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.
Cervical cerclage is the placement of a stitch within and around the perimeter of the cervix, with the aim to reinforce its integrity and keep it closed, to prevent or treat cervical insufficiency and consequent spontaneous preterm birth (PTB). Transvaginal cerclage in pregnancy was first reported in 1955; the case was performed by Dr V. Shirodkar, an Indian obstetrician, in 1951. Many investigators have reported variations on the surgical technique of transvaginal cerclage, and the most common of these is the McDonald procedure. A variety of technical aspects of cervical cerclage have been investigated for their efficacy in prolonging gestation.
Safety and effectiveness of technical aspects of cerclage may vary by the indications for this procedure. When first described, cerclage was used for 2 indications: initially for prior second-trimester loss with painless cervical dilation in the current pregnancy (ie, physical examination indicated) and soon after for recurrent second-trimester loss, not attributable to other causes (ie, history indicated).
Contemporary indications and nomenclature are listed in Table 1 . In women with prior spontaneous preterm birth, singleton gestation, and transvaginal ultrasound (TVU) cervical length of less than 25 mm before 24 weeks, a metaanalysis of randomized trials has shown that ultrasound-indicated cerclage is associated with a significant 30% decrease in preterm birth less than 35 weeks and a significant 36% decrease in perinatal morbidity and mortality. Current guideline statements now support cerclage placement for this indication.
| Name | Indication | Usual GA of placement, wks |
|---|---|---|
| History indicated | Prior multiple (eg, ≥3) second-trimester losses and/or PTBs | 12-14 |
| Ultrasound indicated | Short CL (eg, <25 mm) by TVU | 16-23 |
| Physical examination indicated | Dilated cervix on manual or speculum examination | 16-23 |
These recent efficacy data make a review of the technical aspects of cerclage and their effect on pregnancy outcome timely. An evaluation of the indications, gestational age of placement, contraindications, and complications of cerclage is beyond the scope of this report. Because cerclage placement has not been shown to be beneficial in multiple gestations, the assumption in this review is that cerclage is placed in a woman carrying a singleton. Review of technical aspects of old preconception techniques such as Lash or Mann is not planned because these techniques are used rarely, if at all. Additionally, a review of the technical aspects of transabdominal or laparoscopic cerclage is not planned because these are in many ways technically quite different from transvaginal cerclage.
Our objective was to review the evidence for efficacy of various perioperative technical and management strategies associated with transvaginal cerclage placement, as analyzed by the different indications ( Table 1 ) for this surgical procedure. Each strategy will be reviewed separately. Clinical assessment of the published data will follow evidence-based criteria, emphasizing level I evidence (based on randomized clinical trials [RCT] or metaanalyses) when available.
Sources
MEDLINE, PubMed, EMBASE, and COCHRANE searches were performed 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.
Study selection
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. In the absence of randomized trials adequately covering the intervention or related strategy, analytical data were reviewed. In the absence of experimental or analytical data, observational data were evaluated.
Exclusion criteria included cerclage in multiple gestations, Lash or Mann procedures, cervical occlusion, and open or laparoscopic transabdominal cerclage.
Each aspect of the cerclage technique was reviewed separately. These included preoperative, intraoperative, and postoperative strategies. Preoperative considerations were fetal ultrasound; amniocentesis; screening for infection; and the use of prophylactic antibiotics, tocolytics, and progesterone. Intraoperative considerations included anesthesia method, cervicovaginal preparations, cerclage type (Shirodkar, McDonald), choice of suture, needle and number of stitches, cerclage height, and techniques for reducing prolapsed membranes. Postoperative considerations included outpatient vs inpatient cerclage, activity restriction, and use of reinforcing cerclage.
