High Versus Low Transvaginal Cerclage and Pregnancy Outcomes: A Secondary Analysis of the C‐ STICH Trial

OBJECTIVE: To compare pregnancy outcomes following high versus low vaginal cerclage in women at high risk of preterm birth. DESIGN: Secondary analysis of a multi-centre randomised control trial. SETTING: Obstetric units across the UK. SAMPLE: Women participating in the C-STICH trial who received a transvaginal cerclage. METHODS: Cerclage height was classified as high (with bladder dissection) or low (without bladder dissection). Cerclage technique was determined by clinician preference. For each outcome, regression models were fitted adjusting for pre-specified prognostic variables. MAIN OUTCOME MEASURES: The primary outcome was pregnancy loss defined as miscarriage and perinatal mortality (stillbirth or neonatal death within 7 days). Secondary maternal outcomes included miscarriage and previable neonatal death, stillbirth, gestational age at delivery, preterm pre labour rupture of membranes and sepsis. Secondary neonatal outcomes included early and late neonatal death and sepsis. RESULTS: Of the 2048 women randomised to C-STICH, 1995 had details of cerclage height available: 24% received a high and 76% a low vaginal cerclage. Pregnancy loss rates were similar between the groups (6.5% vs. 7.3%; adjusted risk ratio 0.88, 95% CI: 0.57-1.34). High vaginal cerclage was associated with an increase in mean gestational age of 0.5 weeks and a lower rate of births before 32 weeks (adjusted risk ratio 0.57, 95% CI: 0.37-0.86). CONCLUSION: Pregnancy loss rates do not differ significantly between high and low vaginal cerclage techniques. High cerclage may be associated with a small prolongation of pregnancy in women at high risk of preterm birth and reduction in preterm births < 32 weeks.