Perspectives on the management of the short cervix identified by transvaginal ultrasound during pregnancy: an update for Canadian obstetrical caregivers.

A shortened cervix is often considered to be equivalent to cervical insufficiency, and a cerclage may be offered as an intervention to prolong pregnancy; however, we may not be differentiating between true cervical insufficiency and intrauterine causes of cervical shortening. A recent meta-analysis found no significant reduction in preterm birth < 35 weeks' gestation in women with cerclage compared with no cerclage in the total population of women studied. However, there was a potentially significant reduction in preterm birth < 35 weeks among women with a singleton pregnancy (relative risk [RR] 0.74; 95% confidence intervals [CI] 0.57-0.96), with a singleton pregnancy and a previous preterm birth (RR 0.61; 95% CI 0.40-0.92), and with a singleton pregnancy with a previous mid-trimester loss (RR 0.57; 95% CI 0.33-0.99). An increase was found in preterm birth among twin gestations with cerclage placed for a shortened cervix on transvaginal ultrasound (RR 2.15; 95% CI 1.15-4.01). This unexpected finding underscores the possibility of harm with this intervention. This intervention deserves further study. A national registry or database would allow us to identify women who may benefit more significantly from cerclage by collecting data on possible confounding effects such as concomitant intrauterine infection or placental disease.