Fetal Hydrops (10) Flashcards
What is Fetal Hydrops?
Accumulation of edema fluid in fetus during intrauterine growth
Accumulation of edema fluid in fetus during intrauterine growth
Fetal Hydrops
What are the 2 types of fetal hydrops?
- Immune
2. Nonimmune
What is the current most common form of hydrops and why?
Nonimmune due to successful prophylaxis
What is Immune Hydrops?
Hemolytic disease cause by blood group antigen incompatibility between the mother and fetus!
What pregnancy does immune hydrops affect?
2nd!
Describe the setup for immune fetal hydrops to occur
Rh - mother and Rh + father
= Rh + 1st child
When will the mother become sensitized to the Rh + antigen?
During her first pregnancy with an Rh + child, at the last trimester
How does Rh + fetal blood reach maternal circulation at the last trimester?
Due to loss of cytotrophoblast barrier or during birth iteself
What is the most common Rh + antigen that causes incompatibility?
D
During the first pregnancy, when fetal Rh D+ blood reaches maternal circulation of Rh - , what antibodies will be made?
IgM - cannot cross placenta
When the mother becomes sensitized, what antibodies does she produce and why is the first child not affected?
IgM antibodies cannot cross the placenta
When the second child is Rh D+, what antibodies will become active?
IgG! - can cross placenta
With the second child, how does hemolytic disease begin?
If the fetal blood crosses into maternal circulation, the IgG antibodies will cross the placenta and degrade the fetal RBCs
Greater than ___ ml of fetal Rh + blood into maternal circulation will cause an antibody response
1 mL
The mother’s antibody response depends on the dose of the antigen that reaches her blood stream. How much will need to cross?
1 mL
Once IgG antibodies attach and begin to degrade the fetal RBCs, describe what happens as anemia progresses.
- Anemia
- Causes liver injury and cardiac decompensation
- Liver injury results in decreased albumin synthesis
- Decreased albumin synthesis causes decreased oncotic pressure = edema
- Cardiac decompensation = edema
== Fetal hydrops
Once IgG antibodies attach and begin to degrade the fetal RBCs, describe what happens are hemoglobin is degraded.
- Hb is degraded and releases heme
- Heme is converted to bilirubin
- Increased levels of bilirubin
- Bilirubin deposits in the basal ganglia of the brain
= Jaundice and Kernicterus
A level of bilirubin in the blood greater than ___ will usually cause kernicterus
20
Where does bilirubin get deposited in the brain for kernicterus to occur?
Basal ganglia
What treatment is given to the Rh - mother now?
Rhesus Immune Globin with Anti - D antibodies (RhIg)
When is Rhesus Immune Globin with anti - D antibodies given to the Rh - mother?
28 weeks gestation and within 72 hours of birth of the child
Is RhIg also given after abortions?
Yes
3 causes of nonimmune hydrops?
- Cardiovascular
- Chromosomal anomalies
- Fetal anemia
What cardiovascular defects can cause nonimmune hydrops?
Malformations and arrhythmias
What chromosomal anomalies can cause nonimmune hydrops?
Turner’s syndrome (45X), Trisomy 18 and 21
How do chromosomal anomalies like Trisomy 18 and 21 cause nonimmune hydrops?
They have associated cardiac abnormalities
What is the most common cause of fetal anemia that can cause nonimmune hydrops?
Homozygous alpha-thalessemia
What does Homozygous alpha-thalessemia do?
Deletes all 4 alpha globin chains = fetal anemia
What virus can cause fetal anemia that results in nonimmune fetal hydrops?
Transplacental infection by Parvovirus B19
Describe how Parvovirus B19 causes fetal anemia and thus nonimmune hydrops
- Parvovirus B19 gains entry into normoblasts
- The virus replicates
= RBC apoptosis and aplasia
In nonimmune hydrops associated with fetal anemia, what color are the fetus and placenta?
PALE
In nonimmune hydrops associated with fetal anemia, describe the bone marrow.
Bone marrow exhibits compensatory hyperplasia of erythroid precursors
In nonimmune hydrops associated with fetal anemia, describe what is seen in other places?
Extramedullary hematopoiesis is present in other tissues!
How do RBCs look in nonimmune hydrops due to fetal anemia?
LARGE number of IMMATURE RBCs
– reticulocytes and erythroblasts
A large number of reticulocytes and erythroblasts is known as?
Erythroblastosis Fetalis
Erythroblastosis Fetalis
Large number of immature RBCs due to Fetal anemia c
Turner’s syndrome (45X) is susceptible to what type of fluid accumulation?
Postnuchal fluid = cystic hygroma
Cystic Hygroma
Postnuchal fluid accumulation seen with turner’s syndrome of hydrops
Once the IgG antibodies reach fetal blood and begin degrading, describe what results after anemia.
- Anemia
- Liver injury (hypoxia) and cardiac decompensation
- Liver injury causes decreased synthesis of albumin
- Decreased albumin causes decreased oncotic pressure
= Edema = Hydrops
Once the IgG antibodies reach fetal blood and begin degrading, describe what results with hemoglobin degradation.
- Hemoglobin is degraded to heme
- Heme is degraded to bilirubin
- Bilirubin levels greater than 20 accumulate in the brain (basal ganglia) and tissues
= Jaundice and Kernicterus
