NNJ - Neonatal Jaundice
Ok. For this investigations, it will be conducted in the blood bank. The nurses will send in a EDTA baby sample and 1 plain tube containing the mother's blood and another EDTA tube containing the mother's blood. So we have 1 tube from the baby, usually the cord blood and another 2 from the mother. These 3 tubes will be sent in a biohazard bag that is attached to the request form.
Mostly NNJ is caused by ABO incompatibility. So the first step is to test for baby and mother's blood group and check if there's incompatibility.
So, if the mother is Group O/A and the baby is group AB/B, there is blood group incompatibility. (Mother has anti-B)
If the mother is Group AB and the baby is group O, there's no blood group incompatibility.
For the baby's sample we only do forward grouping. Reason being: they haven't develop antibody yet.
After we determine that there is ABO incompatibility, we proceed to the "antibody titration stage" We either do the anti-A or anti-B titration with freshly prepared group A or B cells. Like erm, if the mother is Group A, baby group B, she has anti-B, so we do anti-B titration.
It's not possible that both Anti-A and Anti-B titration is required, because if the mother is group O, how can baby be of group AB? Unless the baby is not hers?!
Right. So for the titration we label them from 1:1 dilution to 1:1024 dilution.
1. 3 drops of saline is added into all but 1st tube
2. Into tubes "1:1" and "1:2", we drop 3 drops of mother's serum(plain tube)
3. From tube "1:2" to "1:4" transfer 3 drops over after mixing
4. From tube "1:4" to "1:8" transfer 3 drops over after mixing
5. Keep doing this until the last tube where 3 drops will be pipetted away(from steps 1 to 5, don't wash the pipette. Just keep using the same pipette. This is to avoid further dilution.
6.Then, go over to the fridge, take out a unit of blood of A packed cell(for anti-A titration).
Pull out a segment of blood from the unit.
See the "tubing-like" rubber structure containing blood, there's a machine which can actually like fuse part of the "tube" together to create a segment, so we can actually pull out a segment without having to puncture and dirty the blood.7. So to remove impurities, we wash it in 0.9% saline once
8. Then dilute the cells to create a 3-5% cell suspension.
9. Pipette a drop of the cell suspension into all tubes, from 1:1 to 1:1024
10. Incubate all the tubes for 1 hour
11. Centrifuge at low speed, 1000rpm for 15seconds
Read the results. Usually the first 2-3 tubes will be fully haemolysed.
In some tubes, there'll be partial haemolysis, with some agglutinates still present while in some. Record the results. Notify the ward staff/doctor if haemolytic anti-A or anti-B is detected
Thank you!
yanhong 0703979e
Hi yanhong,
ReplyDeleteI would like to ask why is there a need to take an EDTA and plain tube of the mother's blood? And what actions would the doctor/ ward staff will take if haemolytic anti-A or anti-B is detected. Thanks =)
Lok Pui
hi yanhong, just curious why usually the first 2-3 tubes will be fully hemolysed?
ReplyDeletezi shuang
@Lok Pui
ReplyDeleteThe purpose of the plain tube is for the titration. As for the EDTA tube, it is what we will usually use for ABORH testing. It was noticed that if we used EDTA tubes instead of plain tubes for titration, we will not get the haemolytic reaction happening, this is due to the effects of EDTA on the results.
@Zishuang
The first 2-3 titration glass tubes will be fully haemolysed due to the reaction between the Anti-A against A cells or Anti-B against B cells. Haemolysis signifies a strong reaction
@Lok Pui
ReplyDeleteRegarding the actions taken by the ward, i don't know. I assume once notified regarding the situation, they may want to do a Hb test or something like that and check for the baby's Hb level, to see if the baby require a transfusion