Questions and Answers
What is the chance of having a major malformation in an infant with two minor anomalies?
What type of agents can cause structural abnormalities in the fetus?
What is the primary purpose of using ultrasonography in prenatal care?
Which type of minor anomaly is NOT associated with increased risk of major defects?
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Which of the following is an example of a chemical agent linked to birth defects?
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What is a potential risk associated with amniocentesis when performed before 14 weeks of gestation?
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The term VACTERL refers to a group of anomalies involving which components?
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Which prenatal diagnosis technique is considered non-invasive?
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Which measurements are typically utilized to assess fetal growth around the 20-week mark?
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When is the fetus most vulnerable to malformation due to environmental exposure?
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What does maternal serum screening primarily seek to detect?
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What is the correct term for the presence of one or more anomalies that may not be directly harmful on their own?
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Which of the following pairs correctly matches a prenatal diagnosis technique with its invasive nature?
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Which maternal condition is associated with an increased risk of birth defects?
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Which statement best defines ultrasonography?
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What is the importance of recognizing one or more components of congenital anomaly associations?
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When assessing risk for major malformations, how does the chance correlate with multiple minor anomalies?
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Which type of abnormality is NOT directly indicated by ear anomalies?
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In which situation does the fetus directly become infected with an infectious agent?
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What term describes a combination of multiple abnormalities that occur together more frequently than expected by chance?
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Which of the following anomalies is not considered non-random in occurrence?
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What is a significant factor influencing the manifestation of abnormal development in embryos?
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Which of the following outcomes is NOT associated with teratogenic exposure?
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How can teratogens affect developing cells during embryogenesis?
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What preventive measure can be taken to reduce the risk of Neural Tube Defects during pregnancy?
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What role does the dose and duration of exposure to teratogens play in embryonic development?
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Which stage of development is considered entirely safe from teratogen exposure?
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What is a possible mechanism through which teratogens can lead to abnormal embryogenesis?
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Which of the following factors can influence susceptibility to teratogens?
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What is the primary reason for performing chorionic villus sampling (CVS)?
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In which trimester is the maternal serum level of alpha-fetoprotein (AFP) expected to steadily decline after peaking?
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When is amniocentesis typically preferred over chorionic villus sampling?
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What is a key indication for performing cordocentesis?
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What risk factor does NOT contribute to a high-risk pregnancy?
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Which serum marker is produced by the fetal liver and is important for monitoring fetal status during pregnancy?
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What is the purpose of fetal transfusions?
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What abnormal serum screening test finding could indicate the need for further invasive testing?
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Study Notes
Causes of Birth Defects
- Minor anomalies like microtia, pigmented spots, and short palpebral fissures can signal major defects.
- Infants with one minor anomaly have a 3% chance of major malformation; two anomalies raise the risk to 10%; three or more anomalies increase it to 20%.
Environmental Factors
- Infectious agents (e.g., rubella, herpes simplex, varicella, syphilis) can cause birth defects if the mother is infected.
- Physical agents include x-rays and hyperthermia.
- Chemical agents like thalidomide, valproic acid, alcohol, and certain hormones have teratogenic effects.
- Maternal diseases such as diabetes and obesity can contribute to birth defects.
Types of Abnormalities
- Malformations often result from errors during embryogenesis but can occur at any development stage.
- Categories include malformation, disruption, deformation, syndrome, and association.
Principles of Teratology
- The susceptibility to teratogens varies based on the conceptus's genotype and environmental interactions.
- Teratogens may initiate abnormal embryogenesis, affecting growth and function of cells or causing cell death.
Prevention Strategies
- Awareness of teratogen exposure is crucial, particularly in early pregnancy.
- Supplementation of iodine and folate can prevent neural tube defects.
Prenatal Diagnosis Techniques
- Ultrasonography: Non-invasive imaging technique using sound waves to assess fetal growth and congenital anomalies.
- Maternal Serum Screening: Measures biochemical markers like alpha-fetoprotein (AFP) to evaluate fetal health; abnormalities in AFP levels can indicate issues.
- Non-Invasive Testing: Techniques aim to detect malformations without risk to the fetus.
Invasive Techniques
- Amniocentesis: A needle is inserted to withdraw amniotic fluid for karyotyping; usually performed after 14 weeks of gestation.
- Chorionic Villus Sampling (CVS): Involves aspirating fetal tissue from the placenta for genetic testing.
- Cordocentesis: Percutaneous umbilical blood sampling to evaluate fetal cells, usually performed after positive results from non-invasive tests.
High-Risk Pregnancies
- Defined risk factors include advanced maternal age (35 and older), family history of genetic issues, maternal diseases (e.g., diabetes), and abnormal ultrasound or serum screening results.
Treatment Options
- Fetal Transfusion: Blood transfusions may be conducted for fetuses diagnosed with anemia due to maternal antibodies or other causes.
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Description
Explore the various causes of birth defects, including environmental and maternal factors, as well as types of abnormalities. Understand the principles of teratology and how different factors can influence embryonic development. Learn how minor anomalies can indicate potential major defects in infants.
