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Radiology
Turner Syndrome (Monosomy X)
Built from Obstetric Imaging
What’s inside
9 sections · 80 slides
Overview
- What this deck covers
What the condition is
A missing sex chromosome, and the three ways it shows up
- Start with the normal picture
- The missing chromosome
- What the syndrome looks like in a sentence
- Three very different outcomes
- Naming the fluid sac at the neck
- Cystic hygroma in a first-trimester fetus
- What you are looking at in that scan
How common it is
Common at conception, uncommon at birth
- 1:2000
- Who it affects
- Most affected pregnancies are lost early
Why it happens
Complete loss, patchy loss, and a broken second X
- Three routes to the same syndrome
- Complete loss and patchy loss
- Mosaic patients are usually less affected
- When a Y chromosome is in the mix
- The karyotype found before birth is not the one found after
- Reading the karyotype table
- Karyotypes of ultrasound detected cases of Turner syndrome
- Why the karyotype cannot predict the child
- One gene explains the short stature
- How blocked lymph could explain the rest
- The lymphoedema hypothesis in words
The clinical picture
What the child and the adult actually look like
- Features from head to chest
- Features from limbs to organs
- The kidneys are frequently malformed
- The heart carries the greatest risk
- Intelligence is usually normal
- Reading the feature table
- 45,X phenotype: features and their incidence
- 45,X phenotype: features and their incidence (continued)
Finding it before birth
What the scan shows, and what the blood tests cannot
- The scan is usually the first clue
- Nuchal translucency in plain terms
- Septated cystic hygroma at the neck
- Axial neck view with the nuchal fluid measured
- Cystic hygroma seen in four planes
- Why four planes are worth acquiring
- Three-dimensional rendering of a cystic hygroma
- What the FASTER trial found
- Hydrops fetalis: fluid in every space
- Severe skin oedema with effusions and ascites
- What gives hydrops away on the scan
- Effusions and ascites in cross-section
- Bilateral pleural effusions in the fetal chest
- A hygroma that vanishes is not a cure
- Which heart defects show up before birth
- Narrowed left ventricular outflow tract
- What to notice in the outflow view
- Growth and the other scan findings
- Reading the anomaly table
- Fetal congenital anomalies in cases of Turner syndrome
- Fetal congenital anomalies in cases of Turner syndrome (continued)
- Anomaly frequencies as printed in the source
- Maternal blood screening is unreliable here
- A positive cell-free DNA result has three explanations
- Why a positive screen is not a diagnosis
- Where MRI and echocardiography fit
- The two classic signs
- What the referring clinician needs to know
What else it could be
The differential for a thick nuchal translucency or hygroma
- Look-alikes on the scan
- Telling the look-alikes apart
What to do about it
Counselling before birth, surveillance for life
- The pathway once the scan is abnormal
- Before birth there is no treatment
- If the pregnancy continues
- The newborn work-up
- Milder cases surface much later
- Diagnosed late, the growth window closes
- Conditions to watch for over a lifetime
- Cardiac follow-up never stops
- Care is a team activity
Key points
What to carry out of this topic
- Key points: the condition
- Key points: the diagnosis
- References
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- Suggested readings
- Suggested readings (continued)
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition