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Radiology
Fetal Macrosomia and Overgrowth Syndromes
Built from Obstetric Imaging
What’s inside
15 sections · 179 slides
Overview
- What this topic covers
- Two words you will meet on every page
How a baby grows
Cells, hormones and imprinted genes — the machinery that decides final size
- Growth is two things happening at once
- Which hormones actually drive fetal growth
- When the growth-factor system breaks
- Why overgrowth and cancer travel together
- Imprinting: it matters which parent the gene came from
- The chromosome region behind so much of this
- From gene to big baby
- Two very different reasons a fetus is big
- Ways to describe overgrowth
- The rest of the vocabulary, and why diagnosis is late
- Blood vessel anomalies: two different things
Fetal macrosomia
What the word means, how common it is, and what makes a baby grow too large
- Why we say 'suspected' and not 'diagnosed'
- LGA and macrosomia are not the same word
- ≥4500 g
- 6.9%
- What pushes a fetus over the line
- Maternal weight and maternal sugar
- How maternal sugar becomes a big baby
- The dose-response behind that cascade
- 25.3%
- The remaining risk factors
What macrosomia costs
The findings at the bedside, and the risks carried by the baby and the mother
- How it is picked up
- A diabetic big baby has a different shape
- What the baby faces
- 9–24%
- Reading the neonatal outcome table
- Neonatal outcomes by macrosomia class: control and grade 1
- Neonatal outcomes by macrosomia class: grades 2 and 3
- Neonatal outcomes by macrosomia class, as printed
- What the outcome table is telling you
- What the mother faces
Measuring and managing the big fetus
How well the scan performs — and the two arguments that never quite settle
- How fetal weight is estimated
- How well ultrasound actually performs
- Timing, three dimensions and MRI
- What else could explain a big fetus
- Prevention and the conversation that follows
- The case against routine elective cesarean
- What ACOG actually says about cesarean
- Induction: even more contested
- Recurrence, and the long shadow
Overgrowth syndromes
A heterogeneous family of conditions — and the shared logic for suspecting one before birth
- What an overgrowth syndrome is
- How this field grew up
- The prenatal pathway when a syndrome is suspected
- Who should be offered testing before birth
- Comparing the syndromes side by side
- Genetic mechanism and inheritance of the overgrowth syndromes
- Genetic mechanism and inheritance of the overgrowth syndromes (continued)
- Key prenatal features of the overgrowth syndromes
- Key prenatal features of the overgrowth syndromes (continued)
- Key prenatal features of the overgrowth syndromes (continued)
- Key postnatal features of the overgrowth syndromes
- Key postnatal features of the overgrowth syndromes (continued)
- Key postnatal features of the overgrowth syndromes (continued)
- Overgrowth syndromes side by side, first printed page
- Overgrowth syndromes side by side, second printed page
- Overgrowth syndromes side by side, third printed page
Beckwith-Wiedemann syndrome
The commonest overgrowth syndrome, and the one most often recognisable on a prenatal scan
- Where the name comes from
- From one syndrome to a spectrum
- What the syndrome is, in one breath
- 1:10,000
- How it is inherited, and why 11p15 is so sensitive
- The five routes to Beckwith-Wiedemann syndrome
- The genes in the two domains
- When the error happens, and what that implies
- What molecular testing can and cannot do
- Why a negative prenatal test does not close the case
- The postnatal scoring system: cardinal features
- The postnatal scoring system: suggestive features
- What the postnatal score means
- A scoring system built for the scan
- Prenatal scoring system for the Beckwith-Wiedemann spectrum
- Prenatal scoring system for the Beckwith-Wiedemann spectrum (continued)
- Prenatal scoring sheet as printed
- How to use the prenatal score
- What the scan may show
- What the pregnancy itself is at risk of
- The overgrowth itself
- Structural anomalies and what pathology shows
- The newborn's metabolic problems
- Tumours, development and survival
- What the ultrasound literature reports
- Measuring the tongue
- Macroglossia on the inferior coronal view
- Protruding tongue on the sagittal profile
- Three-dimensional view of the enlarged tongue
- Enlarged placenta on ultrasound
- The first-trimester clue
- Omphalocele on ultrasound
- Enlarged echogenic kidneys
- Rare findings, MRI and other tests
- The classic signs, in one place
- What else looks like this
- The differential for an omphalocele
- The differential for a large tongue
- The differential for big kidneys and a big placenta
- Managing a suspected case before birth
- Planning the delivery
- The newborn checklist
- Surgery, testing and the long game
- Tumour surveillance and outlook
Sotos syndrome
Cerebral gigantism: a big head, a long body, an advanced bone age and developmental delay
- What Sotos syndrome is
- The gene behind it
- The shape of the growth
- Where the growth ends up
- Neurology, behaviour and cognition
- What can be seen before birth
- ~21%
- Imaging and the newborn picture
- Managing Sotos syndrome
Weaver syndrome
Overgrowth with a strikingly advanced bone age — and a prenatal picture that is hard to catch
- What Weaver syndrome is
- The gene and what it does
- The growth pattern
- The face and the joints
- The other organs
- Why the scan rarely makes this diagnosis
- Managing Weaver syndrome
Simpson-Golabi-Behmel syndrome
An X-linked overgrowth syndrome with the widest prenatal footprint of them all
- What Simpson-Golabi-Behmel syndrome is
- The gene and the inheritance
- The core features
- What happens around birth
- What the scan shows, with the numbers
- The rest of the ultrasound checklist
- Managing SGBS, and the outlook
The PTEN hamartoma tumour syndromes
One tumour suppressor gene, several named conditions — and one of them starts before birth
- One gene, a family of conditions
- What BRRS is, and what PTEN does
- How a lost brake causes overgrowth
- The classic BRRS features
- The growth pattern in BRRS
- Managing BRRS
Perlman syndrome
Big kidneys, big body, and the worst prognosis in this topic
- What Perlman syndrome is
- The gene behind it
- What the syndrome does
- What the scan shows
- Managing Perlman syndrome, and the outlook
Segmental overgrowth
When only part of the body grows too much: lateralized overgrowth, Klippel-Trenaunay-Weber and Proteus
- Isolated hemihyperplasia
- The three anatomical patterns
- What causes it, and how risky it is
- What the scan can show
- Hypertrophy of the right forearm
- Both lower limbs enlarged three weeks later
- What else makes a body asymmetric
- Managing isolated hemihyperplasia
- Klippel-Trenaunay-Weber syndrome
- The classical triad
- What can go wrong in KTWS
- The scan, and how KTWS is managed
- Proteus syndrome
- How rare, and what causes it
- The diagnostic criteria
- What Proteus syndrome looks like
- The most characteristic sign, and the scan
- Managing Proteus syndrome, and the outlook
Take-home messages
What the referring physician needs to know, and the key points from the topic
- What the referring physician needs to know
- What the referring physician needs to know
- Key points on the big fetus
- Key points on delivery and genetics
- Key points on planning and follow-up
- The whole topic in one shape
- Where to read more
References
The full reference list from the source text
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- References (continued)
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition