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Radiology
Abnormal Hands Focus on the Thumbs
Built from Obstetric Imaging
What’s inside
9 sections · 73 slides
Overview
- What this topic covers
Why the fetal hand is worth a proper look
A cursory glance at the limbs misses information that changes the diagnosis
- The routine scan usually just counts limbs
- Hand problems run from barely there to whole limb missing
- Why the differential list is so long
- Six ways a hand can be abnormal
- What each of those six groups means
- A second way to sort the same findings
- Never stop at the hand
The normal thumb, and the words used about it
Two phalanges, on the radial side - everything abnormal is a change to that
- Bones of the arm and hand
- The radial side of the forearm
- Radial ray in one line
- The five words used for an abnormal thumb
- Four shapes an abnormal thumb takes
- The same shape, two very different situations
Each thumb pattern and what it suggests
Some thumb findings are close to a signature for one disorder
- Hitchhiker thumb
- Hitchhiker thumb seen before and after birth
- Radially deviated thumb on the 20-week scan
- The same deviated thumb on the hand radiograph
- Broad thumb
- Broad thumb beside a mitten hand
- Small or absent thumb
- Absent thumb on the fetal hand
- What to look at in that image
- Two names to think of first
- Extra digits, and why the thumb side matters
- Six digits on a hand radiograph
Fanconi anemia
A thumb sign now, a failing bone marrow later
- 1-5 per million
- The numbers in words
- The genes behind it
- What actually goes wrong in the cell
- Reading that mechanism in plain words
- Two more laboratory fingerprints
- What might be seen before birth
- Less common prenatal findings
- What shows up after birth
- The blood problem the name refers to
- The cancer risk
Holt-Oram syndrome
The heart-hand syndrome: a radial ray thumb and a septal defect
- 1 in 100,000
- The numbers in words
- What the TBX5 gene does
- Why one gene hits both heart and hand
- What defines the syndrome
- Hand and arm findings on ultrasound
- The detail that helps you recognise it
- The heart half of the syndrome
- A hole in the wall between the upper chambers
- A hole in the wall between the lower chambers
- Fanconi anemia versus Holt-Oram at the bedside
Getting the picture
When the hands can be seen, and how to see the thumb
- When the fetal hand can first be seen
- What that timeline means in practice
- Why the thumb is so easy to miss
- What three-dimensional ultrasound adds
- Where MRI fits
- The classic signs to record
What else it could be
The differential diagnosis from the imaging findings
- Look-alike for Fanconi anemia
- Look-alikes for Holt-Oram, part one
- Look-alikes for Holt-Oram, part two
What happens next
From the abnormal thumb on screen to the plan for the family
- The path after an abnormal thumb is seen
- Referral and testing before birth
- Options for a future pregnancy
- Discussing the harder options
- Monitoring the rest of the pregnancy
- Delivery
- An isolated hand abnormality
- A hand abnormality with other findings
- What the referring physician needs to know
- Key points
- The habit worth keeping
- References
- References (continued)
- References (continued)
- References (continued)
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition