In addition to these evidence-based recommendations, the guideline development group also identifies points of best clinical practice in the original guideline document.
Classification of evidence levels (1++ to 4) and grades of recommendations (A-D) are defined at the end of the "Major Recommendations" field.
When Should a History-Indicated Cerclage Be Offered?
B - History-indicated cerclage should be offered to women with three or more previous preterm births and/or second-trimester losses.
B - History-indicated cerclage should not be routinely offered to women with two or fewer previous preterm births and/or second-trimester losses.
When Should an Ultrasound-Indicated Cerclage Be Offered?
Women with a Singleton Pregnancy and No History of Spontaneous Mid-trimester Loss or Preterm Birth
B - The insertion of an ultrasound-indicated cerclage is not recommended in women without a history of spontaneous preterm delivery or second-trimester loss who have an incidentally identified short cervix of 25 mm or less.
Women with a Singleton Pregnancy and a History of Spontaneous Mid-trimester Loss or Preterm Birth
A - Women with a history of one or more spontaneous mid-trimester losses or preterm births who are undergoing transvaginal sonographic surveillance of cervical length should be offered an ultrasound-indicated cerclage if the cervix is 25 mm or less and before 24 weeks of gestation.
C - An ultrasound-indicated cerclage is not recommended for funnelling of the cervix (dilatation of the internal os on ultrasound) in the absence of cervical shortening to 25 mm or less.
Who Should Be Offered Serial Sonographic Surveillance ± Ultrasound-Indicated Cerclage?
B - Women with a history of spontaneous second-trimester loss or preterm delivery who have not undergone a history-indicated cerclage may be offered serial sonographic surveillance, as there is evidence to suggest that those who experience cervical shortening are at an increased risk of subsequent second trimester loss/preterm birth and may benefit from ultrasound-indicated cerclage, while those whose cervix remains long have a low risk of second-trimester loss/premature delivery.
D - Women should be informed that expectant management is a reasonable alternative since there is a lack of direct evidence to support serial sonographic surveillance over expectant management. Furthermore, the majority of women with a history of second-trimester loss/preterm delivery will deliver after 33 weeks of gestation.
Can Cervical Cerclage Be Recommended in Any Other Groups Considered at Increased Risk of Spontaneous Preterm Delivery?
B - The insertion of a history- or ultrasound-indicated cerclage in women with multiple pregnancies is not recommended, as there is some evidence to suggest it may be detrimental and associated with an increase in preterm delivery and pregnancy loss.
Uterine Anomalies and Cervical Trauma
B - History- or ultrasound-indicated cerclage cannot be recommended in other high-risk groups such as women with müllerian anomalies, previous cervical surgery (cone biopsy, large loop excision of the transformation zone or destructive procedures such as laser ablation or diathermy) or multiple dilatation and evacuation.
When Should a Transabdominal Cerclage Be Considered?
D - In women with a previous failed transvaginal cerclage, insertion of a transabdominal cerclage may be considered, but this procedure may be associated with increased maternal morbidity.
Should an Abdominal Cerclage Be Performed Laparoscopically?
D - There is no evidence to support a laparoscopic approach over laparotomy in the insertion of an abdominal cerclage.
How Should a Delayed Miscarriage or Fetal Death Be Managed in Women with an Abdominal Cerclage?
D - Successful evacuation through the stitch by suction curettage or by dilatation and evacuation (up to 18 weeks of gestation) has been described; alternatively, the suture may be cut, usually via a posterior colpotomy. Failing this, a hysterotomy may be required or caesarean section may be necessary.
When Should a Rescue Cerclage Be Considered?
D - The decision to place a rescue suture should be individualised, taking into account the gestation at presentation, as even with rescue cerclage the risks of severe preterm delivery and neonatal mortality and morbidity remain high. A senior obstetrician should be involved in making the decision.
B - Insertion of a rescue cerclage may delay delivery by a further 5 weeks on average compared with expectant management/bed rest alone. It may also be associated with a two-fold reduction in the chance of delivery before 34 weeks of gestation. However, there are only limited data to support an associated improvement in neonatal mortality or morbidity.
D - Advanced dilatation of the cervix (more than 4 cm) or membrane prolapse beyond the external os appears to be associated with a high chance of cerclage failure.
There is no clear evidence that the gestation at which the cerclage is inserted affects the magnitude of prolongation in gestation; however, consideration should be given to the fact that, in cases presenting before 20 weeks of gestation, insertion of a rescue cerclage is highly likely to result in a preterm delivery before 28 weeks of gestation. Furthermore, the decision to place a rescue cerclage beyond 24 weeks of gestation should be individualised and take into account the local gestational age of viability. Improvements in neonatal intensive care have advanced the gestational age of viability to 24 weeks of gestation in most developed countries and, given the potential risk of iatrogenic membrane rupture and subsequent preterm delivery, rescue cerclage can rarely be justified after this gestation. [Evidence level 4]
What Information Should Be Given to Women Before Cerclage Insertion?
