cohort study based on data collected prospectively on singletons between 1 July 2011 and 1 February 2013. Mean cervical, isthmus and cervico-isthmic complex length were measured for deliveries before and after 37 weeks.

RESULTS

A total of 1494 pregnancies were analysed, including 51 cases of spontaneous preterm delivery (3.4%). The cervico-isthmic complex in the first trimester was significantly shorter in patients who delivered before term (43.8 mm vs 47.5 mm, p = 0.04). This difference is related to differences in length at the isthmus (10.7 mm vs 14.1 mm, p = 0.005) rather than at the cervix proper (34.5 mm vs 35.0 mm, p = 0.56).

CONCLUSIONS

Measurement of the cervico-isthmic complex enables detection of a number of patients who will go on to deliver before term. Further studies are necessary to confirm that isthmic length and not cervical length is predictive of preterm delivery.

Cervical pessary for preventing preterm birth

BACKGROUND

Preterm birth is a major health problem and contributes to more than 50% of the overall perinatal mortality. Preterm birth has multiple risk factors including cervical incompetence and multiple pregnancy. Different management strategies have been tried to prevent preterm birth, including cervical cerclage. Cervical cerclage is an invasive technique that needs anaesthesia and may be associated with complications. Moreover, there is still controversy regarding the efficacy and the group of patients that could benefit from this operation. Cervical pessary has been tried as a simple, non-invasive alternative that might replace the above invasive cervical stitch operation to prevent preterm birth.

OBJECTIVES

To evaluate the efficacy of cervical pessary for the prevention of preterm birth in women with risk factors for cervical incompetence.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (1 September 2012), Current Controlled Trials and the Australian New Zealand Clinical Trials Registry (1 September 2012).

SELECTION CRITERIA

We selected all published and unpublished randomised clinical trials comparing the use of cervical pessary with cervical cerclage or expectant management for prevention of preterm birth. We did not include quasi-randomised trials. Cluster-randomised or cross-over trials were not eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion.

MAIN RESULTS

The review included one randomised controlled trial. The study included 385 pregnant women with a short cervix of 25 mm or less who were between 18 to 22 weeks of pregnancy. The use of cervical pessary (192 women) was associated with a statistically significantly decrease in the incidence of spontaneous preterm birth less than 37 weeks' gestation compared with expectant management (22% versus 59 %; respectively, risk ratio (RR) 0.36, 95% confidence interval (CI) 0.27 to 0.49). Spontaneous preterm birth before 34 weeks was statistically significantly reduced in the pessary group (6% and 27% respectively, RR 0.24; 95% CI 0.13 to 0.43). Mean gestational age at delivery was 37.7 + 2 weeks in the pessary group and 34.9 + 4 weeks in the expectant group. Women in the pessary group used less tocolytics (RR 0.63; 95% CI 0.50 to 0.81) and corticosteroids (RR 0.66; 95% CI 0.54 to 0.81) than the expectant group. Vaginal discharge was more common in the pessary group (RR 2.18; 95% CI 1.87 to 2.54). Among the pessary group, 27 women needed pessary repositioning without removal and there was one case of pessary removal. Ninety-five per cent of women in the pessary group would recommend this intervention to other people. Neonatal paediatric care admission was reduced in the pessary group in comparison to the expectant group (RR 0.17; 95% CI 0.07 to 0.42).

AUTHORS' CONCLUSIONS

The review included only one well-designed randomised clinical trial that showed beneficial effect of cervical pessary in reducing preterm birth in women with a short cervix. There is a need for more trials in different settings (developed and developing countries), and with different risk factors including multiple pregnancy.

Assessment of cervical length by transvaginal ultrasonography to predict preterm delivery in twin pregnancy

OBJECTIVE

In singleton pregnancy, short cervix is associated with the risk of spontaneous preterm delivery (SPD). On the other hand, twin pregnancy increases rate of preterm delivery, so this study was designed to evaluate the transvaginal sonographic (TVS) measurement of cervical length (CL) to predict preterm birth in twin pregnancy.

METHODS

This prospective cohort study was performed on 80 twin pregnant women whom the length and funneling of their cervix were evaluated between 22-24 gestational weeks by (TVS). They referred to us at the early signs of labor. Then the gestational age at delivery was recorded. The Fisher exact test and the odds-ratio was used to determine the association between CL and SPD.

RESULTS

Thirty-four (42.5%) women had SPD. Cervical funneling happened in 7.5% of cases and SPD occurred in all women with funneling. There was a significant correlation between CL ≤ 30 mm and SPD (66.7% versus 35.5%, p = 0.029) Also, the risk of SPD was enhanced 3.6 times with CL ≤ 30 mm, CI 95% (1.1-11).

CONCLUSION

We recommend TVS for assessment of CL between 22-24 weeks for prediction of SPD in twin pregnancy.

The use of cervical length and change in cervical length for prediction of spontaneous preterm birth in asymptomatic twin pregnancies

OBJECTIVE

To assess the association between cervical length (CL) and change of CL over two measurements and preterm birth (PTB) at <32 weeks in asymptomatic twin pregnancies.

STUDY DESIGN

This study was undertaken in the multiple pregnancy antenatal clinic at the Security Forces Hospital (SFH), a tertiary care hospital in Riyadh, Saudi Arabia, between November 2005 and October 2010. This study involved 420 women with asymptomatic twin gestations, but only 209 unselected patients completed the study and met the inclusion criteria. All patients had a CL measurement by transvaginal ultrasound at 20-23 weeks, and a second CL measurement was done within 3-5 weeks of the initial measurement. Patients were classified into two groups, group A with significant shortening of CL, and group B without significant shortening of CL. Comparisons between the groups were performed using a chi-square test or a Fisher exact test for categorical variables, whereas Student's t-test or Wilcoxon's rank-sum test was used for continuous variables. We employed ROC curves to compare the diagnostic accuracy of actual cervical length and percent change in cervical length in predicting preterm birth events. All analyses were performed using the SAS/STAT software.

RESULTS

There were 35 (16.7%) patients whose CL shortened by ≥25% (group A), and 174 (83.3%) whose CLs either did not shorten or shortened by <25% (group B). Preterm birth at <28, <30, <32, and <34 weeks gestation was higher in group A than in group B even if the CL was >25mm. The use of CL shortening was superior, but not statistically significantly, to the use of CL for the prediction of PTB at <32 (P=0.0524) and <34 weeks (P=0.281), but CL was preferred for the prediction of PTB at <28 (P=0.037) and <30 weeks (P=0.0457).

CONCLUSION

The test of two CL measurements, the first between 20 and 23 weeks gestation and another CL measurement 3-5 weeks later, with a difference of ≥25%, is a good predictor for preterm birth in asymptomatic twin pregnancies, even if the CL is >25mm.

Comparison of the mechanisms responsible for cervical remodeling in preterm and term labor

Understanding the mechanisms of term and preterm cervical remodeling is essential to prevent prematurity. Is preterm cervical remodeling caused by the same mechanisms that cause cervical remodeling at term, and are these changes accelerated in time? This question has been pondered by obstetricians seeking strategies to prevent preterm labor for many years. Mice represent an informative model of preterm birth. Thus, in this review we discuss the recent findings from mouse models that identify and characterize the initiators and cellular effectors of cervical remodeling at term and preterm labor/delivery. These studies suggest that similarities and differences exist between term and preterm cervical remodeling. Complement is an initiator or mediator in preterm labor/delivery, but is not involved in the physiological process that leads to term delivery. Therefore, complememt constitutes a specific and selective target for potentially preventing preterm delivery, thus improving neonatal health.

Prevention of preterm delivery by 17 alpha-hydroxyprogesterone caproate in asymptomatic twin pregnancies with a short cervix: a randomized controlled trial

OBJECTIVE

The objective of the study was to evaluate the use of 17 alpha-hydroxyprogesterone caproate (17P) to reduce preterm delivery in women with a twin pregnancy and short cervix.

STUDY DESIGN

This open-label, multicenter, randomized controlled trial included women with a twin pregnancy between 24(+0) and 31(+6) weeks of gestation who were asymptomatic and had a cervical length of 25 mm or less measured by routine transvaginal ultrasound. Women were randomized to receive (or not) 500 mg of intramuscular 17P, repeated twice weekly until 36 weeks or preterm delivery. The primary outcome was time from randomization to delivery. Analysis was performed according to the intent-to-treat principle.

RESULTS

The 17P and control groups did not differ significantly for median [interquartile range] time to delivery: 45 (26-62) and 51 (36-66) days, respectively. However, treatment with 17P was associated with a significant increase in the rate of preterm delivery before 32 weeks.

