Cervical Length · Cervical Insufficiency Transvaginal Ultrasound

Step-by-step decision

Choose step by step as prompted; reaching an endpoint gives the management recommendation. You can go back a step or restart anytime.

🎓 Want to practice? Do a case challenge with this pathway → (get a case, choose management step by step, scored).

Full pathway

1. [Decision] Mid-trimester transvaginal cervical length (singleton)
   Mid-trimester transvaginal cervical length (singleton)? (Transvaginal ultrasound (TVU) is the gold standard (empty bladder, sagittal plane, internal to external os, no over-compression, cervix about 50% of the screen). Funneling (internal os opening, progressing downward from the internal os) ± amniotic fluid sludge → raised risk (just document presence, no need to measure funnel depth/width). Short cervix = CL ≤25 mm (<24 weeks).)
   • CL >25 mm, no preterm history → CL >25 mm · low risk
   • CL ≤25 mm, no spontaneous preterm history (incidental) → Short cervix no preterm history · vaginal progesterone
   • CL ≤25 mm and spontaneous preterm history / cervix already dilated → Short cervix + preterm history → cerclage + progesterone
2. [End] CL >25 mm · low risk
   CL >25 mm: low preterm risk; with a preterm history, serial monitoring at 16–24 weeks + progesterone; no intervention needed if asymptomatic.
3. [End] Short cervix no preterm history · vaginal progesterone
   CL ≤25 mm, no spontaneous preterm history (incidental mid-trimester): vaginal progesterone 200 mg/day to ~34–36 weeks; cerclage benefit is unclear for isolated short cervix without preterm history; document funneling/sludge; pessary is ineffective.
4. [End] Short cervix + preterm history → cerclage + progesterone
   CL ≤25 mm and spontaneous preterm history (<24 weeks): ultrasound-indicated cerclage + vaginal progesterone; cervix already dilated/bulging membranes → consider rescue cerclage; prior painless mid-trimester loss = cervical insufficiency, history-indicated cerclage.

Source guidelines & references

• Transvaginal cervical length screening and short cervix management (ACOG; NICE)

This pathway is our own synthesis of the decision logic in the guidelines above (not the guideline verbatim); thresholds and workflows change as guidelines update — in practice follow the latest guideline, your institution's protocol and the individual patient.

Other pathways