A total of 390 634 whole blood and blood components units were prepared in 2007 in NBC. Of these, 8 968 (2.3%) units were discarded. There were many reasons for the discard, among them were deviations from established standards during collection such as suboptimal weight at the end of collection, or as a result of components processing which damaged the blood bags or caused red cells contamination of plasma and platelets concentrates.
Platelet concentrate scored the highest at 6% when compared with the other blood components. The discarded rates of whole blood and packed RBCs were 3.7% and 0.6%, respectively. The reasons behind the discard of whole blood can be attributed to procedures carried out during the collection process. A large-scale study conducted in 17 blood centers in 10 European countries from 2000 to 2002 reported that the mean platelet discard rates for the three years were between 6.7% and 25%. However, the annual mean discard rates from 2000 till 2004 remains at 13%. The discarded platelets included all the platelet units which were damaged during processing regardless of the preparation method as well as those that expired.[15
] In the same European centers, the mean for packed RBC discard rate was 4.5%, varying annually from 0.2% to 7.7%.[11
] The current study showed that the FFP and RBC discard rates were comparable with the Novis study in USA, which reported that the discard rates of FFP ranged from 2% to 2.5% and RBC ranged from 0.1% to 0.7% in 1639 hospitals.[16
Platelet and plasma components contaminated with RBC resulted from ineffective separation of platelet-rich plasma (PRP) or plasma from red cells during centrifugation or processing . This contamination is a known threat to product quality. In this study, 79% (3083) of discarded platelets and 16% (464) plasma were wasted due to this. In this study, all platelets concentrate components were prepared by PRP method. After centrifugation, there were critical steps that can cause red cells contamination of plasma and platelets. The centrifuged blood bags had to be carefully removed from the centrifuge bucket to prevent mixing the red cells with the plasma. Subsequently, these centrifuged blood bags should be carefully reposted onto the plasma extractor (or blood press) and allow gentle pressure to the centrifuged blood bag from the plasma extractor plate. The separation should be done slowly with close monitoring during the transfer of layers of blood components into the satellite bags. The separation is stopped when about 8 mm of plasma remains above the red cells.[18
] This technique is labor intensive. Human factor has strong effect on the quality and purity of the blood components preparation. Another source of contamination of the PRP is the tendency of the bags’ content to swirl during rotor deceleration in an effort to keep its angular momentum causing RBCs and WBCs to be mixed with plasma.[19
In the Components Section of the NBC, there were more than 30 centrifuges. The study could not exactly determine which centrifuge caused significant number of the RBCs contamination with blood components due to lack of records or data on these centrifuges. Although the centrifuge software was able to capture information like the operator's name, date and time, processed details of the centrifuge time, and speed parameters according to the donation identification number (barcode), it was not activated. This needs to be activated so that in the event of any quality problems, full traceability of the centrifugation data is available.[18
The leakage was the second cause of discarded blood and its components, which represented 26% of discarded blood. The frozen blood components that consist of 43% and 27% of discarded FFP and cryoprecipitate, respectively, were due to the leakage. Mishandling of blood bags during collection, processing, and storage or manufacturing errors may be the major causes of defects and leakages of blood bags.[20
] The integrity of plastic bags is essential and precautions should be taken to prevent leakages.[12
] The bag may be damaged during the centrifugation. This happens when the bag is forced to a sharp interior bottom/wall junction or corner, resulting in the bag material being stretched too far, causing a tear.[21
] The defect and leakage at any part of the plastic blood bags can be detected by visual inspection during the processing, after pressure in a plasma extractor, before freezing, and after thawing.[20
The FFP should be stored in cardboard or polystyrene protective containers that minimize the risk of breakage of brittle frozen product during storage, handling, and transportation.[1
] Another approach to decrease the leakage and contamination immediately before immersion of the frozen blood bags in the water bath is that the whole container should be placed in a sterile plastic bag.[12
Twenty five percent (2208) of discarded blood were wasted because of gross lipemic blood components. A particular unit of yellowish white milky gross lipemic aphaeresis platelet was traced to a donor who donated after eating a high-fatty meal of hamburger. The triglyceride level of that donor was elevated to 1303 mg/dl (normal range, 35-160 mg/dl) with a normal cholesterol level.[22
] The case raised an important question—should we advise donors to refrain from eating fatty foods before donation. This is an important issue for donor's health, selection, and recipient confidence. In the United Kingdom, such donations are not released for issue.[22
] Lipaemia itself does not affect the safety of a product but might interfere with the ability to perform viral marker tests.[23
] The doctors and nurses should make an attempt to identify or suspect donors who are at high risk for hyperlipemia prior to donation by asking the donors during the pre-donation interview if they had eaten a fatty meal prior to coming for blood donation. At the NBC, records of regular blood donors can be traced from the BBIS. If their blood components were discarded because of the lipemia, the donors should be investigated for lipid profile. These may assist in minimizing blood component discard due to hyperlipemia.
In overweight blood bags, the amount of anticoagulant is not enough to prevent the blood from clotting and the clotting process may be initiated. On the other hand, there is an excess of anticoagulant in underweight blood that could denature the blood during storage. Suboptimal weight of blood collected would be unsuitable for transfusion and the ratio between volume of blood collected and volume of anticoagulant in the blood bags should be corrected.[25
] In NBC, almost all suboptimal weight of blood units occurred at mobile sessions and not at the center. Small manual spring balances or scales for weighing were still being used in mobile sessions, while blood mixing machines were used in the center. The manual spring balances require the staff nurses to monitor the weight of the blood bags every 30 seconds during the whole blood donation process. Sometimes, the nurses were busy because they have more than the expected donors or the monitoring of the spring balance during blood donation was overlooked. These lead to too much blood going into the collected bags. These problems can be avoided by using the automated blood mixing machines. When sufficient blood has entered the bag, an audiovisual alarm is activated and the blood flow automatically stopped by clamping the tube to prevent further blood flow into the bag.[25
] Low volume of collected blood may be due to several reasons including the discontinuation of donation because of donor's reactions and the blood flow from small vein during phlebotomy and the duration of the donation exceeds 15 minutes. Another reason may be due to the spring balance was not calibrated, thus was unable to measure accurately the volume of blood in the bag. Selecting a good donor, training and monitoring the staffs will help to reduce cases of the underweight blood units.
The results of this study showed that there is no correlation between the number of daily blood collection and the number of discarded whole blood, packed RBC, and platelet. This gives rise to the possibility of a correlation between the number of daily blood collection and the numbers of the staff or due to the extended working hours of the experienced staff in Component Section at NBC. In 2007, there were eleven staffs positioned in the Component Section. The section implemented a policy when a large amount of blood was collected on a given day, the Section would request assistance from experienced staffs from other Section in NBC. Magnussen et al
. report that there was a difference in the quality control measurements of RBC and platelet, where the change involved replacement of a relatively large inexperienced occasional component manufacturing staffs to an experienced regular manufacturing staff.[26
] Some of quality control measurement was out of statistical control. For example, leukocyte count in RBCs and platelet concentration components and volume of the platelets produced by the occasional staff went out of control, but not with the experienced staff. Another study done in 17 Europeans centers noted that there was no association of proportion of discarded platelets with the platelet production.[17