Cervical cerclage to reinforce the cervix by placing a cervical stitch was described in the 1950s by
Shirodkar [57] and McDonald [58]. Indications for both types of cerclage have been obstetrical history,
physical examination, ultrasound findings, or a combination of the above.
In high-risk singleton gestations, cerclage reduces the rate of preterm delivery before 35 weeks as
well as composite perinatal mortality and morbidity [59]. A meta-analysis of five randomised trials that
included a total of 504 women with singleton gestations, previous preterm delivery, and cervical length
less than 25 mm before 24 weeks showed that, having a McDonald or Shirodkar cerclage reduced the
rate of preterm delivery before 35 weeks (RR 0.7, 95% CI 0.6 to 0.9) as well as composite perinatal
mortality and morbidity (RR 0.6, 95% CI 0.5 to 0.9) [59]