Elective cerclage vs. ultrasound-indicated cerclage in high-risk pregnancies

Spontaneous preterm birth and cervical length in a pregnant Asian population

Objective

Preterm birth (birth before 37 weeks of completed gestation) is the leading cause of neonatal death, and has an incidence of 5–13% which is believed to be on the rise. The objective of this study was to determine the rate of spontaneous preterm birth and investigate the relationship between preterm birth and cervical length in a pregnant Asian population.

Materials and methods

A prospective observational study between September 2010 and November 2013 was performed at KK Women’s and Children’s Hospital, Singapore. 1013 women with single viable pregnancies were recruited at less than 14 weeks of gestation between September 2010 and November 2013, excluding those with multiple gestation, pre-existing autoimmune or renal disease or those with current pregnancies complicated by aneuploidy or fetal anomalies. Participant characteristics were obtained from an interviewer-administered questionnaire at the first recruitment visit. Cervical length was measured using ultrasound at each of the 4 antenatal visits (Visit 1: < 14 weeks, Visit 2: 18–22 weeks, Visit 3: 28–32 weeks and Visit 4: > 34 weeks) using the Fetal Medicine Foundation protocol. Data on pregnancy outcomes were obtained from obstetric case notes and records. The main outcome measure examined in this study was that of spontaneous preterm birth and its relationship to cervical length.

Results

There was a significantly shorter cervical length both in the 2nd trimester (18 to 22 weeks) and the 3rd trimester (28 to 32 weeks) in the preterm birth group compared to the term birth group (p = 0.028 and p < 0.001 respectively). In the first trimester (11 to 14 weeks), there was no statistically significant difference in cervical length between the two groups (p = 0.425). ROC curve analysis for cervical length in the preterm birth group for 18 to 22 weeks and 28 to 32 weeks showed an AUC of 0.605 and 0.725 respectively. At 28 to 32 weeks of gestation, a cut-off level at 2.49 cm has a sensitivity of 54.8%, specificity of 82.5%, negative predictive value of 97.9% and positive predictive value of 11.1%.

Conclusion

There is a significantly shorter cervical length in the 2nd and 3rd trimester in the preterm birth group. Cervical length is a moderate predictor of preterm birth with good negative predictive value and a relatively good specificity. Ultrasound cervical length screening for pregnant Asian women between 18 and 22 weeks of gestation with a cutoff of ≥ 2.48cm can help to identify a group of women who are at risk for preterm birth.

Arabin cervical pessary for prevention of preterm birth in cases of twin-to-twin transfusion syndrome treated by fetoscopic LASER coagulation: the PECEP LASER randomised controlled trial

Background

Fetoscopic LASER coagulation of the placental anastomoses has changed the prognosis of twin-twin transfusion syndrome. However, the prematurity rate in this cohort remains very high. To date, strategies proposed to decrease the prematurity rate have shown inconclusive, if not unfavourable results.

Methods

This is a randomised controlled trial to investigate whether a prophylactic cervical pessary will lower the incidence of preterm delivery in cases of twin-twin transfusion syndrome requiring fetoscopic LASER coagulation. Women eligible for the study will be randomised after surgery and allocated to either pessary or expectant management. The pessary will be left in place until 37 completed weeks or earlier if delivery occurs. The primary outcome is delivery before 32 completed weeks. Secondary outcomes are a composite of adverse neonatal outcome, fetal and neonatal death, maternal complications, preterm rupture of membranes and hospitalisation for threatened preterm labour. 352 women will be included in order to decrease the rate of preterm delivery before 32 weeks’ gestation from 40% to 26% with an alpha-error of 0.05 and 80% power.

Discussion

The trial aims at clarifying whether the cervical pessary prolongs the pregnancy in cases of twin-twin transfusion syndrome regardless of cervical length at the time of fetoscopy.

Trial registration

ClinicalTrials.gov Identifier: NCT01334489. Registered 04 December 2011.

Insuffisance cervicale et cerclage cervical

OBJECTIF

La présente directive clinique a pour but de fournir un cadre de référence que les cliniciens pourront utiliser pour identifier les femmes qui sont exposées aux plus grands risques de connaître une insuffisance cervicale, ainsi que pour déterminer les circonstances en présence desquelles la mise en place d'un cerclage pourrait s'avérer souhaitable. RéSULTATS: La littérature publiée a été récupérée par l'intermédiaire de recherches menées dans PubMed ou MEDLINE, CINAHL et The Cochrane Library en 2012 au moyen d'un vocabulaire contrôlé (p. ex. « uterine cervical incompetence ») et de mots clés appropriés (p. ex. « cervical insufficiency », « cerclage », « Shirodkar », « cerclage », « MacDonald », « cerclage », « abdominal », « cervical length », « mid-trimester pregnancy loss »). Les résultats ont été restreints aux analyses systématiques, aux essais comparatifs randomisés / essais cliniques comparatifs et aux études observationnelles. Aucune restriction n'a été appliquée en matière de date ou de langue. Les recherches ont été mises à jour de façon régulière et intégrées à la directive clinique jusqu'en janvier 2011. La littérature grise (non publiée) a été identifiée par l'intermédiaire de recherches menées dans les sites Web d'organismes s'intéressant à l'évaluation des technologies dans le domaine de la santé et d'organismes connexes, dans des collections de directives cliniques, dans des registres d'essais cliniques et auprès de sociétés de spécialité médicale nationales et internationales.

