Rh + and - and Coombs and blood types

  1. I am new to postpartum, and am having some trouble understanding how all this works. The blood type, rh positive or negative, Coombs. Does anyone have a simple or clear way of explaining this or direct me to a source that explains it well? Thank you

    Also, do you guys offer tdap vaccines to the dad's on post partum?
    •  
  2. 22 Comments

  3. by   Rose_Queen
    Not postpartum, but are you familiar with blood transfusions? Why you can give Rh negative blood to an Rh positive patient but why you can't give Rh positive blood to an Rh negative blood. So, if baby is Rh+ but mom is Rh-, there can be problems if blood antigens cross the placenta. Coombs test I'm not familiar with at all, but here's a Wikipedia blurb:

    The indirect Coombs test is used in prenatal testing of pregnant women and in testing blood prior to a blood transfusion. It detects antibodies against RBCs that are present unbound in the patient's serum. In this case, serum is extracted from the blood sample taken from the patient. Then, the serum is incubated with RBCs of known antigenicity; that is, RBCs with known reference values from other patient blood samples. If agglutination occurs, the indirect Coombs test is positive.
    Antenatal antibody screening
    [edit]


    The indirect Coombs test is used to screen pregnant women for IgG antibodies that are likely to pass through the placenta into the fetal blood and cause haemolytic disease of the newborn.
  4. by   prnqday
    Dads are on their own for DTAPs.
  5. by   klone
    I'll do my best:

    If the mom is Rh negative and becomes pregnant with an Rh + baby (which is only possible if the father is Rh +), her body will start forming antibodies against the + Rh if there is any comingling of the baby's and mother's circulation (which can happen during childbirth, or if there is vaginal bleeding, miscarriage, or abdominal trauma during pregnancy). Typically this happens during childbirth, which means that it doesn't affect THAT pregnancy, but will affect subsequent pregnancies if those babies are also Rh+. Because the antibodies will fight off the +Rh, it causes breakdown of the Rh+ fetus's red blood cells. This will cause severe fetal anemia, which can result in SAB, fetal hydrops resulting in IUFD, etc.

    The administration of Rhogam at key points in the pregnancy kills any +Rh blood cells that have gone into the women's body from the Rh+ fetus, which prevents the formation of Rh+ antibodies in the mother's body, protecting future pregnancies.

    Coombs I'm a little less sure on. My understanding is that it measures whether there is the presence of a particular antibody (different from the D antibody that measure Rh, I believe) that can cause hemolysis in the current infant, which can cause hyperbilirubinemia. If an infant is indirect Coombs +, it means the infant is a "setup" for hyperbilirubinemia/jaundice, and the hospital staff will probably be more vigilant for signs of bilirubin, and have a lower threshold for treatment.
  6. by   cracklingkraken
    Quote from klone
    I'll do my best:

    If the mom is Rh negative and becomes pregnant with an Rh + baby (which is only possible if the father is Rh +), her body will start forming antibodies against the + Rh if there is any comingling of the baby's and mother's circulation (which can happen during childbirth, or if there is vaginal bleeding, miscarriage, or abdominal trauma during pregnancy). Typically this happens during childbirth, which means that it doesn't affect THAT pregnancy, but will affect subsequent pregnancies if those babies are also Rh+. Because the antibodies will fight off the +Rh, it causes breakdown of the Rh+ fetus's red blood cells. This will cause severe fetal anemia, which can result in SAB, fetal hydrops resulting in IUFD, etc.

    The administration of Rhogam at key points in the pregnancy kills any +Rh blood cells that have gone into the women's body from the Rh+ fetus, which prevents the formation of Rh+ antibodies in the mother's body, protecting future pregnancies.

    Coombs I'm a little less sure on. My understanding is that it measures whether there is the presence of a particular antibody (different from the D antibody that measure Rh, I believe) that can cause hemolysis in the current infant, which can cause hyperbilirubinemia. If an infant is indirect Coombs +, it means the infant is a "setup" for hyperbilirubinemia/jaundice, and the hospital staff will probably be more vigilant for signs of bilirubin, and have a lower threshold for treatment.
    Thanks, klone! That was a great explanation, and I finally understand it.
  7. by   klone
    Thanks, glad I could help! I wasn't sure if my explanation was actually helpful or just as confusing!
  8. by   klone
    As far as TDap - we give it to mom, starting around 28 weeks. For dads and other family members (called "cocooning") I don't believe it's offered on the postpartum unit, but our hospital network has a public health department on the same campus, and dads and other family members can go to the immunization clinic there and get it for free. We tell them that when they're on campus for the 20-week U/S, they should stop in to the immunization clinic and get their shots at that time.
  9. by   Postpartum RN
    Thank you very much klone your explanation was very clear and helpful!!
  10. by   Jolie
    Quote from klone
    I'll do my best:

    Coombs I'm a little less sure on. My understanding is that it measures whether there is the presence of a particular antibody (different from the D antibody that measure Rh, I believe) that can cause hemolysis in the current infant, which can cause hyperbilirubinemia. If an infant is indirect Coombs +, it means the infant is a "setup" for hyperbilirubinemia/jaundice, and the hospital staff will probably be more vigilant for signs of bilirubin, and have a lower threshold for treatment.
    Just to clarify, there are 2 types of Coombs tests.

    The Direct Coombs is done on the newborn's blood, and if positive, indicates an increased risk of hyperbilirubinemia, usually due to an Rh or ABO incompatibility between mother and baby. This has no bearing on administration of RhoGam.

    The Indirect Coombs test is done on the mother's blood, and if positive, indicates that the mother has already formed antibodies against the baby's positive Rh factor. In this case, a provider may choose NOT to give an injection of RhoGam, since it would be ineffective in preventing antibody formation. (Kind of like closing the barn door after the horse is already out.)

    Fortunately, this is a rare scenario these days. Most Rh(-) women receive RhoGam prophylactically during pregnancy, or following a miscarriage or elective abortion, so sensitivity is rare prior to delivery. Because mixing of maternal and fetal blood can occur at delivery, an indirect Coombs test should be done on all Rh(-) mothers post-partum, and Rhogam given to mothers with a negative indirect coombs test to prevent sensitization that would potentially harm future pregnancies.
  11. by   klone
    Thank you for that clarification!
  12. by   Postpartum RN
    Jolie thank you for the explanation as well!
  13. by   Postpartum RN
    Quote from Rose_Queen
    Not postpartum, but are you familiar with blood transfusions? Why you can give Rh negative blood to an Rh positive patient but why you can't give Rh positive blood to an Rh negative blood. So, if baby is Rh+ but mom is Rh-, there can be problems if blood antigens cross the placenta. Coombs test I'm not familiar with at all, but here's a Wikipedia blurb:
    Yes I am familiar with blood transfusions and the reasons behind why blood is matched.
    I was looking for more explanations into Coombs test and rh positive and negative as it pertains to moms and babies during and after pregnancy and delivery as it is more confusing/complicated to understand; and some posters have explained it well. Thanks
  14. by   Mia415
    good answers on the RH factor here, just wanted to add regarding dads and tdaps - the dad is not your patient, so how will you bill for the cost of the vaccine and get reimbursed for it? Dads should be advised to get it through their PCP, health clinic, walgreens, etc. Pregnant women should recieve the TDAP between 28-36 weeks pregnant, with each recurring pregnancy, in order to maximize antibody transfer to the fetus, which takes about 4 weeks, for optimal protection against the whooping cough until baby gets their first vaccine at 2 mos. Once prenatal clinics comply with this new ACOG/AAP/CDC recommendation, less tdaps should be given postpartum altogether. Just an FYI

close