diagnosis
Last reviewed 01/2018
Incompetence may be ascertained from the patient's history and on vaginal examination.
Other useful investigations include:
- hysterography - radiography of the uterus after instillation of contrast medium - shows a characteristic funnelling of the endocervical canal
- retrograde dilatation - easy insertion of Hegar dilators
- ultrasound scan - incompetence if: - diameter of internal os greater that 15 mm in first trimester; or greater than 20 mm in 2nd trimester; or - endocervical canal greater than 8 mm; or - length of cervix less than 1.5 cm