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Persistent foetal cells


Letty

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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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Does the mother have fetal hgb of her own? Thal minor, persistent fetal hgb . . . I would recall her in 3 months for f/u. Did you do a Fetal Bleed screen test each time to ascertain whether the cells are Rh+? That might be easier.

I've worked places where the OB guys were right on - knowing that they had a Thal minor mother, we would do a baseline KB to see what the mother's fetal hgb was prior to delivery.

Also - doesn't a 300ug dose of RhIg cover a bleed of 30 mL (wb)? why would you be giving so much more? (sorry I don't know the conversion of IU vs ug - maybe someone can enlighten me).

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I note that the original estimation was by Kleihauer, and, apart from the one occasion when the estimate was by flow, all the other estimates have been by Kleihauer.

 

Now, the flow would have used a FITC-labelled anti-D, and so that would directly be measuring D-Positive red cells, so there was certainly an FMH (unless the lady has a Weak D, and then the peak would be in a differrent place, of course).

 

All of the other tests are measuring HbF (by Kleihauer), and I just wonder if, by absolute coincidence, the woman has a natural high level of persistent HbF, and that the fetal cells have been cleared, but that her own red cells have this high level of HbF (this would not be uniform in each red cell, by the way, so may look a bit "mixed-field" for want of a better way of putting it).

 

I just wonder?  I've probably got it completely wrong!!!!!!!!!!!!!!!!!!!!!!!

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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.

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Oh right.  That's knocked that one on the head then!

 

The fact that you have free anti-D in the plasma (although, in itself, not an indication that sufficient anti-D has been given for the measured FMH) does suggest that the lady is able to adsorb the anti-D from the deltoid muscle into the circulation.

 

That leaves the suggestion by your Consultant, which, I must say I find attractive, although this is quite definitely NOT my area of expertise!!!!!!!! - BY A LONG WAY!

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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.

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Some odd-ball possibilities -

mum is a chimera

baby is a D variant that is not being destroyed by the anti-D

baby is really Dneg and the D+ result was wrong

the anti-D being used in the flow is somehow detecting something else

 

does the lady have a positive DAT?  I would expect her to have one if the cells are coated - but you would need a sensitive technique and look for a DP.  If she does, then the anti-D is coating the cells but not destroying them (?? something wrong with her macrophages, RE system??).  If the DAT is negative then the anti-D is not coating the cells and they are not normal D+ cells.

 

Are the results you are getting in the Kleihauer about equivalent to the results you are seeing in the flow?

 

Would be

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