Rh Isoimmunization Lecture Notes

Rh isoimmunization occurs when an Rh-negative mother is exposed to an Rh-positive fetus.
The mother's immune system recognizes the Rh-positive fetal blood cells as foreign and develops antibodies against them.
These antibodies can cross the placenta and attack the baby's red blood cells (RBCs), potentially leading to hemolytic disease, specifically fetal anemia.

Rh incompatibility arises when an Rh-negative mother carries an Rh-positive baby.
The mother's immune system perceives the baby as a "foreign body" due to the Rh factor.
This incompatibility doesn't directly harm the mother, but it poses risks to the fetus.

While Rh incompatibility can be dangerous in subsequent pregnancies, it typically doesn't cause complications in the first pregnancy involving an Rh-negative mother and an Rh-positive fetus.
During the first pregnancy, fetal blood may not mix with the mother's blood, preventing the mother's body from producing antibodies against the Rh factor.
However, blood mixing can occur during delivery, leading to the mother's body developing these antibodies.
In subsequent pregnancies with an Rh-positive fetus, these antibodies can cross the placenta and attack the fetal RBCs, potentially causing Rh disease.
Mixing of maternal and fetal blood is more likely during vaginal deliveries and less likely during C-sections, unless the placenta is damaged during surgery.

Hemolytic Anemia: Destruction of fetal red blood cells.
Jaundice (Kernicterus):
- Increased bilirubin levels can lead to fetal brain damage.
- $↑ bilirubin → fetal brain damage$
Enlarged Spleen: Due to increased RBC destruction
Hydrops Fetalis: Accumulation of fluid in the baby's body.
Stillbirth: Fetal death.

Rh Immunoglobulin (Rho-Gam):
- Administered at 28 weeks of pregnancy.
- Another injection is given within 72 hours after delivery to prevent sensitization.
Intrauterine Blood Transfusion: To treat fetal anemia.
Close Maternal-Fetal Monitoring: To assess the baby's condition.