The comparative analysis of laparoscopic or transvaginal cerclage in pregnancies with cervical insufficiency: a retrospective cohort study

Efficacy of transabdominal cerclage by open laparotomy relative to existing risk factors

INTRODUCTION

To prevent extreme preterm birth, women with cervical insufficiency are eligible for transabdominal cerclage in case of prior failure or technical impossibility for transvaginal cerclage. This study aimed to identify patient characteristics that affect the success rate of transabdominal cerclage to prevent extreme preterm birth in women with cervical insufficiency.

MATERIAL AND METHODS

Single-center retrospective cohort study in 87 women who underwent transabdominal cerclage by open laparotomy during first and early second trimester of pregnancy over a 20-year period. Participants were divided into subgroups according to indication for the intervention. Linear regression and meta-regression-analyses were performed to assess the effect of mean cervical length (before and after transabdominal cerclage placement) and gestational age of previous preterm birth, on gestational age at delivery. Kaplan-Meier analysis was performed to evaluate treatment effects on gestational age at delivery.

RESULTS

Of 87 women, 62 women underwent a history-indicated and 25 an ultrasound-indicated transabdominal cerclage. Fetal survival was 92%: 91% in the history-indicated and 96% in the ultrasound-indicated group. Median gestational age at delivery was 37.3 weeks, with a median pregnancy prolongation of 163.0 days and with 92% of deliveries ≥34 weeks. Between groups, irrespective of singleton and twin pregnancies, outcomes were comparable. Gestational age at delivery was neither affected by cervical length before transabdominal cerclage, distance between transabdominal cerclage and external os, gestational age of previous preterm birth nor additional progesterone treatment.

CONCLUSIONS

The efficacy of transvaginal cerclage placement via open laparotomy during high-risk pregnancy is favorable and relates to fetal survival of 92%. Regardless of indication, pregnancy outcomes after transabdominal cerclage are similar, and independent of gestational age at previous preterm birth, cervical length before transabdominal cerclage placement, distance between transabdominal cerclage and external os, and additional progesterone administration.

Mechanical analysis of cerclage as a treatment for cervical insufficiency

BACKGROUND

The primary treatment for cervical insufficiency is cervical cerclage (mechanical support) with vaginal progesterone (biochemical support). Cerclage is a surgical procedure that mechanically increases the tensile capacity of the cervix. Therefore, it is necessary to analyse the effects of cerclage from a mechanical point of view.

PURPOSE

To analyse cerclage techniques based on physical principles and mechanical forces.

METHODS

We assumed that the cervix is a thin-walled pressure vessel and applied a uniform vertical distribution model, a linear vertical model, and a non-linear vertical distribution model.

RESULTS

According to our model analysis, the higher the position of the thread, the thicker the thread used, and the greater the number of threads, the more effective the confining force on the suture, when performing a cerclage.

CONCLUSION

It is necessary to provide an appropriate cerclage for each patient based on these mechanical characteristics, in addition to considering the risks and benefits and biochemical interactions of the cerclage.