VALEURS

La qualité des résultats est évaluée au moyen des critères décrits dans le rapport du Groupe d'étude canadien sur les soins de santé préventifs (Tableau). RECOMMANDATIONS.

Evaluation of outcomes associated with placement of elective, urgent, and emergency cerclage

OBJECTIVES

The aim of this study was to assess pregnancy outcomes after cervical cerclage.

METHODS

A retrospective analysis of all cervical cerclages placed at Al Qassimi Hospital from 2004 to 2008 was performed. The primary outcome of interest was prolongation of pregnancy beyond 36 wks. Secondary outcomes were premature rupture of membranes, birth weight <1,500 g, and neonatal death.

RESULTS

Cerclage was placed in 145 women: 112 elective, 16 urgent, and 17 emergency groups. Delivery beyond 36 weeks occurred in 79.4, 73.3, and 47.1 % in the elective, urgent, and emergency groups, respectively, p = 0.011. When comparing between elective, urgent, and emergency groups, incidences of low birth weight were 9.8, 13.3, and 33.3 %, respectively, p = 0.06, and premature ruptures of membranes occurred in 7.2, 6.3, and 17.7 %, respectively, p = 0.16. There were five neonatal deaths.

CONCLUSION

Therefore, although cerclage gives best results when it is performed as an elective procedure, emergency cerclage still confers some benefits.

Vaginal progesterone in women with an asymptomatic sonographic short cervix in the midtrimester decreases preterm delivery and neonatal morbidity: a systematic review and metaanalysis of individual patient data

OBJECTIVE

To determine whether the use of vaginal progesterone in asymptomatic women with a sonographic short cervix (≤ 25 mm) in the midtrimester reduces the risk of preterm birth and improves neonatal morbidity and mortality.

STUDY DESIGN

Individual patient data metaanalysis of randomized controlled trials.

RESULTS

Five trials of high quality were included with a total of 775 women and 827 infants. Treatment with vaginal progesterone was associated with a significant reduction in the rate of preterm birth <33 weeks (relative risk [RR], 0.58; 95% confidence interval [CI], 0.42-0.80), <35 weeks (RR, 0.69; 95% CI, 0.55-0.88), and <28 weeks (RR, 0.50; 95% CI, 0.30-0.81); respiratory distress syndrome (RR, 0.48; 95% CI, 0.30-0.76); composite neonatal morbidity and mortality (RR, 0.57; 95% CI, 0.40-0.81); birthweight <1500 g (RR, 0.55; 95% CI, 0.38-0.80); admission to neonatal intensive care unit (RR, 0.75; 95% CI, 0.59-0.94); and requirement for mechanical ventilation (RR, 0.66; 95% CI, 0.44-0.98). There were no significant differences between the vaginal progesterone and placebo groups in the rate of adverse maternal events or congenital anomalies.

CONCLUSION

Vaginal progesterone administration to asymptomatic women with a sonographic short cervix reduces the risk of preterm birth and neonatal morbidity and mortality.

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.

Sonographic cervical length measurement in pregnant women with a cervical pessary

OBJECTIVES

The aims of this study were to describe and assess the feasibility of measuring cervical length by standard transvaginal sonography (TVS) and transperineal sonography (TPS) in women with a cervical pessary and compare these measurements with those obtained with a new transvaginal technique.

METHODS

Measurement of cervical length by TPS was attempted immediately before measurement using TVS in 48 women with a cervical pessary at between 22 and 23 weeks' gestation. The TVS procedure consisted of two types of measurement: in the first, the probe was placed on the anterior fornix (standard technique) and in the second, the probe was inserted into the pessary to touch the anterior cervical lip (new technique). Two physicians consecutively performed these procedures and compared the measurements obtained. Intraclass correlation coefficients (ICCs) with 95% CI were used to evaluate interobserver reliability, and Bland-Altman analysis was used to assess interobserver agreement.

RESULTS

In total, 258 measurements (obtained from 43 women) were analyzed. Interobserver ICCs of the measurements obtained were 0.58 (95% CI, 0.34-0.75) for TPS, 0.65 (95% CI, 0.44-0.79) for the standard TVS technique and 0.97 (95% CI, 0.95-0.98) for the new TVS technique. Bland-Altman analysis showed small mean differences between measurements obtained by two physicians for the three methods, but with narrower limits of agreements (LOA) for the new TVS technique: TPS mean difference - 0.99 mm (95% LOA, - 13.23 to 11.25 mm), standard TVS technique mean difference - 0.23 mm (95% LOA, - 10.90 to 10.44 mm) and new TVS technique mean difference - 0.01 mm (95% LOA, - 2.57 to 2.55 mm). It was apparent from the images obtained that the external os was not visible in 89% of cases when either the TPS or standard TVS technique was used. However, the external os was visible in all cases when the new TVS method was used.

CONCLUSIONS

We propose a new technique for measuring and monitoring cervical length in women with a cervical pessary that provides improved visualization of the cervix and increased reliability in comparison to established techniques.

Transvaginal ultrasonographic measurement of cervical length in asymptomatic high-risk women with a short cervical length in the previous pregnancy

OBJECTIVE

To determine if asymptomatic women at high risk of preterm delivery who had a short cervical length in their previous pregnancy and delivered at term are at increased risk of having a short cervical length in their next pregnancy, and whether they are at increased risk of preterm birth.

