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Radiology
Monochorionic Monoamniotic Twin Gestations
Built from Obstetric Imaging
What’s inside
7 sections · 74 slides
Overview
- What you will learn
Two words, one diagnosis
How many placentas, and how many bags of water
- Start with the two words
- What the diagnosis looks like
- Why these twins are always identical
- Identical and non-identical twins side by side
- Read the diagram carefully
- When the egg splits decides everything
- The splitting clock
- 1 : 10,000
- The rarest kind of twin pregnancy
Finding them on the scan
What to look for, when to look, and what proves it
- How a twin pregnancy comes to light
- Only the scan can answer the real question
- How the scan is worked through
- The systematic check in words
- When to look, and why to look again
- Two fetal heads on a single scan
- Seeing two babies is only step one
- Tangled cords settle the diagnosis
- Cord entanglement before and after birth
- Reading the entanglement picture
- Colour Doppler close-up of the tangled cords
- First-trimester scan of a shared sac
- Entanglement can show up very early
- Counting yolk sacs as a shortcut
- Gestational sac, yolk sac and embryo labelled
- What the labelled picture teaches
- Cords that start next to each other
- Cord insertions side by side on one placenta
- Doppler view of the two insertion points
- The same insertions in the delivered placenta
- Why the two insertion pictures matter
- A delivered placenta with its cord and membranes
- What a placenta shows after birth
Traps and look-alikes
Why an absent membrane is weaker evidence than it feels
- Not seeing a membrane proves little
- Low fluid makes the membrane vanish
- Two fetuses seen without a dividing membrane
- Why this scan is a trap
- The stuck twin
- What else could this be
- Working through the alternatives
- Twins that become one-sac later
What can go wrong
Twin risks, shared-placenta risks, and the cords
- The risk map
- Risks every twin pregnancy carries
- Risks that come from sharing a placenta
- TTTS here is rarer but harder to catch
- How tangled cords cause harm
- How dangerous is entanglement
- > 50%
- Birth defects are more common
Looking after the pregnancy
Detailed scans, repeated checks and a planned early birth
- Checking the babies' anatomy
- Screening and testing for chromosomes
- Telling twin A from twin B is hard
- The surveillance plan across pregnancy
- Watching for placenta-sharing problems
- Measuring the cervix
- When the cervix is already open
- Why heart-rate testing beats the ultrasound score
- Admission for monitoring
- What Doppler adds
- Steroids and a planned early birth
- The delivery plan
After birth and the bottom line
Newborn care, the referral message and key points
- After delivery
- What the referring doctor needs to know
- What the referral must lead to
- Key points
- Key points continued
- References
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- Suggested readings
- Suggested readings (continued)
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition