Our current policy regarding postpartum RhIG workups is that the mother be drawn within 1 hour of delivery to ensure accurate dosing with the Kleihauer-Betke test.  Does anyone else have a time frame and if so do you have a reference for where your time frame came from? 

Our rule is that the RhIg be administered within 72 hours of delivery but we do not have a policy regarding the timing of the specimen collection. Typically, it is done with AM collections the morning following delivery. Also, we do a fetal screen first and only perform the K-B stain if the screen is positive.

What is the rationale behind the 1 hour post-delivery collection?

I believe that the 1 hour rule is to give time for any foetal red cells that are released into the maternal circulation to "re-emerge" from sequestration into the spleen.  Before that, there is a chance that the foetal bleed may be underestimated, as not all of the foetal red cells can be guaranteed to be properly "mixed" in the maternal circulation, precisely because of this sequestration.

 

BUT I COULD BE WRONG!

 

I can't see any problem with what you do kirkaw.

We also do not have a time frame.  The specimen for RhIg workup is usually obtained with the 8 hr post-delivery specimen.  RhIg to be administered within 72 hrs.

No time frame, but prioritized as a STAT draw.

We do not have a time frame.  As David, The specimen for our FMH (or K-B Stain) is usually drawn 8-hours post-delivery (or with the next CBC specimen in the morning.)

 

Donna

We do the same as kirkaw

Our current policy regarding postpartum RhIG workups is that the mother be drawn within 1 hour of delivery to ensure accurate dosing with the Kleihauer-Betke test.  Does anyone else have a time frame and if so do you have a reference for where your time frame came from? 

 

I believe many eons ago the package insert for some of the fetal screen tests referenced the one hour time period but I do not have access to those to confirm.  I believe the rationale was/is that if the fetal cells are ABO incompatible with the mother, the fetal cells will be destroyed by the maternal antibodies so a falsely low value of the amount of fetal bleed may be obtained.  I know everyone here understands that ABO incompatible fetal cells actually provide some natural prophylaxis to the mother for the prevention of immunization to D so may be less of an issue if you're doing the test simply to determine RhIgG dosing.  The same rationale could apply for early removal of D-positive fetal cells from the maternal circulation due to the presence of any prophylactic/antenatal anti-D.  However if the test is being performed to determine the amount of fetal bleed as a diagnosis test for the treatment of the infant, one should be aware of these factors that may affect the result.     

Thank you for all of your input.  Our 1 hour rule is just something we've "always" done and predates me so I do not know the origin.  The current package insert for the K-B stain states, "maternal blood sample should be collected in a syringe with a sterile needle or by evacuated technique, as soon after delivery as possible."

 

The new maternity director at my hospital is questioning our policy for the 1 hr requirement, which is really the only reason I need to find some data or evidence for or against our policy.  I'll keep digging but if anyone else finds out more info in the meantime. . .keep me posted.

 

Thank you.

The Ortho fetalscreen kit states "The maternal blood should be collected as soon as possible after delivery."  Our policy states 1-3 hours after delivery and the order defaults to "Stat".

Yes we go by our package insert as well which states at least an hour after delivery but soon after, so we told nursing to draw them 1-3 hours after delivery.

If you wait until the following day the fetal cells could already be cleared out of the mom's circulation and you would get a false negative.

Edited July 2, 201411 yr by tbostock

The product insert for RhoGAM used to reference specimen collection 1 hour after delivery, but doesn't anymore.

 

The product insert for Immucor's Fetal Bleed Screening Test states that "it is best to wait about an hour after delivery to allow any fetal blood to mix thoroughly in the maternal circulation, but the sample should be collected as soon as possible thereafter". The reference for that is Judd WY, Luban NLC, et al. Prenatal and perinatal immunohematology: recommendations for serologic management of the fetus, newborn infant, and obstetric patient. Transfusion 1990; 30:175-183.

 

Our policy says to draw the patient 1 hour after delivery, if possible, or as soon as possible after that. We consider the order to be an urgent draw - testing is routine. Administration is within 72 hours or before patient dismissal, as everyone as stated.

This is from the British Committee for Standards in Haematology:

 

"Maternal samples for confirmatory ABO and Rh D type and FMH testing should be collected after sufficient time has elapsed

for any FMH to be dispersed in the maternal circulation. A period of 30–45min is considered adequate (Mollison et al.,

1997) and the samples should ideally be taken within 2h of delivery primarily to ensure that the sample is taken prior to

woman’s discharge from the hospital (RCOG, 2011)."

 

Ref: TRANSFUSION  MEDICINE, 2014, 24, 8 - 20