METHODS

This retrospective cohort study included high-risk (those with a history of spontaneous preterm birth, uterine anomaly or excisional treatment for cervical dysplasia) asymptomatic women who were pregnant with a singleton gestation delivering between April 2003 and March 2010, who had had a previous pregnancy and who had transvaginal ultrasonographic cervical length measurement performed at 16-30 weeks' gestation in both pregnancies. Comparison was among women who had a short cervical length (< 3.0 cm) in their previous pregnancy but delivered at term in that pregnancy (Short Term Group), women with a history of a normal cervical length (≥ 3.0 cm) in their previous pregnancy delivering at term (Long Term Group), and women who had a short cervical length (< 3.0 cm) in their previous pregnancy delivering preterm (Short Preterm Group). Primary outcomes were spontaneous preterm birth at < 37 weeks' gestation and cervical length. Secondary outcomes were spontaneous preterm birth at < 35 weeks and < 32 weeks, low birth weight, maternal outcomes and neonatal morbidity.

RESULTS

A total of 62 women were included. Women in the Short Term Group were more likely to have a short cervical length in their next pregnancy compared with those in the Long Term Group (10/23 (43.5%) vs. 4/26 (15.4%), respectively) but not as likely as women in the Short Preterm Group (9/13 (69.2%); P=0.003). Women in the Short Term Group were not at an increased risk of spontaneous preterm birth at < 37 weeks in the next pregnancy compared with women in the Long Term Group (2/23 (8.7%) vs. 2/26 (7.7%), respectively), but women in the Short Preterm Group were at an increased risk (6/13 (46.2%); P<0.0001). Compared with women in the Short Term and Long Term groups, women in the Short Preterm Group were also at an increased risk of threatened preterm labor (6/23 (26.1%) and 4/26 (15.4%) vs. 9/13 (69.2%), respectively; P=0.002) and of receiving corticosteroids for fetal lung maturation (6/23 (26.1%) and 4/26 (15.4%) vs. 11/13 (84.6%), respectively; P<0.0001).

CONCLUSION

Although high-risk asymptomatic women with a short cervical length in their previous pregnancy who delivered at term are at increased risk of having a short cervix in their next pregnancy, they are not at increased risk of preterm birth.

Follow-up cervical length in asymptomatic high-risk women and the risk of spontaneous preterm birth

OBJECTIVE

To determine whether further cervical length shortening by transvaginal ultrasonography in asymptomatic high-risk women with a short cervical length adds additional predictive value for spontaneous preterm birth and perinatal morbidity.

STUDY DESIGN

Women with a history of spontaneous preterm birth, loop electrosurgical excision procedure, cone biopsy or uterine anomaly, who were pregnant with singleton gestations and were found by transvaginal ultrasonography to have a cervical length <3.0 cm at 20 to 28 weeks' gestation, and who underwent a follow-up cervical length within 3 weeks were evaluated, comparing those with further cervical length shortening (>10%) to those without further shortening. Primary outcomes were spontaneous preterm birth <35 weeks' gestation and perinatal morbidity. Secondary outcomes included spontaneous preterm birth <37 weeks, <34 weeks, <32 weeks, birth weight <2500 g, maternal and other neonatal outcomes.

RESULT

Compared with women without further cervical shortening, those with further shortening were found by univariate analyses to have higher rates of spontaneous preterm birth <35 weeks (34.8 versus 8.5%, P = 0.014), <37 weeks (56.5 versus 21.3%, P = 0.003), <34 weeks (30.4 versus 2.1%, P = 0.001), <32 weeks (21.7 versus 0%, P = 0.003), birth weight <2500 g (60.9 versus 17.0%, P<0.0001), neonatal intensive care unit admission (47.8 versus 17.0%, P = 0.006) and composite perinatal morbidity (43.5 versus 14.9%, P = 0.009). Logistic regression revealed the only independent predictors of spontaneous preterm birth <35 weeks were further cervical length shortening (adjusted odds ratio (aOR) 5.73; 95% confidence interval (CI) 1.31 to 24.43) and gestational age at short cervical length (aOR 0.95; 95% CI 0.91 to 0.99).

CONCLUSION

Further cervical length shortening in asymptomatic high-risk women with a short cervical length is an important independent predictor of spontaneous preterm birth <35 weeks and perinatal morbidity.

Prevention of preterm birth based on a short cervix: cerclage

In an attempt to prevent preterm birth, clinicians have recommended cerclage for women with shortened cervical length and other worrisome sonographic cervical features in the mid-trimester, although randomized trials have not supported this practice. Emerging data suggest that preterm birth is a complex and poorly understood syndrome comprising several anatomic and functional components. As a result, preventive efforts have been mostly empiric and generally ineffective. Plausibly, effective preterm birth therapies exist, but matching the effective treatment with the correct patient has been problematic. Mid-trimester cervical changes visualized with vaginal sonography likely represent a pathologic process of premature cervical ripening and not real mechanical disability which has been traditionally treated with suture support. Cerclage may effectively reduce preterm birth in carefully selected women who have experienced a prior early preterm birth and who have shortened mid-trimester cervical length.

Goals and strategies for prevention of preterm birth: an obstetric perspective

Complications of prematurity surpass congenital malformations as the leading cause of infant mortality in the United States. Since 1990, there has been a steady rise in preterm birth, alarming health professionals from all disciplines. This review from a prenatal perspective confirms those concerns and describes the risks and opportunities that may attend efforts to improve the health of fetuses, newborns, and infants. Fetal and live-born outcomes are included.

A randomized controlled trial of cervical scanning vs history to determine cerclage in women at high risk of preterm birth (CIRCLE trial)

OBJECTIVE

We sought to compare history-indicated placement of cervical cerclage based on history- vs ultrasound-indicated placement in women at risk of preterm birth.

STUDY DESIGN

We conducted a randomized controlled trial of history-indicated cervical cerclage suture based on history (clinician preference) vs ultrasound (< 20 mm cervical length) indicated in women at increased risk.

RESULTS

The incidence of the primary outcome, preterm delivery between 24(+0) and 33(+6) weeks, was similar: 19/125 (15%) in the history-indicated group vs 18/122 (15%) in the ultrasound-indicated group (relative risk [RR], 0.97; 95% confidence interval [CI], 0.54-1.76). Those women randomized to the ultrasound-indicated arm were significantly more likely to receive a cerclage (32% vs 19%; RR, 1.66; 95% CI, 1.07-2.47) and progesterone (39% vs 25%; RR, 1.55; 95% CI, 1.06-2.25).

CONCLUSION

Screening women at high risk with cervical ultrasound to determine cerclage placement results in more intervention but similar outcome compared with history-indicated placement.

Novel developments on cervical length screening and progesterone for preventing preterm birth

Cervical length (CL) measured by transvaginal ultrasound is an effective screening test for the prevention of preterm birth (PTB). The criteria for an effective screening test are all met by CL. It studies an important condition (PTB); it is safe and acceptable by >99% of women; it recognises an early asymptomatic phase that precedes PTB by many weeks; it has a well-described technique, is reproducible, is predictive of PTB in all populations studies so far; and, perhaps most importantly, it has been shown that 'early' treatment is effective in prevention. These two interventions, effective only in specific populations, are ultrasound-indicated cerclage and vaginal progesterone.

Ultrasound-predicated versus history-predicated cerclage in women at risk of cervical insufficiency: a systematic review

The aim of this systematic review was to compare pregnancy outcomes and cerclage-related complications of ultrasound-predicated versus history-predicated cerclage in patients at risk of cervical insufficiency due to a history of preterm delivery (PTD). A structured search was performed in PubMed, Embase, and the Cochrane Library to identify potentially relevant articles from January 1980 through July 2007. Studies were included if ultrasound-predicated cerclage was compared to history-predicated cerclage in women with a singleton gestation and a history of PTD. The PubMed, Embase, and Cochrane search yielded 537, 643, and 42 articles, respectively. In addition, 1194 "Related articles" (PubMed) and 87 "Cited in/cited by" (ISI-WOS) from all potentially relevant articles were assessed. After critical evaluation for relevance and quality, 6 articles remained. Five of the 6 included studies showed no differences in pregnancy outcome (PTD or pregnancy loss <24 weeks) between the ultrasound-predicated and the history-predicated cerclage groups. In 1 prospective cohort study, PTD below 30 weeks was significantly lower in the ultrasound group. The included studies showed that in the ultrasound group, 40% to 68% of the patients did not require cerclage. The majority of studies provided insufficient data to draw conclusions regarding cerclage-related complications. In conclusion, using ultrasound to identify women at risk of cervical insufficiency because of a history of PTD reduces cerclage rates and results in similar pregnancy outcomes as cerclage placement on the basis of history alone.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After reading this article, the reader should be able to identify his or her own management of women with prior history of preterm delivery with respect to the possible use of cerclage, design a diagnostic strategy for his or her own patients to determine whether history or ultrasound-based decision making is appropriate in the practice setting, and translate best-practices with respect to definition of cervical shortening in his or her own practice.

Use of transvaginal ultrasonography to predict preterm birth in women with a history of preterm birth

OBJECTIVE

To investigate whether cervical length measured by transvaginal ultrasonography predicts spontaneous preterm birth at < 35 weeks' gestation in women with a history of spontaneous preterm birth, stratified by spontaneous preterm birth history subtype (preterm premature rupture of membranes (PPROM) or preterm labor with intact membranes at onset of labor).

METHODS

This retrospective cohort study included women with a history of spontaneous preterm birth that were subsequently pregnant with singleton gestations, compared with a low-risk control group. Transvaginal ultrasonographic cervical lengths were measured at 24 to 30 weeks of gestation. The primary outcome was spontaneous preterm birth at < 35 weeks. Secondary outcomes included spontaneous preterm birth at < 37 weeks and < 34 weeks, low birth weight, Cesarean delivery and perinatal morbidity and mortality. Multiple logistic regression analysis was used to control for potential confounders and calculate odds ratios and 95% confidence intervals. Receiver-operating characteristics (ROC) curves were used to determine the best cut-off for transvaginal ultrasound cervical length in predicting spontaneous preterm birth at < 35 weeks.

RESULTS

Women with a history of spontaneous preterm birth with intact membranes at onset of labor (n = 42) had a shorter cervical length (3.28 cm) than women with a history of spontaneous preterm birth with PPROM at onset of labor (n = 48, cervical length 3.77 cm; P = 0.019), and both subgroups had shorter cervical lengths than the low-risk control group (n = 103, cervical length 4.30 cm; P < 0.0001). Both subgroups were associated with spontaneous preterm birth at < 35 weeks, < 37 weeks, < 34 weeks and birth weight < 2500 g. ROC curves determined that the best cut-off for cervical length to predict spontaneous preterm birth at < 35 weeks was 3.0 cm. By multiple logistic regression analysis, the only independent predictors of spontaneous preterm birth at < 35 weeks were cervical length < 3.0 cm, a history of spontaneous preterm birth and antepartum bleeding in the current pregnancy. In women with a history of spontaneous preterm birth, a cervical length as measured by transvaginal ultrasonography of < 3.0 cm had a sensitivity of 63.6%, specificity of 77.2%, positive predictive value of 28.0% and negative predictive value of 93.8%, for preterm birth at < 35 weeks.

CONCLUSION

Women with a history of spontaneous preterm birth with preterm labor and intact membranes at the onset of labor have shorter cervices than women with a history of spontaneous preterm birth and PPROM at the onset of labor, and both groups have shorter cervices than a low-risk control group. Both groups of women with a history of spontaneous preterm birth have an increased risk of recurrent spontaneous preterm birth at < 35 weeks, and this is predicted by a transvaginal ultrasound cervical length of < 3.0 cm.

Transvaginal sonographic measurement of cervical length to predict preterm birth in asymptomatic women at increased risk: a systematic review

OBJECTIVES

To estimate the ability of cervical length measured by transvaginal ultrasonography in asymptomatic high-risk women to predict spontaneous preterm birth.

METHODS

MEDLINE, PubMed, EMBASE and the Cochrane Library were searched for articles published in any language between January 1980 and July 2006, using the keywords 'transvaginal ultrasonography' or ('cervix' and ('ultrasound' or 'ultrasonography' or 'sonography')); and ('preterm' or 'premature') and ('delivery' or 'labour/labor' or 'birth'), identifying cohort studies evaluating transvaginal ultrasonographic cervical length measurement in predicting preterm birth in asymptomatic women who were considered at increased risk (because of a history of spontaneous preterm birth, uterine anomalies or excisional cervical procedures), with intact membranes and singleton gestations. The primary analysis included all studies meeting the inclusion criteria. Secondary analyses were also performed specifically for (1) women with a history of spontaneous preterm birth; (2) those who had undergone an excisional cervical procedure; and (3) those with uterine anomalies.

RESULTS

Fourteen of 322 articles identified (involving 2258 women) met the criteria for systematic review. Cervical length measured by transvaginal ultrasonography predicted spontaneous preterm birth. The shorter the cervical length cut-off the higher the positive likelihood ratio (LR). The most common cervical length cut-off was < 25 mm. Using this cut-off to predict spontaneous preterm birth at < 35 weeks, transvaginal ultrasonography at < 20 weeks' gestation revealed LR+ = 4.31 (95% CI, 3.08-6.01); at 20-24 weeks, LR+ = 2.78 (95% CI, 2.22-3.49); and at > 24 weeks, LR+ = 4.01 (95% CI, 2.53-6.34). In women with a history of spontaneous preterm birth (six studies involving 663 women) cervical length at < 20 weeks revealed LR+ = 11.30 (95% CI, 3.59-35.57) and at 20-24 weeks LR+ = 2.86 (95% CI, 2.12-3.87), but there were limited data on the use of cervical length of more than 24 weeks in this group (one study involving 42 women). In women who had had excisional cervical procedures, two studies presented data on cervical length (one at < 24 weeks and one at > 24 weeks), finding cervical length at < 24 weeks to be predictive of spontaneous preterm birth at < 35 weeks (LR+ = 2.91, 95% CI, 1.69-5.01). One study (of 64 women) evaluated cervical length in women with uterine anomalies, finding it predictive of spontaneous preterm birth at < 35 weeks (LR+ = 8.14, 95% CI, 3.12-21.25).

CONCLUSION

Cervical length measured by transvaginal ultrasonography in asymptomatic high-risk women predicts spontaneous preterm birth at < 35 weeks. Further research may be warranted to evaluate the use of transvaginal ultrasonography after 24 weeks' gestation in women with a history of spontaneous preterm birth, and in women with uterine anomalies.

Primary, secondary, and tertiary interventions to reduce the morbidity and mortality of preterm birth

Interventions to reduce the morbidity and mortality of preterm birth can be primary (directed to all women), secondary (aimed at eliminating or reducing existing risk), or tertiary (intended to improve outcomes for preterm infants). Most efforts so far have been tertiary interventions, such as regionalised care, and treatment with antenatal corticosteroids, tocolytic agents, and antibiotics. These measures have reduced perinatal morbidity and mortality, but the incidence of preterm birth is increasing. Advances in primary and secondary care, following strategies used for other complex health problems, such as cervical cancer, will be needed to prevent prematurity-related illness in infants and children.

Recurrent preterm birth

Recurrent preterm birth is frequently defined as two or more deliveries before 37 completed weeks of gestation. The recurrence rate varies as a function of the antecedent for preterm birth: spontaneous versus indicated. Spontaneous preterm birth is the result of either preterm labor with intact membranes or preterm prelabor rupture of the membranes. This article reviews the body of literature describing the risk of recurrence of spontaneous and indicated preterm birth. Also discussed are the factors which modify the risk for recurrent spontaneous preterm birth (a short sonographic cervical length and a positive cervicovaginal fetal fibronectin test). Patients with a history of an indicated preterm birth are at risk not only for recurrence of this subtype, but also for spontaneous preterm birth. Individuals of black origin have a higher rate of recurrent preterm birth.

Contemporary Use of Cervical Cerclage

Although it was devised over 50 years ago, only recently controlled randomized trials have evaluated the efficacy of cervical cerclage. Cerclage was originally devised for women with both prior preterm birth (PTB) and cervical changes in the current pregnancy. Evidence suggests that transvaginal cerclage probably prevents second trimester loss/PTB in women with >or=3 PTB/second trimester loss (history-indicated cerclage best placed at 12 to 14 wk); and in women with a prior PTB 16 to 36 weeks and transvaginal ultrasound cervical length<25 mm in the current pregnancy (ultrasound-indicated cerclage at 14 to 23 6/7 wk).

Pregnancy on intensified hemodialysis: fetal surveillance and perinatal outcome

OBJECTIVES

To evaluate the effect of intensive fetal surveillance via Doppler ultrasound and fetal non-stress test on the perinatal outcome of pregnant women undergoing an intensified hemofiltration scheme.

METHODS

Five consecutive pregnancies of women undergoing intensified hemodialysis were analyzed due to the following parameters: maternal background, hemodialysis schedule during pregnancy, blood pressure, occurrence of fetal complications, occurrence of obstetric complications, gestational week at delivery, mode of delivery, and newborn outcome and follow-up.

RESULTS

All pregnancies resulted in a live birth, mean gestational age was 32 weeks. Intrauterine growth restriction occurred in 4 fetuses, pathological umbilical artery flow velocity waveforms in 2. The mean birth weight was 1,764 g (range 1,274-2,465 g). Cesarean section was performed in 3 patients because of fetal distress. None of the patients developed severe complications like pre-eclampsia.

CONCLUSIONS

Although intensified dialysis enables the maintenance of stable uteroplacental and fetal perfusion, intensive fetal monitoring is mandatory to reduce perinatal morbidity and mortality in pregnant women on maintenance dialysis.

Do screening-preventative interventions in asymptomatic pregnancies reduce the risk of preterm delivery—A critical appraisal of the literature

Recent research has suggested that women who experience preterm delivery (PTD) may be identified earlier in pregnancy and before onset of symptoms. Interventions commenced at this earlier asymptomatic stage may offer an opportunity to prevent PTD or lengthen gestation sufficiently to reduce adverse perinatal outcome. Our objective was to examine the evidence that supports or refutes this approach to preventing PTD. We therefore conducted a systematic search and critical appraisal of the identified literature. We found evidence that introducing screening-preventative strategies for asymptomatic pregnancies may reduce the rate of PTD. Evidence for screening and selective treatment exists for: asymptomatic bacteriuria; bacterial vaginosis in low-risk population groups; elective cervical cerclage in high-risk pregnancies; indicated cervical cerclage in women with short cervical length on ultrasound; prophylactic progesterone supplementation in high-risk pregnancies, and smoking cessation. However, for most other strategies, such as increased antenatal attendance, or routine administration of prophylactic micronutrients, the evidence is inconsistent and conflicting. Information on neonatal outcomes apart from PTD (such as serious neonatal morbidity and mortality) was found to be lacking in most studies. It was therefore not possible to establish whether preventing PTD or prolonging gestation would correlate to improved perinatal outcome, and this lessened the potential clinical usefulness of any proposed preventative strategy. No studies were found that evaluated the effectiveness of combining screening-preventative strategies. The review concludes with a suggested an antenatal management plan designed to prevent PTD based on current practice and the evidence presented in this article.

The role of cervical cerclage in obstetric practice: can the patient who could benefit from this procedure be identified?

This editorial critically examines the definition of "cervical insufficiency." The definition, the clinical ascertainment, efforts to develop an objective method of diagnosis, as well as the nature of cervical disease leading to spontaneous mid-trimester spontaneous abortion and preterm delivery are reviewed. The value and limitations of cervical sonography as a risk assessment tool for spontaneous preterm delivery are appraised. The main focus is on the role of cervical cerclage to prevent an adverse pregnancy outcome. The value of assessing the presence or absence of endocervical inflammation in the outcome of cerclage placement is discussed.

Noninvasive cerclage for the management of cervical incompetence: a prospective study

OBJECTIVE

The aim of this study was to evaluate the efficacy and safety of a noninvasive cerclage pessary in the management of cervical incompetence.

METHODS

This is a prospective cohort study of all pregnant women treated for cervical incompetence during a 4-year period. Women with known risk factors for preterm delivery had transvaginal ultrasonography every 2-3 weeks after 17-19 weeks of gestation. Those with progressive shortening of cervix diagnosed before 30 weeks were treated with a cerclage pessary when the cervical length was < or = 25 mm. The pessary was electively removed at 34-36 weeks. The course and outcome of pregnancy were recorded.

RESULTS

Thirty-two women were treated with a cerclage pessary. There were nine twin and two triplet pregnancies. Fifteen (47%) had two or more risk factors for preterm delivery. The mean gestational age at cerclage was 23 (17-29) weeks, cervical length 17 (5-25) mm. Two women required delivery before the onset of labor due to severe intrauterine growth restriction and one due to HELLP syndrome. These were excluded from further analysis. In the remaining 29 women, the interval between cerclage and delivery was 10.4 (2-19) weeks, mean gestational age at delivery 34 (22-42) weeks, and birth weight 2,255 (410-4,045) g. Thirteen (45%) women delivered before 34 weeks. There were a total of 35 live-born infants and four intrapartum fetal deaths (all between 22 and 25 weeks gestation). All women complained of increased vaginal discharge, but no other significant complications were observed that could be attributed to the use of pessary.

CONCLUSION

Cerclage pessary may be useful in the management of cervical incompetence. Whether it can be a noninvasive alternative to surgical cerclage merits further investigation.

Strategies for prevention-cervical cerclage

Transvaginal cervical cerclage was introduced as a treatment for cervical incompetence in 1951. Over the years, our understanding of this clinical entity has changed tremendously, which has implications for obstetric management. This review focuses on the obstetric management of women considered to be at high risk of preterm delivery due to cervical incompetence at different stages of pregnancy.

Late or emergency (salvage) cerclage of a dilated cervix after tissue support with Pelvicol implant: a case

Our objective was to evaluate the effectiveness of a late or emergency (salvage) cerclage after tissue reinforcement with Pelvicol natural implant, in preventing premature rupture of the fetal membranes and advancing pregnancy prolongation. A flat sheet of Pelvicol, a sterile acellular natural (porcine) implant was used in an emergency cerclage to reinforce the thin tissues of a widely dilated cervix in a 24 weeks' twin gestation with prolapsed unruptured membranes, without contractions, placental abruption, or intrauterine infection. The gestation was extended to 38 weeks without any complications. Two live healthy newborns were delivered by elective cesarean section due to a nonvertex/vertex presentation. The implant was found to be attached almost unaltered firmly on the outer surface of the membrane sac just opposite to the internal os. It seems that Pelvicol is safe and apparently protects by clothing the thinned, soft, and weak wall of a significantly dilated uterine cervix and the bulging or protruding gestational membranes. It also reinforces and strengthens the tissue thickness and resistance, rendering more accurate and safe the otherwise delicate and risky late cerclage. The technique gives hopes that it can help in pregnancy prolongation.

Controversies regarding cervical incompetence, short cervix, and the need for cerclage

Cervical incompetence (CI) is not an all or nothing phenomenon but a continuous variable. CI and preterm labor are not distinct entities but rather part of a spectrum leading to preterm delivery. Cervical length (CL) is an independent variable in the prediction of preterm delivery, to which it is inversely related. Application of a primary transvaginal cervical cerclage appears to be an unnecessary intervention in about 50% of women presenting with a history suggesting cervical incompetence. A better alternative for women with a history of or risk factors for CI is transvaginal ultrasonographic follow-up of CL. To facilitate the comparison of studies of CI, the authors suggest a nomenclature reflecting the different stages of prevention: primary, secondary, and tertiary transvaginal cervical cerclage.

Preterm deliveries among women with MacDonald cerclage performed due to cervical incompetence

OBJECTIVE

The study was aimed to assess the impact of obstetric risk factors for preterm delivery among women with MacDonald cerclage performed due to cervical incompetence.

STUDY DESIGN

A cohort study was conducted including all patients with MacDonald cerclage performed at 12-14 weeks gestation due to cervical incompetence (n = 793). Deliveries occurred between the years 1988 and 2002 in a University Medical Center. A multiple linear regression model was used to assess the impact of maternal characteristics as well as pregnancy complications on the length of pregnancy.

RESULTS

The following factors were found to be associated with preterm delivery among these patients, in the univariate analysis: nulliparity, fertility treatments, severe preeclampsia, second-trimester bleeding, premature rupture of membranes (PROM), chorioamnionitis and placental abruption. Using a multiple linear regression model, with backward elimination, the impact of these variables on the length of pregnancy was assessed (R(2) = 0.33, p < 0.001). The mean gestational age at birth among patients without risk factors was 38.1. Second-trimester bleeding reduced gestational age by 6.4 weeks, chorioamnionitis by 5.6 weeks, placental abruption by 5.1 weeks, PROM by 3.2 weeks and severe preeclampsia by 2.4 weeks.

CONCLUSIONS

Second-trimester bleeding, chorioamnionitis, placental abruption, PROM and severe preeclampsia are ominous signs for preterm delivery among patients with MacDonald cerclage performed due to cervical incompetence.

Role of ultrasound in screening patients at risk for preterm delivery

The ultrasound assessment of the cervix has contributed to the understanding of the pathways to preterm birth. Transvaginal ultrasound measurement of the cervix provides an objective and noninvasive tool for the evaluation of cervical status. Despite widespread use of this procedure, standardization of measurement indications, technique, and interval between examinations has not been achieved. The American College of Radiology has recently recommended that the cervix and lower uterine segment be imaged as part of every obstetric ultra-sound examination in the second trimester. These guidelines specifically suggest a search for a short cervix (less than 30 mm) or funneling. The expert panel on women's imaging further recommended evaluating the cervix sonographically on both the initial examination and all follow-up examinations for twin gestations. The American Institute of Ultrasound in Medicine guidelines indicate that evaluation of the uterus, including cervix, should be performed, but does not indicate specifically that the cervix should be measured. In contrast, the American College of Obstetricians and Gynecologists, although recognizing that cervical length assessment may be helpful in predicting the risk of preterm delivery (particularly from a negative predictive value), does not recommend routine use of cervical length measurement because of the lack of proved treatment or intervention methods. A review of the literature suggests that at the time of this writing the role of routine screening of low-risk women with cervical length assessment by ultrasound is not supported. In contrast, in women at risk for preterm delivery(eg, women with a prior history of preterm birth or women with multiple gestations) cervical length assessment may be useful for its negative predictive value. At present, however, there is no therapeutic intervention that has been proved to decrease the risk of preterm delivery in women with a documented cervix on ultrasound.

Effectiveness of cervical cerclage for a sonographically shortened cervix: a systematic review and meta-analysis

OBJECTIVE

The purpose of this study was to determine the effectiveness of cerclage for a shortened cervix on transvaginal ultrasound scanning in terms of the rates of preterm delivery and adverse neonatal and maternal outcomes.

STUDY DESIGN

Pre-MEDLINE and MEDLINE, EMBASE, and the Cochrane Library were searched for human studies that compared cerclage placement to no cerclage on the basis of transvaginal ultrasound findings of a short cervix (< or =2.5 cm). Two authors independently determined eligibility and abstracted data. Meta-analyses were conducted when possible.

RESULTS

Thirty-five studies were reviewed; 6 studies were eligible and were included in the analysis. There was no statistically significant effect of cerclage on the rates of preterm delivery (<37, <34, <32, and <28 weeks of gestation), preterm labor, neonatal mortality or morbidity, gestational age at delivery, or time to delivery. Birth weight was significantly higher with than without cerclage (P=.004).

CONCLUSION

The available evidence does not support cerclage for a sonographically detected short cervix. A randomized controlled trial is needed to determine whether this intervention will reduce adverse neonatal outcomes.

Cervical incompetence prevention randomized cerclage trial: Emergency cerclage with bed rest versus bed rest alone

OBJECTIVE

The purpose of this study was to compare preterm delivery rates and neonatal morbidity/mortality rates for women with cervical incompetence with membranes at or beyond a dilated external cervical os that was treated with emergency cerclage, bed rest plus indomethacin, versus just bed rest.

STUDY DESIGN

Women with cervical incompetence with membranes at or beyond a dilated external cervical os, before 27 weeks of gestation, were treated with antibiotics and bed rest and randomly assigned for emergency cerclage and indomethacin or bed rest only.

RESULTS

Twenty-three women were included; 13 women were allocated randomly to the emergency cerclage and indomethacin group, and 10 women were allocated randomly to the bed rest-only group. Gestational age at time of randomization was 22.2 weeks in the emergency cerclage and indomethacin group and 23.0 weeks in the bed rest-only group. Mean interval from randomization until delivery was 54 days in the emergency cerclage and indomethacin group and 20 days in the bed rest-only group (P=.046). Mean gestational age at delivery was 29.9 weeks in the emergency cerclage and indomethacin group and 25.9 weeks in the bed rest-only group. Preterm delivery before 34 weeks of gestation was significantly lower in the emergency cerclage and indomethacin group, with 7 of 13 deliveries versus all 10 deliveries in the bed rest-only group (P=.02).

CONCLUSIONS

Emergency cerclage, indomethacin, antibiotics, and bed rest reduce preterm delivery before 34 weeks compared with bed rest and antibiotics alone.

Preterm delivery: an overview

Preterm delivery is the leading factor causing neonatal mortality and morbidity. We have conducted a PubMed literature search to obtain an update on the etiology, diagnostic problems and therapeutic considerations of preterm delivery. Approximately 5-10% of all births are premature. Preterm labor is associated with preterm rupture of membranes, cervical incompetence, polyhydramnion, fetal and uterine anomalies, infections, social factors, stress, smoking, heavy work and other risk factors. The diagnosis is made on the patients presenting symptoms, clinical findings and of progressive effacement and dilatation of the cervix. Biochemical markers of preterm delivery are of minor importance in daily clinical work. Measurement of the cervix, however, is a practical and valuable tool to predict preterm delivery. Cervical cerclage can be useful in selected cases. Antibiotics may help to prevent preterm labor in cases of known etiologic agents (e.g. preterm rupture of membranes and urinary infection). The use of tocolytic agents such as beta-sympathetic receptor stimulators can be advocated for a few days. There is evidence that their long-term use is not beneficial and could even be harmful to the fetus. Calcium channel blockers (nifedipine) and a new selective oxytocin receptor antagonist, atosiban, appear to be as effective as beta-sympathomimetic drugs on uterine contractions with fewer side-effects. Prostaglandin synthetase inhibitors such as indomethacin may prevent uterine contractions and can be used prior to the 32nd week of pregnancy. A single course of corticosteroid treatment in two doses of 12 mg betamethasone or 6 mg of dexamethasone is important for the prevention of respiratory distress between the 24th and 34th weeks of pregnancy. Multiple doses may be harmful and should be avoided. In these cases management should depend on gestation age (fetal maturity). Uterine contractions after 34 weeks' gestation are not an indication for tocolytic treatment.