<prompt> Cervical incompetence is when the cervix measures less than1 cm1.5 cm2 cm2.5 cm  <response>: Cervical incompetence diagnosis : History of repeated midtrimester painless cervical dilatation with escape of liquor amnii followed by painless expulsion of products of conception Passage number 6-8 Hegor dilator beyond internal os without resistance Absence of opening snap on withdrawal of Hegar dilator Hysterography showing funnel shaped shadow During pregnancy ,sonography showing sho cervix 25 mm. Speculum examination showing dilatation of internal os with herniation of membranes. Ref: Dutta Obs 9e pg 161. 