CONCLUSION

Twice-weekly injections of 17P did not prolong pregnancy significantly in asymptomatic women with a twin pregnancy and short cervix.

Vaginal progesterone vs. cervical cerclage for the prevention of preterm birth in women with a sonographic short cervix, previous preterm birth, and singleton gestation: a systematic review and indirect comparison metaanalysis

OBJECTIVE

No randomized controlled trial has compared vaginal progesterone and cervical cerclage directly for the prevention of preterm birth in women with a sonographic short cervix in the mid trimester, singleton gestation, and previous spontaneous preterm birth. We performed an indirect comparison of vaginal progesterone vs cerclage using placebo/no cerclage as the common comparator.

STUDY DESIGN

Adjusted indirect metaanalysis of randomized controlled trials.

RESULTS

Four studies that evaluated vaginal progesterone vs placebo (158 patients) and 5 studies that evaluated cerclage vs no cerclage (504 patients) were included. Both interventions were associated with a statistically significant reduction in the risk of preterm birth at <32 weeks of gestation and composite perinatal morbidity and mortality compared with placebo/no cerclage. Adjusted indirect metaanalyses did not show statistically significant differences between vaginal progesterone and cerclage in the reduction of preterm birth or adverse perinatal outcomes.

CONCLUSION

Based on state-of-the-art methods for indirect comparisons, either vaginal progesterone or cerclage are equally efficacious in the prevention of preterm birth in women with a sonographic short cervix in the mid trimester, singleton gestation, and previous preterm birth. Selection of the optimal treatment needs to consider adverse events, cost and patient/clinician preferences.

Silk-based injectable biomaterial as an alternative to cervical cerclage: an in vitro study

OBJECTIVE

New therapies to prevent preterm birth are needed. Our objective was to study an injectable biomaterial for human cervical tissue as an alternative to cervical cerclage.

STUDY DESIGN

Human cervical tissue specimens were obtained from premenopausal gynecological hysterectomies for benign indications. A 3-part biomaterial was formulated, consisting of silk protein solution blended with a 2-part polyethylene glycol gelation system. The solutions were injected into cervical tissue and the tissue was evaluated for mechanical properties, swelling, cytocompatibility, and histology.

RESULTS

The stiffness of cervical tissue more than doubled after injection (P = .02). Swelling properties of injected tissue were no different than native tissue controls. Cervical fibroblasts remained viable for at least 48 hours when cultured on the biomaterial.

CONCLUSIONS

We report a silk-based, biocompatible, injectable biomaterial that increased the stiffness of cervical tissue compared to uninjected controls. Animal studies are needed to assess this biomaterial in vivo.

Limited relationship between cervico-vaginal fluid cytokine profiles and cervical shortening in women at high risk of spontaneous preterm birth

Objective

To determine the relationship between high vaginal pro-inflammatory cytokines and cervical shortening in women at high risk of spontaneous preterm labor and to assess the influence of cervical cerclage and vaginal progesterone on this relationship.

Methods

This prospective longitudinal observational study assessed 112 women with at least one previous preterm delivery between 16 and 34 weeks’ gestation. Transvaginal cervical length was measured and cervico-vaginal fluid sampled every two weeks until 28 weeks. If the cervix shortened (<25 mm) before 24 weeks’ gestation, women (cases) were randomly assigned to cerclage or progesterone and sampled weekly. Cytokine concentrations were measured in a subset of cervico-vaginal fluid samples (n = 477 from 78 women) by 11-plex fluid-phase immunoassay.

Results

All 11 inflammatory cytokines investigated were detected in cervico-vaginal fluid from women at high risk of preterm birth, irrespective of later cervical shortening. At less than 24 weeks’ gestation and prior to intervention, women destined to develop a short cervix (n = 36) exhibited higher cervico-vaginal concentrations than controls (n = 42) of granulocyte-macrophage colony-stimulating factor [(GM-CSF) 16.2 fold increase, confidence interval (CI) 1.8–147; p = 0.01] and monocyte chemotactic protein-1 [(MCP-1) 4.8, CI 1.0–23.0; p = 0.05]. Other cytokines were similar between cases and controls. Progesterone treatment did not suppress cytokine concentrations. Interleukin (IL)-6, IL-8, granulocyte colony-stimulating factor (G-CSF), interferon (IFN)-γ and tumour necrosis factor (TNF)-α concentrations were higher following randomization to cerclage versus progesterone (p<0.05). Cerclage, but not progesterone treatment, was followed by a significant increase in cervical length [mean 11.4 mm, CI 5.0–17.7; p<0.001].

Conclusions

Although GM-CSF and MCP-1 cervico-vaginal fluid concentrations were raised, the majority of cervico-vaginal cytokines did not increase in association with cervical shortening. Progesterone treatment showed no significant anti-inflammation action on cytokine concentrations. Cerclage insertion was associated with an increase in the majority of inflammatory markers and cervical length.

Laparoscopic cervicoisthmic cerclage: technique and systematic review of the literature

BACKGROUND AND AIMS

To report on and review the outcome after laparoscopic cervicoisthmic cerclage (LCC) and robotic-assisted laparoscopic cervicoisthmic cerclage.

METHODS

We reported on 4 cases of LCC and conducted a systematic review of the literature up to May 2012 to identify obstetric outcomes after LCC and robotic-assisted LCC.

RESULTS

The median age of our series was 35 years (range: 31-41) with median previous pregnancies 3.5 (2-5). All 4 women had successful obstetric outcomes with a median gestational age at delivery of 37 weeks (range: 36-38). The systematic review identified 25 studies (162 women underwent LCC and 3 had robotic-assisted LCC). In the interval LLC studies, the median age was 33 years (range: 22-42); with a median gestational age at delivery of 37 weeks (range: 34-38). For prophylactic LCC, the median age was 31 years (range: 27-41); with a gestational age at delivery of 37 weeks (range: 19-39). Two of the three robotic-assisted LCC procedures were done prophylactically. The median age was 27 years (range: 23-37) with a median gestational age at delivery of 37 weeks (range: 35-38).

CONCLUSION

LCC is feasible during and in between pregnancies as well as in congenitally malformed uteri. Current evidence suggests that LCC might be of benefit in selected cases of cervical insufficiency with short cervices.

Is the accuracy of prior preterm birth history biased by delivery characteristics?

To assess the sensitivity of birth certificates to preterm birth history and determine whether omissions are randomly or systemically biased. Subjects who experienced a preterm birth followed by a subsequent pregnancy were identified in a regional database. The variable "previous preterm birth" was abstracted from birth certificates of the subsequent pregnancy. Clinical characteristics were compared between subjects who were correctly versus incorrectly coded. 713 subjects were identified, of whom 65.5% were correctly coded in their subsequent pregnancy. Compared to correctly coded patients, patients who were not correctly identified tended to have late and non-recurrent preterm births or deliveries that were secondary to maternal or fetal indications. A recurrence of preterm birth in the subsequent pregnancy was also associated with correct coding. The overall sensitivity of birth certificates to preterm birth history is suboptimal. Omissions are not random, and are associated with obstetrical characteristics from both the current and prior deliveries. As a consequence, resulting associations may be flawed.

The Use of Total Cervical Occlusion along with McDonald Cerclage in Patients with Recurrent Miscarriage or Preterm Deliveries

OBJECTIVES

To study the fetal outcome with the use of McDonald cerclage and total cervical occlusion in women with recurrent mid-trimester miscarriages or preterm deliveries, as well as complications of total cervical occlusion in the women.

METHODS

Prospective descriptive observational study on patients with two or more mid-trimester miscarriages, deliveries before 36 weeks, or patients who have experienced failure of transvaginal cerclage.

RESULTS

Twenty-six women were studied. Of these, 92% delivered at term. Two women delivered at 33 and 35 weeks, respectively. There was one neonatal death. Take home baby rate was 96.2%. There was no serious maternal morbidity among the patients.

CONCLUSION

The addition of external cervical OS occlusion to McDonald cerclage could improve fetal outcome in women with recurrent mid-trimester miscarriages and preterm deliveries.

Does increasing body mass index affect cerclage efficacy?

OBJECTIVE

To study the relationship between body mass index (BMI) and gestational age (GA) at delivery in patients with cervical insufficiency (CI) undergoing cerclage.

STUDY DESIGN

We accessed a database of patients with singleton gestations undergoing cerclage (N=168) for a well-characterized history of CI, shortened cervix <2.5 cm with a history of prior preterm delivery or prolapse of membranes through the external os. Univariate and multivariate logistic regression analysis were performed to compare obstetrical outcomes between obese and normal-weight patients.

