Practical clinical aspects of Rh-prophylaxis John T. Queenan

223
Queenan et al., Rh-prophylaxis
Review article
J. Perinat. Med.
l (1973) 223
Practical clinical aspects of Rh-prophylaxis
John T. Queenan, Jörg Schneider
Dept. of Obstetrics and Gynecology, Louisville General Hospital, Louisville,
Kentucky/USA
Dept. of Obstetrics and Gynecology of the University of Bonn/Germany
1. Review of history of Rh problem including
the comments on perinatal mortality rates
In 1939, LEVINE [40] postulated that Morbus
haemolyticus neonatorum was due to a fetal
blood group antigen, inherited from the father,
invading the maternal circulation and causing
maternal immunization. The next year, LANDSTEINER and WIENER [39] found that antigen, the
rhesus factor. At that time, 45% of all rhesus
immunized pregnancies resulted in intrauterine
or neonatal death. Because of these discoveries,
rhesus incompatibility could be managed on a
rational basis. Preterm delivery and improved
techniques in neonatal management including
exchange transfusions decreased the perinatal
mortality rate to 22% [l, 2, 12, 63].
The introduction of the amniocentesis and
amniotic fluid analysis in the management of the
rhesus immunized pregnancy further lowered the
perinatal mortality rate to 8% [9]. In spite of
this dramatic decrease from 45 to 8%, a further
reduction in perinatal mortality is unlikely.
2. History of development of anti Rh immune globulin
In the early 1960's, two groups of investigators,
FINN and CLARKE in Liverpool [18, 19; 20] and
GORMAN, FREDA and POLLACK in New York
City [25], concurrently, but independently, embarked on programs that culminated in a System
of rhesus immune prophylaxis.
In 1961, FINN [20] demonstrated a high incidence
J. Perinat. Med. l (1973)
Curriculum vitae
JOHN THOMAS QUEENAN,
M. D., was born 1933 in
Aurora, Illinois.
Study of medicim at Notre
Dame University, South
Bend, Indiana (gradnated
witb a B. S. degree), and at
Cornell University Medical
College, M. D. Internship,
Bellevue Hospital, New York,
Second Division (Cornell),
1958—1959. Assistant Resident in Obstetrics and
Gynecology, New York LyingIn Hospital, 1959—1962.
Since 1972 Professor and Chairman, Dept. of Obstetrics and
Gynecology, University of Lomsville School of Medicine.
Author of many publications on Immunologe in Obstetrics; one
textbook.
of transplacental hemorrhage at the time of
delivery. By use of the KLEIHAUER-BETKE stain
technique, a method of detecting fetal erythrocytes in the maternal circulation, he noted that
fetal cells were present in the ABO compatible
pregnancies but not in the incompatible pregnancies. He speculated that if fetal erythrocytes could
be destroyed in the maternal circulation by
administration of a rhesus antibody, maternal
immunization might be prevented. He showed
that rhesus negative volunteers cleared rhesus
positive erythrocytes rapidly from their circulation following intramuscular injection of rhesus
antibodies [20].
16*
224
Queenan et al., Rh-prophylaxis
In 1909, THEOBALD SMITH [61] showed that in
the presence of exccss diphtheria antibody, the
corresponding antigen would not immunize.
Operating on this principle, FREDA, GORMAN and
POLLACK developed a concentrated rhesus antibody preparation. They showed that the administration of this preparation within 72 hours
after injection of the Rh-antigens in volunteers
would protect against rhesus immunization [25].
The first postpartum patients were treated in
1962 and 1963. Because of the work of these
research teams, our current method of rhesus
immune prophylaxis has evolved [49,50]. Between 1963 and 1965 several groups throughout
the world were working on the practical application of these experiments [49,50 55]. During
1966 and 1967 the effectiveness of this prophylaxis has been clinically established [14, 30, 69].
In spite of these developments, rhesus immunization still exists äs a major cause of perinatal
mortality. Critical scrutiny of large clinical
trials indicates significant failure rates. This
report will review current international practices of rhesus immune prophylaxis, äs well äs
outline some of the problems and potential
Solutions.
production when injected into rhesuS negative
volunteers [62]. Several fclinical studies have
shown, however, that this "natural protection"
is relative. Rhesus immunization does occur
in an ABO incompatible pregnancy, but at a
lower incidence.
Large controlled series showed that the risk of
immunization to a term rhesus negative
mother with an ABO compatible rhesus
positive infant is 14—17% [5, 66]. All rhesus
negative unimmunized mothers delivering rhesus
positive infants should receive Rh immune
prophylaxis regardless of the compatibility of
the ABO System.
A mismatched blood transfusion is a rare but real
possibility. Rhesus negative patients receiving
rhesus positive blood should be covered with
adequate amounts of human Rh immune globulin. One vial (300//g) will prevent immunization from a fetal bleed of 15 ml of packed
red blood cells. Trial studies by POLLACK in
rhesus negative male volunteers given 500 ml
rhesus positive erythrocytes have shown that
adequate doses of Rh immune globulin will
prevent immunization. In his study, 18 out of
22 control (unprotected) volunteers were immunized whereas in the treated group there were
no mmun 2a
3 Indications
i
i ti°ns 'm 22 volunteers [23]. BARTSCH
recently demonstrated that up to 50 ml of RhThe rhesus antigen is present only on the human positive fetal blood could be immunologically
erythrocyte. The major cause of rhesus im- inactivated by 300 ^g of Rh immune globulin
munization is the antigenic Stimulus of a [6].
pregnancy. The work of numerous investigators The risk of immunization r in spontaneous
has shown that transplacental hemorrhage in- abortion with completion curettage has been
creases with advancing gestation [16, 17, 20, estimated to be 3—4% [21, 53]. Unfortunately,
56, 68]. A further fetal erythrocyte invasion of the many spontaneous abortions are not treated by
maternal circulation occurs at the time of delivery. the physician. The only Symptoms may be
A traumatic delivery, cesarean section or placental amenorrhea f ollowed by a heavier than normal
disruption äs with manual removal, premature period. Rh immune prophylaxis may be of benefit
Separation or previa, increases the incidence of a to some rhesus negative women having sponfeto-maternal bleed [17, 36, 48, 65, 67]. When taneous abortion, however, it should be conFINN found that the incidence of postpartum sidered according to the individual Situation,
fetal erythrocytes in the maternal circulation was Protection is particularly important in patients
much lower in ABO incompatible pregnancies, who do not already have their family.
he theorized a "natural protection". This con- The risk of rhesus immunization due to
firmed the work of STERN and his colleagues induced abortion has been shown to be 5.5%
who in 1961 showed that when .rhesus positive by QUEENAN et al. [54]. Since the rhesus antigen
erythrocytes were coated with incomplete anti-D is present on the fetal red blood cell äs early
in vitro, they did not cause rhesus antibody äs the 38th day of gestation and since the
J. Perinat. Med. l (1973)
225
Qucenan et al., Rh-prophylaxis
placental circulation is intact at the time of the
procedure, rhesus immunization is a definite
possibility [8].
In a combined study of 145 rhesus negative patients
having induced abortions, 8 became immunized [54]. Of
these 8, one had demonstrable fetal cells after abortion,
6 had no demonstrable cells and one was not done. This
study indicates that induced abortion does pose the threat
of immunization but the finding of cells in the maternal
circulation does not mean that the patient will become
immunized, nor does the absence of fetal cells give assurance that the patient will not become immunized.
All rhesus negative patients undergoing suction curettage
after 6 weeks gestation should be protected with Rh
immune globulin. The only exceptions are patients already
immunized to the rhesus factor and patients with a known
rhesys negative mate. The same indications would pertain
to those patients undergoing saline or hysterotomy abortions. With saline or hysterotomy abortions, i t may be
necessary to determine the rhesus type of the cord blood
[59]. Since slightly over 40% of the fetuses will be rhesus
negative, this could result in a considerable saving of Rh
immune globulin. If this is not possible or the results are
doubtful, the patient should be treated anyway.
The 300//g of Rh immune globulin, the
Standard dose given after füll term deliveries
in the United States, can be reduced for
abortions. The feto-placental blood volume is
small and most of the feto-maternal hemorrhages
are relatively slight. If a smaller dose offers
protection, the vaccine could be conserved. In
some European countries äs Germany and England, the physician has ampules of 100, 200 and
300 % of Rh immune globulin at his disposal.
Two additional situations warrant consideration
for rhesus prophylaxis. Rhesus negative patients
with a ruptured ectopic pregnancy can spill fetal
erythrocytes into the maternal peritoneal cavity.
The cells enter the maternal circulation via the
subdiaphragmatic lymphatics [31]. Hydatidiform
mole is reported to be capable of immunizing.
The mechanism is less clear but perhaps molar
tissue contains the antigen for rhesus antigen.
These situations should be considered on an
individual basis for rhesus prophylaxis.
The amniocentesis has been shown to be a
potentially immunizing procedure [17, 38,
52, 67]. In their study on induced abortions,
QUEENAN et al. found fetal erythrocytes in 25 out
of 41 patients following amniocentesis for
instillation of hypertonic saline [54]. Increased
J. Perinat. Mcd. l (1973)
interest in genetic studies through improved
techniques in detecting certain prenatal disorders
has given rise to an increase in the number of
amniocenteses done early in gestation. If the
patient is rhesus negative and the pregnancy
aborted due to the presence of a genetic disorder,
she will be appropriately covered with Rh
immune globulin after the abortion. However, if
this pregnancy is allowed to continue until term,
a feto-maternal hemorrhage secondary to the
amniocentesis could cause immunization. If
not treated, she Stands the chance of being
immunized by the end of the pregnancy before
effective prophylaxis can routinely be given.
There are a few centers that routinely give Rh
immune globulin intramuscularly to the
unimmunized rhesus negative patient following prenatal amniocentesis for genetic
studies. Intravenous administration of Rh immune globulin has been feit to be an adjunct in
this Situation [23]. In this way, the dose of Rh
immune globulin can be titrated so that just the
amount needed to cover the Stimulus can be
given to the patient.
4. Quantitating fetal hemorrhage
Identification of macrotransfusions of more than
15 ml of packed fetal erythrocytes will help
eliminate many of the prophylaxis failures. Three
hundfed g of Rh immune globulin intramuscularly will protect against an immunization of 15 ml of packed fetal erythrocytes
[43].
To identify these patients, routine screening by a
KLEIHAUER-BETKE smear or ASHBY fetal cell test
should be performed. This is of particular
importance in the high risk Situation (manual
removal of placenta, cesarean section, external
Version, etc.). Years ago it was held that 0.1 to
0.24 ml of rhesus positive blood is the minimum
amount necessary to immunize a rhesus negative
person [3]. This is probably wrong. It is not
known whether there is a minimum dose of Rh
antigen, which is necessary for immunization.
Some rhesus negative persons are very good
immune responders for genetic reasons, others
cannot be immunized even. by large doses of
rhesus antigen. In clinical practice it has also
Queenan et al., Rh-prophylaxis
226
appeared that feto-maternal microtransfusions
below 1% HbF/HbA cannot be securely diagnosed even with the greatest care. Even with the
most skilled laboratory technicians, small fetomaternal bleeds are difficult to detect. For this
reason, if commercially available, all rhesus
negative mothers must be treated with Rh
immune globulin after delivering a rhesus
positive infant (with or without controlling
HbF-cell transfusion).
5. Dose
The first series of investigations concerning anti-D prophylaxis were carried out with anti-D raw sera and anti-D
immune globulin preparations, the content of which could
only be tested by serology in titers (COOMBS Test) [15, 26,
58]. The serological titer determinations in these preparations, however, yielded such varying results even on
identical specimens, that Statements concerning dose can
only be viewed äs estimations. HUGHES-JONES, et al. [34]
and POLLACK et al. [47] have stated radioimmunoassay
methods which permit determination of the anti-D content
of the preparations in micrograms and determination of the
binding factor. The variance of these tests, however, is
still relatively high. Until today, we still do not have a
Standard preparation for international comparison.
I£ the first basic requirement for recommending a
dose is knowing the content of the preparation,
the second basic requirement would be knowing
the amount of rhesus antigen transfused into
the maternal circulation. In the early years it was
feared that an augmentation o£ the immunization rate could take place after an underdose
[14, 46]. We now know that such an underdose
has to be feared only, if at all, after giving very
small amounts of anti-D [28, 42], Many groups,
especially in Europe, have controlled the deliveries of all rhesus negative mothers systematically for diffusion of fetal erythrocytes for this
reason. In most instances, the results comply
with the data in Tab. I [57]. In addition, one can
now rely on the fact that only in l—4 cases per
1000 deliveries feto-matfernal macrotransfusions of more than 25—50 ml of fetal blood
take place [6, 57].
Despite inadequate methods for controlling
quantitatively the transfusion of rhesus antigen
and despite the inaccuräte knowledge of the
anti-D content of the anti-D preparations, the
postpartum anti-D prophylaxis has shown convincing success around the world within the past
few years. This is only understandable, if one
supposes, that in most cases the clinical investigation series were carried out with overdoses.
Probably relatively few incomplete rhesus antibodies are necessary to prevent immunization.
IgM-antibodies do not affect the incidence of immunisation [33],
The minimum dose of Rh immune globulin is not
known. According to GÜNSON [28], it might
ränge around 5 //g for 0.5 ml of rhesus positive
erythrocytes. Diminishing the anti-D dose for
clinical use, however, is not of such great importance any more. Anti-D preparations are at
hand in large quantities and are relatively inexpensive. An overdose has no side effects, it
only increases the safety. In many places it
is routine to administer 250—300/jg of äiiti-D
postpartum. A committee of experts from the
World Health Organisation [64] concluded that
20—25
of anti-D are sufficient to inactivate
the rhesus antigen which is contäined in l ml of
packed fetal erythrocytes. Therefore a dose of
250-—300 ^g of anti-D is sufficient to immunologically inactivate at least 20—30 ml of fetal
rhesus positive blood. With general ädministration of this dose, more than 99% of all patients
are treated with an overdose of anti-D.
If you want to prove a larger feto-maternal transfusion with safety, it is necessary, However, to
carry out a HbF-cell screening test äs the KLEI-
Tab. I. HbF cell findings postpartum.
HbF cells
HbA cells
Estimated amount of fetal
blood transfused
Number in percent
negative + traces
>0.01-1.0°/00
>1.0-2.0%0
>2°/oo
p
50 mm3— 5 ml
5— 10ml
>10 ml
73.5%
24.6%
0-9%
1-0%
J. Perinat. Med. l (1973)
Queenan et al., Rh-prophylaxis
HAUER-BETKE. If this is not feasible for technical
reasons, it is advisable to check l—2 days after the
injection of Rh immune globulin to determine if
sufficient free anti-D antibodies can be found in
thematernalblood (BÖRNER [10]).If HbF cells can
still be demonstrated, or if antibodies cannot be
shown, an additional injection of anti-D is recommended.
If only limited amounts of anti-D are at band, or
possibilities are limited for financial reasons, the
dose of anti-D generally administered can be
lowered to 200 /^g, and eventually to even less.
A general administration of doses under lOO/jg,
however, is not possible without further precautions. If one wants to lower the dose to this
extent, an" intensive control of transfusion of fetal
erythrocytes is recommendable, which in turn
takes more personnel. If one is forced to give
special treatment to patients with increased risks,
a selection according to the following points,
in order of importance, is recommended:
1. Primigravidae with ABO compatible infant,
2. Mothers with operative deliveries,
3. Women with early termination of pregnancy.
Except for the first series of investigations by
GORMAN, FREDA and POLLACK [22], the first
treatments were all carried out with intravenously
administered anti-D preparations [13, 30, 50].
For fear of transmitting hepatitis one gradually
turned to fractioned y-globulin preparations. In
some countries, for instance the United States,
it is forbidden to administer y-globulin preparations intravenously. In contrast, in many
European countries specially fractioned anti-D
preparations have been used since 1967 in large
numbers for the successful prophylaxis of
sensibilization in the rhesus System. Incidents
after these treatments have not been reported.
The discussion over the optimal route of
administration (intramuscular or intravenously) is not yet closed. The series of clinical
investigations which have helped to establish
anti-D prophylaxis worldwide have mäinly been
carried out with intramuscular preparations. In
his studies on volunteers, POLLACK [45] gave
intramuscular anti-D 72 hours after intravenous
administration of the antigen without an incidence
of immunization.
J. Pcrinat. Med. l (1973)
227
However, it cannot be disregarded that for
Optimum treatment, Rh immune globulin
should be administered äs soon äs possible
after the transfusion of the antigen. The
distribution of the anti-D throughout the
organism will be expedited after intravenous
injection. Even though the mechanism which
underlies this prophylaxis is not known, it has
been shown that the elimination of fetal erythrocytes from the blood circulation will take
place very rapidly via the spieen after intravenous administration of anti-D. Therefore,
with intravenous administration of anti-D, the
resorption time necessary with intramuscular
injection does not exist, besides the fact that
the resorption of the preparations is often uneven and especially slow in adipose tissue.
Although equilibration of intravascular and
extravascular anti-D content of the organism
takes place within 48 hours after intravenous äs
well äs intramuscular injection of the same anti-D
preparation [35], one has to surmise that with
intramuscular administration part of the substance gets lost by enzymatic destruction in the
adipose tissue. Whether the prolonged diffusion
from an anti-D depot in the adipose tissue increases the security of the prophylactic effect, is not
clear.
Since the clinical results with decreased doses, or
doses adapted to the HbF-cell transfusion with
intravenously applied anti-D are excellent [28,
41, 42, 60], the Commission of the World Health
Organisation also recommended that with the
intravenous administration of anti-D only
half the Standard dose used for intramuscular
injection is necessary (10—12//g/ml of packed
cells).
An intravenous administration of anti-D has
been especially successful in situations when an
iatrogenic mistransfusion of rhesus positive
blood (for instance 500 ml) had to be inactivated
immunologically. The administration
of
5,000—7,000 ^g of Rh immune globulin is
technically difficult. An intravenous preparation,
however, can be administered in large quantities
without clinical side effects, and in emergencies
even äs an intravenous drip. Treatments like this
should, however, always be carried out in a
larger hospital.
Queenan et al., Rh-prophylaxis
228
The preferred application o£ anti-D depends
upon how many physicians are at band for the
care of the recently delivered patients. The
intravenous injection should only be carried out
by physicians, whereas the intramuscular injections can be carried out by nurses.
7. Complications
Rh immune globulin has been shown to be
completely nontoxic, suppresses only the immune response against which it is directed, has
no effect on other unrelated immunities and
in particular, causes no damage to the Immunologie System äs a whole [24].
Use of intramuscular and intravenous y-globulin
is infrequently associated with unexplained
febrile reactions. The nature of these is unclear
and there is no proof that they are immunologic. Febrile reactions have occurred only
rarely with anti-D prophylaxis. Since administration frequently occurs simultaneously with
breast engorgement, it is difficult to implicate
the anti-D immunoglobulin. To date, we have
not had a single untoward reaction to the intramuscular administration of Rh immune globulin
[51]. Also intravenously applied IgG-anti-D is
tolerated without reactions, if it is made specially
for this type of application.
The incidence of allergic reaction (fever,
urticaria, serum sickness, erythema multiforme,
asthma, transitory peripheral numbness) is
1:10.000 [4]. The majority of complications
reported have been limited to local discomfort,
erythema and the occurrence of hives.
Inadvertent administration of Rh immune globulin to rhesus positive mothers, the baby,
immunized patients and even to the husband has
led to no ill effect s. The antepartum administration has had no effect on the baby, except for an
occasional positive direct COOMBS test. The
only time that a reaction is to be feared is in
patients who are hypo-y-globulinemic [27].
The value of anti-D in the presence of the Du
factor has been debated. The D u factor is a
mitigated D factor. If a mother with factor D u is
erroneously administered anti-D, however, no
reaction is to be expected, especially if the infant
is rhesus positive. If the mother is rhesus negative
and the infant D u positive, an anti-D prophylaxi8
is recommended by most ei&topean authors, since
the rhesus negative mother could be immunized
against the D of the infant. If the mother is D u
and the infant D, an immunization of the mother
against the D of the infant is possible. It is very
doubtful, however, if anti-D prophylaxis makes
sense in such cases^ since the Du erythrocytes of
the mother absorb most of the injected anti-D.
8. Utilization
Rh immune globulin has the potential of being
100% effective if given at the right time and in
the right dose. To insure proper Utilization of
Rh immune globulin, a systemized' 'hospital
program should be instituted.
To acquaint the obstetrical and laboratory staff
with the mechänism of rhesus immunization and
prophylaxis, inservice educational programs
should become routine in each hospital. Next, a
definite protocol should be drawn up by the
obstetricians äs to a routine procedure for every
rhesus negative patient being admitted to the
delivery suite. This should include a check of the
prenatal records to see that the blood group and
rhesus factor were indeed done during pregnancy.
If not an immediate specimen should be öbtäined
and sent to the laboratory for tests. If the patient
is rhesus negative, it should be caref ully noted and
proper attention given to obtaining a cord blood
specimen following delivery and a maternal
blood specimen when the patient leaves the
delivery suite. The specimens should be immediately transported to the laboratory. The
rhesus factor and direct COOMBS are determined
on the infants blood. If the rhesus factor is
positive and the direct COOMBS negative, a cross
match is done on the maternal blood and she
becomes a candidate for Rh immune globulin.
There will be instances when the cord direct
COOMBS will be positive due to änother factor
besides the rhesus factor (ABO incompatibility,
irregulär antibody äs anti Kell, etc.)* In these
instances, the mother is still a candidate for Rh
immune globulin. In Europe, if the indirect
COOMBS test in the blood of the mother is dubious,
positive or 1:2 in the rhesus System, the mother
will be a candidate for anti-D prophylaxis.
J. Perinat. Med. l (1973)
Quecnan et al., Rh-prophylaxis
The laboratory should assume the responsibility
of dispensing a vial of Rh immune globulin
with the patients name on it to the postpartum
floor. Routine Standing Orders should then
permit the nurse (or the doctor i£ the application
is intravenously) to inject the medication and
record it on the chart. Ideally, the patient should
receive this medication äs soon after delivery äs
possible.
When this patient is discharged, a System should
be developed whereby a double check is obtained by the discharge clerk that the medication
has indeed been given. The utilization rate in
every hospital should be 100%. If not, the
Chairman of the department and the hospital
Director should be required to explain the reason
for the omissions.
It is the doctors and hospital duty to see that any
rhesus negative, unimmunized patient be protected with Rh immune globulin, unless the
patient herseif signs a wahrer refusing the medication. If the patient has inadvertently been
discharged without receiving the medication
within 72 hours postpartum, she should be
contacted and given the medication. This can be
done äs long äs 4—5 weeks postpartum providing the indirect COOMBS is negative.
All patients undergoing induced abottions
should automatically be given Rh immune
globulin. In individualized situations, those
having spontaneous abortions should also be
protected.
Controversy exists over the need to administer Rh immune
globulin in patients having postpartum tubal ligation. She
should not have a problem from an obstetrical standpoint.
However, the women's Immunologie picture should not
be jeopardized. If later in life an ernergency occurs and
rhesus negative blood is unavailable, it would be impossible
to give rhesus positive blood if she were immunized.
Giving a rhesus positive blood transfusion to a negative
patient is a once in a lifetime Situation; it is only used in a
life threatening Situation. If this patient were immunized,
this would not be possible.
Even if all these parameters are met and every
woman receives Rh immune globulin föllowing
each obstetrical event, there will still remain those
patients that become immunized during the
course of the pregnancy. Small fetal hemorrhages
229
during the second and third trimester can
account for a small number of immunizations.
The first investigators assumed that the maximal
transfusion of the rhesus antigen takes place
intrapartum and immediately postpartum. It was
further assumed that the majority of rhesus
negative patients are relatively unsusceptible for
a first antigenic Stimulus during pregnancy. The
great success of the prophylaxis carried out
postpartum exclusively has confirmed these
assumptions. The effect of the postpartum anti-D
prophylaxis is around 90%; that means, that
only 10% of the naturally immunized patients will
now be immunized if prophylaxis is carried out
consequently.
Since this prophylaxis most probably has to be
carried out in future generations, it is essential to
carry it out äs perfect äs possible. The availability
of anti-D in sufficient amounts is secured through
immunized male long term donors and through
plasmapheresis. It is possible, however, that a
part of the prophylaxis failures is due to the
fact that some rhesus negative patients are
already "primed" during their first pregnancy.
Probably the administration of anti-D post
partum leads in a number of these primed cases
to a suppression of the secondary response, so
that only after the end of a föllowing pregnancy
does the development of antibodies occur.
Since we know now that during pregnancy
continuously small amounts of fetal rhesus
positive erythrocytes (and leucocytes) cross over
into the maternal circulation, it has been discussed that the preimmunization and possibly a
secondary response can be prevented by the
administration of anti-D in the last trimester
of pregnancy (perhaps 28—32 weeks of gestation)
[7, 11, 29]. These investigations, however, are
not yet clinically significant and lead to an
excessively higher use of anti-D.
Finally, an interesting consideration of HINDEMANN [32] is to give rhesus negative newborn
females born from Rh-positive mothers antiD immediately postpartum. He thinks that
by this, a first immunization by a materno-fetal
transfusion of rhesus positive erythrocytes can
be ruled out.
Keywords: Anti-D-prophylaxis, feto-maternal transfusion, HbF, Rh-erythroblastosis, Rh immune prophylaxis.
J. Perinat. Med. l (1973)
230
Queenan et al., Rh-prophylaxis
Zusammenfassung
Praktische klinische Aspekte der Rh-Prophylaxe
Die Entwicklung verschiedener Behandlungsmethoden
wie z. B. Austauschtransfusion, Fruchtwasseranalyse und
intrauterine Transfusion führte beim Rh-bedingten Morbus
haemolyticus neonatorum in den letzten 30 Jahren zu
einer Herabsetzung der perinatalen Mortalität von 45%
auf 8%. Dieser Prozentsatz wird nochmals wesentlich
verringert, wenn die Prophylaxe der Rhesus-Sensibilisierung mit Anti-D allgemein durchgeführt wird. Die
Entwicklung dieser Prophylaxe ging von zwei Beobachtungen aus. FINN und CLARKE in Liverpool konnten als
erste nachweisen, daß bei ABO-inkompatibler Blutgruppenkonstellation zwischen Mutter und Kind nur
sehr selten fetale Erythrozyten im mütterlichen Blut zu
finden sind. Sie folgerten daraus, daß die Ursache das
Vorhandensein von spezifischen Antikörpern im ABOSystem ist und zogen eine Verbindung zu der bei ABOinkompatibler Blutgruppenkonstellation herabgesetzten
Sensibilisierungsrate Rh-negativer Mütter. POLLACK, GOR>
MAN und FREDA in New York gingen von Beobachtungen
aus, die TH. SMITH schon 1909 gemacht hatte: Bei aktiven
und passiven Impfungen, sogenannten Simultanimpfungen,
ist es in vielen Fällen möglich, die aktive Immunisierung zu
unterdrücken, wenn der spezifische Antikörper im Überschuß verabreicht wird. POLLACK et al. haben als erste
eindeutig bei Versuchspersonen bewiesen, daß die antigene
Wirkung von Rh-positiven Erythrozyten durch intramuskuläre Injektion von hochkonzentriertem Anti-Dy-Globulin verhindert werden kann. In den seit der
ersten Behandlung Rh-negativer Mütter vergangenen
ersten 10 Jahren wurde die Wirksamkeit dieser Prophylaxe weltweit bewiesen und ist zur klinischen RoutineMethode geworden. Einige Probleme bei der Durchführung dieser Prophylaxe sind aber noch nicht ganz gelöst. Zudem will man versuchen, die Zahl der wenigen
Versager noch weiter herabzusetzen. Da die Wirksamkeit
der zugeführten Antikörper nur gewährleistet ist, wenn
sie im Überschuß angeboten werden, ist die Sicherheit
der Prophylaxe zunächst davon abhängig, daß die in die
Mutter eingeschwemmte Menge fetalen Blutes (Antigen)
bestimmte Größenordnungen nicht übersteigt. Die quantitative Überprüfung der fetomaternalen Transfusion bei
allen Rh-negativen Entbundenen führt vielerorts zu
Schwierigkeiten. Aus Tab. I ist jedoch ersichtlich, daß nur
in 1% der Fälle eine Einschwemmung von mehr als
10 ml fetalen Blutes in den mütterlichen Kreislauf post
partum zu erwarten ist. Diese Zahlen wurden an einem
Gesamtkollektiv von fast 7000 Müttern, die mit derselben
Färbe- und Zähltechnik überprüft wurden, gewonnen.
Man ist derzeit der Ansicht, daß auf 1000 Entbindungen
nur 2—4 Fälle eintreten, bei denen die eingeschwemmte Menge fetalen Blutes 25—50 ml übersteigt.
POLLACK et al., sowie BARTSCH haben aber vor kurzem
eindeutig gezeigt, daß 250—300 Mikrogramm IgG-antiD intramuskulär verabreicht genügen, um bis zu
50 ml Rh-positives Nabelschnurblut immunologisch
zu inaktivieren. Nimmt man diese Dosis als Standarddosis, so werden zweifellos viele Frauen mit zu großen
Dosen behandelt. Da Anti-D aber heute in großen Mengen
zur Verfügung steht und vielerorts relativ billig ist,
scheint dieses Vorgehen gerechtfertigt, zumal keinerlei
Nebenwirkungen nach Verabreichung dieser Präparate
bekannt sind. Da man andererseits nicht weiß, welche
Minimaldosis Rh-positiver Erythrozyten zur Sensibilisierung einer Rh-negativen erwachsenen Frau führt (mit
Sicherheit genügen weniger als 0,1—0,24 ml Rh-positiven
Blutes) und Minimaleinschwemmungen von weniger als
50mm3 fetalen Blutes quantitativ aus methodischen
Gründen nicht erfaßt werden können, müssen alle Rhnegativen Frauen nach Geburt eines Rh-positiven
Kindes behandelt werden. Die Herabsetzung der Standarddosis erscheint in dieser Situation also nur gerechtfertigt, wenn die Dosis an die Menge eingeschwemmter
Erythrozyten adaptiert wird. Dies ist mit der HbF-ZellZählmethode nach KLEIHAUER oder mit der serologischen
Bestimmung des Antikörperüberschusses möglich. Ob der
Laboraufwand für diese Bestimmungen oder die Verabreichung von Anti-D im Überschuß die aufwendigeren
Methoden sind, kann jeweils nur ari Ort und Stelle entschieden werden. Will man auch fetomaternale Makrotransfusionen von mehr als 50 ml Blut erfassen, so ist
man gezwungen, bei allen Rh-negativen Müttern eine
HbF-Zeltkontrolle oder eine Bestimmung der Einschwemmung mit Differential-Agglutination durchzuführen. Keine Zweifel gibt es mehr darüber, daß alle Rhnegativen Frauen nach einer Fehlgeburt oder Interruptio mit Anti-D behandelt werden müssen. Auch
nach Eileiterschwangerschaften und Blasenmolen empfiehlt sich die Behandlung wenn nicht absolut sicher ist,
daß der Partner Rh-negativ ist. Das Sensibilisierungsrisiko nach Interruptiones beträgt bis zu 5,5%. Allerdings sind die Einschwemmun gsmengen fetaler Erythrozyten bei Schwangerschaftsabbruch in den ersten 12
Wochen relativ gering. Man kann deshalb in diesen Fällen
die Standarddosis vermindern (100 Mikrogramm?). Ein
noch nicht befriedigend gelöstes Problem ist andererseits die
Festlegung der Dosisangaben Immunglobulin-anti-D in den
für die Verwendung bestimmten Ampullen. Zur Zeit erfolgt sie in Mikrogramm. Da diese Bestimmungen für alle
international angewandten Präparate gegenwärtig nur in
den Laboratorien von HUGHES-JONES und POLLACK erfolgen, ist ein hoher Grad an Zuverlässigkeit gewährleistet. Bis heute ist es jedoch nicht gelungen, ein Standardpräparat für internationale Vergleiche zu gewinnen. Da die
Dosisangaben auf den Präparaten also nur mit einer relativ großen Streubreite akzeptiert werden können, ist es
zu empfehlen, im Zweifel hoch zu dosieren. Die lange
Zeit gehegte Befürchtung, daß Unterdosierungeh von
Anti-D zu einer Steigerung der Sensibilisierungsrate führen,
ist allerdings wahrscheinlich unbegründet. Der Grenzwert
für die Wirksamkeit von Anti-D dürfte bei 5 Mikrogramm pro 0,5 ml Erythrozyten liegen. Die Diskussion
über die Frage, ob es besser ist, Anti-D intramuskulär oder
intravenös zu verabreichen, ist noch nicht abgeschlossen.
Es ist gesichert, daß die Elimination fetaler Erythrozyten
aus dem mütterlichen Kreislauf nach intravenöser
J. Perinat. Med. l (1973)
Queenan et al., Rh-prophylaxis
Verabreichung von Anti-D schneller erfolgt als nach
intramuskulärer Gabe. Andererseits verteilt sich intravenös
oder intramuskulär appliziertes IgG-anti-D 2wischen
intravasalem und extravasalem Raum innerhalb 48 Stunden
nach Injektion in gleicher Weise. POLLACK hat außerdem
bewiesen, daß 72 Stunden nach Gabe des Antigens intramuskulär verabreichtes Anti-D voll wirksam ist. Die
Sorge mancher Autoren vor Zwischenfällen bei intravenöser Verabreichung von y-Globulin ist zumindest bei
der vielerorts intravenös durchgeführten Anti-D-Prophylaxe durch keinerlei Nebenreaktionen untermauert
worden. Ist man gezwungen, große Mengen Anti-D, z. B.
5000—7000 Mikrogramm, in kurzer Zeit zu verabreichen
(z. B. nach Fehltransfusionen Rh-positiven Blutes), so ist
dies im allgemeinen nur auf intravenösem Wege möglich.
Allerdings müssen die intravenös angewandten
y-Globuline speziell präpariert sein und solche Behandlungen sollten nur im Krankenhaus mit Intensiv-
231
überwachung des Patienten erfolgen. Noch nicht gelöst ist
die Frage, ob es empfehlenswert ist, mit Anti-D zu behandeln, wenn die Mutter die Blutgruppe Du, das Kind D
besitzt und ob es sinnvoll ist, Frauen mit zweifelhaft
positivem COOMBS- oder Enzymtest Anti-D zu verabreichen. In klinischen Untersuchungsreihen wird gegenwärtig geprüft, ob die Versagerquote vermindert
werden kann, wenn man die Anti-D-Prophylaxe
bereits im letzten Drittel der Schwangerschaft durchführt. Diese Frage kann voraussichtlich erst in einigen
Jahren beantwortet werden. Die letzte in die Diskussion
geworfene Frage stammt von HINDEMANN. Er schlägt vor,
bereits bei Rh-negativen weiblichen Neugeborenen
die Prophylaxe durchzuführen, wenn die Mütter dieser
Kinder Rh-positiv sind. Jedenfalls sind materno-fetale
Transfusionen während der Geburt nicht ganz so selten
wie früher angenommen worden ist.
Schlüsselworte: Anti-D-Prophylaxe, feto-maternale Mikrotransfusion, HbF-Zellen, Immunglobulin-anti-D, Rh-Erythroblastose.
Resumo
Aspects pratiques et cliniques de la prophylaxie de
Rh-sensibilisation
Le developpement de diverses methodes therapeutiques,
telles que la transfusion d'echange, Panalyse du liquide
amniotique et la transfusion intra-uterine, a permis d'
abaisser depuis trente ans de 45% a 8% le taux de mortalite
perinatale dans les cas de morbus haemolyticus neonatorum consecutif au Rhesus. Or, ce pourcentage peut etre
encore fortement reduit gräce a Tapplication generale de la
prophylaxie de Rh-sensibilisation avec anti-D, cette
prophylaxie etant le resultat des deux observations suivantes: FINN et CLARKE de Liverpool furent les premiers ä
constater la presence tres rare d'erythrocytes foetaux dans
le sang maternel dans les cas de constellation incompatible
des groupes sanguins ABO entre la mere et Fenfant. Par
voie de consequence, ils expliquerent cela par la presence
d'anticorps specifiques dans le Systeme ABO et ils etablirent un lien de cause a effet avec la baisse du taux de
sensibilisation pour la constellation incompatible des
groupes sanguins ABO chez les meres ä Rh negatif.
POLLACK, GORMAN et FREDA a New York partirent d'
observations deja faites en 1909 par TH. SMITH: Pour la
vaccination active et passive, dite sero-vaccination, il est
possible dans beaucoup de cas de reprimer l'immunisation
active en administrant l'anticorps specifique en excedent.
POLLACK et ses collaborateurs ont ete las premiers ä
demontrer de fa§ön probante sur des sujets d'e^perimentation que Peffet antigenique d'erythrocytes Rh positif
peut £tre contrevenu par injection intramusculaire de
y-globuline anti-D a tres forte concentration. Depuis dix
ans que
traite les meres ä Rh negatif, on a pu prouver
dans le monde entier Pefficacite de cette prophylaxie qui
est devenue entre-temps une methode de clinique de
routine. L'application, toutefois, continue de poser
J. Perinat. Med. l (1973)
quelques problfemes, d'autant plus qu'on cherche a
reduire davantage encore Peffectif des sujets «recalcitrants», pourtant peu nombreux. L'efficacite des anticorps
administres n'etant assuree qu'a dose excedentaire, la
garantie de la prophylaxie depend donc en premier
lieu de ce que la quantite de sang foetal (antigene)
penetrant dans la mere ne depasse pas un certain
niveau. Le controle quantitatif de la transfusion foetomaternelle chez toutes les accouchees a Rh negatif cause
bien souvent des difficultes. Le Tab. l montre
cependant, que dans 1% des cas seulement, la penetration de sang foetal dans la circulation maternelle
post partum depasse 10 ml. Ces chiffres ont pu etre
etablis apres examen de pres de 7000 meres avec la meme
technique de coloration et de comptage. On estime
actuellement que sur 1000 accouchements, 2—4 cas
seulement rev^lent une penetration de sang foetal dans
la circulation maternelle superieure ä 25 ml. POLLACK
et ses collaborateurs ainsi que BARTSCH ont, neanmoins,
demontre recemment que l'administration intramusculaire de 250—300 microgrammes d'IgG-anti-D suffit
pour inactiver immunologiquement jusqu'ä 50 ml de
sang ombilical ä Rh positif. Si on prend cette dose pour
norme, on constate que beaucoup de femmes sont sans
aucun doute traitees a trop forte dose. Mais les preparations
d'anti-D etant disponibles aujourd'hui en grande quantite
et, de plus, relativement peu coüteuses, ce procede semble
Justine, d'autant plus qu'on ne leur connait aucun effet
secondaire. Mais comme, d'autre part, on ignore quelle
dose minimale d'erythrocytes Rh positif provoque la
sensibilisation d'une femme adulte a Rh negatif (moins de
0,1—0,24 ml de sang Rh positif suffisent certainement) et
que, pour des raisons de methode, il n'est pas possible
d'enregistrer quantitativement des «penetrations» mini-
232
malcs inferieures a 50 mm3 de sang foetal, il est necessaire
de traiter toutes les femmes a Rh negatif qui ont donne
naissance a un enfant a Rh positif. La baisse de la dose
standardisee ne parait donc justifiee qu'a condition que la
dose soit adaptee a la quantite d'erythrocytes «penetres»,
ce qui est possible soit par la methode de comptageglobules HbF de KLEIHAUER, soit par la definition
serologique de l'excedent d'anticorps. II appartient de
decider sur place s'il est plus economique d'effectuer ces
definitions serologiques ou d'administrer un anti-D
excedentaire. Si on veut aussi enregistrer des macro-transfusions foeto-maternelles de plus de 50 ml de sang, on
est oblige de proceder chez toutes les meres a Rh negatif
ä un controle HbF ou a une definition de la «penetration»
avec agglutination differentielle. II n'y a plus de doute
sur la necessite de traiter a l'anti-D toutes les femmes a
Rh negatif apres une fausse couche ou une Interruption
de gravidisme. De meme, le traitement est recommande
apres des grossesses tubaires et des moles hydatiformes
s i on n'est pas absolument certain que le partenaire ait un
Rh negatif. Le risque de sensibilisation peut aller
jusqu'ä 5,5% apres des interruptions de gravidisme.
Les quantites penetrantes d'erythrocytes foetaux en cas
d'interruption de grossesse sont relativement basses dans
les 12 premieres semaines. On peut donc reduire la dose
standardisee dans ces cas-lä (100 microgrammes?). Par
ailleurs, on n'a toujours pas reussi ä resoudre de fagon
satisfaisante le probleme des indications de dose d'immunoglobuline anti-D dans les ampoules devant etre
utilisees. Elle se fait actuellement en microgramme. Ces
definitions ne s'effectuant presentement que dans les
laboratoires de HUGHES-JONES et POLLACK pour toutes les
preparations employees a l'echelon international, la garantie est pratiquement assuree. On n'a toutefois, pas
encore reussi a fabriquer un produit Standard pour des
equivalences internationales. Comme, donc, les indications
de dose sur les preparations ne peuvent etre regues qu'avec
une marge relativement grande, il est recommande dans le
doute de pratiquer une forte dose, bien qu'on n'ait probablement plus besoin de craindre une hausse du taux de
sensibilisation ä la suite de dosages trop bas d'anti-D. La
Queenan et al., Rh-prophylaxis
valeur-limite pour Tefficacite de l'anti-D devrait se situer
aux alentours de 5 microgramrnes pro 0,5 ml d'6rythrocytes. La discussion se poursuit toujours pour savoir s'il
est plus indique d'administrer l'anti-D par voie intramusculaire ou intraveineuse. On sait seulement avec
certitude que Padministration intraveineuse d'anti-D
provoque une elimination plus rapide des erythrocytes
foetaux de la circulation maternelle. D'autre part,
PIgG-anti-D applique par voie intraveineuse ou intramusculaire se repartit pareillement entre Pespace intravasculaire et extravasculaire en nioins de 48 heures apres
Pinjection. POLLACK a demontre, en outre, que 72 heures
apres Padministration de Pantigene, Panti-D injecte par
voie intramusculaire est entierement efficace. Bien des
auteurs redoutent des accidents dans Padministration intraveineuse de y-globuline; or, la prophylaxie d'anti-D
appliquee bien souvent par voie intraveineuse n'a
revele aucune reaction secondaire. Si on est oblige, du
reste, d'administrer en peu de temps de grandes quantites
d'anti-D, par ex. 5000—7000 microgrammes (a la suite,
par ex. de transfusions manquees de sang Rh positif),
cela n'est possible eri general que par voie intraveineuse.
Toutefois, les y-globujines appliquees par voie intraveineuse doivent etre specialement preparees et de tels traitements ne devraient se faire qu'ä Phöpital, sous la surveillance intensive de la patiente. On ne sait pas encore,
par ailleurs, s'il faut recommander d'äppliquer un traitement d'anti-D lorsque la mere a le groupe sanguin Du et
Penfant D, de meme lorsque le test de COOMBS ou le test
enzymatique ne sont pas clairement positif s. Des series
d'assais cliniques ont Heu actuellement pour determiner
s'il est possible de reduire le taüx d'echecs en appliquant la
prophylaxie anti-D des le dernier tiers de Ja grossesse. On
pense ne pas pouvoir obtenir des resultats definitifs a ce
sujet avant plusieurs annees. La derniere question soulevee
vient de HINDEMANN qui emet la possibilite d'äppliquer
la prophylaxie deja chez les nouveaux-nes de sexe
feminin ä Rh negatif lorsque les meres de ces enfants
ont un Rh positif. Les transfusions materno-foetales ä
Paccouchement ne sont plus tout-ä-fait aussi rares, en
tout cas, qu'on le supposait anterieurement.
Mots-cles: y-globulin anti-D, HbF, micro-transfusion foeto-maternelle, morbus haemolyticus neonatorunij prophylaxie de Rh-sensibilisation.
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Abstracts l, 5, 7, 3
John T. Queenan, M. D.
Professor and Chairman
Dept. of Obstetrics and Gynecology
University of Louisville
Louisville, Kentucky 40202/USA
J. Perinat. Med. l (1973)