OnlineMedEd: Obstetrics - "Alloimmunization"

Question 1

List the three Rh antigens and their likelihood of causing alloimmunization.

Answer 1

• L: not immunogenic
• D: immunogenic
• K: immunogenic

(“Lewis Lives; Duffy Dies; Kal Kills.”)

Question 2

To cause symptoms, the titers have to be greater than ____________.

Answer 2

1:8

Question 3

Go through the screening process for alloimmunization.

Answer 3

•First, test the mom.
- If she is Rh+ then she cannot develop antibodies to Rh+. End screening there.

• Second, if mom is Rh-, then test dad.
- If dad is Rh-, then stop screening there.

•Third, if dad is Rh+ or his status is unknown, then test mom’s antibodies.
- If mom doesn’t have antibodies, then stop screening.

• Fourth, if mom has sufficient titers (greater than 1:8), then do a transcranial doppler.
- If the transcranial doppler is negative, resume normal prenatal care.

•Last, if the transcranial doppler is positive, decide if it’s appropriate to induce labor based on gestational age. (If older than 32 weeks, deliver. If younger, test via PUBS.)

Question 4

When should you give RhoGAM in a pregnancy at risk for developing antibodies?

Answer 4

28 weeks and within 72 hours of delivery