Second trimester pregnancy loss and preterm delivery may be considered an obstetrical syndrome. A multifactorial approach to the diagnosis of true cervical insufficiency is paramount. Surgical modification of the cervix benefits those with at least 3 second trimester losses or preterm deliveries, those with 2 early second trimester losses when no other cause for loss is identified, and those with a previous second trimester loss or preterm birth with ultrasound findings of a short cervix defined as less than 25 mm. Multifetal pregnancies do not benefit from cerclage and causes harm in those with ultrasound or physical examination identified cervical changes.