Funneling of the internal cervical os

Last revised by Henry Knipe on 16 Sep 2018

Cervical funnelling is a sign of cervical incompetence and represents the dilatation of the internal part of the cervical canal and reduction of the cervical length.

Greater than 50% funnelling before 25 weeks is associated with ~80% risk of preterm delivery.

Radiographic features

Good scanning technique is essential, as excessive pressure with the probe, or presence of a distended bladder may artificially narrow the canal. Preferably, a transvaginal scan is recommended for accurate assessment of cervical length and measurement of funneling.

  • percentage funnelling: funnel length/(functional cervical length + funnel length)
  • shape of funneling: V-shaped or U-shaped. U-shaped funneling have a higher risk of preterm delivery 4
  • depth and width of the funnel: V-shaped funnel has a depth with no width; however, U-shaped funnel has the width as an important parameter

See also

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