Foetal and maternal scanning Flashcards
Why is x-ray imagine (e.g. CT) bad?
Ionizing radiation
Why is ionising radiation bad?
Birth defect s- teratogenic
Increased cancer risk - carcinogenic
Germ cell mutation - genetic risk
Characteristics of MRI
Magnets
Non-ionising radiation
Works without amniotic fluid
Difficult to use when baby moving
When do most routine scans take place in pregnancy?
11-14 weeks and 18-21 weeks
What is the Saving Babies’ lives programme?
More scans and care for high risk pregnancies
What is an embryo?
until 8 weeks post fertilisation
What is a foetus?
From 8 weeks fertilisation
Why do we not use CRL after 14+1 weeks?
Inaccurate - use head circumference instead
Ultrasound in pregnancy
Sound waves create image
Less damaging
Main modality in pregnancy
Diagnosis/assessment of early pregnancy conditions
Higher frequency = more detail but less depth
early pregnancy = higher frequency
When will an early pregnancy be non viable (CRL)?
When CRL is less than 7mm
What is ectopic pregnancy?
+ve pregnancy test
No gestation sac
What is chronicity?
Multiple pregnancies
Chorion around them but separate amnion
Why are dichorionic babies good?
No twin-twin transfusions
When is first appointment?
Between 8-10 weeks
Which chromosome causes Down’s?
21
Which chromosome causes Edward’s?
18
Which chromosome causes Patau’s?
13
What measurements are taken in ultrasounds?
CRL and nuchal translucency
What does a low PAPP-A indicate?
T21/18/13
What does high hCG indicate?
T21
What does low hCG indicate?
T13/18
What does low PAPP-A indicate?
Placenta isn’t growing very well, start aspirin and more growth scans
What happens in the 11-14 week scan?
First ultrasound
Heart rate detection
Accurate dating
Screening for abnormalities
When will combined test be done?
CRL 45-84
When will quad test be done?
CRL is larger than 85
What is Booker’s appointment?
14+1 to 20 weeks - screen for Down’s
Hormonal changes in Down’s syndrome?
AFP and estriol go down and hCG and inhibin go up
What is the borderline for aneuploidy action?
1:150
When do you do amniocentesis?
Less than 16 weeks
When do you do CVS?
11-14 weeks
What is NIPT?
Non-invasive prenatal testing
Where is NIPT currently offered?
Twins
How does NIPT work?
Taking blood from mother which also contains baby’s blood
cffDNA in maternal plasma increases with gestation
What happens at 20 week scan?
Looks for 11 different conditions
What happens in mid-pregnancy scan?
Identifies any abnormalities that indicate baby will die shortly after birth/need treatment before birth
Conditions screened between 18 and 20 weeks
Anencephaly Open spina bifida Cleft lip Diaphragmatic hernia Gastrochisis Exomphalos Cardiac abnormalities Renal genesis Skeletal dysplasia Edward's syndrome Patau's syndrome
What is anencephaly?
Absence of cortical brain tissue and cranial vault - incompatible with life
What is spina bifida?
Neural tube fails to close, varying severity
What is cleft lip?
Gap between lip and nose
What is gastroschisis?
Extra-abdominal herniation of bowel loops through para-umbilical abdominal wall defect
What is omphalocele?
Gut herniation via abdominal wall defect, covered by membrane, strong association with other abnormalities and belly button
Examples of cardiac anomalies in babies
Transposition of great arteries
Atrioventricular septal defect
Tetralogy of Fallot
HLHS
Kidney issues in foetus
Bilateral renal agenesis
No amniotic fluid
What is pulmonary hypoplasia?
No amniotic fluid means lungs can’t grow
