RhoGam is given at 28 weeks in Rh-negative mothers to prevent maternal sensitization. It may be administered prophylactically, or after any type of exposure risk that occurs after 28 weeks of gestation (e.g., amniocentesis, second-trimester miscarriage or abortion, after version).
Rhogam is given within 72 hours in order to suppress antibody production in the mother. This is done following delivery, pregnancy termination, following any abdominal trauma, ectopic pregnancy, version, or after procedures such as amniocentesis or chorionic villus sampling.
RhoGam causes lysis of the fetal RBCs from an Rh-positive infant that may have entered the Rh-negative mother’s bloodstream. By destroying the fetal RBCs, the mother does not form antibodies against them. This should protect the woman from becoming sensitized in future pregnancies.
The woman may complain of localized tenderness and stiffness at the IM injection site. Other side effects can include a mild and transient fever, headache; and rarely an allergic response.
Before RhoGam is given, it must be determined that the mother is Rh negative and has not been sensitized by previous pregnancies. This can be determined by the Coombs blood test, which must be negative. A positive Coombs test indicates the mother has already been sensitized and has the presence of antibodies.
The standard dose for RhoGam is 300 mcg and should only be given to the mother, never the infant. If there is a large fetal-maternal transfusion, a larger dose of RhoGam may be ordered.
The 50 mcg microdose of RhoGam is indicated after a first trimester miscarriage or abortion, ectopic pregnancy, or following chorionic villus sampling.
Because RhoGam is most often considered a blood product informed consent may be required, along with the agency routine of verifying correct dosage and patient identity, as you would do if administering a blood transfusion, i.e., watch for allergic response (for 20 minutes after administration).
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