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Letty

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Everything posted by Letty

  1. Letty

    Auto anti-G?

    Apologies, you are quite right, and i have edited my post. Regardless of the ethics of performing the testing, i would still be interested to know how you can differentiate between the two.
  2. We have a 92 yr old patient who was transfused three units of blood 18 months ago. She was recently re-admitted with infection and haematemesis when pre-transfusion testing revealed the presence of anti-Fya plus apparent anti-C+D (with positive autocontrol) in her plasma. Her D group is weakly positive, so we duly referred samples to our reference centre to confirm her group and our suspicions of an anti-G (due to variations in reaction strength). Her group has been reported as O RhD positive (Weak D) C-c+E+e+K+but the anti-G detected is reported to be Auto. My question is, how can the reference centre determine whether the antibody is allo or auto? - Surely an allo anti-G will cross-react with the patient's own cells, leading to a positive auto and subsequent elution of the antibody from the patient red cells? The reference centre failed to explain why the antibody must be an auto, despite being quizzed by ourselves and were absolutely adamant that it wasn't an allo anti-G.
  3. Here in the UK, not only do we perform an antibody ID but we also refer for quantification. If the prophylaxis is detected in the 28 wk bloods then repeats are obtained as though the antibody were immune. If it is detected for the first time after 28 wks then we refer for quantification but do no further testing if the antibody level is within the reference range for prophylaxis (unless detected immediately prior to delivery)
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  6. Hi Jermin We took up FDNA testing just over a year ago but still test all cord samples from D negative mothers to confirm the accuracy of the FDNA results. We perform a retrospective comparison of results on a weekly basis and have found a number of discrepancies during that time. All of these discrepancies have been carefully investigated by us and IBGRL, where appropriate. Two of them were false positive FDNA results whereby the phenotype of the neonate didn't match the genotype...this scenario (D negative baby following a D positive genotype test result) will occur, albeit rarely, owing to the presence of a non-expressed RHD gene. We have also had two false negative FDNA results due to insufficient foetal DNA in the maternal blood sample. By testing the cord the risk to the Mum was minimized as she was able to receive post-natal anti-D immunoglobulin. Rather more worrying, two discrepancies have highlighted poor practice on labour ward - a cord that was sampled from the sluice (yes, really) that IBGRL was able to show couldn't have belonged to the mother in question and twins who were initially both grouped as D negative but patient recall showed one of the them to be D positive! By testing the cord and feeding-back any discrepancies to IBGRL it also helps to inform the accuracy of the test. Although we group the cord samples, we stopped performing DATs on these samples many years ago and only perform a DAT in the presence of maternal antibodies or for clinical investigation of jaundice. Hope this helps Letty
  7. Letty

    RhD status

    We've seen the blood group "change" from D negative to D positive during the course of the pregnancy on a couple of occasions...using the same reagents and technology and confirmed as weak D positive by NHSBT Filton. As Malcom suggests, they typed as R2r.
  8. Hello We have a patient who has flummoxed our Haematologists and I wondered whether any of the experts could shed any light on the situation.... The patient is an 80 yr old female with an apparent warm automimmune haemolytic anaemia post THR. She has previously had a low-ish but stable haemoglobin of 105 g/L with a history of a positive DAT (C3b) and non-specific reactions in the BioVue IAT panel (May this year). She has been actively haemolysing since her operation with evidence of spherocytes and polychromasia in her blood film. Our reference service has reported the following: DAT IgM 2+ C3c 2+ C3d 4+ and an enzyme only pan-agglutinin. There is no evidence of cold agglutinins present in any of her samples. Is it possible to have a warm autoimmune haemolytic anaemia associated with IgM antibodies and why would she suddenly start haemolysing post-op with no evidence of previous active disease?
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  11. David, the anti-D has been issued gradually over the course of the last few weeks in response to the persistent presence of foetal cells. BCSH guidelines state that further anti-D should be given as dictated by the volume of foetal cells remaining, hence the disproportionate volume of anti-D given.
  12. Ah, sorry Malcolm, I've misled you. All samples were referred for flow to confirm the presence of foetal cells: the last report confirmed that although the volume is now less than 4 mL, there are still foetal cells present. I believe the BCSH guidelines state that follow-up should be continue, with additional prophylaxis, every 72hrs (for IM anti-D) until the foetal cells have cleared.
  13. Hello, we're trying to manage a post natal foetal maternal haemorrhage that's got us all flummoxed.... Mrs M delivered an RhD positive baby girl on the 20th October and a post-natal Kleihauer showed approximately 5 mL of foetal cells. The sample was duly sent to our local reference centre for confirmation by flow and an 8 mL bleed was confirmed. Mrs M was given 1000 IU prophylactic anti-D and asked to return in 72 hours for follow-up Kleihauer. The samples arrived a little late but were received and processed according to protocol....and showed a foetal leak of 6 mL by flow. The patient has now had four follow-up samples and a total of 3000 IU anti-D and yet today's sample is still showing the presence of foetal cells. We have confirmed the presence of free anti-D in Mrs M's plasma. What could explain this persistence of foetal cells in the maternal circulation? Our Consultant Haematologist has suggested possible splenic pathology leading to an inability to clear the RhD positive cells despite prophylactic anti-D cover. Do we need to stop follow-ups but recall Mrs M in 6 months to test for the presence of immune antibodies?!
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