Anti-D (Rh-D Immunoglobulin)

Last updated 20.09.12

 

 

Definition

-  Immunoglobulin (mainly IgG) directed against D antigen of Rhesus positive RBCs

 

Features

-  Blood product

-  Supplied from blood of Rh (D) negative donors

-  Used to prevent Rhesus Isoimmunisation in Rhesus (D) negative pregnant women

-  Supresses immune response to RH (D) positive fetal RBCs in maternal blood

-  250 IU neutralises 2.5ml RBCs (5ml whole blood)

-  625 IU neutralises 240 fetal red cells/50 low power fields or 6ml RBCs (12ml whole blood)

-  Kleihauer test determines sensitisation & dose required

-  Can cross placenta to fetus but given small dose & most is destroyed in passage across placenta minimal/nil effect on fetus

-  Compared to continous maternal production in Rhesus Isoimmunisation

-  Typically lasts 6 weeks in serum

-  Therefore routine prophylaxis at 28 & 34 weeks gestation + post partum

-  Schedule 4 medicine

-  Stored at between 2-8oC (refrigerated)

 

Indications

-  Rh (D) negative women

-  Unless already isoimmunisated then it is ineffective

-  1st trimester

-  CVS

-  Miscarriage

-  Not necessary for threatened miscarriage <12 weeks gestation

-  TOP

-  Ectopic pregnancy

-  2nd or 3rd trimester

-  APH

-  Amniocentesis or Cordocentesis

-  External cephalic version (ECV) of breech presentation (successful or not)

-  Abdominal trauma

-  Routine prophylaxis at 28 & 34 weeks gestation

-  Post partum

-  Within 72hrs of delivery if baby Rh (D) positive

 

Contraindications/Cautions

-  Rhesus positive women

-  Rhesus negative women with evidence of isoimmunisation to Rh (D)

-  Isolated IgA deficiency

-  Any contraindication to IMI

-  Avoid live attenuated virus vaccines 2 weeks prior to 3 months after Anti-D

 

Dose

-  Intramuscular injection (IMI) only

-  Vials of 250 IU or 625 IU

-  250 IU (50mcg)

-  1st trimester sensitising event

-   Vaginal bleeding

-   Miscarriage

-  625 IU (125mcg)

-   1st trimester sensitising event if twins or greater gestations

-   2nd or 3rd trimester sensitising event

-   Vaginal bleeding

-   Miscarriage, Stillbirth

-   Routine antenatal prophylaxis at 28 & 34 weeks

-   Routine post partum

 

Procedure

-  Check maternal blood group & antibody screen

-  Determine if already isoimmunised

-  Confirm maternal blood group rhesus status

-  May detect presence of previous Anti-D administered

-  +/- Kleihauer

-  Determine dose based on gestation & pregnancy

-  Intramuscular injection (IMI)

-  Should be given within 72hrs of suspected exposure (sensitising event, delivery, etc.)

 

 

 

References

 

Peninsula Health CPG: Anti-Rh (D) Immunoglobulin: June 2010