After each strategy was reviewed, evidence levels were assigned based on the evidence according to the new method outlined by the US Preventive Services Task Force ( Table 2 ).
| Grade | Definition | Suggestions for practice |
|---|---|---|
| A | The USPSTF recommends the service. There is high certainty that the net benefit is substantial. | Offer/provide this service |
| B | The USPSTF recommends the service. There is high certainty that the net benefit is moderate, or there is moderate certainty that the net benefit is moderate to substantial. | Offer/provide this service |
| C | The USPSTF recommends against routinely providing the service. There may be considerations that support providing the service in an individual patient. There is at least moderate certainty that the net benefit is small. | Offer/provide this service only if other considerations support the offering or providing the service in an individual patient |
| D | The USPSTF recommends against the service. There is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits. | Discourage the use of this service |
| I Statement | The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of the service. Evidence is lacking or is of poor quality or conflicting, and the balance of benefits and harms cannot be determined. | Read the clinical considerations section of USPSTF recommendation statement. If the service is offered, patients should understand the uncertainty about the balance of benefits and harms. |
| Levels of certainty regarding net benefit | |
|---|---|
| Level of certainty a | Description |
| High | The available evidence usually includes consistent results from well-designed, well-conducted studies in representative primary care populations. These studies assess the effects of the preventive service on health outcomes. This conclusion is therefore unlikely to be strongly affected by the results of future studies. |
| Moderate | The available evidence is sufficient to determine the effects of the preventive service on health outcomes, but confidence in the estimate is constrained by such factors as: • The number, size, or quality of individual studies. • Inconsistency of findings across individual studies. • Limited generalizability of findings to routine primary care practice. • Lack of coherence in the chain of evidence. As more information becomes available, the magnitude or direction of the observed effect could change, and this change may be large enough to alter the conclusion. |
| Low | The available evidence is insufficient to assess effects on health outcomes. Evidence is insufficient because of the following: • The limited number or size of studies. • Important flaws in study design or methods. • Inconsistency of findings across individual studies. • Gaps in the chain of evidence. • Findings not generalizable to routine primary care practice. • Lack of information on important health outcomes. More information may allow the estimation of effects on health outcomes. |
a The USPSTF defines certainty as a “likelihood that the USPSTF assessment of the net benefit of a preventive service is correct.” The net benefit is defined as a benefit minus the harm of the preventive service as implemented in a general, primary care population. The USPSTF assigns a certainty level based on the nature of the overall evidence available to assess the net benefit of a preventive service.
Study selection
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. In the absence of randomized trials adequately covering the intervention or related strategy, analytical data were reviewed. In the absence of experimental or analytical data, observational data were evaluated.
Exclusion criteria included cerclage in multiple gestations, Lash or Mann procedures, cervical occlusion, and open or laparoscopic transabdominal cerclage.
Each aspect of the cerclage technique was reviewed separately. These included preoperative, intraoperative, and postoperative strategies. Preoperative considerations were fetal ultrasound; amniocentesis; screening for infection; and the use of prophylactic antibiotics, tocolytics, and progesterone. Intraoperative considerations included anesthesia method, cervicovaginal preparations, cerclage type (Shirodkar, McDonald), choice of suture, needle and number of stitches, cerclage height, and techniques for reducing prolapsed membranes. Postoperative considerations included outpatient vs inpatient cerclage, activity restriction, and use of reinforcing cerclage.
After each strategy was reviewed, evidence levels were assigned based on the evidence according to the new method outlined by the US Preventive Services Task Force ( Table 2 ).
| Grade | Definition | Suggestions for practice |
|---|---|---|
| A | The USPSTF recommends the service. There is high certainty that the net benefit is substantial. | Offer/provide this service |
| B | The USPSTF recommends the service. There is high certainty that the net benefit is moderate, or there is moderate certainty that the net benefit is moderate to substantial. | Offer/provide this service |
| C | The USPSTF recommends against routinely providing the service. There may be considerations that support providing the service in an individual patient. There is at least moderate certainty that the net benefit is small. | Offer/provide this service only if other considerations support the offering or providing the service in an individual patient |
| D | The USPSTF recommends against the service. There is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits. | Discourage the use of this service |
| I Statement | The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of the service. Evidence is lacking or is of poor quality or conflicting, and the balance of benefits and harms cannot be determined. | Read the clinical considerations section of USPSTF recommendation statement. If the service is offered, patients should understand the uncertainty about the balance of benefits and harms. |
| Levels of certainty regarding net benefit | |
|---|---|
| Level of certainty a | Description |
| High | The available evidence usually includes consistent results from well-designed, well-conducted studies in representative primary care populations. These studies assess the effects of the preventive service on health outcomes. This conclusion is therefore unlikely to be strongly affected by the results of future studies. |
| Moderate | The available evidence is sufficient to determine the effects of the preventive service on health outcomes, but confidence in the estimate is constrained by such factors as: • The number, size, or quality of individual studies. • Inconsistency of findings across individual studies. • Limited generalizability of findings to routine primary care practice. • Lack of coherence in the chain of evidence. As more information becomes available, the magnitude or direction of the observed effect could change, and this change may be large enough to alter the conclusion. |
| Low | The available evidence is insufficient to assess effects on health outcomes. Evidence is insufficient because of the following: • The limited number or size of studies. • Important flaws in study design or methods. • Inconsistency of findings across individual studies. • Gaps in the chain of evidence. • Findings not generalizable to routine primary care practice. • Lack of information on important health outcomes. More information may allow the estimation of effects on health outcomes. |
a The USPSTF defines certainty as a “likelihood that the USPSTF assessment of the net benefit of a preventive service is correct.” The net benefit is defined as a benefit minus the harm of the preventive service as implemented in a general, primary care population. The USPSTF assigns a certainty level based on the nature of the overall evidence available to assess the net benefit of a preventive service.
