Chapter 10--Diseases of Infancy and Childhood Flashcards
A morphologic defect present at birth
Congenital anomaly
What % of fertilization are so anomalous that they never develop into a viable conceptus?
20%
Complete absence of an organ and its associated primordium
Agenesis
Absence of an organ due to failure of the developmental anlage
Aplasia
Absence of an opening usually of a hollow visceral organ
Atresia
In the context of malformation, refers to abnormal cellular organization
Dysplasia
Enlargement of an organ associated with increased number in cells
Hyperplasia
Underdevelopment of an organ with decreased number of cells
Hypoplasia
Decreased organ size due to decreased cell size
Hypotrophy
Intrinsic disturbances in morphogenesis; typically multifactorial and not caused by single genetic defect
Malformation
Extrinsic disturbances in morphogenesis causing a secondary destruction of a previously developmentally normal tissue; NOT heritable!
Disruptions
Example of disruption
Amniotic band resulting from an amniotic rupture that causes fibrous stranding that encircles, compresses or attaches to a developing body part
Result from an external disturbance in morphogenesis. Caused by localized or generalized compression by abnomal mechanical forces and they manifest as abnormalities in shape, form or position (club feet)
Deformations
Most common underlying factor in deformations
Uterine constraint; first pregnancy, small uterus, leiomyomas
Constellation of anomalies resulting from one initiating aberration that leads to multiple secondary effects
Sequence
Classical example of a sequence
Potter sequence
What happens in potter sequence?
Oligohydramnios–decreased amniotic fluid–causes fetal compression with facial flattening, hand and foot malpositioning, hip dislocation, and chest compression with Hypoplasia
Combination of anomalies that cannot be explained on the basis of one initiating aberration and a subsequent cascade.
Syndrome
Most syndromes are caused by a single pathology that simultaneously affects several tissues (viral infection or chromosomal abnormality)
3 causes of developmental anomalies
Genetic causes
Environmental causes
Multifactorial causes
2 genetic causes of developmental anomalies
Chromosomal abnormalities
Single gene mutations
5 examples of chromosomal abnormalities that cause developmental anomalies?
Trisomy 21 (Down Syndrome) Klinefelter Syndrome (47 XXY) Turner Syndrome (XO) Trisomy 13 (Patau syndrome) Trisomy 18 (Edwards syndrome)
How do single gene mutations cause developmental anomalies?
Loss of function genes that drive organogenesis or development; hedgehog genes
5 examples of environmental causes of developmental anomalies
Viruses Drugs and chemicals Alcohol Radiation Maternal diabetes
Most common fetal viral infection? What does it result in?
Cytomegalovirus–mental retardation, microcephalic, deafness
What trimester is the highest risk period for cytomegalovirus infection?
Second trimester
What is congenital rubella syndrome?
A rubella infection (German measles/3 day measles) occurring before 16 weeks of gestation that can result in tetras of defects: cataracts heart defects deafness mental retardation
An agent or factor that causes a malformation in an embryo?
Teratogen
Examples of drugs and chemicals that act as environmental causes of developmental anomalies (5 examples)
Thalidomide Folate antagonists Androgenic hormones Anticonvulsants 13-CIS-retinoic acid
Most widely used Teratogen?
Alcohol
Structural anomalies, cognitive and behavioral deficits related to alcohol use in mother
Fetal alcohol spectrum disorders
Classic teratogenic phenotype that describes infants most severe affected by fetal alcohol spectrum disorders
Fetal alcohol syndrome
Teratogenic phenotype of fetal alcohol syndrome
Growth retardation Microcephaly Atrial septal defects Short palpebral fissures (elliptic space bw medial and lateral can't hi of the two open eye lids) Maxillary Hypoplasia
Large fetus caused by maternal diabetes is called?
Fetal macrosomia
Series of malformations occurring with maternal diabetes; hyperinsulinemia resulting in increased body fat, muscle mass and organometallic, cardiac anomalies neural tube defects and other CNS malformations
Fetal macrosomia
Interaction of environmental factors with mutated genes; independently they may have no or minimal effect
Multifactorial causes of developmental anomalies
Two examples of multifactorial causes of developmental anomalies
Congenital hip dislocation–shallow Acetabular socket (genetics) and a breech delivery (environment)
Neural tube defects–genetic predisposition (genetic) and low maternal folate (environmental)
Importance of timing and teratogenic insult
Timing of any teratogenic insult influences the nature and incidence of the anomaly produced–a given agent can have a significantly different outcome depending on when it is encountered
Embryonic period of development
First 8 weeks after fertilization
Teratogenic influence of the early (first 3 weeks) of the embryonic period
Either kills, so many cells die causing spontaneous abortion or limited numbers of cells are affected such that the fetus can recover without consequence
Fetal period of development
Weeks 9-36
Sensitivity to teratogens during the fetal period
Greatly reduced to teratogenic agents; the fetus is still susceptible to growth retardation
Do teratogens and genetic defects typically act on the same developmental pathways?
