Auntie-D Posted November 12, 2015 Share Posted November 12, 2015 With the national shortage (absence) of 250iu and 500iu units of anti-D, is anyone collecting data of the number of babies with iatrogenic HDN due to overdose of prophylaxis? Could this happen? Could for example, a 13 week old foetus be exanguinated by the mother being given Rhopylac? We have been giving Rhophylac 1500iu for all gestation and some women have multiple doses. I daren't ask in the lab in case someone laughs at me. I have been distinctly uneasy in issuing myultiple lots of Rhophylac for ladies under 20 weeks Link to comment Share on other sites More sharing options...
galvania Posted November 13, 2015 Share Posted November 13, 2015 roll on non-invasive foetal DNA testing on all Dneg mums........ Auntie-D 1 Link to comment Share on other sites More sharing options...
Malcolm Needs ☆ Posted November 19, 2015 Share Posted November 19, 2015 Hi Auntie-D, Sorry to have taken so long to reply to this, but I wanted to be certain, and so I asked Dr Shubha Allard, who, in turn, asked Dr Edwin Massie and Dr Megan Rowley. They have all replied, but, for some reason, I am unable to copy and paste their answers. If you can PM me with an email address, I will pass on their answers. MalcolmOr even Edwin Massey! Link to comment Share on other sites More sharing options...
pstruik Posted November 20, 2015 Share Posted November 20, 2015 Of course, if this was in the US the OP would be Other Side of the Pondering ... I'll get my coat Mabel Adams, Malcolm Needs, amym1586 and 2 others 5 Link to comment Share on other sites More sharing options...
Mabel Adams Posted November 23, 2015 Share Posted November 23, 2015 Malcolm, can you not give us the upshot of what the experts said? I'm assuming we need not worry about overdosing with RhIG but please tell us if that is not correct. Link to comment Share on other sites More sharing options...
Malcolm Needs ☆ Posted November 23, 2015 Share Posted November 23, 2015 I've managed to do it, but PLEASE, if anyone feels the need to contact any of these experts, do it through me, rather than directly, otherwise I could be in deep trouble! To add my point of view..... If you look in Mollison (11th Ed. Ch 5. P166) it says there are 100,000-200,000 Rh binding sites on normal RhD +ve cells (wow, that seems like a lot to me!) If you give a large amount (1500 IU) of anti-D Ig to a RhD negative woman then the anti-D Ig will bind the RhD binding sites on those RhD +ve fetal cells, which are present in very small amounts relative to the mother's RhD-ve cells (0.1% fetal red cells is an FMH of about 2-3mL, 1% fetal red cells is an FMH of about 25mL). So all the anti-D is concentrated on the few fetal cells which are then removed because lots of their binding sites are covered (also in Mollison, I love Mollison!). If you give 1500 IU anti-D Ig pre-delivery and the baby is RhD positive then the anti-D Ig will cross the placenta and will bind to the fetal cells too BUT all of the fetal cells are RhD positive and each of them will get a little bit of anti-D which spreads it very thin and the small number of anti-D molecules bound to the the huge number of binding sites is insufficient to cause even a tiny bit of haemolysis. That is presumably why having a maternal immune anti-D level of <1 IU/mL (which is what you get with 1500 IU anti-D Ig) is not associated with HDN and a level of >10 IU/mL is associated with HDN. It is the 'dose' of anti-D relative to the RhD+ve binding sites. The anti-D audit (2013) dosage table is attached. 95% are using 1500 IU for RAADP, about a third use 1500 IU post delivery and a third for PSEs after 20 weeks. And 13% are using 1500 IU for PSEs and terminations <20 weeks. Megan Dr Megan RowleyConsultant HaematologistNHS Blood and TransplantNorth London Blood CentreCharcot Road ColindaleLondon NW9 5BG From: Needs MalcolmSent: 17 November 2015 13:42To: Massey Edwin; Allard ShubhaCc: Rowley MeganSubject: RE: A Query. Thanks very much indeed Edwin. Malcolm Needs CSci FIBMSReference Service Manager - TrainingRed Cell ImmunohaematologyNHSBT-Tooting Centre75 Cranmer TerraceTootingSW17 0RB From: Massey EdwinSent: 13 November 2015 15:27To: Allard Shubha; Needs MalcolmCc: Rowley MeganSubject: RE: A Query. I agree with SHubha I am not aware that it has ever been described as having done harm even with large doses given in early pregnancy. weak positive DATs are seen after delivery in a proportion as you know but DAT positivity is usually not associated with significant haemolysis. Even with repeated doses the level would remain in the low risk range compared with immune anti-D. Levels peak below 1IU/ml even if measured a couple of hours after an intravenous dose with a decay that eventually matches that of im anti-D. Edwin PS Shubha I am giving a presentation on the subject next week and planned to read the letter you sent me (twice) and respond whilst preparing for the presentation - sorry to appear slow MasseyAssociate Medical Director for Diagnostic and Therapeutic ServicesNHS Blood and TransplantNorth Bristol ParkNorthwayFilton,BristolBS34 7QH From: Allard ShubhaSent: 13 November 2015 11:32To: Needs MalcolmCc: Rowley Megan; Massey EdwinSubject: RE: A Query. Dear Malcolm I am not aware of any evidence that the higher dose is harmful in early pregnancy The guidelines state a 'minimum' dose in relation to gestation so this does not preclude using the higher dose formulations Megan's Anti D NCA audit will show data on how many centres using the 1500IU dose throughout pregnancy Kind regards Shubha Dr Shubha Allard From: Needs MalcolmSent: 13 November 2015 11:22To: Allard ShubhaSubject: A Query.Importance: Low Hi Shubha, NOT URGENT! This was posted on a website (PathLabTalk) to which I belong, and I would like to allay the fears, but I can't actually find anything in the literature to so do. "With the national shortage (absence) of 250iu and 500iu units of anti-D, is anyone collecting data of the number of babies with iatrogenic HDN due to overdose of prophylaxis? Could this happen? Could for example, a 13 week old foetus be exanguinated by the mother being given Rhopylac? We have been giving Rhophylac 1500iu for all gestation and some women have multiple doses. I daren't ask in the lab in case someone laughs at me. I have been distinctly uneasy in issuing myultiple lots of Rhophylac for ladies under 20 weeks " Do you know of anything? With best wishes, Malcolm Malcolm Needs CSci FIBMSReference Service Manager - TrainingRed Cell ImmunohaematologyNHSBT-Tooting Centre75 Cranmer TerraceTootingSW17 0RB Ppt0000000.ppt galvania, Cliff and AMcCord 3 Link to comment Share on other sites More sharing options...
Auntie-D Posted November 24, 2015 Author Share Posted November 24, 2015 Malcolm - this is why I love this site! True sharing of knowledge Cliff, galvania, Malcolm Needs and 3 others 6 Link to comment Share on other sites More sharing options...
Malcolm Needs ☆ Posted November 24, 2015 Share Posted November 24, 2015 Me too! Auntie-D 1 Link to comment Share on other sites More sharing options...
Auntie-D Posted November 25, 2015 Author Share Posted November 25, 2015 (edited) And idiots like me make even you have to think Grief that's dreadful grammar! Edited November 25, 2015 by Auntie-D Malcolm Needs 1 Link to comment Share on other sites More sharing options...
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