8 - Congenital Defects Flashcards
What does congenital mean?
Present at birth
How many percent of live births have some sort of defect?
20%
How many percent of birth defects are due to unknown causes/multi-factorial?
70%
How many percent of birth defects are due to genetics?
15% e.g downs syndrome
How many percent of birth defects are due to drugs?
10% e.g accutane and thalidomide
How many percent of birth defects are due to environmental factors?
10% e.g infectious and chemical agents - rubella - CMV - zika - alcohol
What is a major congenital defect and how many percent of births are major?
Anomaly that requires surgical treatment
Causes significant handicap
6%
What is a minor congenital defect and how many percent of births are minor?
Anomaly that doesn’t require intervention
Causes minimal handicap
15%
What is cryptochidism and what is its incidence?
Undecended testis 7.6:1000 births 1-4% of live male births most correct within 3 months 1% still undescended at 1 year
Name 5 major congenital defects?
- Anecephaly
- Cleft lip and cleft palate
- Spina bifida
- Hyposapadias
- Phocomelia
Name 5 minor congenital defects?
Micropenis Cryptorchidism Auricular ear tag or pit Rocker bottom feet Overlapping digits
Anecephaly
failure of anterior neuropore to close resulting in malformed head and brain
Spina bifida
failure of posterior neuropore to close leading to the spine and its contents herniating out the back of the child
Hypospadias
defect in the formation of the male urethra where it opens out an unusual place – classified as a major defect but is rarely life threatening
Cleft lip
failure of maxillary and medial nasal prominences to fuse
Cleft palate
failure of palatine shelves to fuse
Holoprosencepahly
loss of midline structures – severity can vary
Omphalocele
where the abdominal contents do not correctly return to the body from the umbilical cord
Gastrochisis
defect in the anterior abdominal wall through which the abdominal contents herniate
Phocomelia
malformation of the limbs – thalidomide
Talipes equimovarus
club foot where foot is rotated internally at the ankle
Cryptorchidism
undescended testicles – minor – 7.6:1000 – 1-4% of births – most spontaneously correct within 3 months. Still undescended in 1% at 1 year of age – 20X increased risk of developing malignancy
Syndactyly
digits fused together
Polydactyly
extra digits
Ankyloglossia
tongue tie – unusually short and thickened frenulum
Congenital diaphragmatic hernia
some of the gut herniates into the thorax through the oesophageal hiatus preventing correct development of the lungs and leaving the baby cyanotic
Hydatidiform mole
cell diploid but all derived from the father due to fertilisation of an empty egg
Sirenomelia
epiblast cells stop invaginating too early meaning insufficient mesoderm is produced and the lower body parts are fused together
Situs invertus
left and right body axes are the opposite way around
Atrial septal defect
blood can flow between two atria
Ventricular septal defect
blood can flow between two ventricles
AV canal
lack of atrioventricular septum
Patent ductus arteriosus
failure of ductus arteriosus to close
Coarctation of aorta
aortic narrowing around where the ductus arteriosus inserts
Transposition of the great vessels
incorrect connection of outflow tracts to the chambers
Truncus arteriosus
failure of truncus arteriosus to properly divide into the aorta and pulmonary trunk
Tetralogy of Fallot
overriding aorta that can also break through to the wrong side of the heart
Pelvic kidney
kidneys do not migrate upwards to the posterior abdominal wall
Horseshoe kidney
kidneys fuse at the bottom to form a horseshoe shape
Vitelline duct abnormality
Meckel’s diverticulum - small pocket of remaining vitelline duct outpocketing from the ileum
Oesophgeal atresia
chronic narrowing of the oesophagus
Tracheo-oesophageal fistulae
abnormal connection between the trachea and oesophagus
Pyloric stenosis
narrowing of the pylorus leading from the stomach to duodenum
Duodenal atresia
closure of the lumen of the duodenum
Jejunal atresia
closure of the lumen of the jejunum
Malrotation
improper rotation of the midgut that can lead to volvulus (strangulation) and obstruction
• Imperforate anus – malformation of the rectum
Imperforate anus
malformation of the rectum
Hirschprung’s disease
lack of ganglion cells to the intestines meaning they cannot function correctly
What occurs during week one after fertilisation?
- Fertilisation in ampulla region of uterine tube within 24 hours of ovulation
- 3 days after fertilization – ball of cells – morula
What occurs in week 2 after fertilisation?
Trophoblast, embryoblast differentiates into two layers
2 cavities are formed
What are the names of the 2 layers the trophoblast differentiates into?
Syncytioblast and cytotrophoblast
What are the names of the 2 layers the embryoblast differentiates into?
Epiblast dorsally and hypoblast ventrally
What are the names of the two cavities formed?
Amniotic cavity dorsal to epiblast and yolk sac cavity ventral to hypoblast
What occurs during week three after fertilisation?
o Two layers transformed by gastrulation into three germ layers
o Ectoderm – mesoderm – endoderm
o Establishes body axes – cranial/caudal – dorsal/ventral – left/right
