A blood banker reported that her hospital transfusion service has recently received shipment of several hemolyzed units of leukoreduced RBCs. In order to determine the magnitude of the problem the hospital staff centrifuged segments from leukocyte-reduced RBC units; 20% of the centrifuged segments showed hemolysis upon receipt. In comparison, the inquiring blood banker states that according to records for October and November 2001 (a time during which hemolyzed leukocyte-reduced RBCs were received), 19 NON-leukocyte reduced RBCs had segments analyzed for hemolysis; none were hemolyzed. The inquiring blood banker reports that the blood supplier prepares leukocyte-reduced RBCs by using in-line filters or by using filters that are added via a sterile connection.  She was interested to know if one of the above methods favored hemolysis, but was told that the hospital transfusion service could not determine which method was used to prepare any specific leukocyte-reduced RBC unit. The hemolysis was seen in segments of RBC units that ranged in age from 4 to 30 days from date of draw; there was no obvious correlation between age of the RBCs and degree of hemolysis. None of the RBCs had been irradiated or further modified. RBC units showing hemolyzed segments were returned to the blood supplier for analysis; the supplier reported that less than one third of the returned RBC units showed hemolysis in the primary container. However, the supplier did confirm that several of the returned units had free hemoglobins with levels of 400 mg/dL or more. The inquiring blood banker is interested to learn if other transfusion services have experienced hemolyzed leukocyte-reduced RBCs. She wants to know if there is an acceptable upper limit for hemolysis of a leukoreduced RBC, and if there is a relationship between hemolysis in a product's segments and hemolysis in the actual product.

The following comments were submitted.

1. A blood banker from Barcelona wrote that one possible explanation for finding excessive hemolysis in a blood product segment without similar hemolysis in the blood product container might be caused by the sealer used for sealing the segments. In the responding blood banker's experience, sometimes a sealer used to divide the segments has a problem with its radio frequency, and this might cause an excess of hemolysis in the segment; the product in the primary container would appear to be OK. This phenomenon might explain a lack of relationship between hemolysis present in segments but not in product containers. (Editor's note: In the scenario described by the inquiring blood banker, hemolysis was reported to be found in the segments AND in the products, so additional mechanisms for the hemolysis might be at play, at least for the product/segment pairs that showed hemolysis.)

2. A blood banker from the United Kingdom wrote that in the UK, 100% of red cells (as well as platelets and FFP) are leukocyte-reduced. In-line filters are used for filtering blood donations destined to be used as red cell units and FFP. Units destined for platelet production have a filter attached using a sterile connecting device, once the buffy coat has been separated. According to the responding blood banker, hemolysis has not been reported to be a problem either with the contents of the bleed line or the red cells in the product container.

3. A blood banker from the Northwestern United States wonders if finding significant hemolysis in a shipped red cell unit would be an indication for filing a biological product deviation report with the FDA.

ADDENDA Dec. 12, 2001

3a. As a follow up to reply #3 the same responding blood banker added that there is a deviation code for hemolyzed segments:

** Unsuitable product, QC-95-03 = Unit or segment hemolyzed

4. A California blood center medical director reported that an abstract from the 2001 ASH Meeting suggests that pre-storage leukocyte reduction does not cause increased hemolysis or enhanced red cell fragility. See Blood, November 16, 2001; 98(11): 543a (abstract #2271). In their study, the authors conclude "Filtered red cells, especially those filtered in the cold, were less hemolysed during storage than their non-filtered counterparts and filtration was beneficial when implemented before 14 days of storage." (Editor's note: Based on this reply, one has to wonder why inquiring blood banker's institution has been shipped so many units that show hemolysis both of segments and actual product. Could it be due to a manufacturing step being out of control, and if so, which one?  Could it be due to the way the products are being shipped after they leave the collection center? Other possibilities may also exist.)

5. A blood center has written to the e-Network Forum that it has had reports of hemolysis in units of leukocyte-reduced units in the past few months. Unfortunately, based on what they have written to the e-network forum, they appear in need of as much help in figuring this out as the inquiring blood banker's transfusion service. Here is what they say: "Our thoughts are that they are related to filtering units that are older than a few days (allowable with one type of filter), as our inventory has been larger since 9/11 and we have older units on the shelf, but cannot confirm this theory. We are wondering how to evaluate the acceptability of such units. The filter manufacturers have not been helpful. Is there an acceptable level of free hemoglobin in a unit? Are these units with a small amount of hemolysis OK to use? Can this be prevented?"

ADDENDA Dec. 18, 2001

6. A Canadian blood banker wrote that Canada has employed universal pre-storage leukoreduction since 1998. She reported that the Canadian Blood Services (CBS) initially had concerns about the effect of leukoreduction on red cell concentrates, because of reports that there was hemolysis in leukoreduced units or in the segments. Consequently, the Research & Development arm of CBS did experiments to determine the effect of leukoreduction filtration on the generation of hemolysis. Data were recently presented in poster form (abstract #2271) at the 2001 ASH meeting (which is the same reference as that mentioned in reply #4 above). A summary of this study entitled "Pre-storage leukoreduction and low temperature production reduce hemolysis of stored red cell concentrates" is provided by one of the study authors and is presented below, however the e-network is referred to the abstract for complete details. The authors of the study (Maria I.C. Gyongyossy-Issa, Sandra Weiss, Petra Welsh, Samuel O. Sowemimo-Coker, Randy B. Garcez, Richard L. Emery, Dennis A. Gastineau, Karen L. Johnson, and Dana V. Devine) used pool-split/filter, non-filter experimental set-ups and Pall in-line leukoreduction filters. They found that whole blood filtration reduced the amount of hemolysis seen both in the blood units and in the segments, and reduced the osmotic fragility of the red cells. This was true immediately after filtration as well as at time points during and at the end of a 42-day storage period. Furthermore, it was found that pre-storage leukocyte reduction of cold units reduced the amount of hemolysis and osmotic fragility when compared to units filtered at room temperature: the differences were statistically significant. In the authors' opinion, the study data showed that filtration is NOT responsible for unit or segment hemolysis, because leukocyte reduction filtration improves the blood product. What is not yet known, however, is the actual cause of the hemolysis when it is observed. It has been noticed that clear additive solution makes units look more hemolysed, especially if they are sitting next to non-leukoreduced units. Finally, according to the responding blood banker, in-line filter sets have a "transfer leg closure" that is now being examined to determine whether it contributes to increasing the shear.

ADDENDA Dec. 29, 2001

7. A California blood banker suspects that mechanical hemolysis might be causing the problems described by the inquiring blood banker. She reports that hemolysis can occur if those filtering the blood try to 'help the red cells through the reduction filters' when the blood has stopped flowing by rolling the primary bag and squeezing the blood through the filter. This could cause hemolysis to appear only in the segments (if only that amount was squeezed through the filter and segments made prior to that portion entering the final bag) or in the entire unit (if most of the blood was squeezed through the filter)

ADDENDA Jan. 2, 2002

8. A blood banker in Maryland wanted to know if the inquiring blood banker had considered sickle cell trait as a possible cause of the hemolysis. In response to this question, the inquiring blood banker has looked back at all the testing data provided by their blood provider; it appears their supplier performs hemoglobin S testing whenever it is verified that a returned RBC unit has a plasma hemoglobin of 400 mg/dL or more. According to the inquiring blood banker, none of 18 RBC units with plasma hemoglobin of 400 mg/dL or more contained hemoglobin S. The inquiring blood banker adds that during the month of December, 16 leukoreduced red cell components were returned to the supplier because of hemolysis. This is a substantially lower number than what was being returned during October and November.

Please submit comments to the e-Network Forum.

Ira A. Shulman, MD
CBBS e-Network Forum Editor & Moderator