They can/do and will result in similar anomalies. Example: valproate embropathy–valproic acid (an anti-seizure medication) is teratogenic and disrupts the homeobox transcription factors. Homeobox gene mutations give rise to the same congenital anomalies
Most common cause of neonatal mortality
Congenital anomalies
Second most common cause of neonatal mortality
Prematurity
When does the greatest mortality of childhood occur?
In the first year and then declines progressively
When is a baby considered preterm?
Birth before 37
Birth before 42 weeks
POST-term
What are appropriate age and weight for gestation?
Between 10th and 90th percentile; below 10=small and above 90 is large
What are the major risk factors for prematurity? (4)
Preterm premature rupture of the placental membranes (PPROM)
Intrauterine infection
Uterine, cervical and placental structural abnormalities
Multiple gestational
What is PPROM?
Preterm premature rupture of the placental membrane
What is the most common cause of prematurity?
Preterm premature rupture of the placental membranes
What is the pathophysiology of PPROM?
Placental inflammation and matrix metalloproteinase activation
What is choroioamnionitis?
Inflammation of the placental membrane
What is funisitis?
Inflammation of the umbilical cord
Organisms associated with intrauterine infection and prematurity
Urea plasma urealyticum Mycoplasma hominids Gardnerella vaginalis Trichomonas Gonorrhoea Chlamydia
What are the 3 categories of causes for fetal growth restriction/intrauterine growth retardation?
Fetal
Placental
Maternal
Fetal causes of fetal growth restriction/intrauterine growth retardation
Despite adequate maternal nutritional supply, there is compromised fetal growth potential; typically there is symmetric growth restriction–all organ systems are proportionally affected
What are 3 fetal causes of fetal growth restriction/intrauterine growth retardation?
Chromosomal abnormalities (trisomies) Congenital anomalies Congenital infections (TORCH)
What does TORCH stand for?
Toxoplasmosis Other Rubella Cytomegalovirus Herpes virus
Placental causes of fetal growth restriction/intrauterine growth retardation
Vigorous fetal growth in the 3rd trimester demands adequate placental growth and development; defects in placental supply typically cause asymmetric growth retardation, with relative sparing of the brain
What are 7 placental causes of fetal growth restriction/intrauterine growth retardation?
- Umbilical-placental vascular anomalies
- Placental abrupt ion-placenta separates from uterus
- Placenta Previn (low lying placenta)
- Placental thrombosis and infarction
- Placental infections
- Multiple gestations
- Placental mosaicism
What is placental mosaicism?
Genetic mutations arising after zygote formation lead to two genetic populations of cells within the placenta and/or fetus
What kind of fetal growth restriction/intrauterine growth retardation causes is the most common?
Maternal
What do maternal causes of fetal growth restriction/intrauterine growth retardation result in?
Decreased placental blood supply
What are the 7 maternal causes of fetal growth restriction/intrauterine growth retardation?
Preeclampsia--high blood pressure and protein in urine Hypertension Inherited thrombophilias Malnutrition Narcotic or alcohol Intake Cigarette smoking Certain drugs (teratogens)
5 risks associated with prematurity? What complications are associated with prematurity?
Hyaline membrane disease (neonatal respiratory distress syndrome) Necrotizing enterocolitis Sepsis Intravenricular hemorrhage Long term complications
Causes of neonatal respiratory distress?
Respiratory distress syndrome Maternal sedation Blood or fluid aspiration Fetal head injury Umbilical cord around neck
Most common cause of neonatal respiratory distress?
Respiratory distress syndrome (also known as hyaline membrane disease)
Incidence of neonatal RDS is 60% in infants born before 28 weeks of gestation and less than 5% of infants born after how many weeks gestation?
37 weeks
Key feature of respiratory distress syndrome
Inadequate pulmonary surfactant
Cell type that makes surfactant
Type II pneumocytes
Surfactant production by type II pneumocytes is highest at what week of gestation?
30? 35??
What is surfactant made of?
Phospholipids and glycoproteins
Decreased surfactant results in ___ alveolar surface tension, progressive alveolar _____ and increasing inspiratory pressures required to expand the ____
Increased
Atelectasis
Lung alveoli