Congential defects Flashcards
1
Q
What is a congenital defect
A
this means that it is present at birth
2
Q
describe the statics of congenital defects
A
- Around 20% of live births have some defect
- 75% are minor anomalies – not immediately life threatening – does not require intervention immediately
- 25% are major structural anomalies- not compatible outside the uterus require some
3
Q
what is a minor anomaly
A
75% are minor anomalies – not immediately life threatening – does not require intervention immediately
– Approx 15%
– Anomaly does not usually require intervention
– Causes minimum handicap
– Children with 1 minor anomaly have 3% chance of a having a major malformation
4
Q
what is a major anomaly
A
- 25% are major structural anomalies- not compatible outside the uterus require some
– Approx 6% (3% live births plus 3% diagnosed later)
– Anomaly that requires medical/surgical treatment
– Causes significant handicap
5
Q
what is the leading cause of infant mortality
A
congenital defects
6
Q
what are the causes of congenital defects
A
- Genetic/chromomse (13-15%) - down syndrome
- Drugs (7-10%) – acne medication (Accutane) and thalidomide
- Environmental (7-10%) – infectious agents (rubella, CMV, Zika) chemical agents alcohol
7
Q
what is the name of an acne medication that can cause congenital defect
A
Accutane – vitamin A retinoic acid – gets stored in fat and has toxic levels of vitamin A that can pass across the placenta
8
Q
what is the percentage of causes of congenital defects that we do not know about
A
- 70% of all birth defects we don’t know what the cause is or it is multifactorial
9
Q
what has the USA and 77 other countries done to reduce the risk of not enough folic acid intake
A
- USA and 77 countries fortify flour and cereals to increase general population intake
10
Q
what does not enough folic acid cause
A
neural tube defects such as ..
- spina bifida
- skull bone doest form
11
Q
why is it important to take folic acid before you become pregnant
A
- usually don’t find out till you miss a period by that point around 28 days has gone this means that you miss the important formation steps of the baby
12
Q
what week is the embryo stage too and form
A
3-8 weeks
13
Q
what weeks are the foetal stage to and from
A
9-38 weeks
14
Q
what is the foetal period
A
foetal period is a growth period and the embryonic period is a patterning stage
15
Q
name some examples of major congenital defects
A
- anencephaly
- cleft lip and cleft palate
- omphalocele
- gastroschesis
- hypospadias
- phocomelia
- spina bifida
- talipes equinovarus
16
Q
name some examples of minor congenital defects
A
- auricular ear tag or pit
- supernumerary nipples
- cryptorchidism
- syndactyly
- rocker bottom feet
- polydactyly
- overlaying digits
- micropensi
17
Q
what is anencephaly
A
- The uterus is contracting and the physical movement of the brain against the wall of the uterus can dmage the brain and lead to significant brian damage
- They can survive for a couple of years and it depends on how much of the brain has been damaged
- They have a face but know skull
18
Q
what is Hypospadias
A
- It is a problem of the male external genital not closing properly
- Opening of the urethra hasn’t closed down the shaft of the penis
- It needs surgical correcting
19
Q
what is cryptorchidism
A
- Undescending testes
- Most spontaneously correct within 3 months
- Undescended testis incidence 7.6:1000
- Cryptorchidism 1-4% of live male births, most spontaneously correct within 3 months
- Still undescended in 1% at 1 year of age.
- 20x increased risk of developing testicular malignancy
- It also potentially leads to male infertility as well
20
Q
what does cryptorchidism lead to infertility
A
- In the scrotum the testes is one to two degrees cooler but if it is stuck in the body cavity it gets heated up and this can lead to infertility
21
Q
how does holoprosencephaly vary
A
- This is loss of midline structrues down the midline
- Can vary from mild to sever
22
Q
what can cause holoprosencephaly
A
- Can be genetic or environmental (alcohol consumption)
23
Q
where can we detect cleft lip and cleft palate
A
- We can detect these earlier and do surgery to correct them in uterus
- Better regenertative capacity in utero
- Better diagnostic tools for earlier detection
24
Q
what is congenital diaphragmatic hernia
A
- The diaphragm separate the thoracic from abdominal cavity, but in some babies it doesn’t and there is a defect in the diaphragm that allows the liver and the gastrointestinal loops to go into the thoracic cavity
- The lungs still need to form
- Intestines can push the heart and lungs across, this constricts the left and right lung from being able to develop
25
how do you repair congenital diaphragmatic hernia
- Repairs can be done with simple sutures or for large defect a synthetic patch such as Gor-tex, polytetrafluoroethylene (Teflon), Dacron and tendon.
- In utero repair via laproscopy can allow lungs to develop
26
what is gastroschsis
- This is split belly where the abdomen body wall hasn’t closed and you have loops of the intestine that fall out into the ammonitic sac, it is toxic and up against the uterine wall
27
how is gastroshciss repaired
- Gastroschisis reduction of bowel back into the abdomen may not be possible initially without undue tension.
- A prosthetic silo is gradually tightened, and after a few days can be removed
28
what happens in week one of fertilisation
- Fertilisation in ampulla region of uterine tube within 24 hours of ovulation
- 3 days after fertlsiation – ball of cells morula
- Then you start cell division and become a zygote until 3 days after fertilisation you become the morula
- They still continue to divide and form a blastocyst
29
describe how the blastocyte impacts
- The blastocyst hatches from the zona pellucida which allows implantation - this prevents any sperm getting in and happens around day 5
- Blastocyst implants to the endometrium around day 6
- The cells around the outside become the placenta
30
what happens in week 2
Trophoblast differentiates into 2 layers
Embryoblast differentiates into 2 layers
2 cavities formed
-
31
what are the two layers that the trophoblast differentiates into in week 2
Trophoblast differentiates into 2 layers
- Syncytioblast
- Cytotrophoblast
- These are mutil nucleated cells that form the vili and push around and form the placenta proper
32
what are the two layers that the embryoblast differentiates into in week 2
Embryoblast differentiates into 2 layers
- Epiblast dorsally
- Hypoblast ventrally
- Comes from the inner cell mass and forms two layers the epiblast and hypoblast this forms the primordial germ cells
33
what are the two cavities formed in week 2
2 cavities formed
- Amniotic cavity dorsal to epiblast
- Yolk sac cavity ventral to hypoblast
34
what is a hydatitidform mole
- Molar pregnancy
- These are where there is no embryo and just placenta because the syncytioblast only come from the placenta
- The placenta comes from the paternal genes and the placenta is thereof reforms when you have a anucular egg and then undergo cell division but they all come from the father
- Or you have two sperm that go into the a nucular and produce 46 XX or 46
- Whole of the uterus is filled with the placenta
- Moles are generally lagre and composed of grape like clusters of swollen chorionic villi
35
what is a partial hydatirfomr
- Two sperm fertilise one egg so there are 69 chromosmes
- So there are two lots of paternal genes that fomr more placenta but maternal genes that give the embryo
- Some evidence of embryonic development can be found
- Karyotype usually triploid
- 69XXX, 69XXY, 69XYY
36
what happens in week three
• Two layers transformed by gastrulation into three germ layers
– Ectoderm
– Mesoderm
– Endoderm
– But everything comes from the epiblast, in the midline running down there are invaginations, everything streams into the middle and goes underneath and into the three layers, the cells that invaginate and move in and round happen in the midline this establishes the three germ layers and the body axis, decides where the head is and the body is, body axis is determined during gastrulation
• Establishes body axes
– Cranial / caudal
– Dorsal / ventral
– Left / right
37
what does the ectoderm form
nervous system and skin
38
what does the mesoderm form
muscle, connective tissue, bone
39
what does the endoderm form
gut
40
what is Milagros carron
- Epiblast cells stop invaginating too soon, insufficient mesoderm is produced
- It is often associated with kidney and gastrointestinal defects so few survive to have the legs separated
41
what is situs inerversus
* Situs inversus 0.01% of population
| * Complete reversal of organs in body cavity,
