What is the necessity of RhoGAM (Rho(D) immune globulin)?

From the Guidelines

RhoGAM is necessary for Rh-negative women who have had a spontaneous or induced abortion at less than 12 weeks of gestation to prevent Rh sensitization, as recommended by the Society for Maternal-Fetal Medicine 1. The use of RhD immune globulin (RhIg) has reduced the burden of perinatal morbidity and mortality attributable to RhD alloimmunization.

• Key points to consider:
  • RhD alloimmunization can occur when an RhD-negative pregnant person is exposed to the RhD antigen, typically through carrying an RhD-positive fetus.
  • The consequences of RhD alloimmunization increase with each subsequent pregnancy and are associated with the need for fetal transfusion, fetal hydrops, stillbirth, preterm delivery, and hemolytic disease of the newborn.
  • The preventive use of RhoGAM has dramatically reduced the incidence of Rh disease, making it a crucial intervention in prenatal care for Rh-negative women.
  • A 50 mg dose of RhIg within 72 hours of the spontaneous or induced abortion is adequate to cover the volume of potential feto-maternal hemorrhage in the first trimester, although a 300 mg dose may be used if the lower dose is unavailable 1.
• The Society for Maternal-Fetal Medicine recommends offering both RhD testing and RhIg administration for spontaneous and induced abortion at less than 12 weeks of gestation in unsensitized, RhD-negative individuals, as the limited data supporting RhD testing and RhIg administration for first-trimester abortion do not justify additional restrictions on abortion access 1.

From the FDA Drug Label

CLINICAL PHARMACOLOGY HyperRHO S/D Full Dose is used to prevent isoimmunization in the Rho(D) negative individual exposed to Rho(D) positive blood as a result of a fetomaternal hemorrhage occurring during a delivery of an Rho(D) positive infant, abortion (either spontaneous or induced), or following amniocentesis or abdominal trauma The administration of Rho(D) Immune Globulin (Human) within 72 hours of a full-term delivery of an Rho(D) positive infant by an Rho(D) negative mother reduces the incidence of Rh isoimmunization from 12%–13% to 1%–2%.(9)

The administration of Rho(D) Immune Globulin (Human), also known as Rhogam, is necessary to prevent Rh isoimmunization in Rho(D) negative individuals exposed to Rho(D) positive blood. The treatment is most effective when administered within 72 hours of exposure, and it can reduce the incidence of Rh isoimmunization from 12%–13% to 1%–2% 2. Key points include:

• Prevention of isoimmunization: Rhogam prevents the immune system of Rho(D) negative individuals from reacting to Rho(D) positive red blood cells.
• Timing of administration: Administration within 72 hours of exposure is crucial for effective prevention of Rh isoimmunization.
• Reduction of isoimmunization incidence: Rhogam can reduce the incidence of Rh isoimmunization from 12%–13% to 1%–2%.

From the Research

Necessity of Rhogam

• The necessity of Rhogam, also known as Rho(D) immune globulin (RhIG), varies depending on the individual's Rh blood type and pregnancy status 3, 4, 5, 6, 7.
• RhIG is generally administered to D-negative mothers without anti-D at 28 weeks of gestation and shortly after delivery to prevent Rh hemolytic disease of the fetus and newborn 3.
• However, current guidelines suggest that pregnant mothers with molecularly defined weak D types 1,2,3,4.0, and 4.1 do not need RhIG as they are unlikely to produce alloanti-D when exposed to fetuses with D-positive red cells 3.
• Women with Asian-type DEL (c.1227G>A) also do not form alloanti-D when exposed to D-positive red cells, and therefore do not require RhIG before and after delivery 3.
• Obesity is a risk factor for failure of RhIG, and could lead to an increase in hemolytic disease of the fetus and newborn (HDFN) 4.
• Cell-free DNA (cfDNA) tests can be used to predict fetal red blood cell antigen genotypes and prioritize the administration of RhIG to Rh(D)-negative pregnant people, especially during RhIG shortages 5.
• RHD genotyping can enhance the accuracy of Rh(D) antigen classification, mitigating alloimmunization risks and the unnecessary use of Rh Immunoglobulin, and optimizing blood product utilization 7.

Special Considerations

• The optimal administration of RhIG, especially in obese women, is not clearly established 4.
• The use of RhIG has dramatically decreased the incidence of hemolytic disease of the fetus and newborn resulting from the production of anti-D by an Rh-negative woman, but instances of Rh immunization continue to occur due to failure to administer RhIG when indicated or in the appropriate dose 6.
• Integrating RHD genotyping into routine transfusion medicine practices can improve patient safety and resource management, particularly during critical shortages of Rh(D)-negative blood supplies 7.