Efficacy of cerclage, progesterone and pessary in preventing preterm birth in women with prior excision of the cervix: A systematic review
Studies have demonstrated an increased risk of preterm birth (PTB) in women with a prior knife cone biopsy (KCB) or large loop excision of the transformation zone (LLETZ). PTB is the leading cause of neonatal morbidity and mortality worldwide. Interventions to prolong pregnancy are indicated following the finding of a mid-trimester cervical length <25mm. Whether cerclage presents superior efficacy over progesterone and the Arabin pessary is a question that remains unanswered.
We searched Pubmed, Scopus and Cinahl databases to identify eligible studies. We included any randomised controlled trials and observational studies comparing either vaginal cerclage, progesterone, intramuscular 17-α hydroxyprogesterone caproate or Arabin pessary to one another or a control group, in pregnant women with prior LLETZ or KCB. Two independent reviewers screened papers for inclusion and assessed risk of bias. Cases of uncertainty were resolved by discussion with a third review author. The GRADE approach was used for quality assessment. All analyses were performed using Revman 5.4.1 and results were presented as forest plots.
We identified 6 eligible retrospective cohort studies for inclusion in this review. All 6 studies reported outcomes for cerclage vs no cerclage. There is no evidence to support the use of history-indicated cerclage to prolong pregnancy in women with prior cervical surgery. There is insufficient evidence to draw conclusions on neonatal outcomes following the siting of a vaginal cerclage. There is no evidence surrounding the use of other interventions to prevent PTB in this cohort.
In women with prior LLETZ or KCB of the cervix, those receiving a vaginal cerclage are at a higher risk of PTB. Results are likely biased due to confounding. Studies comparing interventions to one another are required to determine the comparative efficacy of interventions in preventing PTB in women with prior cervical surgery.