Testing III

Chronic villus sampling

• 1. removal of tissue specimen from fetal portion of placenta
• 2.tissue reflects genetic makeup of fetus
• 3.can do chromosomal testing
• 4. guided by ultrasound

Between 10-12 weeks, allows enough time for abortion.

• 1. vaginal spotting/bleeding immediately afterward
• 2. miscarriage
• 3. rupture of membranes
• 4. chorioamnionitis
• 5. If Rh- should have rhogam

percutaneous umbilical blood sampling

it is guided by ultrasound, provides direct access to fetal circulation by withdrawing blood

1. needle is inserted into fetal umbilical vessel (vein), usually punctured near its insertion into the placenta.

2. a small amount of blood is removed & tested immediately by the APT test to ensure its fetal origin

3. getting chromosomal bilirubin & hematocrit

4. if performed before 10 weeks may have limb defects

continous FHR monitoring for several minutes to 1 hour, a repeated ultrasound exam 1 hour after to ensure that no further bleeding or hematoma has occured.

• Mothers blood is different than the baby, mothers antibodies attack baby RBC and breaks them down causing bilirubin. When the RBC's are destroyed anemia happens.
• Milder effects than RH incompatibility

If the mother is RH- and baby RH+, mother will need to be given rhogam by 72 hours.

Usually given at 28 weeks as preventive.

causes severe anemia & ascites which are fetal hydrops fetalis

its a maternal blood test for antibody sensitization.

Tests newborn blood for antibodies.

If coombs is +: already has antibodies and can't reverse