Amniocentesis and CVS
Methods of chromosomal evaluation <ul><li>Non invasive: </li></ul><ul><ul><li>Fetal cells from maternal blood  </li></ul><...
Invasive techniques <ul><li>Amniocentesis: </li></ul><ul><ul><li>Late  –  second trimester after 15 weeks </li></ul></ul><...
karyotype fish PCR
What can be evaluated? <ul><li>Chromosomal aberrations: </li></ul><ul><ul><li>Trisomy,  </li></ul></ul><ul><ul><li>Monosom...
Amniocentesis <ul><li>First introduced by Serr and Fuchs and Riis in the 1950s for fetal sex determination </li></ul><ul><...
Mid Trimester Amniocentesis <ul><li>Per coetaneous  </li></ul><ul><li>20-23g needle </li></ul><ul><li>Ultrasound guided </...
 
 
complications <ul><li>Pregnancy loss  0.3-1.0%. </li></ul><ul><li>Increase risk: </li></ul><ul><ul><li>Needle larger than ...
Complications <ul><li>Leakage of amniotic fluid (better prognosis than spontaneous leakage) </li></ul><ul><li>Amnionitis <...
Amniocentesis and HIV positive women  <ul><li>Increased rate of vertical transmission </li></ul><ul><li>Chemoprophylaxis p...
Multiple Gestation <ul><li>Three methods: </li></ul><ul><ul><li>Indigo carmine injection to the first sac </li></ul></ul><...
Early Amniocentesis: 9-14 weeks <ul><li>Introduced at late 80 th   </li></ul><ul><li>10-14 weeks gestation </li></ul><ul><...
Chorionic villus sampling <ul><li>Was developed in the 80 th </li></ul><ul><li>percutaneous transabdominal with 19-20g nee...
Chorionic villus sampling <ul><li>Was developed in the 80 th </li></ul><ul><li>percutaneous transabdominal </li></ul><ul><...
 
 
<ul><li>15-30mg each aspiration </li></ul><ul><li>20mg ideal for cytogenetic testing </li></ul><ul><li>30-40mg for cytogen...
CVS results <ul><li>Direct analysis  examines the trophoblast cells of the placenta (very rapidly dividing cells) </li></u...
Risk of invasive procedure  <ul><li>Early amniocentesis: </li></ul><ul><ul><li>High pregnancy loss </li></ul></ul><ul><ul>...
Risk of invasive procedure - CVS <ul><li>Transabdominal CVS as safe as second trimester amniocentesis </li></ul><ul><li>Tr...
mosaicism   <ul><li>True  chromosomal mosaicism is when two or more abnormal cells lines are detected in two or more cultu...
mosaicism <ul><li>Most often involving trisomic cell and normal cells </li></ul><ul><li>1-2% of pregnancies undergoing CVS...
Mosaicism (trisomic cells) in CVS <ul><li>Option of an additional prenatal diagnostic procedure (amniocentesis or fetal bl...
Mosaicism (trisomic cells) in CVS <ul><li>Four possible conditions: </li></ul><ul><ul><li>Mosaicism only in the placenta n...
Mosaicism (trisomic cells) in amniotic fluid   <ul><li>Probably there are trisomic cells in the fetus </li></ul><ul><li>Th...
Uniparental Disomy <ul><li>Arises when an individual inherits two copies of a chromosome pair from one parent and no copy ...
How does UPD happen?   <ul><li>Loss of a chromosome from a trisomic zygote, &quot;trisomic rescue&quot;  </li></ul><ul><li...
Trisomic rescue following an error in meiosis   heterodisomy
Trisomic rescue followed an error in meiosis II   isodisomy
UPD - health concerns in people  for two possible reasons: <ul><li>Parental imprinting in the case of heterodisomy and iso...
Clinical consequences of UPD   <ul><li>molecular UPD testing should be considered for certain chromosomes (including 6, 7,...
Factors considered when trying to predict the outcome of mosaicism   <ul><li>the chromosome involved   </li></ul><ul><ul><...
Factors considered when trying to predict the outcome of mosaicism <ul><li>The tissues affected and level of trisomy in th...
Factors considered when trying to predict the outcome of mosaicism <ul><li>method of ascertainment      </li></ul><ul><ul>...
Factors considered when trying to predict the outcome of mosaicism <ul><li>ultrasound findings      </li></ul><ul><li>pres...
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37233502 amniocentesis-and-cvs

  1. 1. Amniocentesis and CVS
  2. 2. Methods of chromosomal evaluation <ul><li>Non invasive: </li></ul><ul><ul><li>Fetal cells from maternal blood </li></ul></ul><ul><ul><li>preimplantation embryos (PGD) </li></ul></ul><ul><li>Invasive: </li></ul><ul><ul><li>amniotic fluid (amniocentesis) </li></ul></ul><ul><ul><li>placenta (chorionic villus tissue) </li></ul></ul><ul><ul><li>Fetal blood </li></ul></ul>
  3. 3. Invasive techniques <ul><li>Amniocentesis: </li></ul><ul><ul><li>Late – second trimester after 15 weeks </li></ul></ul><ul><ul><li>Early – earlier than 15 weeks </li></ul></ul><ul><li>Chorionic villus sampling (CVS) </li></ul><ul><ul><li>Abdominal </li></ul></ul><ul><ul><li>Trans cervical </li></ul></ul><ul><ul><li>Trans vaginal </li></ul></ul><ul><li>Fetal blood sampling </li></ul>
  4. 4. karyotype fish PCR
  5. 5. What can be evaluated? <ul><li>Chromosomal aberrations: </li></ul><ul><ul><li>Trisomy, </li></ul></ul><ul><ul><li>Monosomy, </li></ul></ul><ul><ul><li>Polyploidy, </li></ul></ul><ul><ul><li>Marker chromosome, </li></ul></ul><ul><ul><li>Deletion, duplication, inversion, translocation, ring chromosome . </li></ul></ul><ul><li>Genetic aberrations (DNA) </li></ul><ul><li>Infectious disease </li></ul><ul><li>Biochemical markers (AFP) </li></ul>
  6. 6. Amniocentesis <ul><li>First introduced by Serr and Fuchs and Riis in the 1950s for fetal sex determination </li></ul><ul><li>Only at the late 70 th a static ultrasound was used to locate the placenta and amniotic fluid pocket </li></ul><ul><li>Only In 1983, Jeanty reported a technique of amniocentesis ’’ under ultrasound vision ’’ </li></ul>
  7. 7. Mid Trimester Amniocentesis <ul><li>Per coetaneous </li></ul><ul><li>20-23g needle </li></ul><ul><li>Ultrasound guided </li></ul><ul><li>Usually 20cc amniotic fluid </li></ul><ul><li>Results – 2 to 3 weeks </li></ul>
  8. 10. complications <ul><li>Pregnancy loss 0.3-1.0%. </li></ul><ul><li>Increase risk: </li></ul><ul><ul><li>Needle larger than 18g </li></ul></ul><ul><ul><li>Multiple needle insertion </li></ul></ul><ul><ul><li>Discoloration of the fluid </li></ul></ul><ul><ul><li>High AFP, multiple late abortions, previous vaginal bleeding </li></ul></ul><ul><ul><li>Placental perforation – recent studies didn ’ t find correlation </li></ul></ul>
  9. 11. Complications <ul><li>Leakage of amniotic fluid (better prognosis than spontaneous leakage) </li></ul><ul><li>Amnionitis </li></ul><ul><li>Vaginal bleeding </li></ul><ul><li>Needle puncture of the fetus </li></ul><ul><li>Long term complications: </li></ul><ul><ul><li>Respiratory distress?? </li></ul></ul><ul><ul><li>Isoimmunization?? </li></ul></ul>
  10. 12. Amniocentesis and HIV positive women <ul><li>Increased rate of vertical transmission </li></ul><ul><li>Chemoprophylaxis previous to amniocentesis appears to be beneficial in preventing vertical transmission </li></ul>
  11. 13. Multiple Gestation <ul><li>Three methods: </li></ul><ul><ul><li>Indigo carmine injection to the first sac </li></ul></ul><ul><ul><li>A single needle puncture sampling technique (Jeanty 1990) </li></ul></ul><ul><ul><li>Simultaneous visualization of two needles on each side of the separating membrane (Bahado-Singh 1992) </li></ul></ul><ul><ul><li>Abortion risk – probably higher </li></ul></ul><ul><ul><li>Detailed description of fetus position and placental location </li></ul></ul>
  12. 14. Early Amniocentesis: 9-14 weeks <ul><li>Introduced at late 80 th </li></ul><ul><li>10-14 weeks gestation </li></ul><ul><li>Only the amniotic (inner) sac should be aspirated </li></ul><ul><li>Approximately 1 cc for gestational age </li></ul><ul><li>Higher rate of pregnancy loss, talipes equinovarus, and post procedural amniotic fluid leakage </li></ul><ul><li>laboratory failure op to 20% </li></ul>
  13. 15. Chorionic villus sampling <ul><li>Was developed in the 80 th </li></ul><ul><li>percutaneous transabdominal with 19-20g needle </li></ul>
  14. 16. Chorionic villus sampling <ul><li>Was developed in the 80 th </li></ul><ul><li>percutaneous transabdominal </li></ul><ul><li>transvaginal </li></ul><ul><li>transcervical </li></ul>
  15. 19. <ul><li>15-30mg each aspiration </li></ul><ul><li>20mg ideal for cytogenetic testing </li></ul><ul><li>30-40mg for cytogenetic and other direct molecular and biochemical tests </li></ul>
  16. 20. CVS results <ul><li>Direct analysis examines the trophoblast cells of the placenta (very rapidly dividing cells) </li></ul><ul><ul><li>Results in few hours </li></ul></ul><ul><ul><li>greater vulnerability to mitotic error </li></ul></ul><ul><li>Cultured analysis examines the fibroblast like cells of the villus stroma or mesenchymal core. </li></ul><ul><ul><li>Approximately 7-10 days </li></ul></ul><ul><ul><li>Accurately reflect the chromosomes of the fetus.   </li></ul></ul>
  17. 21. Risk of invasive procedure <ul><li>Early amniocentesis: </li></ul><ul><ul><li>High pregnancy loss </li></ul></ul><ul><ul><li>High fetal malformations </li></ul></ul><ul><ul><li>High rate of multiple needle insertions (4.7%) </li></ul></ul><ul><ul><li>High rate laboratory failures (1.8%) </li></ul></ul><ul><li>Late amniocentesis: </li></ul><ul><ul><li>“ Low ” pregnancy loss (0.3-1%) </li></ul></ul><ul><ul><li>Low rate of multiple needle insertions (1.7%) </li></ul></ul><ul><ul><li>Low rate laboratory failures (0.2%) </li></ul></ul>
  18. 22. Risk of invasive procedure - CVS <ul><li>Transabdominal CVS as safe as second trimester amniocentesis </li></ul><ul><li>Trans abdominal and transcervical CVS are equally safe and efficacious, provided that centers have expertise with both approaches </li></ul><ul><li>In approximately 3 – 5% of cases, clinical circumstances will support one approach over the other </li></ul><ul><li>Limb reduction – not after 9 weeks </li></ul>
  19. 23. mosaicism <ul><li>True chromosomal mosaicism is when two or more abnormal cells lines are detected in two or more culture flasks from the same individual. </li></ul><ul><li>Pseudomosaicism is a term used to describe two abnormal cell lines that are found in only one culture flask (not reported to the patient) </li></ul>
  20. 24. mosaicism <ul><li>Most often involving trisomic cell and normal cells </li></ul><ul><li>1-2% of pregnancies undergoing CVS </li></ul><ul><li>0.1% of pregnancies undergoing amniocentesis </li></ul><ul><li>Clinical outcome of chromosomal mosaicism is strongly dependent on the specific chromosome involved and the number of trisomic cells in both the placenta and the fetus </li></ul>