RESULT

Prior preterm delivery <35 weeks in obese vs normal-weight patients was significantly higher (44% vs 9%), odds ratio=6.9 (95% CI: 2.5, 18.5), with lower mean GA at delivery (32.6±7.0 vs 37.2±3.4 weeks, P<0.001). After controlling for confounders, BMI remained significantly predictive of prematurity (coefficient: -0.12, adjusted R (2)=0.24), such that every additional 1 unit of BMI was associated with a 1-day reduction in GA at delivery (P=0.03).

CONCLUSION

An inverse correlation exists between BMI and GA at delivery in patients with CI receiving cerclage. The findings are unexpected given the protective effect of obesity on spontaneous preterm delivery.

Is sonographic assessment of the cervix necessary and helpful?

Transvaginal sonography of the cervix has emerged as a useful window into preterm parturition. Cervical sonography allows measurements of cervical length (CL), which can aid clinicians in identifying women at risk for preterm birth. The use of transvaginal assessments of CL can assist in the triage of patients with possible preterm labor. Recent studies also support the use of CL measurements as a means of determining appropriate candidates for cerclage placement and progesterone supplementation to reduce the risk of premature birth, further highlighting the importance of this modality in modern obstetric management.

Gestational age at cervical length measurement and preterm birth in twins

OBJECTIVES

To estimate the risk of preterm delivery of twin pregnancies based upon sonographic cervical length measurement and gestational age at measurement.

METHODS

Twin pregnancies that delivered between 1999 and 2005 and that underwent sonographic measurement of cervical length between 13 and 34 + 6 weeks' gestation were identified and a retrospective review performed. Women with anomalous pregnancies, multifetal reduction, cerclage placement or medically indicated deliveries before 35 weeks were excluded. Logistic regression analysis was used to estimate the risk of preterm delivery before 35 weeks.

RESULTS

A total of 561 women underwent 2975 sonographic cervical length measurements during the study period. The rate of preterm delivery before 35 weeks was 19.4%. The risk of delivery before 35 weeks decreased by approximately 5% for each additional mm of cervical length (odds ratio (OR) 0.95 (95% CI, 0.93-0.97); P < 0.001) and by approximately 6% for each additional week at which the cervical length was measured (OR 0.94 (95% CI, 0.92-0.96); P < 0.001).

CONCLUSION

The gestational age at which cervical length is measured is an important consideration when estimating the risk of spontaneous preterm birth in twins. The risk of preterm delivery is increased at earlier gestational ages and as cervical length decreases.

Prediction and prevention of spontaneous preterm birth in twin gestations

The incidence of twin gestation has increased significantly over the past 30 years. One of the most significant public health implications of this trend is the increased incidence of preterm birth (PTB). Efforts to improve neonatal outcomes must address the rate of PTB, particularly among multiple gestations, which contribute a disproportionate share to the burden of PTB and neonatal morbidity. There is evidence that sonographic cervical length assessment and fetal fibronectin testing can identify twin pregnancies at risk for PTB, but, to date, there are no proven interventions for prevention of PTB in this population. Perhaps the most promising is vaginal progesterone, which has been shown to reduce the risk of PTB in a cohort of women that included twin gestations. However, the study lacked statistical power to definitively answer this question. Identification of an appropriate treatment for twin gestations recognized to be at increased risk for prematurity will help to decrease overall rate of PTB, a significant public health problem in the United States.

Cerclage for cervical shortening at fetoscopic laser photocoagulation in twin-twin transfusion syndrome

OBJECTIVE

The purpose of this study was to evaluate the benefit of cervical cerclage for cervical length ≤ 25 mm at the time of fetoscopic laser photocoagulation (FLP) for twin-twin transfusion syndrome.

STUDY DESIGN

A multicenter, retrospective cohort study was conducted with 163 patients with a short cervix before FLP for twin-twin transfusion syndrome. Seventy-nine of the patients (48%) had cerclage placement at the surgeon's discretion. The outcome measures that were compared were gestational age at delivery and perinatal mortality rates for patients with cerclage and those who were treated conservatively. Outcomes were evaluated with the use of comparative statistics.

RESULTS

There were no differences in the preoperative variables, except cerclage was performed more frequently for a cervical length of ≤ 15 mm (P < .001). There were no differences in the gestational age at delivery (28.8 ± 5.4 vs 29.1 ± 5.6 weeks with and without cerclage, respectively; P = .15); perinatal mortality rates were similar between the 2 groups.

