Blood typing the infant of a Rh negative mother

When the mother of a newborn baby is Rh negative and the father is Rh positive, there is a good chance that the baby will be a positive blood type. Blood in the umbilical cord and the placenta will be only the baby’s blood. Here are instructions on how to obtain a sample:

  1. At the time of birth do not rush the clamping and cutting of the cord. I like to see the placenta birthed (this will usually take longer than 30 minutes if Nature’s way is followed) before clamping and cutting of the cord.
  2. Take the bowl with the placenta to the kitchen and get everything together before taking your blood sample. You will need
    • 2 pairs of nonsterile gloves to protect yourself from body fluids
    • 1 container with a lid in which to put the placenta
    • 1 blue waterproof 17- by 21-inch underpad
    • 1 3-cc syringe and needle
    • 1 purple test tube with stopper (Check with your local hospital to determine what color stopper they prefer. The purple stopper tube has an anticlotting chemical in it to prevent the blood from clumping.)
  3. Before putting on your gloves, write the necessary information on the label of the test tube in very tiny printing. Remember: it is very important that blood samples not get mixed up at the hospital. You will get along well with the blood bank if you mark your samples carefully. In my area, we print the mother’s full name and date of birth, the title “Cord Blood,” baby’s date of birth, and mother’s personal health number. When you get to the blood bank, they will also want you to fill out a requisition. On that form, put attendant’s name, pager number, the physician’s name, and the mother’s date of birth and personal health number. Write for the instructions “Type infant cord blood for screening; infant of Rh negative mother.”
  4. Now that you have all your supplies together and the tube is labeled, take the cord blood before inspecting the placenta. Pull the placenta out of the bowl and put it on the blue pad so that it is sitting on the counter with the cord draped over the edge of the counter; the clamp is on the end of the cord. You want to keep the label of the tube clean and legible, so you may want to change your gloves or wipe blood off them on the blue pad’s edge. Take the lid off the tube and hold it at the clamped end of the cord. Cut off the clamp by making a fresh cut in the cord and allow the blood to run into the test tube. When a half-inch of blood has accumulated in the bottom of the tube, close the tube and rock the blood back and forth. If you can’t get enough blood you may have to squeeze the blood down from higher up in the cord or cut the cord again near one of the black blood pools that you can see along the cord. Occasionally you may have to run the 3-cc needle into one of the vessels on the fetal side of the placenta, draw back on the plunger to extract the blood, and then squirt it into the test tube.
  5. Now you can do a complete inspection of the placenta and then put it away with a lid and label on it in the refrigerator.
  6. When you take the test tube to the lab, ask the technician to page you with the results as soon as possible. If the baby’s blood is Rh negative, ask the lab to fax a copy of the result for your records. If the baby’s blood is Rh positive, the lab will require a blood draw from a vein in the mother’s arm. Again, be sure you have the requisite stopper color test tube. The maternal sample is taken to the lab and checked for baby’s blood cells. If there are none in the mother’s blood, a low dose (120 micrograms) of WinRho (Rhogam in the United States) is given. If baby cells are present in mother’s blood, I have had as many as 900 micrograms prescribed. The package includes instructions on how to give the injection intramuscularly. It is given into the large muscle on the upper outer quadrant of the thigh. If you have to give more than 300 micrograms, you must give it in multiple sites. Injecting anything under the skin can cause harm, so be very careful you are sure of what you are doing and that you’ve had good instruction.  There will be an instruction leaflet in the box of Winrho (Rhogam), read it carefully before giving each injection because the information can change.

First published by Midwifery Today , 2004, updated Nov 18, 2008
UPDATE: September 2014 Article by Sara Wickham in the United Kingdom on a test to help limit the number of women who receive Rhogam (WinRho) unnecessarily in pregnancy. http://www.sarawickham.com/research-updates/yet-more-evidence-to-help-women-avoid-unnecessary-anti-d/

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