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Radiology
Twin Reversed Arterial Perfusion Sequence
Built from Obstetric Imaging
What’s inside
12 sections · 82 slides
Overview
- What this deck covers
One placenta, two very different twins
What the condition actually is, in plain terms
- Two twins, one working heart
- Why the blood flow runs backwards
- Who actually carries the risk
- Acardiac twin and normally formed twin in one uterus
- The words you need
- Sharing a placenta is the precondition
How often it happens
A rare diagnosis, but perhaps less rare than the textbooks say
- 1:35,000
- The rarity may be overstated
- Which twin pregnancies are affected
Why it happens
An early vascular accident, and what it does to both twins
- The leading explanation
- How an acardiac twin comes about
- Why the acardiac twin is so deformed
- A second, less accepted theory
- From ‘acardia’ to ‘TRAP’
- Radiograph of an acardiac fetus with no skull
- Postmortem appearance of an acardiac fetus
- What those two specimens teach
What the acardiac twin looks like
From a recognisable body to a shapeless mass
- The clinical picture in one line
- Common features of the acardiac mass
- Acardiac twin seen in two and three dimensions
- What to notice in those two images
Making the diagnosis with ultrasound
Three findings, and the one that settles it
- The findings that secure the diagnosis
- From suspicion to confirmed diagnosis
- Absent heartbeat is the rule, not the law
- Rudimentary heart and retrograde flow on colour Doppler
- Reading the colour on those images
- “
- Arterial blood flow entering an acardiac twin
- Why ‘pathognomonic’ matters here
Watching the pump twin
The baby with something to lose, and how to monitor it
- Why the pump twin can fail
- Signs the pump twin is decompensating
- Reading those warning signs
- The pump twin needs more than a heart check
- Fetal echocardiography is recommended
- Cord abnormalities in both twins
- Umbilical cord in cross-section
- Why cord anatomy is worth knowing here
Sizing the acardiac twin
Why size predicts how hard the pump twin has to work
- Ordinary measurements do not work
- One commonly used weight formula
- Measuring the longest dimension of an acardiac mass
- What the calipers are doing
- Why the size ratio matters
- Outcomes above and below a ratio of 0.7
- Where those numbers come from
- Doppler adds a second layer
What else it could be
Two look-alikes, and the finding that separates them
- Sorting an abnormal cotwin with no heartbeat
- Mistaking TRAP for a dead twin
- Mistaking TRAP for a placental tumour
Treatment
Cutting the acardiac twin out of the circulation
- The goal of management
- When intervention is recommended
- Treat everyone, or treat on findings?
- Findings that commonly trigger therapy
- Sometimes the problem settles itself
- Cord occlusion: the shared principle
- Ways to occlude the cord
- Radiofrequency ablation in plain terms
- Why a small needle matters
- What the published series report
- Published outcomes of radiofrequency ablation for TRAP
- Twin Reversed Arterial Perfusion Outcomes
- Twin Reversed Arterial Perfusion Outcomes: pregnancy outcome
- Twin Reversed Arterial Perfusion Outcomes: weight ratios
- Notes attached to that table
- 80%
- What that registry actually was
- Reported and theoretical risks of RFA
- The problem before 16 weeks
Outcomes
What happened before intervention, and what is known after
- Outcome without intervention
- 79%
- Reading that older review
- Life after birth
What the referring physician needs to know
The message to carry away
- The referral message
- Key points: what it is
- Key points: what to do
- The whole topic in five steps
- Suggested readings
- Suggested readings (continued)
- References
- References (continued)
- References (continued)
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition