Flashcards in Isoimmunization Deck (34):
WHat is the formation of maternal antibodies?
What is the most common antigen involved in sioimmunization?
Rh specifically the D antigen
Patients with the D antigen are what?
When does isoimmunization occur?
Rh D-negative woman is pregnant with a fetus that is Rh D-positive. Can cause an antibody response against fetal RBCs
What characterizes isoimmunization?
How much blood is sufficient to cause isoimmunization?
Less than 0.1 mL of Rh d-positive blood
Is IgG the first or secondary antibody response?
What is the combination of fluid accumulation in at least 2 extravascular compartments called?
How do you diagnose isoimmunization?
Test for antibodies
The higher the titer, the more significant the antibody response
What do you do if fetal anemia or hydrophic changes are found?
Cordocentesis of percutaneous umbilical blood sampling (PUBS) to measure direct fetal HCT
How do you evaluate fetal anemia?
Amniotic fluid assessment of bilirubin levels
Loo for hydropic changes
Measure blood viscosity of MCA (will have increased flow)
How do you manage isoimmunity?
Direct transfusion under US guidance of antigen-negative rbc's to the fetus (want HCT >30%)
What can you give for prevention of isoimmunization?
GIve RhoGAM or Rhophylac to all RhD-neg women at 28 weeks and w/i 72 hours of delivery
What is a test that can identify fetal erythrocytes in materal circulation and the appropriate dose of Rh immunoglobulin to be administered.
WHat is a test that can be used to determine if the patient has received sufficient antibody.
Indirect Coombs test (positive means the dosage was adequate)
What is the Kell Antigen?
Results from a blood transfusion. Unique anemia results from destruction and suppression of hematopoietic precursor cells and hemolysis is limited
What is where there is maternal-fetal incompatibility usually associated with mild fetal anemia and newborn hyperbilirubinemia. Not associated w/ severe fetal disease.
ABO hemolytic disease
What is the proliferating tropoblast that gives rise to a layer of extraembryonic mesoderm on its intersurface (outer)
What is the inner sac that develops at the dorsal surface of the embryonic dis forming a transparent sac that fills amniotic fluid.
What is where each fetus is surrounded by an amnion and a chorion?
What is where each fetus is surrounded by an amnion, but a single chorion?
What is where twins will share a common sac as the amnion and chorion have already developed?
What is where there is arterial-venous anastomoses that forms between the fetus resulting in blood flow from one to another?
Twin-twin transfusion syndrome
What is the name for the twin that has impaired growth, anemia, hypovolemia, oligohydramnios (from decreased urine output)?
What is the twin that may have hypervolemia, HTN, polycythemia, CHF, can have polyhydramnios (due to increased urine output)
What is when fetal weight is less than 10th percentile for gestational age?
IUGR (intrauterine growth restriction)
What is later onset IUGR usually realted to?
Decreased placental function and nutrient transport
WHat usually causes IUGR?
placenta growth early and rapidly compared to the fetus; has large surface area
Which type of IUGR is more commonly associated w/ heritable factors, immunologic abnormalities, chronic maternal disease, fetal infection, multiple pregnancies?
What constitutes a IUGR diagnosis?
A discrepancy of more than 2 cm
DO an ultrasound for biparietal diameter (BPD), head circumference (HC), femur length, abdominal circumference (AC)
What syndrome is from the fetus' attempt to compensate for poor placenta oxygen transfer by increasing the HCT o more than 5% resultin gin marked polycytehmia. Can lead to thrombosis, heart failure, hyperbilirubinemia.
What is where the infant weighs 4000-4500 grams or greater.
What is an LGA infant?
Large for gestational age. >90%