  21. 25. Mosaicism (trisomic cells) in CVS <ul><li>Option of an additional prenatal diagnostic procedure (amniocentesis or fetal blood sampling) </li></ul>
  22. 26. Mosaicism (trisomic cells) in CVS <ul><li>Four possible conditions: </li></ul><ul><ul><li>Mosaicism only in the placenta not affecting the fetus or placental function. </li></ul></ul><ul><ul><li>Mosaicism only in the placenta not affecting the fetus but alter placental function (IUGR) </li></ul></ul><ul><ul><li>Trisomy cells are both in the placenta and in the fetus </li></ul></ul><ul><ul><li>Trisomy cells in the placenta and uniparental disomy in the fetus </li></ul></ul>
  23. 27. Mosaicism (trisomic cells) in amniotic fluid <ul><li>Probably there are trisomic cells in the fetus </li></ul><ul><li>The true level and distribution of trisomic cells cannot be accurately assessed with any prenatal procedure </li></ul><ul><li>Ultrasound is often the best judge of how a baby is developing </li></ul>
  24. 28. Uniparental Disomy <ul><li>Arises when an individual inherits two copies of a chromosome pair from one parent and no copy from the other parent </li></ul><ul><ul><li>Maternal UPD – two copies from the mother </li></ul></ul><ul><ul><li>Paternal UPD – two copies from the father </li></ul></ul>
  25. 29. How does UPD happen? <ul><li>Loss of a chromosome from a trisomic zygote, &quot;trisomic rescue&quot; </li></ul><ul><li>Duplication of a chromosome from a monosomic zygote, &quot;monosomic rescue&quot; </li></ul><ul><li>Fertilization of a gamete with two copies of a chromosome by a gamete with no copies of the same chromosome, called gamete complementation. </li></ul>
  26. 30. Trisomic rescue following an error in meiosis heterodisomy
  27. 31. Trisomic rescue followed an error in meiosis II isodisomy
  28. 32. UPD - health concerns in people for two possible reasons: <ul><li>Parental imprinting in the case of heterodisomy and isodisomy </li></ul><ul><li>Unmasking of recessive conditions in some cases of isodisomy </li></ul>
  29. 33. Clinical consequences of UPD <ul><li>molecular UPD testing should be considered for certain chromosomes (including 6, 7, 11, 14, 15) that are known to have adverse phenotypic imprinting effects.   </li></ul>
  30. 34. Factors considered when trying to predict the outcome of mosaicism <ul><li>the chromosome involved </li></ul><ul><ul><li>A mosaic finding 18 or 21 is likely to have worse implications </li></ul></ul><ul><ul><li>mosaic finding for trisomy 15 or 16 is likely to have less implications (trisomy 15 or 16 cells cannot survive ) </li></ul></ul>
  31. 35. Factors considered when trying to predict the outcome of mosaicism <ul><li>The tissues affected and level of trisomy in those tissues </li></ul><ul><ul><li>The tissue affected cannot be evaluated </li></ul></ul><ul><ul><li>The level of trisomy can be only estimated    </li></ul></ul>
  32. 36. Factors considered when trying to predict the outcome of mosaicism <ul><li>method of ascertainment    </li></ul><ul><ul><li>CVS shows that the placenta is affected </li></ul></ul><ul><ul><li>Amniotic fluid suggests that at least one fetal tissue may be affected </li></ul></ul><ul><ul><li>Fetal blood sampling confirms the diagnosis of chromosomal mosaicism </li></ul></ul>
  33. 37. Factors considered when trying to predict the outcome of mosaicism <ul><li>ultrasound findings    </li></ul><ul><li>presence/absence of uniparental disomy    </li></ul><ul><li>number of previous case reports known in the literature   </li></ul>
  34. 38. Thank you

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