TERATOLOGY.pptx

Teratology is the study of abnormalities of physiological development. Detailed teratology has been discussed in this PPT.

1. TERATOLOGY OBSTETRICS AND GYNECOLOGY

2. INTRODUCTION Teratology is the study of abnormalities of physiological development. It is often thought of as the study of human congenital abnormalities, but it is broader than that, taking into account other non-birth developmental stages, including puberty; and other organisms, including plants.

3. DEFINITION The science that studies the causes of structural, functional, behavioral & metabolic disorders present at birth: - size arrangement or composition of any organ or part of the body. Teratology is a branch of science that studies the causes, mechanisms, and patterns of abnormal development and its environmental agents, or teratogens ~(Moore and Persaud , 2008).

4. TERATOGENS TERATOLOGY

5. TERATOGENS Teratogens  are substances that may cause birth defects via a toxic effect on an embryo or fetus. These are also defined as agents extrinsic to embryo or fetus which can exert a deleterious effects leading to an increased risk of: Malformations: Physical defects Carcinogens: Risk of cancer Mutagenesis: Increased risk of genetic diagnosis Altered functions: MR Deficient growth: IUGR Abortion /Still birth

6. Teratogens can be classified as: Viruses that infect the mother and in turn may infect and damage the fetus during development Agents that come from the external environment that physically affect the mother and can harm a developing fetus Agents that are ingested by the mother, inhaled from the environment, or otherwise let into the maternal and fetal bodies. X-Rays Hyperthermia TORCH T: Toxoplasmins O: Other R: Rubella C: Cytomegalovirus H: Herpes Drugs Alcohol Food Additives Environmental chemicals Pollutants

7. Wilson’s PRINCIPLES OF TERATOLOGY TERATOLOGY

8. PRINCIPLES OF TERATOLOGY Susceptibility to teratogenesis depends on the genotype of the fetus & mother. Susceptibility to teratogens varies with the developmental stage at the time of exposure. The most sensitive period for inducing birth defects is the 3rd – 8th weeks of gestation, the period of embryogenesis or organogenesis.

9. 3. Manifestations of abnormal development depend on dose and duration of exposure to a teratogen. 4. Teratogens act in specific ways on developing cells & tissues to initiate abnormal embryogenesis. 5. Access of an adverse environmental agent to developing tissues depends on the nature of the agent. 6. The expression of deviant development increase in degree as dosage increases from the no-effect to the lethal level.

10. SUSCEPTIBILITY TO TERATOGENESIS DEPENDS UPON

11. THE SENSITIVITY OF THE EMBRYO TO THE TERATOGENIC AGENTS INCLUDE THE FOLLOWING PRE DIFFERENTIATION STAGE- the embryo is not susceptible to teratogens. The teratogens may either cause death of the embryo by killing all or most of the cells or they may have no apparent effect on embryo. Resistant strain ( 5-9 days ) of gestation. EMBRYONIC STAGE- stage of intensive differentiation, mobilization and organization. Therefore embryo becomes more susceptible to teratogens (10-14 days) of generation.

12. Types of anomalies TERATOLOGY

13. TYPES OF ANOMALIES Visible deviations of structure Non-visible deviation or deviations of function occurring as a result of enzyme deficiency which result in abnormal chemical functions called ‘inborn errors of metabolism’ involving protein, carbohydrates, lipids & pigments. Anomalies existing at birth or long before birth – such are called congenital anomalies.

14. Incidence

15. Frequency of congenital anomalies A Muscular-skeletal 38% B Integumentary 20% C CNS 14% D GIT 9% E Genitourinary 9% F Respiratory 2%

16. Classification of anomalies TERATOLOGY

17. 1. Failure of development Agenesis An organ or body part may be subjected to developmental failure Scrotum Agenesis

18. 2. Incomplete development In growth: dwarfism, gigantism In union: cleft palate, double uterus In subdivisions: heart chambers, body cavities, double ureters, multiple kidneys, double gall bladders In metabolism: sickle cell anaemia In histological differentiation: thickened skin, stenosis In number: multiple digits, multiple nipples, twinning

19. 3. Embryonic persistence Any embryonic structure which persist instead of disappearing Meckel’s diverticulum cervical cyst thyroglossal cyst

20. 4. Misplacements Ectopic Thyroid Ectopic Pregnancy Ectopic Testes

21. CAUSATIVE FACTORS IN TERATOGENESIS TERATOLOGY

22. 1. HEREDITY Example: Cleft lip and palate (orofacial cleft) Syndactyly Syndactyly is a condition wherein two or more digits are fused together.

23. Syndactyly

24. 2.ENV I RONMENT

25. 3. IONIZING RADIATION

26. 4. PATHOGENS Rubella virus- german measles: Symptoms of CRS include problems with the eyes such as cataracts, ears such as deafness, heart, and brain. Problems are rare after the 20th week of pregnancy. Herpes simplex- herpes of the eye, herpes infection of the brain, and neonatal herpes when it affects a newborn, among others

27. 5.MATERNAL DISEASE

28. 6.HEAVY METALS LIKE MERCURY AND LEAD

29. MECHANISM OF TERATOGENESIS The Mechanism of Teratogenesis fall into broad categories based on the etiology of congenital malformations: (a). Errors in genetic programming based on deviations in the genotypes of the embryo or the low probability for error of the normal genotype. (b). Environmental agents or factors that interact with an embryo during the period of development (drugs, chemicals, radiation, hyperthermia , infections, abnormal maternal metabolic states, or mechanical factors ). The etiology of human malformations includes both genetic and environmental factors.

30. Teratogenic agents TERATOLOGY

31. COMMON TERATOGENIC DRUGS

32. Teratogenic outcomes Exposure to teratogens can result in a wide range of structural abnormalities such as cleft lip, cleft palate, dysmelia , anencephaly, ventricular septal defect. Exposure to a single agent can produce various abnormalities depending on the stage of development it occurs.

33. Diagnosis TERATOLOGY

34. DIAGNOSTICS PRENATAL DIAGNOSTICS POSTNATAL EXAMINATION

35. prevention TERATOLOGY

36. PRIMARY PREVENTION

37. Secondary prevention