CONCLUSION

The benefit of cerclage for patients with short cervix before FLP remains questionable.

Cervical stitch (cerclage) for preventing preterm birth in singleton pregnancy

BACKGROUND

Cervical cerclage is a well-known surgical procedure carried out during pregnancy. It involves positioning of a suture (stitch) around the neck of the womb (cervix), aiming to give a mechanical support to the cervix and thereby reducing the risk of preterm birth. The effectiveness and safety of this procedure remains controversial.

OBJECTIVES

To assess whether the use of cervical stitch in singleton pregnancy at high risk of pregnancy loss based on a woman's history and/or ultrasound finding of 'short cervix' and/or physical exam improves subsequent obstetric care and fetal outcome.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2011) and reference lists of identified studies.

SELECTION CRITERIA

We included all randomised trials of cervical suturing in singleton pregnancies carried out when pregnancy was considered to be at sufficiently high risk of pregnancy loss for cerclage to be potentially indicated. We included any study that compared cerclage with either no treatment or any alternative intervention.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed trials for inclusion. Two review authors independently assessed risk of bias and extracted data. Data were checked for accuracy.

MAIN RESULTS

We included 12 trials (involving 3328 women). When cerclage was compared with no treatment, there was no statistically significant difference in perinatal deaths (8.4% versus 10.7%) (risk ratio (RR) 0.78; 95% confidence interval (CI) 0.61 to 1.00; eight trials, 2391 women) and neonatal morbidity (9.6% versus 10.2%) (RR 0.95; 95% CI 0.63 to 1.43; four trials, 818 women), despite significant reduction in preterm births (average RR 0.80; 95% CI 0.69 to 0.95; nine trials, 2898 women). Cervical cerclage was associated with the higher rate of maternal side effects (vaginal discharge and bleeding, pyrexia) (average RR 2.25; 95% CI 0.89 to 5.69; three trials, 953 women). Caesarean section rates were significantly higher after cervical cerclage (RR 1.19; 95% CI 1.01 to 1.40; 8 trials, 2817 women).There was no evidence of any important differences across all prespecified clinical subgroups (history-indicated, ultrasound-indicated)One study that compared cerclage with weekly intramuscular injections of 17 α-hydroxyprogesterone caproate in women with a short cervix detected by transvaginal ultrasound, failed to reveal any obvious differences in obstetric and neonatal outcomes between the two management strategies.Two studies compared the benefits of performing cerclage based on previous history with cerclage, only if the cervix was found to be short on transvaginal ultrasound. There was no significant difference in any of the primary and secondary outcomes.

AUTHORS' CONCLUSIONS

Compared with no treatment, cervical cerclage reduces the incidence of preterm birth in women at risk of recurrent preterm birth without statistically significant reduction in perinatal mortality or neonatal morbidity and uncertain long-term impact on the baby. Ceasarean section is more likely in women who had cervical suture inserted during pregnancy.The decision on how best to minimise the risk of recurrent preterm birth in women at risk, either because of poor history of a short or dilated cervix, should be 'personalised', based on the clinical circumstances, the skill and expertise of the clinical team and, most importantly, woman's informed choice.

Prevention of preterm birth

Preterm birth (delivery before 37 completed weeks of gestation) is common and rates are increasing. In the past, medical efforts focused on ameliorating the consequences of prematurity rather than preventing its occurrence. This approach resulted in improved neonatal outcomes, but it remains costly in terms of both the suffering of infants and their families and the economic burden on society. Increased understanding of the pathophysiology of preterm labor has altered the approach to this problem, with increased focus on preventive strategies. Primary prevention is a limited strategy which involves public education, smoking cessation, improved nutritional status and avoidance of late preterm births. Secondary prevention focuses on recurrent preterm birth which is the most recognisable risk factor. Widely accepted strategies include cervical cerclage, progesterone and dedicated clinics. However, more research is needed to explore the role of antibiotics and anti-inflammatory treatments in the prevention of this complex problem.

Elective and emergency cervical cerclage and immediate pregnancy outcomes: a retrospective observational study

Objectives

To look retrospectively at patients undergoing elective, ultrasound indicated and rescue cervical cerclage, examine the immediate pregnancy outcomes and compare them.

