fetal Development And Clinnical Imaging Flashcards
What is the Chorion?
The chorion is formed from mesoderm and trophoblasts and becomes the wall of thee chorionic cavity.
What is the Chorionic cavity?
It’s the anechoic fluid collection in which the embryo, amnion and yolk sac are suspended and grow.
Known as the gestational sac.
What is an Anembryonic pregnancy ?
Pregnancy in which a gestational sack grows but an embryo fails to develop
It’s the earliest sign that something has gone wrong in the pregnancy .
How many placentas do Monochorionic twins have?
One placenta
How many placentas do Dichorionic twins have?
Two placentas
What does the The Nuchal test / combined screening at 11-13 weeks involve?
- Maternal age is a risk factor
- Maternal blood sample, for the measurement of the placenta products of free B-hCG and PAPP-A
- US at 11-13 weeks to look at/ measure / examine:
~ collection of fluid behind the fetal neck (Nu Hal translucency)
~ Fetal nose and palate
~ heart rate of fetus
~ flow of blood across the tricuspid valve of fetal heart and ductus venosus
What does B- HCG stand for ?
Beta - human chorionic gonadotropin
What does PAPP-A stand for?
Pregnancy associated plasma protein - A
Blood tests also can determine the risk for which syndromes?
Trisomy 21 (Downs syndrome)
Trisomy 18 (Edward’s syndrome)
Trisomy 13 (Patau syndrome)
The blood test is used with other risk factors eg: maternal age
Which results indicate Risks for Chromosomal abnormalities ?
- Increased in nuchal translucency as measured in mm
- Low PAPP-A levels
- High hCG levels
What does FASP stand for?
Fetal anomaly screening program
At how many weeks gestation is a FASP Ultrasound is performed ?
Between 18 weeks and 20 weeks and 6 days
What are the 11 conditions screened for at 20 week scan?
- Anencephaly
- Open Spina bifida
- Cleft lip
- Congenital heart disease
- Diaphragmatic hernia
- Gastroschisis
- Exophalos
- Bilateral renal agenesis
- Lethal skeletal dysplasia
- Edward’s syndrome (T 18)
- Patau syndrome (T13)
What are the 4 common Congenital heart diseases?
TGA - transposition of the great arteries
AVSD - Atrioventricular septal defect
TOF - Tetralogy of Fallot
HLHS - Hypoplastic left heart syndrome
What is the Neural plate?
How does the neural plate form into the neural tube?
The neural plate is a disc shaped cluster of cells that clump together about two weeks after conception
The neural plate rolls into a tube called the neural tube at three weeks after conception, and this new tube is the beginning of the central nervous system
The front of the neural tube will inflate to form the brain and the portion of the tube behind the brain forms the spinal cord .
What are Neural tube defects and how common are they?
Common - 1/1000 births
A variety of defects most result from a lack of closure of the neural tube.
What is Anencephaly?
Severe congenital condition in which a large part of the skull is absent along with the cerebral hemispheres of the brain,
Early appearances involve absence of the skull with protruding brain.
As pregnancy progresses, the amniotic fluid degrades the brain .
75% will be still born
What is Associated Talipes?
“Tethering” of the spinal cord
May have difficulty walking, bladder and bowel control
What are Risk factors for cleft lip and palate ?
- genetics
- environmental agents such as second hand exposure to smoke
- Medications such as phenytoin, sodium valproate, topiramate and methotrexate
- smoking and tobacco
- folate deficiency
- maternal obesity
- Diabetes - T1 or T2 Moore risk than gestational
What are Cleft lip and palate and how are they detected?
Can be syndromic
Detected using coronal views on USS - 30% still missed
Babies need assisted feeding
What is Gastroschisis?
An abdominal wall defect where the intestines develop on the outside and are completely open to air when the baby is born.
What is Exomphalos / Omphelcele ?
An abdominal wall defect where the intestines are outside the body but remain covered by a membrane
What is Ductus arteriosus ?
Duct between the aorta and pulmonary artery
Open in uterus but closes shortly after birth
Babies with TGA its their only hope of survival
What is a Congenital diaphragmatic hernia?
What are the associated risks?
Organs take up space in the chest ——-> This prevents the lungs from growing properly
Pulmonary hypertension
Will be difficult for lungs to expand and get enough O2 when the baby is born.
They can be repaired
What is Bilateral renal agenesis?
- no development of kidneys
- Little and amniotic fluid
- Lungs cannot develop properly
- Absent stomach and bladder bubble
- No kidneys
How is placenta praevia managed?
Discovery at 20 week scan
Repeat scan @ 32 weeks
If still low consult obstetrics to discuss delivery and repeat scan at 36 weeks
What other Normal variants are visible on us ?
Choroid plexus cysts
Echo genie foci in the heart
2 vessels in the umbilical cord
What Isolated findings require further assessment ?
Nuchal fold > or equal to 6mm
Ventriculomegaly - atrium > or equal to 10mm
Echo genie bowel = bone density
Renal pelvis dilitation > 7mm
Fetal biome try measurement <5th centile
