BLOOD TYPES & INCOMPATIBILITIES
MAJOR BLOOD TYPES
Blood typing is an important test that should be done prenatally. There are over
100 factors present in the red blood cell, however, there are only a few that can
cause sensitization prolems in pregnancy and during childbirth. The other factors
do not cause any significant problems as they are very weak. The four types of
human blood are A, B, AB and O. Each factor refers to a specific antigen (proteins
which cause the formation of antibodies).
Type A has A antigens and lacks B factors and therefore recognizes B as a foreign
substance.
Type B has B antigens and lacks A factors and therefore recognizes A as a foreign
substance.
Type AB has both A and B antigens and has no problem with accepting both of these
substances into the body system. It recogizes all bloods as compatible.
Type O lacks both antigens (A and B) and recognizes both of these factors as foreign
substances.
When a foreign blood protein is identified, the antigen causes an antibody to be
formed in the body system so that the invading substance can be destroyed in the
future if the substance is introduced into the body system again. In the case of
of these four blood groups, the antibodies are congenitally present in the body
system by means of the blood group.
| BLOOD GROUP |
ANTIGEN ON RBC |
ANTIBODIES IN SERUM |
| O (46%) |
None |
Anti - A & B
(Universal Donor) |
| A (41%) |
A |
Anti - B |
| B (9%) |
B |
Anti - A |
| AB (4%) |
A & B |
Neither
(Universal Recipient) |
These four blood groups contain those blood proteins that are the most reactive
when wrongly combined with each other (such as in a wrongly matched transfusion).
This is due to the inherent sensitivity of the blood cells and the immediate
antibody reaction that occurs with foreign blood factors.
ABO INCOMPATABILITY
ABO problems are relatively common, but less severe than aquired blood
incompatabilities. Since the antibodies for another type are inherently present
on the red blood cells and do not increase, reactions are usually less severe.
The infants at risk are:
- Group A or B infants of Group O mothers (50% of all cases). Mother O, baby A
is more common. Mother O, baby B is more severe. Some midwives will take cord
blood on all type O mothers due to this frequency.
- Group B or AB infants of Group A mothers.
- Group A or AB infants of Group B mothers.
Theory is that severe cases are usually not seen because they abort spontaneously.
Another interesting item about ABO problems is that an Rh- mother with sufficient
Anti-A or Anti-B in her system will often destroy any invading fetal blood BEFORE
an aquired sensitization can be established. However, this cannot be depended on
as a preventative.
Rh FACTORS
Rh (Rhesus) factors are the second most reactive substances to be found in the
blood. These are a group of related factors which usually occur together and of
which Rho(D) is the most reactive. The Rho
When Rh+ (Rh positive) blood is introduced into the body system of an Rh- (Rh
negative) person, the Rh- blood recognizes the Rh factor as a foreign substance
and begins to form antibodies in order to destroy the invading cells. Rh+ blood
may enter the blood stream of an Rh- person in any of the following ways:
- A wrongly typed blood transfusion.
- A placental leakage due to slight abruptions during the pregnancy of an Rh-
pregnant woman carrying an Rh+ baby. This can immunize the Rh- baby against Rh+
blood factors in an Rh+ woman before birth, although this is not common.
- Slight abruptions or invasive medical diagnostic procedures (such as
amniocentsis) performed during pregnancy which may allow the mother's and baby's
blood to mix and initiate antibody formation with an Rh- mother and an Rh+ baby.
- After the birth of an Rh+ baby when placental detachment takes place and the
bloodstream of the mother and baby may mix, the Rh+ blood may enter the maternal
bloodstream and initiate antibody formation (whole blood usually does not mix in
the normally detached placenta during pregnancy).
The initial introduction of Rh+ blood into the Rh- body system causes no immediate
adverse reaction. However, during the days following the blood mixing incident,
antibody formation takes place. The anti-Rh antibodies will remain in the system
of the Rh- person to destroy any other Rh+ blood with which it comes into contact.
With a sensitized pregnant women this means that any future pregnancies with a Rh+
baby may be compromised because the anti-Rh antibodies cross the placenta and may
result in blood cell destruction in the Rh+ baby. Sensitization can become
progressively worse as more Rh+ babies are carried by an sensitized Rh- pregnant
woman (this does not always happen). Any Rh- babies she carries are not at risk.
If both parents are Rh-, they will probably have Rh- babies. However, it is possible
for two Rh+ parents to have an Rh- baby if both are carrying a gene for Rh
negativity and pass it to their offspring (this happened in my family with my few
of my sisters and with my own daughter being Rh- with two Rh+ parents).
Du FACTOR (Duffy factor)
The Du factor is related to the Rh group of blood factors. It is important because
in cases where the Rh group is missing (Rh-), the Du factor is sometimes present.
In such situations, the Du factor usually compensates for the lack of other Rh
factors and causes the blood stream to respond as if it where Rh+. Such cases
would be reported as Rh- Du+. These women are RARELY at risk for Rh problems and
are most often treated as if Rh+ (except with a transfusion).
KELL FACTOR
About 90% of the population is Kell negative, leaving the other 10% Kell positive.
Although the Kell factor is rare, it is strongly antigenic and is significant in a
small percentage of pregnancies. Anti-Kell antibodies can be formed in response
to a Kell+ transfusion into a Kell- person. This can cause severe hemolytic
transfusion reactions. This is the most common way for
a Fell sensitization to occur. A Kell+ baby could also sensitize either case,
subsequent Kell+ babies would be at risk for hemolytic anemia. It is good to know
the father's blood type since one out of 500 people have both genes dominant for
the Kell factor, most have a dominant and recessive gene which can result in a 50%
chance of contributing a Kell+ gene to the baby. In cases of previous
sensitization of a Kell- mother, if the baby's father is Kell+, gene contribution
during the type of conception can determine the chances of a Kell+ baby.
OTHER MINOR FACTORS
C and E factors are also minor factors which, together with Kell, contribute to
2% of all neonatal incompatibility problems. If a infant develops early jaundice
for no apparent cause, then it is important to obtain detailed blood typing of
both parents to determine the reason for jaundice. These factors are routinely
not checked during prenatal blood typing studies.
LAB TESTS
The lab should check for the major blood types (A,B,AB,O) and the
Rho(D). If the woman is found to be Rh+ or Rh- Du+
no further testing is necessary. If any of the following conditions are
present these further tests may be important to perform:
- The mother is Rh- and pregnant for the first time.
- The mother is Rh- with known sensitization from a previous pregnancy or
transfusion.
- The mother has obtained anti-Kell antibodies after being sensitized from a
previous pregnancy or transfusion and the father is Kell+.
- The mother is Rh- and has not been sensitized by a previous pregnancy.
If the father has been checked to make sure he can only produce Rh- offspring
should the mother pass on any further testing. This is especially important
in situations where blood products (such as Rhogam) are not used for religious
reasons. The genetic testing (zygosity) can help the parents to determine what
risks they may be taking and plans can be made for the number of children they
may be considering for their family.
LABORATORY TESTS
INDIRECT COOMBS TEST
This test can screen for minor blood factors and the presence of antibodies in
the body system. It is always done on an Rh- mother and some labs may do it
with every mother to make sure that there are no antibodies present (such as a
A+ mother with an anti-Kell). This test detects the presence of antibodies
(anti-Rh and others) only. If the Indirect Coombs comes up positive, another
test is necessary to determine the type and level of antibody in the blood.
Rh ANTIBODY TITER
If an Indirect Coombs test comes back positive, this test determines the type
and quantity of antibodies in the blood. Since the anti-Rh is the most
sensitizing, they are the ones most likely to rise during the pregnancy and
cause problems. Depending on the level of other antibodies (anti-Kell), etc.)
they could cause hemolytic problems in the baby and need to be monitored. It
will need to be repeated several times during pregnancy (32 weeks, 36 weeks,
and 38 weeks). A low titer (no higher than 1:16) may not represent a problem
for the baby. In any test higher than 1:64 or above, a intrauterine exchange
transfusion may be suggested (risks and benefits should be thoroughly research
before performing this procedure and discussed completely with the clients).
A woman with severe Rh sensitization carrying an Rh+ baby is not a candidate for
a home birth. However, it is possible for a mother with a high titer to deliver
a perfectly healthy Rh+ baby without the resulting jaundice.
DIRECT COOMBS TEST
This test determines the presence of antibodies on the red blood cells (RBCs).
It allows the midwife to know if the baby's blood cells are being destroyed and
diffentiates what antibody reaction may be occuring (Rh, Kell, etc.).
BILIRUBIN TESTS
A bilirubin test may be done to determine how much RBC destruction is occuring
and how fast it is happening. Serial titers will be done to determine how fast
the rate is rising or falling. This determines the relative risk to the baby.
Bilirubin is the byproduct of RBC destruction and this test is a measure of the
result of the hemolytic process.
KLEIHAUSER-BETKE STAIN
In any case where a possibility of blood mixing is suspected, the Kleihauser-Betke
stain should be done. This test calls for maternal blood to be taken in a
lavendar top (EDTA) tube. It checks for fetal blood cells in the mother's
system and is usually done only when excessive fetal transfusion is suspected
to determing if the mother needs more than one injection of Rhogam. One dose
of Rhogam covers 15 ml of fetal red blood cells or 30 ml of fetal whole blood.
The Kleihauser-Betke stain could also be used to determine whether fetal
transfusion has taken place in any Rh- mother of an Rh+ baby, in order to
avoid an unnecessary injection of Rhogam. A small transfusion of fetal cells
should be detectable, as this test is very sensitive. However, a slight risk
of sensitization is still present.
RHOGAM
When a Rh- mother gives birth to a Rh+ baby, an injection of Rhogam will
be recommended. Rhogam is an immume globulin substance derived from human
blood serum. It works by entering the maternal bloodstream and tagging any
fetal blood which may be present rendering it invisible to the mother's body
system until she can eliminate it. The sensitization is avoided. Occasionally
two or more injections will be necessary, based on the amount of fetal blood
in the mother's system. Rhogam is administered within 72 hours after the
birth in the upper, outer quandrant of the mother's buttock area (behind and
below the pelvic crest on the outside of the body). Although it is reported
as being very effective, Rhogam does not totally eliminate the possibility
of problems.
Some things to remember when Rhogam treatment is considered:
- Rhogam is a blood product. For some clients (such as Jehovah's Witnesses) who use
no blood products medically, it is a matter of individual choice whether they
accept Rhogam as a blood product or not. The midwife needs to determine how
she feels about personal preferences and her midwifery practice under these
circumstances and whether there are Jehovah Witness health care practitioners
in the region that support this choice.
- Since Rhogam is a blood product, reactions similar to transfusion reactions
may occur. Symptoms include:
- Heat at the injection site.
- Constricting pain in the chest or lumbar region.
- Flushing of the face.
- Bleeding from wounds.
Symptoms may be milder than a blood transfusion, but medical help should be
sought immediately.
Before Rhogam is administered, the lab must recheck the mother's blood for blood
type and factor sensitivity to make sure she is Rh- and that she has remained
unsensitized.
- Blood related diseases can be passed to the mother (hepatitis, HIV, etc.).
I have not heard of a synthetic form of Rhogam developed yet at this time.
- Rhogam is administered in any of the following situations:
- The transfusion of Rh+ blood into the blood stream of an Rh- person.
- When an unsensitized woman has given birth to an Rh+ baby and has a negative
Direct Coombs test.
- When an unsensitized woman has a miscarriage or abortion (sensitization
usually doesn't occur before 8 weeks gestation).
- After an Rh- woman undergoes an invasive diagnostic procedure involving
potential bleeding (such as amniocentesis).
- Many medical practitioners are recommending Rhogam prophylactically for ALL
unsensitized Rh- women. This is very expensive and another example of medical
misuse and abuse of a practice that was meant to help a few, but is not required
for the entire population.
Approximately 13% of those Rh- mothers who have not received Rhogam after giving
birth to a Rh+ baby will become sensitized during their first pregnancy. Rhogam
is said to be about 93% effective.
Rhogam is an expensive product requiring a prescription. Most midwives do not
usually keep a supply on hand since it has a short "shelf-life" and must be
discarded when the expiration date is reached. The client can obtain a prescription
for the product from her health care provider and have it available for her birth.
With recent developments, there is a standardized type of Rhogam sold as a
pharmaceutical product that has fewer problems with blood product reactions
occuring and does not need to be crossmatched with the mother's blood type.
CLIENTS & MIDWIVES CHOOSING NOT TO USE RHOGAM
If a woman refused to use Rhogam for religious or other reasons, and the midwife
is comfortable working with her and the client's health care provider is
supportive, there are things that the midwife and Rh- client can do to reduce
the possibility of sensitization during her pregnancy or keeping sensitization
to a minimum in a sensitized client. Building a strong placental bed will help
to minimize problems.
Some suggestions include the following to be used during pregnancy:
A good, nutritious diet helps to establish and strengthen the placental bed
and minimized the risk of premature separation.
Citrus fruits and juices three times a day and a bioflavinoid complex tablet
(600 mg daily) can help strengthen the placental bed.
Eliminating fluoridized water and toothpaste (fluoride interferes with the
body's ability to form and properly distribute collegen (the principle protein
involved in attaching the placenta to the uterus).
1 gram of activated charcoal daily.
1 teaspoon of magnesium powder in water daily (epsom salts).
Kelp, sea vegetables or mineral supplements daily.
Fresh garlic or garlic oil perles (10 perles or 3-6 cloves daily).
Elder flower tea daily.
These things can be done after the birth to prevent or minimize sensitization
from occurring:
- Allow the cord to stop pulsing before cutting. This will allow as much of
the blood as possible to drain from the placenta and then creating less of a
back-wash on the maternal side. If there is no titer in the mother, it does not
increase the likelihood of jaundice in the baby.
- Allow the remaining blood to drain freely into the cord blood tubes and
placental pan. Do not clamp the cord until it is completely drained (for the
same reason as given above).
- Check the fundus but do not apply massage. Massage can irritate the uterine
lining and cause unnecessary bleeding.
- Watch carefully for signs of placental separation and gently assist delivery
with cord traction or the mother squatting. Tell the mother to be aware of
contractions and push with them. Avoid traumatic placental delivery at all costs!
The following situations will place a woman at higher risk for blood mixing to
occur:
- Bleeding during labor. This can be from a slight placental abruption or a
marginal placenta previa. Either of these can cause the fetal blood to enter
the mother's system.
- Excessive bleeding postpartum associated with partially detached placenta
which may be taking some time to deliver.
- Manual or otherwise aggressive placental removal.
- If twins are suspected, clamp immediately to avoid possible twin to twin
transfusion.
GUIDELINES FOR MATERNAL BLOOD TYPE Rh NEGATIVE CLIENTS
Blood typing and antibody screen are considered initial blood work unless the
mother already knows her blood type and Rh factor (type D). For mothers having
Rh negative blood type and the antibody screen is negative, discuss risks and
benefits of prenatal Rhogam.
The midwife may suggest a repeat screen at least at 28 weeks and 36 weeks.
If prenatal antibody screen is positive, the midwife may have the client
consult with her health care provider.
The midwife should be prepared to draw maternal blood for antibody screen
immediately postpartum. If positive, the midwife should order fetal cell count
and suggest the client consult with her health care provider.
Preparation should be made to test cord blood for Rh factor and type
immediately postpartum. If the baby's blood type is Rh+, the client should
arrange for Rhogam administration within 72 hours.
MoonDragon's Birthing Guidelines - Variations of Pregnancy
Information obtained from Understanding Lab Work in the Childbearing Year -
A guide for practitioners and consumers of health care in childbirth
by Anne Frye. Thankyou Anne!
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