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Radiology
Cervical Length and Spontaneous Preterm Birth
Built from Obstetric Imaging
What’s inside
13 sections · 104 slides
Overview
- What you will learn here
Preterm birth: the size of the problem
Who is affected, and why prediction matters
- What counts as a preterm birth
- 1 in 10
- The rate fell, then climbed back
- The strongest warning sign we have
The cervix and what short means
Anatomy, the measurement, and the cut-offs
- The cervix has two opposite jobs
- Where the cervix sits in the female pelvis
- Closed cervical canal in an early pregnant uterus
- What is actually being measured
- Short means different things at different times
- The same 25 mm, four different meanings
- Why that percentile shift matters
- Other definitions used in the trials
- A short cervix is commoner in twins
How well cervical length predicts preterm birth
Three things change the answer
- Three things change how good the prediction is
- The shorter it gets, the steeper the risk
- What the pooled evidence shows
- Finding it early is worse news
- Twins start from a higher baseline
- The same test performs differently in different women
- A practical way to grade the risk
- Risk of Spontaneous Preterm Birth (SPB) Before 35 Weeks of Gestation
Why the cervix shortens
Cause, consequence, or both?
- The question nobody has settled
- Several roads lead to the same short cervix
- Infection turns up remarkably often
- The shorter the cervix, the more likely the bugs
- Inflammation switches on late and hard
- Contractions are a surprisingly weak explanation
- A stretched uterus is a different story
- The old idea of a weak cervix
- Why that label is now questioned
- The missing measurement
- Where the pathophysiology leaves us
Finding a short cervix
Who gets screened, when, and how often
- It almost never announces itself
- The cervix belongs in the anatomy scan
- Who the guidelines say to screen
- How often to repeat the scan
- Only trained hands should do it
How to measure the cervix
Transvaginal first, transabdominal as a screen
- Why the transvaginal route wins
- The transvaginal sequence, step by step
- Getting the probe pressure right
- Drawing the line
- Measuring the cervix through the vagina
- What to notice in those two images
- The transabdominal alternative
- Five landmarks to hunt for
- Measuring the cervix through the abdomen
Funnelling, sludge and other findings
What the picture shows besides a number
- The cervix opens in a predictable order
- The shape sequence as the cervix gives way
- Funnel shapes at the internal os
- What to notice in the funnel images
- Does funnelling add anything?
- Why treatment still keys off length
- Sludge in the amniotic fluid
- What about MRI?
Treating a short cervix: vaginal progesterone
Two old ideas, retested with modern trials
- Two treatments, both older than the problem
- Screening 24,000 women to find the short ones
- What that trial found
- A second trial, a different preparation
- The gel trial results
- Pooling everything: the EPPPIC review
- What EPPPIC concluded
- What is actually available now
Treating a short cervix: cerclage
The stitch, and who actually benefits
- Stitch placed around the cervix
- What the picture shows
- Three questions decide the stitch
- Where the decision path splits
- No prior preterm birth: the headline answer
- But one subgroup did benefit
- When the cervix keeps shortening on treatment
- Prior preterm birth: the early evidence
- The NICHD MFMU cerclage trial
- What that trial showed
- The pooled answer for prior preterm birth
- When the cervix is already open
- What exam-indicated cerclage buys
- Before you offer the stitch
The pessary
A promising start that later trials did not confirm
- Where the pessary stands today
- The trial that raised hopes
- A large trial that did not agree
- The trial that stopped early
- Why that trial was stopped
Twins
Higher baseline risk, weaker evidence
- Twins start closer to the edge
- Cerclage in twins with a short, closed cervix
- Cerclage in twins with a dilated cervix
- Two very different answers in twins
- Progesterone in twins: the evidence splits
- The meta-analysis that found a benefit
- The pessary in twins
- The trial still running
- So should twins be screened at all?
Putting it together
What the referring physician needs to know
- What the referring physician needs to know
- Where the guidance stops short
- Key points to carry away
- Key points, continued
- The whole topic in one line each
- References
- References (2 of 6)
- References (3 of 6)
- References (4 of 6)
- References (5 of 6)
- References (6 of 6)
- Suggested reading
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition