The incompetent cervix--a review.

Repeated midtrimester pregnancy loss due to incompetence of the cervical os has long been recognised as a treatable condition, but the aetiology, diagnosis and management of this condition remain controversial. Some women have clinically obvious cervical incompetence and may benefit from a cerclage operation, but criteria for early diagnosis are not universally agreed upon. Universal agreement on the aetiology and diagnostic criteria is a prerequisite for determining which women may benefit from surgical management.