Results
Preoperative considerations
Fetal ultrasound
There are no specific randomized trials assessing the effectiveness of performing an ultrasound before a cerclage ( Table 3 ). Based on indirect evidence and clinical common sense, an ultrasound should be performed before every cerclage placement to ensure fetal viability, confirm gestational age, and assess fetal anatomy to rule out clinically significant structural abnormalities. At least a crown-rump length and some method of aneuploidy screening or testing should be offered when cerclage is performed before 18 weeks (eg, history indicated), and an anatomic survey performed when cerclage is planned later (eg, ultrasound or physical exam indicated) (recommendation B; level: low; Table 3 ).
| Variable | Evidence | Historic comparison | |||
|---|---|---|---|---|---|
| History indicated | Ultrasound indicated | Physical examination indicated | Shirodkar, 1955 a | McDonald, 1957 a | |
| Preoperative | |||||
| Fetal ultrasound | Yes (B; low) b | Yes (B; low) | Yes (B; low) | N/A | N/A |
| Amniocentesis | No (D; low) | No (C; low) c | Consider (C; moderate) | N/A | N/A |
| Perioperative antibiotics | No (D; low) | No (D; low) | No (D; low) | No | No |
| Perioperative tocolytics | No (D; low) | Consider (C; low) | Consider (C; low) | No | No |
| Perioperative progesterone | No (D; low) | No (D; low) | No (D; low) | No | No |
| Intraoperative | |||||
| Anesthesia | Spinal (B; low) | Spinal (B; low) | Spinal (B; low) | ND | ND |
| McDonald vs Shirodkar | McDonald (B; moderate) | McDonald (B; moderate) | McDonald (B; moderate) | Shirodkar | McDonald |
| Suture | Operator’s preference (I; moderate) | Operator’s preference (I; moderate) | Operator’s preference (I; moderate) | Human fascia lata (later changed to Mersilene thread) | Silk (but “not ideal”), later #4 Mersilene suture |
| Needle | Operator’s preference (I; low) | Operator’s preference (I; low) | Operator’s preference (I; low) | Aneurism needle | Mayo needle |
| Cerclage height | Place stitch as high as possible (B; moderate) | Place stitch as high as possible (B; moderate) | Place stitch as high as possible (B; moderate) | Place stitch as high as possible | Place stitch as high as possible |
| Number of stitches | 1 (B; moderate) | 1 (B; moderate) | 1 (B; moderate) | 1 | 1 |
| Membrane prolapse management | Operator’s preference (I; low) | Operator’s preference (I; low) | Operator’s preference (I; low) | ND | ND |
| Postoperative | |||||
| Outpatient | Yes (B; moderate) | Yes (B; moderate) | Yes (B; moderate) | ND | ND |
| Activity restriction | No (I; low) | Individualize (I; low) | Individualize (I; low) | Bed rest for 15 days | Bed rest for 3-7 days |
| Repeat cerclage later if necessary | No (D; low) d | No (D; low) d | No (D; low) d | No | Yes (but poor outcome) |
a All physical examination–indicated cerclages;
b USPFTF grade and level of certainty provided in parentheses (see details of scoring in Table 2 );
c Consider offering amniocentesis only if external cervical os is dilated;
d Consider only if cerclage slips off cervix because of poor technique.
