**4. Cervical cerclage**

Cervical cerclage is effective in reducing the risk of preterm birth in high-risk pregnancies. Studies have proven that it contributes to statistically significantly fewer premature births before 33 weeks of gestation.

Specifically, in women with cervical cerclage, the rate of deliveries before 33 weeks was 13% compared to 32% observed in women without cervical cerclage Furthermore, a meta-analysis of randomized trials investigating the effectiveness of ultrasound-guided cervical suture placement in women with a history of secondtrimester miscarriage or preterm delivery concluded that deliveries before 35 weeks' gestation were statistically significantly less in cases where suture cervical cerclage was placed compared to cases where some other treatment was followed (RR 0.57; 95% CI 0.33, 0.99 and RR 0.61; 95% CI 0.40, 0.92, respectively). Thus, cervical suture placement as a means of preventing preterm delivery in singleton pregnancies is indicated according to the guidelines in the following cases [32–36]:

History of one or more second-trimester miscarriages associated usually in a future pregnancy with painless cervical dilation and absence of signs of labor or rupture of fetal membranes. History of cervical cerclage in a previous pregnancy due to painless dilatation of the cervix during the second trimester. Painless cervical dilatation was found on physical examination. Ultrasound findings in combination with a history of preterm delivery, i.e. preterm delivery before 34 weeks in a previous pregnancy and cervical length in the current pregnancy below 25 mm as found in an ultrasound check before 24 weeks of pregnancy [36–40].

However, the effectiveness of placing a suture around the cervix of women carrying twins is not entirely certain also, whether the indications for cervical suture placement in twin pregnancies are equivalent to those in singleton pregnancies is still under investigation.

A study comparing selective cervical ligation with simple observation, but without determining whether and what risk factors were present, found no statistically significant difference between the two comparison groups. This result is similar to that of singleton pregnancies where routine cervical cerclage in all pregnancies without appropriate case selection has been found to offer no benefit [36–40].

A meta-analysis of randomized trials involving the use of cervical suture ligation in both singleton and twin pregnancies according to cervical length and setting a threshold of less than 15 mm in singleton pregnancies and less than 25 mm in twin pregnancies concluded that in singleton pregnancies with a positive history, there was a statistically significant benefit in reducing the risk of delivery before 35 weeks (RR 0.74, 95% CI 0.57, 0.96). When there was a miscarriage or premature birth in the second trimester in the history, the probability of risk was even lower (RR 0.57 and 0.61, respectively). However, in twin pregnancies without a positive history, it was seen that cervical ligation increased by 2 times the risk of delivery before 35 weeks of gestation (RR 2.15, 95% CI 1.15, 4.01). This result, however, comes from a single study that included a small number of cases, although it is reasonable to conclude that the placement of a cervical cerclage suture in twin pregnancies in which a short cervical length is found in a random check without the presence of a history, does not offer

#### *Cervical Length and Perinatal Outcome DOI: http://dx.doi.org/10.5772/intechopen.113835*

a benefit. However, the possible benefit of twin pregnancies with a short cervical length and the presence of risk factors has not yet been clarified.

Furthermore, placing a cervical ligation suture in women with twin pregnancies due to a cervical length of less than 25 mm before 24 weeks gestation and using the sequential cervical length measurement approach found that ligation may clinically significantly reduce preterm birth before 34 weeks compared with conservative management such as bed rest (36.7% in the band group vs. 50% in the rest group) [36–42].

This study demonstrated that suture ligation in twin pregnancies does not harm but instead provides a benefit when cervical length decreases on consecutive ultrasound measurements. Data on the placement of suture cervical cerclage in twin pregnancies with a history of preterm birth or second-trimester miscarriage are unfortunately lacking.
