FIGURE 8 Tying the cerclage
Make the first tie as close as possible to the cervical core so that it creates a visible, and palpable, depression in the soft tissue at the area of the knot. Inset: Cerclage tie secured by a figure of 8.
9. Trim the ends of the tape to 3 cm to facilitate easy identification and manipulation at the time of removal. Place a figure of 8, using bright blue Prolene #1 (Ethicon), around the knot, securing it to the posterior surface of the cervical core (FIGURE 9). The tape should encircle the firm part of the cervix near the internal os, as shown by transvaginal ultrasonography in FIGURE 10. (Helpful hint: Place surgical gauze under pressure around the cervix to support hemostasis after removal of the clamps. Remove the gauze approximately 30 minutes after the procedure.)
FIGURE 9 Mark the cerclage
Place a figure of 8, using bright blue Prolene #1, around the knot of the cerclage, securing it to the posterior surface of the cervical core.
FIGURE 10 Final placement
The cerclage tape should encircle the firm part of the cervix near the internal os, as shown by transvaginal ultrasonography.
Technique is applicable to most cerclage procedures
One potential limitation of this technique is the fact that it is based on surgical experience in a single center, although it includes more than 2,000 operations performed at that center. Therefore, we lack data on the ease of teaching and reproducing this technique. Nevertheless, our approach incorporates various elements that previously were proposed to enhance the effectiveness of cerclage. It likely will be applicable to most cerclage procedures, with the exception of a few unique cases. These unique cases—most of them involving the failure of conventional cerclage—may require more elaborate technique.
As for data on the location of biomechanical stresses on cervical tissue during pregnancy, the literature indicates that the forces of maximum deformation begin internally at the level of the cervico-uterine junction.12 If not successfully resisted, these forces will proceed down along the cervical canal and could lead to premature pregnancy loss.
Although the superiority of a high cerclage has not yet been proven clinically, it appears to be more effective than low placement because it is more likely to provide support at the right location.
As pregnancy progresses, the challenge to the cervix increases—not only because of increasing uterine volume but also because of greater uterine activity. Both raise the risk of cerclage slippage and displacement.15 To address these issues, several investigators proposed an approach that excludes the slippery mucosal layer.1,13,14
The original Shirodkar cerclage and its modifications—but not the McDonald cerclage and its subsequent modifications—included an “anchor” suture attaching the cerclage band to the firm cervical stromal layer as a means to prevent downward slippage and displacement.1 It remains to be seen whether this addition of a figure of 8 using nonabsorbable suture, as proposed here, is indeed effective.
We believe that, if a standardized way to perform effective cerclage can be agreed upon, we also might devise a better way to compare results based on proper patient selection.
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