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RhoGam Background + Applications

RhoGAM is a sterile solution containing immunoglobulin G (IgG) anti-D (anti-Rh) for use in preventing Rh immunization. It is manufactured from human plasma containing anti-D from Rh-negative donors immunized with Rh-positive red blood cells. A single dose of RhoGAM contains sufficient anti-D (300 µg or 1500 IU) to suppress the immune response to up to 15 mL of Rh-positive (fetal) red blood cells.

RhoGAM is indicated for administration to Rh-negative women not previously sensitized to the Rho(D) factor, unless the father or baby are conclusively Rh-negative, in case of:

  • Delivery of an Rh-positive baby irrespective of the ABO groups of the mother and baby. Because it takes time to develop antibodies, these effects are not usually seen in the first Rh-positive pregnancy, but may cause harm to any Rh-positive fetuses in the future.

  • Antepartum prophylaxis at 26 to 28 weeks gestation

  • Antepartum fetal-maternal hemorrhage (suspected or proven) as a result of placenta previa, amniocentesis, chorionic villus sampling, percutaneous umbilical blood sampling, other obstetrical manipulative procedure (e.g., version) or abdominal trauma. (Of note, if the hemorrhage is substantial enough - multiple doses may be warranted)

  • Actual or threatened pregnancy loss at any stage of gestation

  • Ectopic pregnancy

Before the 1960s, there was no method available to prevent Rh sensitization during Rh-incompatible pregnancies. Rh sensitization can result in hemolytic disease of the fetus and newborn (HDFN), a condition in which the red blood cells of the fetus are destroyed by the mother's antibodies. This condition can have serious effects for the baby. At that time, HDFN affected 9%-10% of all pregnancies and contributed significantly to fetal deaths in the US. Innovators were needed for this complex problem. RhoGam was the answer!!

Essentially the RhoGam injections are fooling the body via passive antibody immunosuppression that helps prevent Rh sensitization. The idea is to provide the body with passive antibodies so that it doesn't produce its own antibodies which would result in a more active immune response. If passive Rh antibodies were given to an Rh-negative mother, it would reduce her body's attempt to produce active antibodies against her baby. Tricking the body into thinking it has already produced a response.

The image below helps illustrate this prevention mechanism:

Rh disease has essentially been eradicated in high-income countries because of the novel injection. It's safe to say this low-tech solution is still having a major impact and newborns are continuing to thrive because of its existence,

February 26, 2024

Author: Joshua Ishmael, MBA, MLS(ASCP)CM, NRP

Pass with PASS, LLC.

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