Can someone show me where "it is written" that lab blood draws (any lab draws) must not be done during transfusions and how long of a wait period after the transfusion?

 

All 'it is written's should be the property of each individual facility, approved by your medical director or pathologist.

Here is one discussion regarding drawing blood specimens and transfusions: https://www.phlebotomy.com/pt-stat/stat0513.html

There are also old threads here in Pathlabtalk on this topic.

Scott

We will draw blood is the patient is receiving a transfusion. We put a comment on the results stating the patient was being transfused at the time of draw. We will draw a patient 15 minutes after transfusion. Here is the reference we used for our policy.

 

Elizalde, J.I., Clemente, J., Marin, J.L.,Panes, J., Aragon, B., Mas, A., Pique, J.M., Teres, J. "Early changes in hemoglobin and Hematocrit levels after packed red cell transfusion in patients with acute anemia." Transfusion Practice. Volume 37. (1997): 573.

This is something I found on the CAP website: (For some stupid reason I did not copy the URL.)

From the CAP website:

 

Optimum timing of post-transfusion phlebotomy is critical for ensuring meaningful laboratory testing results, and medical judgment is required in making this determination. Several factors must be considered, including the type and amount of blood product given, purpose of the test (that is, the question it is intended to answer), and clinical setting.

In general, it is best to perform phlebotomy when the patient’s circulatory system is in homeostasis. A patient who is bleeding or undergoing blood product transfusion, or both, is not in a steady state. Whenever possible, samples for laboratory testing should be postponed until bleeding has stopped and transfusion is complete. One obvious exception to this rule, however, would be the setting of massive transfusion, during which monitoring certain laboratory values, such as cell counts and coagulation parameters, is essential to guide ongoing therapy. Variables such as patient blood volume, cardiac output, renal function, and volume of blood products transfused affect how quickly homeostasis is achieved following transfusion.

For the evaluation of post-transfusion increments in hemoglobin, hematocrit, and platelet counts, a practical approach is to draw blood samples within 10 to 60 minutes after completing transfusion, as this time interval is aimed at measuring peak recovery.1 Results determined from blood samples drawn later than 60 minutes post-transfusion are increasingly affected by confounding conditions, such as splenic sequestration, sepsis, and consumption.^1,2 If the intent is to determine the extent of such confounding processes on red cell and platelet counts, one should combine a 10-minute post-transfusion sample with sequential samples drawn at one hour and 24 hours post-transfusion.

Alterations in chemistry test results following transfusion are not usually a concern in the low-volume transfusion setting. However, assay results may be affected for varying periods following transfusion of large amounts of blood products, as seen in massive transfusion, red cell, or plasma exchange—particularly if the recipient has impaired hepatic or renal function. Banked storage of red cells results in elevated plasma levels of hemoglobin, potassium, LDH, and iron in the blood unit that may, particularly in the metabolically impaired patient, be reflected in the post-transfusion laboratory values. In addition, citrate anticoagulant present in blood products may result in transient hypocalcemia in the recipient.³ Therefore, following large-volume transfusions or exchanges, waiting 12 to 24 hours before drawing samples for chemistry assays will provide results that are more reflective of the patient’s underlying metabolic state.