Revisiting the short cervix detected by transvaginal ultrasound in the second trimester: Why cerclage therapy may not help

Objective: The purpose of this study was to identify the risk factors that are associated with increased neonatal morbidity in patients who were treated for sonographic evidence of internal os dilation and distal cervical shortening during the second trimester. Study Design: From May 1998 to June 2000 patients between 16 and 24 weeks of gestation with the following sonographic criteria were randomly assigned to McDonald cerclage or no cerclage: internal osdilation and either membrane prolapse into the endocervical canal at least 25% of the total cervical length but not beyond the external os or a shortened distal cervix