Amniocentesis
We could identify no RCT assessing the effectiveness of performing a precerclage amniocentesis. Placing a cerclage in a woman with overt, clinical intraamniotic infection (IAI) places both fetus and mother at great morbidity and even mortality risks and is considered an absolute contraindication. The prevalence of subclinical IAI depends on the clinical circumstance and cerclage indication.
We could identify no published report investigating the prevalence of subclinical IAI in women undergoing history-indicated cerclage, but it is probably present in less than 1% of these women because their cervix is typically closed and long. Therefore, amniocentesis is not indicated before history-indicated cerclage.
Subclinical IAI complicates about 1-2% of pregnancies in women undergoing ultrasound-indicated cerclage. The prevalence can be as high as 4-9% if the fluid is also cultured for Ureaplasma and Mycoplasma species ; however, the clinical significance of colonization with these microbes is unclear. In general, shorter cervical length (CL) is associated with higher rates of IAI. In approximately 75% of cases, women screened with TVU and found to have a short CL will have a closed and long cervix when examined by speculum and/or manual examination, and their rate of IAI is extremely low. The presence of sludge as detected by ultrasound has been associated with IAI in asymptomatic patients with a short cervix. Nonetheless, we could find no report that suggests improved pregnancy outcomes result from using amniocentesis, and thus, it is not recommended.
Subclinical IAI is discovered in approximately 13-28% of women with acute cervical insufficiency (mostly asymptomatic cervical dilatation on digital examination) in the second trimester and who may be considered candidates for physical examination-indicated cerclage. Amniotic fluid harvested from women with cervical dilatation of 2 cm or more, and cultured for Ureoplasma and Mycoplasma, reveals an approximately 50% incidence of IAI.
We could find no RCT evaluating the safety and efficacy of amniocentesis for women with cervical changes prior to physical examination-indicated cerclage, but an ongoing RCT may help address this important clinical issue. Amniocentesis to rule out infection in women with second-trimester cervical dilatation up to 4 cm has not been associated with higher PTB or preterm premature rupture of membranes rates.
Amniocentesis might help select patients who will benefit most from physical examination-indicated cerclage and eliminate from consideration those who will likely not benefit. Although the use of precerclage amniocentesis has been associated with better outcomes compared with management without amniocentesis, women managed with amniocentesis were not compared with the women who declined to have the amniocentesis in these reports. For example, in one study, women without IAI as confirmed by amniocentesis were compared with and had better pregnancy outcomes than women who had either positive cultures or who declined amniocentesis (some of whom likely had positive cultures). If amniotic fluid is sent for culture, it may take several days for the laboratory to confirm no growth, but results from other methods for detecting subclinical IAI such as amniotic fluid Gram stain and glucose can be obtained rapidly.
In summary, amniocentesis is unnecessary for women before history-indicated cerclage (recommendation D; level: low; Table 3 ). There is insufficient evidence to recommend an amniocentesis for women with cervical shortening before ultrasound-indicated cerclage or with the presence of intraamniotic sludge as detected by ultrasound (recommendation C; level: low; Table 3 ). There is also insufficient evidence to recommend an amniocentesis for women with acute cervical insufficiency (ie, cervical dilatation by digital examination) in the second trimester prior to a physical examination-indicated cerclage. Alternatively, amniocentesis can be discussed and offered if utilized to select women for cerclage and exclude those with subclinical IAI, given the high rate (13-28%) of colonization. Subclinical IAI should be considered a contraindication to cerclage (recommendation C; level: moderate; Table 3 ).
Perioperative assessment for genital tract infection and empiric antibiotic treatment
We could identify no specific randomized trial assessing the effectiveness of assessing for genital tract infection and empiric antibiotic treatment before cerclage. There is insufficient evidence to evaluate whether the common practice of preoperative screening for and treating gonorrhea, chlamydia, or other sexually transmitted infections (STIs) is beneficial. STI screening should probably be done based on risk factors.
In women undergoing a history-indicated cerclage, whose cervix is not short or dilated, the empiric use of prophylactic antibiotics is not indicated because this strategy has not been found to be beneficial.
In candidates for ultrasound- or physical examination–indicated cerclage because of cervical changes, the association with IAI and inflammation is directly proportional to the severity of cervical changes (the more the cervix is dilated or short, the higher the incidence of IAI) and indirectly related to the gestational age at which these changes are detected (the earlier in pregnancy the cervix dilates and/or shortens, the higher the incidence of IAI). Ureaplasma urealiticum , if cultured for, is the most common organism isolated.
Four of the RCTs that evaluated the efficacy of ultrasound-indicated cerclage used antibiotics at the time of cerclage. Unfortunately, no separate analysis was performed regarding their effect, except for an abstract, which reported no benefit from the use of antibiotics and tocolytics compared with the use of neither. In at least 2 RCTs, the control group received the same antibiotics as the cerclage group.
Although some small retrospective and poorly controlled studies have suggested benefit to antibiotics (and tocolytics) for physical-indicated cerclage, the evidence is insufficient to recommend their use.
In summary, we recommend caution for use of antibiotics at the time (perioperative) of either ultrasound- or physical examination–indicated cerclage. Antibiotics for the prevention of PTB have been associated with harm in other populations at infectious risk for PTB (recommendation D; level: moderate; Table 3 ).
Tocolytic agents
We could find no randomized trial specifically assessing the effectiveness of prophylactic tocolytics before a cerclage.
Asymptomatic women receiving a history-indicated cerclage, usually performed at 12-14 weeks, are not experiencing contractions and therefore would not be expected to have any benefit from tocolysis.
Painful uterine contractions with cervical change (ie, clinical preterm labor) in symptomatic patients is an absolute contraindication to cerclage placement.
Regarding ultrasound-indicated cerclage, most asymptomatic women with a short CL at less than 24 weeks have evidence of some contractions when they are placed on external monitoring. Usually these are irregular and not felt by the patient who has been screened with a scheduled TVU CL. Cervical mucus inflammatory markers, such as interleukin (IL)-8, fetal fibronectin, and others, have been reported as being helpful in predicting who might benefit from cerclage, but at this time their use is investigational. In a cohort of women with short CL less than 25 mm, those with normal cervicovaginal IL-8 had less PTB with cerclage, whereas in those with elevated IL-8, cerclage was associated with higher rates of PTB, as compared with no cerclage.
Prostaglandin metabolite levels are high both before and after cerclage in women with second-trimester cervical dilatation. These associations raise the question of the utility of tocolytics (including antiinflammatory agents) with (or without) cerclage for asymptomatic women with a short CL. In an RCT, women at high risk for PTB because of both a prior poor obstetric history and a short TVU CL received either indomethacin and an ultrasound-indicated cerclage or bed rest alone. The combination of indomethacin and cerclage was associated with a significantly decreased incidence of PTB compared with those who did not receive either. Thus, the attributable effect of indomethacin could not be formally assessed. This is the RCT, albeit small, in which cerclage seemed to be most effective compared with other similar RCTs. In women who received ultrasound-indicated cerclage, perioperative indomethacin for short TVU CL less than 25 mm at 14-23 weeks did not prevent PTB less than 35 weeks.
In women undergoing physical examination–indicated cerclage, indomethacin has been associated with nonsignificant trends for preventing PTB as compared with no indomethacin.
In summary, there is insufficient evidence to routinely recommend tocolytics at the time of cerclage (recommendation D; level: low for history-indicated cerclage; recommendation C; level: low for ultrasound- and physical examination–indicated cerclage; Table 3 ).
Progestogens
There are no specific randomized trials assessing specifically the effectiveness of giving progestogens before a cerclage. 17-alpha hydroxyprogesterone (17P) has been shown to be effective in preventing recurrent PTB in women with prior spontaneous PTB. Women already on 17P because of a prior PTB, who also have indication(s) for cerclage, should continue 17P.
Although there were no significant statistical differences, the use of 17P in women with prior PTB was associated with trends for a cumulative beneficial effect with ultrasound-indicated cerclage placed for short CL.
In summary, the evidence is insufficient to assess the risks and benefits of progesterone use at the time of cerclage. We do not suggest its routine use perioperatively (recommendation D; level: low; Table 3 ). Women already on 17P because of a prior PTB, who also have indication(s) for cerclage, should continue the 17P.
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