Shortening of the cervical canal

Last revised by Karwan T. Khoshnaw on 15 Sep 2018

Shortening of the uterine cervical canal as the name implies refers to an abnormal shortening of the uterine cervical length. It is considered a sign of cervical incompetence during pregnancy and can lead to premature delivery.


  • primary (i.e. congenital/idiopathic)
  • secondary
    • multiple gestations
    • obstetric/gynecological trauma
    • increase in prostaglandins 4

Radiographic features

In a single pregnancy, the cervical length is usually considered to be ~4 cm up until 37 weeks, while in multifetal pregnancy it can often be <3 cm by 32 weeks 1

An endocervical canal length of <3 cm or <2.5 cm (depends on the institution) is considered diagnostic of shortening 4,5.

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