Short cervix in twin pregnancies: current state of knowledge and the proposed scheme of treatment

Short cervical length (SCL) should be defined as a cervical length (CL) less than 25 mm between 18 and 22 weeks of gestation. This definition of SCL is fully applicable for singleton pregnancies, but is not entirely correct for twin pregnancies.Thus far, there are no explicit guidelines on the treatment of twin pregnancy with a SCL. The use of progesterone in the treatment of SCL, and preterm birth (PTB) prophylaxis, is one of the interventions recommended by the Polish Ministry of Health for cervical shortening in singleton pregnancies. In twin pregnancies, attention should be paid to the potential benefits of using vaginal progesterone in the reduction of neonatal mortality as well as lowering the incidence of neonatal complications; specifically in a group of patients with twin pregnancies and CL less than 25 mm or below the 10th percentile for the gestational age, measured between 18 and 22 weeks of gestation. It remains difficult to ascertain the benefits of using pessaries in the prevention of PTB in twin pregnancies. The usage of pessaries appears to be beneficial only in selected subpopulations of patients with asymptomatic CLs less than 25 mm or 10th percentile for gestational age. The use of cervical cerclage in PTB prevention in twin pregnancies is limited to cases where the external cervical dilation is > 1 cm and < 4 cm between 16 and 24 weeks of gestation. Considering the necessity for screening for asymptomatic shortening of the cervix in twin pregnancies, establishing a standard practice in the case of positive screening results is seemingly crucial.