Rh D IMMUNOGLOBULIN (ANTI-D)
Introduction
Rh D immunoglobulin (Anti D) should be given to Rh D negative women who
have no preformed anti-D antibodies during pregnancy if they experience a
“sensitising” event in which there is a risk of fetal blood crossing into the maternal
circulation.
The administration Anti-D has been shown to result in a significant reduction in the incidence
of Rh isoimmunisation.
Anti D should be administered within 72 hours for successful immunoprophylaxis
after the appropriate sentinel event.
If this time frame is missed a dose up to 10 days may still provide some protection.
Blood should be taken from the mother before administration of the Rh D
immunoglobulin to confirm her blood group and in more severe cases to assess the
magnitude of feto-maternal transfusion by Kleihauer testing, in order to determine if
increased doses of anti-D are required.
Pathology
As little as 0.1 ml of Rh (D) positive fetal blood can result in maternal isoimmunization. 2
Preparations
Rh (D) Immunoglobulin-VF (for IM dosing):
●
250 IU the (50 mcg, “minidose”)
♥
250 IU of Anti-D Antibody will protect against immunization of up to
2.5 mls of
fetal red blood cells. 3
●
625 IU (or 125 mcg):
♥
625 IU of Anti-D Antibody will protect against immunization of up to
6 mls of fetal red blood cells.
Rhophylac (human Anti-D CSL Behring) immunoglobulin solution for IV or IM
injection.
●
Glass syringe pre-filled with 1500 IU (300μg) 2mL solution for IV injection
Dose in FMH: 1500 IU (300μg) vial will suppress the immunizing potential of
<15mL of Rh (D) positive red cells.
Maximum dose 15,000 IU (3000μg), independent of whether the transfusion
volumes are > 300mL of Rh (D) positive blood
Administration: 2mL (1500 IU) per 15-60 seconds; within 72 hours of
complication
The use of higher or second doses should be based on quantitative
assessment of feto-maternal transfusion by Kleihauer test.
If studies indicate the quantity of feto-maternal haemorrhage is greater
than 6mls of fetal red blood cells, further doses should be administered.
For haemorrhages greater than 6 mL, the recommended dose is 100 IU per
mL Rh(D) positive red blood cells.
Indications
The indications for giving Anti D immunoglobulin for potentially sensitising events
include:
All Rh (D) negative women (who have not actively formed their own Anti-D) should be
offered Anti-D:
In the ED setting:
1.
First Trimester: Give 250 IU “Minidose”: 1
●
Ectopic Pregnancy
●
Miscarriage, (including cases of incomplete abortion and curettage):
♥
Note that many sources state that there is insufficient evidence to
suggest that a threatened miscarriage before
necessitates Anti-D. 1
12
weeks
gestation
However there remains some diversity of opinion about whether this
means that anti-D should not be given.
The British Blood Transfusion Society and the RWH give the
following advice: 4,5
♥
Anti-D is not indicated for threatened miscarriage before 12
weeks gestation but “consider” giving Anti D if there is heavy or
repeated
bleeding or associated abdominal pain, especially if
gestation is close to 12 weeks.
In cases of multiple (i.e twins or more) pregnancies where a sensitizing
event occurs in the first trimester, the 625 IU dose should be given (rather
than the 250 IU dose).
2.
Beyond First Trimester: Give 625 IU:
●
Abdominal trauma sufficient to cause feto-maternal transfusion
●
Antepartum hemorrhages
If bleeding continues intermittently after 12 weeks, give Anti D Ig at 6 weekly
intervals. 4
Outside the ED setting:
1.
2.
First Trimester: Give 250 IU “Minidose”:
●
Termination of pregnancy
●
Chorionic villi sampling (genetic studies).
Beyond First Trimester: Give 625 IU:
●
Amniocentesis/ cordocentesis (genetic studies)
●
External cephalic version of a breech presentation, (whether
successful or not).
●
Routine antenatal dosing for Rh negative mothers:
♥
All Rh (D) negative women (who have not actively formed
their own AntiD) at approximately 28 weeks gestation and
again at approximately 34
weeks gestation.
●
Post-natally, within 72 hours:
♥
All women who deliver an Rh (D) positive baby should have
quantification
of feto-maternal haemorrhage to guide the
appropriate dose of anti-D prophylaxis.
Contraindications/ Precautions: 1
These include:
1.
Women with preformed anti-D antibodies:
●
Rh (D) immunoglobulin should not be given to women with preformed
Anti-D antibodies
except where the preformed Anti-D is due to the antenatal
administration of Rh (D)
immunoglobulin.
If it is unsure whether the Anti-D detected in the mother’s blood is passive or
preformed, the treating clinician should be consulted.
If there is continuing doubt, Rh (D) immunoglobulin should be administered.
2.
An Rh(D) positive individual.
3.
Use caution in patients with a history of prior systemic allergic reactions
following the administration of human immunoglobulin preparations.
Consent
Note that anti - D is a blood product and so informed consent must be obtained from
the patient before administration.
Resources
●
Australian Red Cross Blood Service 9694 0111.
●
CSL Bioplasma: 1800 063 892
References
1.
Guidelines for the use of Rh (D) Immunoglobulin (Anti-D) in obstetrics in
Australia.
RANZOG, November 2011.
2.
Sheila Bryan, Ectopic Pregnancy and Bleeding in Early Pregnancy in
“Textbook of Adult Emergency Medicine”, Cameron et al 4th ed 2015.
3.
National Blood Authority - Guidelines on the prophylactic use of Rh D
immunoglobulin (anti D) in Obstetrics. NH&MRC 6 June 2003.
4.
RWH Clinical Guidelines February 2012.
5.
H. Qureshi et al. BCSH guideline for the use of anti-D immunoglobulin for the
prevention of haemolytic disease of the fetus and newborn. 2014. doi:
10.1111/tme.12091
Dr J. Hayes
Reviewed 27 May 2015