Definitions in Congenital Anomalies ✅ Flashcards
(29 cards)
What % of live births are affected by congenital abnormalities?
3-6%
What % of neonatal deaths in the UK are caused by congenital abnormalities?
20-25%
What is congenital malformation defined as?
A defect in the structure of an organ or a part of an organ due to abnormal development
What proportion congenital malformations have a congenital cause?
1/4
What is the case with the cause of most congenital malformations?
They have multifactorial or unknown causes
What % of congenital defects are caused by teratogens?
5-10%
What is a teratogen?
Any chemical, maternal physical condition, or deficiency that can alter fetal development or function
Give 4 examples of teratogens
- Maternal alcohol or drug misuse
- Maternal anti-convulsant use
- Congenital infection
- Maternal disorders, e.g type 1 diabetes mellitus
What is disruption defined as?
An anomaly which occurs when a fetal structure starts growing normally, but growth is disrupted by something which disrupts the process
What can cause disruptions leading to rterminal limb defects as a result of disrupted blood supply?
- Amniotic bands
- Chorionic villus sampling
What causes amniotic bands?
Thought to be formed when amnion ruptures early and fetal limb is forced into chorionic cavity, resulting in vascular compression followed by necrosis
What do amniotic bands result in?
Absent digits or limbs
When can chorionic villus sampling result in a similar anomaly to amniotic bands?
If carried,, out too early in pregnancy (around 8-10 weeks)
How can chorionic villus sampling lead to disruptions leading to terminal limb defects?
Due to vascular disruption,potentially haemorrhage from injured chorionic villi
What is deformation defined as?
An external force that results in an alteration of shape of a previously normally formed structure
When do deformation abnormalities normally occur?
In a second half of pregnancy when the fetus is large in comparison to the uterine size
What is dysplasia defined as?
Abnormal organisation of cells into tissues?
When do congenital dysplasias normally develop?
During embryogenesis
Give 3 examples of congenital dysplasias?
- Haemangiomas
- Osteogenesis imperfecta
- Achondroplasia
What is sequence defined as?
Groups of related abnormalities that stem from a single initial major anomaly that alters the development of other surroundings or related tissues or structures
Give 2 example of congenital sequence abnormalities
- Pierre Robin sequence
- Potter’s sequence
What happens in Pierre-Robin sequence?
A small jaw (micrognathia) leads to the tongue being displaced posteriorly, which results in a cleft palate
What happens in Potter’s sequence?
A single anomaly (renal abnormality) causes decreased fetal urine output and associated oligohydraminos. This leads to pulmonary hypoplasia and typically flattened facial features
What other congenital abnormality is Potter’s sequence an example of?
Deformation