Before history- or ultrasound-indicated cerclage insertion, a woman should be given information about the potential complications, which should include the following:
B - Cerclage insertion is associated with a doubling in risk of maternal pyrexia but no apparent increase in chorioamnionitis.
B - Cerclage insertion is not associated with an increased risk of preterm prelabour rupture of membranes (PPROM), induction of labour or caesarean section.
B - The insertion of a cervical suture is not associated with an increased risk of preterm delivery or second-trimester loss.
Before any type of cerclage insertion, women should be informed of the following:
D - There is a small risk of intraoperative bladder damage, cervical trauma, membrane rupture and bleeding during insertion of cervical cerclage.
D - Cervical cerclage may be associated with a risk of cervical laceration/trauma if there is spontaneous labour with the suture in place.
Should Amniocentesis to Detect Infection Be Performed Before Rescue or Ultrasound-Indicated Cerclage?
D - In selected cases where there is suspicion of intra-amniotic infection, amniocentesis may be performed to aid the decision about rescue cerclage, as the presence of infection is associated with a poor prognosis.
D - Amniocentesis before rescue cerclage does not appear to increase the risk of preterm delivery before 28 weeks of gestation.
Is Amnioreduction Before Rescue Cerclage Recommended?
D - There is an absence of data to either refute or support the use of amnioreduction before insertion of a rescue cerclage.
Should Perioperative Tocolysis Be Used for Insertion of Cerclage?
D - There is no evidence to support the use of routine perioperative tocolysis in women undergoing insertion of cerclage.
Can Cerclage Be Performed as a Day-Case Procedure?
C - Elective transvaginal cerclage can safely be performed as a day-case procedure.
Which Technique and Material Should Be Used?
D - The choice of transvaginal cerclage technique (Shirodkar versus McDonald) should be at the discretion of the surgeon.
C - There is no current evidence to support the placement of two purse-string sutures over a single suture.
Is There a Role for Post-Cerclage Serial Sonographic Surveillance of Cervical Length?
D - While routine serial sonographic measurement of the cervix is not recommended, it may be useful in individual cases following ultrasound-indicated cerclage to offer timely administration of steroids or in utero transfer.
Is There a Role for Repeat Cerclage When Cervical Shortening Is Seen Post-Cerclage?
D - Placement of an ultrasound-indicated cerclage in the presence of cervical length shortening cannot be recommended as, compared with expectant management, it may be associated with an increase in both pregnancy loss and delivery before 35 weeks of gestation.
Is Fetal Fibronectin Testing Useful Following Insertion of a Cervical Cerclage?
C - Routine fetal fibronectin testing is not recommended post-cerclage. However, the high negative predictive value of fetal fibronectin testing for subsequent delivery at less than 30 weeks of gestation in asymptomatic high-risk women with a cerclage in place may provide reassurance to women and clinicians in individual cases. However, the increased false-positive rate of fetal fibronectin testing in such women makes the finding of a positive result less useful.
When Should the Cerclage Be Removed?
Should the Cerclage Be Removed following PPROM?
D - In women with PPROM between 24 and 34 weeks of gestation and without evidence of infection or preterm labour, delayed removal of the cerclage for 48 hours can be considered, as it may result in sufficient latency that a course of prophylactic steroids for fetal lung maturation is completed and/or in utero transfer arranged.
C - Delayed suture removal until labour ensues or delivery is indicated is associated with an increased risk of maternal/fetal sepsis and is not recommended.
Grades of Recommendations
A - At least one meta-analysis, systematic review or randomised controlled trial rated as 1++, and directly applicable to the target population; or
A systematic review of randomised controlled trials or a body of evidence consisting principally of studies rated as 1+, directly applicable to the target population and demonstrating overall consistency of results
B - A body of evidence including studies rated as 2++ directly applicable to the target population, and demonstrating overall consistency of results; or
Extrapolated evidence from studies rated as 1++ or 1+
C - A body of evidence including studies rated as 2+ directly applicable to the target population and demonstrating overall consistency of results; or
Extrapolated evidence from studies rated as 2++
D - Evidence level 3 or 4; or
Extrapolated evidence from studies rated as 2+
Good Practice Point - Recommended best practice based on the clinical experience of the guideline development group
Classification of Evidence Levels
1++ High-quality meta-analyses, systematic reviews of randomised controlled trials or randomised controlled trials with a very low risk of bias
1+ Well-conducted meta-analyses, systematic reviews of randomised controlled trials or randomised controlled trials with a low risk of bias
1– Meta-analyses, systematic reviews of randomised controlled trials or randomised controlled trials with a high risk of bias
2++ High-quality systematic reviews of case–control or cohort studies or high-quality case–control or cohort studies with a very low risk of confounding, bias, or chance and a high probability that the relationship is causal
2+ Well-conducted case–control or cohort studies with a low risk of confounding, bias, or chance and a moderate probability that the relationship is causal
2– Case–control or cohort studies with a high risk of confounding, bias, or chance and a significant risk that the relationship is not causal
3 Non-analytical studies, e.g., case reports, case series
4 Expert opinion