Congenital Development/Abnormalities Flashcards
Congenital abnormality/anomaly/birth defect
An abnormality in structure, function or metabolism present at birth causing physical or mental disability
Common congenital abnormalities
Heart defects
Neural tube defects
Down’s Syndrome
Causes of congenital abnormalities
Neonatal sepsis
Birth asphyxia and birth trauma
Preterm birth
Risk factors for congenital abnormalities
Genetics (inherited or sporadic) e.g. consanguinity
SES/demographics e.g. nutrition (folate) or environment or age
Infections e.g. rubella, zika, syphilis
Teratogens
Ethnicity e.g. Ashkenazi Jews and Finns have an increased risk of CF and haemophilia C
Classification of congenital abnormalities
Malformation
Deformation
Dysplasia
Disruption
Malformation
Flawed development of structure or organ
Deformation
Alteration of a structure due to extrinsic pressures
Dysplasia
Abnormal organisation of cells or tissue
Disruption
Alteration of an already formed organ
Syndrome
A single chromosomal or gene problem resulting in multiple congenital abnormalities
Sequence
Multiple congenital abnormalities developing as a consequence of one congenital abnormality e.g. renal agenesis leading to skeletal abnormalities
Common syndromes
Down's (21) Patau (13) Edward's (18) Kleinfelter (XXY) Turner's (XO)
Down’s syndrome features
Upwards and outwards slanted eyes Flattened nasal bridge Low-set folded ears Flat back of the head Below average weight and length at birth Broad hands with short fingers Mild to moderate learning difficulties Cardiac defects Duodenal atresia (narrowing or closure)
Examples of teratogens
Warfarin - chondrodysplasia and microcephaly
Thalidomide - limb and heart defects
Rubella - deafness
Syphilis
Zika - microcephaly
Alcohol - FAS
Radiation - microcephaly and spina bifida
Androgens - masculinisation of external genitalia
Hyperthermia - foetal death and neural tube defects
Pesticides - neural tube defects
Examples of teratogens
Warfarin - chondrodysplasia and microcephaly
Thalidomide - limb and heart defects
Rubella - deafness
Syphilis - congenital syphilis
Zika - microcephaly
Alcohol - FAS
Radiation - microcephaly and spina bifida
Androgens - masculinisation of external genitalia
Hyperthermia - foetal death and neural tube defects
Pesticides - neural tube defects
When are teratogens likely to cause damage?
Between week 3-9 during organogenesis due to the peak sensitivity of different organs as they develop so this is period when most birth defects develop
FAS signs
Upturned nose Thin lip Rail road track ears due to under development Smooth philtrum (no cupid's bow) Underperform in school
Edwards syndrome features
Cleft lip/palate Small head Small jaw and mouth Clenched fists with overlapping fingers Congenital heart defects Hernia Horseshoe kidney/renal agenesis/cystic kidneys Learning disabilities Seizures Flexed big toe Usually die within first year of life
Patau syndrome features
Congenital heart defect Cleft lip/palate Small or absent eye(s) Microcephaly Small penis or enlarged clitoris Single-lobed brain Usually die within days of birth
Prevention of congenital abnormalities
Preimplantation genetic testing (IVF)
Antenatal screening - combined screening (week 10-14), 20-week anomaly scan
In-utero diagnostic tests e.g. amniocentesis or CVS
Why should birth defects be detected?
Termination
Treat in-utero (e.g. cleft lip/palate, pulmonary shunts, transfusion), maternal, or post-delivery
Adapt time of delivery and birth plan
Prepare parents
Female hermaphrodites
Congenital adrenal hyperplasia causes virilisation = male external genitalia
Male hermaphrodites
Leydig cell hypoplasia (insensitive to LH)
Androgen insensitivity syndrome
Causes undervirilisation resulting in female external genitalia
Swyer’s syndrome
Male hypogonadism/ XY gonadal dysgenesis
Due to alteration of SRY gene
Hypospadias
Failure of urethral folds to fuse causing proximal
Surgical correction
Cryptorchidism
Unilateral and bilateral undescended testes
A testis Cannot be manipulated into the bottom of the scrotum without undue tension of the spermatic cord
Congenital kidney abnormalities
Duplex kidney Unilateral or bilateral absent kidney Mayer-Rokitansky syndrome Polycystic kidneys Vesicular urethral reflux (may correct after 5yrs) Posterior urethral valves Ureterocele Hypospadias Horseshoe kidney Pelvic kidney Megaureter Zinner syndrome (ipsilateral agenesis and seminal vesicle cyst) Buried penis (scrotal skin and penis merged)
Partial or complete inguinal hernia in children
Due to insufficient closure or no closure of the Processus Vaginalis
Hydrocoeles of the cord
The processus vaginalis does not close properly to form a second testis
