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Difficulty: Very hardNormal Pregnancy and Prenatal Care

A healthy 24-year-old primigravida presents for preconception counseling. She is subsequently confirmed pregnant and initiates prenatal care at 8 weeks gestation. Her initial laboratory workup reveals she is blood type A-negative. Assuming an uncomplicated pregnancy course that concludes with the term vaginal delivery of a healthy Rh(D)-positive neonate, arrange the following routine alloimmunization screening and prophylaxis steps in the correct chronological sequence from the first trimester through the postpartum period.

  1. 1Initial prenatal ABO/Rh(D) blood typing and baseline maternal serum indirect antiglobulin testing
  2. 2Repeat maternal indirect antiglobulin testing to confirm the continued absence of alloimmunization
  3. 3Routine antepartum prophylactic administration of a standard 300-mcg dose of anti-D immune globulin
  4. 4Qualitative erythrocyte rosette testing on maternal blood to detect massive fetal-maternal hemorrhage
  5. 5Postpartum administration of anti-D immune globulin with the dose adjusted via quantitative testing (e.g., Kleihauer-Betke)

Answer

The correct chronological sequence is: 1) Initial prenatal ABO/Rh(D) blood typing and baseline maternal serum indirect antiglobulin testing, 2) Repeat maternal indirect antiglobulin testing to confirm the continued absence of alloimmunization, 3) Routine antepartum prophylactic administration of a standard 300-mcg dose of anti-D immune globulin, 4) Qualitative erythrocyte rosette testing on maternal blood to detect massive fetal-maternal hemorrhage, and 5) Postpartum administration of anti-D immune globulin with the dose adjusted via quantitative testing.
The correct chronological sequence for managing an Rh(D)-negative pregnant patient begins with an initial prenatal ABO/Rh(D) blood typing and baseline maternal serum indirect antiglobulin testing to establish baseline status. At 28 weeks gestation, repeat maternal indirect antiglobulin testing must be performed to confirm the continued absence of alloimmunization. Immediately following this blood draw, routine antepartum prophylactic administration of a standard 300-mcg dose of anti-D immune globulin is given. Postpartum, after delivery of an Rh(D)-positive neonate, qualitative erythrocyte rosette testing on maternal blood is performed to detect significant fetal-maternal hemorrhage. Finally, postpartum administration of anti-D immune globulin is given within 72 hours, with the dose adjusted based on quantitative testing (such as the Kleihauer-Betke test) if the initial qualitative screen was positive.

Step-by-Step Solution

1
Identify the baseline initial prenatal testing requirements for an unsensitized Rh(D)-negative pregnant patient.
Initial prenatal ABO/Rh(D) blood typing and baseline maternal serum indirect antiglobulin testing must be performed first to establish the lack of pre-existing antibodies.
A baseline must be established in the first trimester before any potential sensitization events occur.
2
Determine the required screening immediately prior to third-trimester prophylaxis.
A repeat maternal indirect antiglobulin test is required at 28 weeks gestation.
It is necessary to confirm the patient has not become sensitized during the pregnancy before administering the prophylactic immune globulin.
3
Administer the standard antepartum prophylaxis.
Routine antepartum prophylactic administration of a standard 300-mcg dose of anti-D immune globulin is given.
This provides passive immunity during the third trimester and must be given only AFTER the 28-week antibody screen is drawn to avoid an iatrogenic positive screen.
4
Identify the appropriate initial postpartum screening test following delivery of an Rh(D)-positive neonate.
Qualitative erythrocyte rosette testing is performed on maternal blood.
This screens for massive fetal-maternal hemorrhage > 30 mL to determine if a single standard dose of immune globulin is sufficient or if quantitative testing is needed.
5
Administer the final targeted prophylaxis.
Postpartum administration of anti-D immune globulin is given, dosed according to quantitative testing (e.g., Kleihauer-Betke) if the rosette test was positive.
Adequate dosing must be given within 72 hours postpartum to neutralize all fetal erythrocytes and prevent permanent maternal alloimmunization.

Key Concept

Rh(D) alloimmunization prevention requires a strict chronological sequence: initial first-trimester screening, repeat screening at 28 weeks prior to routine antepartum prophylaxis, and postpartum qualitative/quantitative fetal-maternal hemorrhage testing to guide the final postpartum prophylactic dose.
Estimated Time:1m 30s
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Normal Pregnancy and Prenatal Care

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