should be followed by the injection of 300 ug RhIG. If a subsequent amniocentesis is
done more than 21 days later, an additional injection of 300 ug RhIG should be given.
e. RhIG is supplied as sterile, clear, and injectable for intramuscular
administration into the mother within 72 hours after delivery if she meets the above
criteria. It is a highly concentrated solution of lgG anti-RhO(D) (about 300 ug of
anti-RhO(D) globulin) derived from human plasma. RhIG, like other immune serum
globulin preparations, does not transmit hepatitis.
f. If the newborn is known to be RhO(D)-positive, and the blood bank receives a
request for RhIG, the following procedures should be done before administering the
RhlG to the mother:
ABO grouping of mother.
RhO(D)-typing of mother, including DU test read microscopically.
Testing of mother's serum for unexpected antibodies.
(4) A compatibility test between the mother's red blood celIs and the sample
of diluted RhIG included with each vial of RhlG is optional.
g. Anti-RhO(D) antibody can be detected In the mother's serum 12 to 60 hours
after injection, and may continue to be detected for as long as 5 months. If anti-RhO(D)
is present 6 months after delivery, it can be assumed that this represents active
immunization, and failure of the RhIG to block alloimmunization. Such failures are
infrequent, and may be caused by undetected RhO sensitization, that existed prior to the
administration of RhlG. RhIG does not reverse Rh sensitization, but rather prevents its
occurrence. Early in RhO alloimmunization, the antibody may not be detectable by
standard antibody-screening procedures.
h. The amount of RhlG supplied in one container is generally sufficient, if the
fetomaternal blood is 30 ml or less. The entire contents of the container should be
injected, since the volume of Rh-positive fetal cells that enters the maternal circulation is
2-21. MASSIVE FETOMATERNAL HEMORRHAGE
a. When a massive fetomaternal hemorrhage occurs (greater than 30 ml of
whole blood), one container of RhIG is an insufficient dose to suppress
aIIoimmunization from this larger immunogenic challenge. Recognition of the massive
fetomaternal hemorrhage is of great importance. A careful microscopic examination
should be made using the mother's postpartum specimen to detect a massive
hemorrhage. The most practical method for its detection is the search of a mixed field
pattern of micro-agglutinates among a background of un-agglutinated cells, in the
microscopic reading, of the DU test in the mother. The material supplied by the