Design

This was a retrospective observational study using the maternity and neonatal databank to identify patients having cervical cerclage between 1985 and 2009 inclusive. Data extracted included patient demographics, gestation of suture insertion, gestation at delivery, mode of delivery and initial pregnancy outcome. Further information on selected patients having cerclages over 16 weeks gestation was collected from case-notes.

Setting

Aberdeen Maternity Hospital, North East Scotland.

Participants

All patients having cervical cerclage between 1985 and 2009.

Main outcome measures

Gestation at delivery, live birth rate and birth weight.

Results

A total of 177 sutures were inserted – 116 electively and 61 as an emergency procedure. Time trends of cervical cerclage revealed a bimodal distribution and in the last four years there has been a general increase in the number of emergency sutures while the number of elective cerclages has remained relatively constant. There was little difference in the gestation at delivery between the elective and emergency cerclage groups (35 and 33 weeks, respectively), live birth rate (93% and 92%, respectively) and the difference in mean birth weight did not reach statistical significance. Case-notes were obtained for 25 patients undergoing ultrasound indicated cerclage and nine patients undergoing rescue cerclage. There was a higher suture associated complication rate in the rescue cerclage group (33% vs. 12% in the ultrasound indicated cerclage group) and the mean gestation of delivery was lower (26 weeks vs. 32 weeks). The birth weight was significantly lower and the neonatal death rate higher in the rescue cerclage group.

Conclusions

Elective and ultrasound indicated cervical cerclage appear to have low complication rates and high live birth rates. Rescue cerclage has a high complication rate and is therefore associated with poor outcome.

Endocervical immune mediator production following successful rescue or ultrasound indicated cerclage placement

OBJECTIVE

Placement of a cervical cerclage at mid-trimester in women at risk for preterm labor is a common procedure with apparent benefits for some women. However, the changes that occur in the cervix following this procedure remain incompletely identified.

METHODS

We evaluated the endocervical concentrations of mediators involved in extracellular matrix (ECM) stabilization or degradation prior to, and up to 120 days following, cerclage placement in 53 women who underwent an ultrasound-indicated or a rescue cerclage at 15-25 weeks of gestation due to a cervical length <1.5 cm. All delivered a healthy neonate at term. Samples were tested by enzyme-linked immunosorbent assay for concentrations of hyaluronan (HA), 27 kDa heat shock protein (hsp27), transforming growth factor-β (TGF-β), extracellular matrix metalloproteinase inducer (CD147/EMMPRIN), and matrix metalloproteinase (MMP)-1 and -8.

RESULTS

Concentrations of both HA and hsp27 were highest at the time of cerclage placement and then decreased while TGF-β and EMMPRIN increased in concentration following the procedure. The highest mean EMMPRIN level was measured at >90 days following the procedure while TGF-β levels peaked at 61-90 days post-cerclage. MMP-1 and MMP-8 were not detected over the study time period.

CONCLUSION

In women with a successful cerclage placement the selective regulation of mediators inhibits progression of ECM degradation and cervical ripening.

SOGC Clinical Practice Guideline. Ultrasonographic cervical length assessment in predicting preterm birth in singleton pregnancies

OBJECTIVES

To review (1) the use of ultrasonographic-derived cervical length measurement in predicting preterm birth and (2) interventions associated with a short cervical length.

OUTCOMES

Reduction in rates of prematurity and/or better identification of those at risk, as well as possible prevention of unnecessary interventions.

EVIDENCE

Published literature was retrieved through searches of PubMed and The Cochrane Library up to December 2009, using appropriate controlled vocabulary and key words (preterm labour, ultrasound, cervix, incompetent cervix, transvaginal, transperineal, cervical length, fibronectin). Results were restricted to general and systematic reviews, randomized controlled trials/controlled clinical trials, and observational studies. There were no date or language restrictions. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The evidence and this guideline were reviewed by the Diagnostic Imaging Committee and the Maternal Fetal Medicine Committee of the Society of Obstetricians and Gynaecologists of Canada, and the recommendations were made according to the guidelines developed by The Canadian Task Force on Preventive Health Care (Table 1).

BENEFITS, HARMS, AND COSTS

Preterm birth is a leading cause of perinatal morbidity and mortality. Use of the ultrasonographic technique reviewed in this guideline may help identify women at risk of preterm birth and, in some circumstances, lead to interventions that may reduce the rate of preterm birth.

SPONSORS

The Society of Obstetricians and Gynaecologists of Canada.