incompetent cervix

an internal os >1.0 cm (by US) is considered dilated
normal cervical length is >3.0 cm
tx: circlage
- contraindicated if fetal parts or cord are seen in the cervical canal
hourglass deformity:
- seen when the cervix is open to the external os
- amniotic membranes herniate through to the vagina

Charles E. Kahn, Jr., MD - 2 February 1995
Last updated: 1 October 2013