Rh-sensitization

Fetomaternal hemorrhage (FMH), which can occur during pregnancy or delivery, triggers an Rh-negative mother's immune system to develop antibodies against the antigens in her baby's blood if Rh-positive (occurring in about 60% of pregnancies involving Rh-negative mothers). This is called Rh-sensitization or alloimmunization. While this is the most common cause for Rh-sensitization, there are other ways in which sensitization can occur. For instance, Rh-sensitization can also occur when someone with Rh-negative blood receives a transfusion of Rh-positive blood or blood components, such as platelets.

While the placenta-cell layer (trophoblast) usually prevents the fetus's blood from entering the mother's bloodstream, certain conditions can create FMH. The resulting Rh-sensitization can occur during any of these events:

  • Delivery
  • Miscarriage
  • Amniocentesis
  • Chorionic villus sampling
  • Placental abruption
  • Manual extraction of placenta
  • External version (breech repositioning)
  • Abortion

Typically, only a small number of antibodies are produced in the first pregnancy. During delivery, however, the mother's immune system becomes sensitized to the Rh factor. In subsequent pregnancies, the mother produces a greater number of antibodies, which can cross the placenta to destroy the fetal red blood cells and create significant health risks for the baby. With each subsequent Rh-positive pregnancy, the mother's antibody reaction is faster, with potentially more severe consequences.

An Rh-negative mother needs to receive anti-D IgG treatment during her first pregnancy and immediately following delivery to prevent Rh-sensitization that could endanger an Rh-positive fetus, particularly in future preganancies.

  1. Zipursky A, Paul V. The global burden of Rh disease. Arch Dis Child Fetal Ed. March 2011 Vol 96 No 2: F84-85.
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Important Safety Information

WARNING: INTRAVASCULAR HEMOLYSIS IN ITP
This warning does not apply to Rh (D)-negative patients treated for the suppression of Rh isoimmunization.
Intravascular hemolysis leading to death has been reported in Rh (D)-positive patients treated for immune thrombocytopenic purpura (ITP) with Rh (D) Immune Globulin Intravenous (Human) products. Intravascular hemolysis can lead to clinically compromising anemia and multi-system organ failure, including acute respiratory distress syndrome (ARDS); acute renal insufficiency, renal failure, and disseminated intravascular coagulation (DIC). Monitor patients for signs and symptoms of intravascular hemolysis in a healthcare setting for at least 8 hours after administration. See full prescribing information for complete boxed warning.

Rhophylac®, Rho(D), Immune Globulin Intravenous (Human), is indicated for suppression of rhesus (Rh) isoimmunization in:

  • Pregnancy and obstetric conditions in non-sensitized, Rh (D)-negative women with an Rh-incompatible pregnancy, including routine antepartum and postpartum Rh prophylaxis and Rh prophylaxis in cases of obstetric complications or invasive procedures.
  • Incompatible transfusions in Rh (D)-negative individuals transfused with blood components containing Rh (D)-positive red blood cells.

For suppression of Rh isoimmunization, Rhophylac can be administered IM or IV. Consider IV administration if reaching the muscle is of concern.

Rhophylac is indicated to raise platelet counts in Rh (D)-positive, non-splenectomized adult patients with chronic immune thrombocytopenic purpura (ITP). For the treatment of ITP, Rhophylac must be administered IV.

Rhophylac is contraindicated in individuals with known anaphylactic or severe systemic reaction to human immune globulin products, and in IgA-deficient patients with antibodies to IgA and a history of hypersensitivity to Rhophylac or any of its components. Do not administer Rhophylac to the newborn infant of a mother who received Rhophylac postpartum.

Allergic or hypersensitivity reactions may occur with Rhophylac; early signs of hypersensitivity include generalized urticaria, chest tightness, wheezing, hypotension, and anaphylaxis.

Rhophylac is derived from human plasma. The risk of transmission of infectious agents, including viruses and, theoretically, the Creutzfeldt-Jakob disease (CJD) agent, cannot be completely eliminated.

Suppression of Rh Isoimmunization: The most common adverse reactions in the suppression of Rh isoimmunization with Rhophylac (≥0.5% of patients) are nausea, dizziness, headache, injection-site pain, and malaise.

Immune Thrombocytopenic Purpura: The most serious adverse reactions in patients receiving Rh (D) immune globulin have been observed in the treatment of ITP. ITP patients being treated with Rhophylac should be alerted to and monitored for signs and symptoms of intravascular hemolysis, including back pain, shaking chills, fever, and hematuria. Potentially serious complications of intravascular hemolysis include clinically compromising anemia, acute renal insufficiency, and, very rarely, disseminated intravascular coagulation, and death.

The most common adverse reactions observed in the treatment of ITP (>14% of patients) are chills, pyrexia/increased body temperature, headache, and hemolysis. In patients with preexisting anemia, Rhophylac may increase the severity of anemia.

Immunoglobulin administration may transiently interfere with the immune response to live virus vaccines, such as measles, mumps and rubella.

Please see full prescribing information for Rhophylac.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.


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