<qa>  What is the SIS performed for all patients at the same setting of TVUS?SIS will be performed for all patients at the same setting of TVUS. With the patient in the lithotomy position, . A 6 or 8 French Foleys catheter will be inserted through the external cervical os into the cervical canal. Its balloon tip will be inflated with 2-3 mL of saline, depending on patient comfort, to help hold it in place. The speculum was then removed. 