Bedside Snapshot
  • What it is: Human anti‑D (RhO) immunoglobulin used to prevent Rh sensitization in Rh‑negative patients exposed/potentially exposed to Rh‑positive fetal RBCs.
  • Primary ED/L&D jobs: Give after first‑trimester bleeding, ectopic, abortion, trauma, procedures, or delivery when indicated and patient is Rh‑negative (and non‑sensitized).
  • Timing: As soon as possible; efficacy best within 72 hours of sensitizing event.
  • Common dose: 300 µg IM (covers ~30 mL fetal whole blood) ≥12 weeks; 50 µg IM often used <12 weeks; IV formulations exist.
Protocol tip: Confirm maternal blood type/antibody screen; if unknown, treat based on likely Rh‑negative risk and clinical scenario per local policy.
Brand & Generic Names
  • Generic Name: Rho(D) immune globulin (human)
  • Brand Names: RhoGAM, HyperRHO, Rhophylac (IV/IM)
Medication Class

Human anti‑D immunoglobulin preparation that opsonizes Rh‑positive fetal erythrocytes in maternal circulation, preventing maternal immune sensitization and anti‑D antibody formation.

Pharmacology

Mechanism of Action:

  • Passive anti‑D antibodies bind Rh‑positive fetal RBCs → facilitate clearance before maternal immune system mounts a primary response.

Pharmacokinetics:

  • Routes: IM (most common), some products allow IV (e.g., Rhophylac).
  • Onset/duration: Detectable anti‑D within hours; protective levels persist for weeks.
Indications
  • Rh‑negative, non‑sensitized patients after potential fetomaternal hemorrhage: miscarriage/abortion, ectopic pregnancy, antepartum bleeding, abdominal trauma, invasive procedures (amniocentesis, CVS), and at delivery of an Rh‑positive infant.
  • Routine antepartum prophylaxis at 28 weeks gestation for Rh‑negative, non‑sensitized pregnancies (per OB protocols).
Dosing & Administration

Available Forms:

  • Prefilled syringes or vials: 50 µg, 300 µg IM; some products provide IV option.

Common Dosing (examples):

Scenario Typical Dose Notes
Early pregnancy loss/bleeding (<12 weeks) 50 µg IM once Some guidelines accept 50–120 µg depending on product availability.
≥12 weeks gestation events 300 µg IM once Covers ≈30 mL fetal whole blood (≈15 mL RBCs).
Routine prophylaxis 300 µg IM at 28 weeks Plus 300 µg within 72 h postpartum if infant is Rh‑positive.

Massive fetomaternal hemorrhage may require additional dosing based on Kleihauer‑Betke test or flow cytometry (OB determines total dose).

Contraindications

Contraindications:

  • Known IgA deficiency with anti‑IgA and history of severe hypersensitivity to human immune globulin.
  • Rh‑positive patients or already sensitized (anti‑D positive) patients — consult OB/Transfusion Medicine.

Precautions:

  • Hypersensitivity reactions (rare); observe after administration.
  • Hemolysis risk in Rh‑positive or certain conditions; ensure appropriate patient selection.
  • Blood product: theoretical infection risk is extremely low with modern screening/pasteurization.
Adverse Effects

Common:

  • Injection site soreness, mild fever, headache, myalgias.

Serious (rare):

  • Anaphylaxis (especially with IgA deficiency), hemolytic reactions if given to Rh‑positive individuals.
Special Populations
  • Renal/hepatic impairment: No routine dose change; follow product labeling.
  • Pregnancy: Indicated for prophylaxis in appropriate scenarios; benefits outweigh risks.
  • Lactation: Generally considered compatible.
Clinical Pearls
Think Rh in bleeding/trauma: Any Rh‑negative pregnant patient with bleeding or abdominal trauma warrants urgent consideration for Rho(D) immune globulin.
Timing matters: Give as soon as possible, ideally within 72 hours of the sensitizing event.
References
  • 1. ACOG. (2017, reaffirmed 2024). Prevention of Rh D Alloimmunization (Practice Bulletin). American College of Obstetricians and Gynecologists.
  • 2. CDC. (2024). Rh Incompatibility – Prevention and Control. https://www.cdc.gov/
  • 3. RhoGAM [Prescribing information]. (2023). Ortho‑Clinical Diagnostics.
  • 4. Rhophylac [Prescribing information]. (2023). CSL Behring.
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Medical Disclaimer
  • For Educational Purposes Only: This content is intended for educational reference and should not be used for clinical decision-making.
  • Not a Substitute for Professional Judgment: Always consult your local protocols, institutional guidelines, and supervising physicians.
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