Congenital Anomalies Flashcards
Define congenital anomalies
Birth defects
Developmental malformation
Types of Congenital anomalies
Malformation Deformations Disruptions Sequence Syndromes
Causes of congenital malformations
Gene defects Chromosomal abnormalities Multifactoral disorders Teratogenic agents Unknown (idiopathic) Environmental Congenital infections
Discuss Malformations (primary) anomalies
Intrinsically abnormal developmental process
Multifactoral (polygenic)
Affects single or multiple systems
Define Malformations (primary) anomalies
A morphological defect of a part of an organ that has resulted from an abnormal development process.
Examples of Malformations.
Meckel’s diverticulum
Congenital heart disease
Anencephy
When do malformations (primary) anomalies form?
During embryogenesis.
Discuss disruption (secondary) anomalies.
Destructions of previous normal organs.
Arise from external disturbances in morphogenesis.
Morphological alterations of structures after formations.
Comes from breakdown or interference with an originally normal developed process.
Causes of Disruption (secondary) anomalies caused by environmental/instrinsic factors
Fetal infections
Chemical
Radiation
Hypoxia
Examples of Disruption (secondary) anomalies
Congenital infection
Amniotic bands
Discuss Deformations
An intrinsic disturbance in morphogenesis mainly due to compression of the fetus by biochemical forces.
An abnormal form, shape, or position of a body part that is present because of abnormal mechanical forces.
Compression can be localized of generalized
Underlying causes in Deformation anomalies
Uterine constraint
Maternal factors
Fetal placement factors
Examples of Deformation anomalies
Club foot (Congenital Talipes Equinovarus)
Classifications of club foot
Positional
Idiopathic
Secondary club foot
Which joint is effected in club foot?
Talo-calcaneal-navicular joint (TCN)
What does equinus means?
Downward facing
What scoring measure is used in club foot?
Pirani score
What is the treatment for club foot?
Ponseti method. Correction phase (manipulations and casts, achilles tendon cut) Maintenance phase
Discuss Sequence anomalies.
A cascade of events triggered by one abnormality.
Is the triggers of Sequence anomalies external of internal?
External disturbances
Example of Sequence anomalies?
Oligohydramnios->fetal compression->abnormalities of hands and feet, hip dislocations, lung hypoplasia.
Causes of oligohydramnios?
Maternal of fetal causes
Define Syndrome anomalies
A group of anomalies occurring together with a specific common etiology.
Name examples of Syndrome anomalies
Down syndrome
Turner’s syndrome
Klinefelter syndrome
Discuss Neural tube defects
Some part of the neural tube or its coverings has not closed.
Most common malformation
How can a neural tube defect be diagnosed Prenatal?
Ultrasound Invasive test (amniocentesis and fetal cord sampling; chorionic villus sampling) Serum screening (Maternal->alpha fetoprotein elevation at 16 weeks)
Two classifications of Spinal Dysraphism
Open and closed
What is Spina Bifida Occulta?
Vertebral (usually lumbosacral) defect with normal cord and membranes. Skin covers the defect; skin might be abnormally pigmented, by a hairy patch or dermal sinus.
Describe Meningocele spinal defect
Meningeal sac protrudes through a bony defect and is covered by skin.
Describe Meningomyelocele spinal defect
The skin overlying the sac ruptures, exposing the abnormal meninges, nerve roots and abnormal/incompletely formed spinal cord.
Define Hydrochephalus
The presence of excessive amounts of CSF within the cranial cavity
Discuss hydrochephalus
Usually caused by obstruction of CSF flow with dilation of the ventricular system proximal to the obstruction
OR the overproduction of CSF
OR the defective reabsorption of CSF
Clinical signs of hydrochephalus
Macrocephaly Widely separated sutures Huge frontanelles Relatively small face Usually progressive, resulting in intellectual impairment, spastic paraplegia and cerebellar ataxia
Causes of Hydrochephalus
Arnold Chiari malformation (obstruction of CSF at foramen magnum, usually occurs with spina bifida)
Inflammation or haemorrhage, obstruction of aqueduct Sylvius
Genes
How can hydrochephalus be treated?
Ventricular shunt, one way valve to drain the CSF into the peritoneal cavity.
What is Exencephaly?
Brain tissue covered by membranes, only without cranial vault.
What is Anencephaly?
Cranial vault is missing, base of the skull is poorly formed; the coverings of the brain fail to develop, developing brain is exposed to amniotic fluid; cerebrum and cerebellum usually absent; base of the skull is usually disorganized brain tissue and blood vessels; cranial end of the neural tube fails to close; Acrania
What isEncephalocoele?
Defect of the skull, frequently occipital
Usually midline
May be syndromic
