Cervical cerclage (tracheloplasty), also known as a cervical stitch, is used for the treatment of cervical incompetence, a condition where the cervix has become slightly open and there is a risk of miscarriage because it may not remain closed throughout pregnancy. Usually this treatment would be done for a woman who had suffered one or more miscarriages in the past, in the second trimester of pregnancy.

The treatment consists of a strong suture being inserted into and around the cervix early in the pregnancy, usually between weeks 12 to 14, and then removed towards the end of the pregnancy when the greatest risk of miscarriage has passed.

From http://en.wikipedia.org/wiki/Cervical_cerclage