History of mid-trimester loss or short cervix, suspected cervical incompetence
Recommended: Transvaginal Ultrasound for cervical length (CL) is the preferred imaging study for history of mid-trimester loss or short cervix, suspected cervical incompetence. Serial TVUS in second trimester for at-risk patients.
Recommended study
Transvaginal Ultrasound for cervical length (CL)
Serial TVUS in second trimester for at-risk patients. CL < 25 mm before 24 weeks gestation suggests insufficiency.
If the default doesn't apply
Difficult visualization (anterior fibroid, scarring)
US
Translabial / transperineal US
No contrast
Watch-outs
Funneling at internal os
Indicates progressive change; consider cerclage placement.
Pearls
- Measure during voiding-emptied bladder, no probe pressure, multiple measurements over time.
- Cerclage indicated for history of mid-trimester loss + short cervix on TVUS.
- Vaginal progesterone reduces preterm birth in singleton with short cervix.