Red blood cells

Red blood cells: Particulate matter

abby.wolfe — Tue, 09 Jan 2024 14:09:03 +0000

Red blood cells: Particulate matter

Particulate matter can be the result of blood collection and/or component manufacturing processes. Composed of platelets, white blood cells, RBCs, and/or fibrin, particulate matter may increase during storage of an RBC unit.

There are several categories of particulate matter that may be found within RBC units:

Clots and fibrin strands
- Clots and fibrin strands result from the activation of the clotting processes and can be a mixture of clotting proteins (including fibrin) and platelets. Blood is collected and processed in bags that contain anticoagulants to inhibit the clotting processes. RBC units containing clots and/or fibrin strands should NOT be transfused and should be reported to Canadian Blood Services using the feedback form on blood.ca.
- Clots may appear as small to large dark red or purple masses that do not dissipate with gentle manipulation.
Cellular aggregates
- Cellular aggregates may appear as white and opaque masses that do not dissipate with gentle manipulation. RBC units containing cellular aggregates should NOT be transfused and should be reported to Canadian Blood Services using the feedback form on blood.ca.
White particulate matter (WPM)
- WPM is a non-cellular material and is a normal constituent of blood. The presence of WPM does not render a blood component unacceptable for transfusion.
- WPM is a lipid-rich material that appears white in colour and variable in shape, from flattened specks to a greasy film. Generally, there are low numbers of WPM per RBC unit.
Cold agglutinins
- Cold agglutinins form large RBC masses that do not dissipate with gentle manipulation to smaller RBC aggregates. Blood components containing cold agglutinin masses should NOT be transfused and should be reported to Canadian Blood Services.

Red blood cells: Lipemia

abby.wolfe — Fri, 05 Jan 2024 19:58:01 +0000

Red blood cells: Lipemia

Lipemia is the presence of excessive amounts of lipid particles in the blood. Lipemia is not objectively measured. Because lipemic blood samples may interfere with donor testing for infectious diseases, its presence is subjectively identified although not measured. When the presence of lipemia interferes with testing, these units are discarded and are not distributed.

Lipemia in an RBC unit results from donor factors:

Fatty meals before blood donation
Chronic conditions such as hypercholesterolemia

Visual appearance

Lipemia may result in a lighter shade of red, cloudiness and decreased lucency of the unit.
The appearance of a lipemic RBC unit has been compared to a strawberry milkshake.
Lipemia may result in a milky white appearance.

Red blood cells: Hemolysis

abby.wolfe — Fri, 05 Jan 2024 19:36:59 +0000

Red blood cells: Hemolysis

Hemolysis is the breakdown of RBCs and the subsequent release of intracellular contents into the supernatant. The release of hemoglobin, pigmented protein in RBCs, has an important influence on the appearance of RBC units and segments. Hemolysis of stored RBCs is a normal process and increases with storage times. Some degree of hemolysis is acceptable and expected.

The CSA Standards define unacceptable hemolysis as ≥ 0.8% of red cell mass in 90% of units tested at expiry. However, visual assessment of supernatant colour is the only non-destructive means to estimate hemolysis in a red cell unit. Assessing the supernatant colour is very subjective and it is difficult to define a “cut-off” colour for determining a unit’s acceptability. Supernatant colour estimates supernatant hemoglobin concentration; however, a unit’s percent hemolysis value is also influenced by factors other than supernatant hemoglobin concentration such as hematocrit and total hemoglobin. For example, an increase in hematocrit and/or total hemoglobin will result in a lower percent hemolysis when the supernatant hemoglobin is held constant. The supernatant hemoglobin concentration is therefore only one of the factors that should be considered when determining the percent hemolysis of an RBC unit.

Figure 1. Formula for estimating percent hemolysis of an RBC unit.

The presence of RBCs in the supernatant may be mistaken for hemolysis. If hemolysis is suspected, it may be worthwhile to allow the unit to settle for 24 hours or more to minimize RBC contamination of the supernatant prior to inspection for hemolysis.

There are many causes of hemolysis; some relate to the manufacturing process and subsequent handling of RBC units:

Temperature extremes
Product processing
Bacterial contamination
Mishandling
Incompatible solutions

Visual appearance

The loss of intact RBCs may result in a lower hematocrit and a brighter red colour.
Hemolysis caused by bacterial contamination may result in a dark purple to black discolouration (see section on bacterial contamination).
Free hemoglobin within the supernatant of RBCs will cause a discolouration that will vary from a light pink tinge to a dark red almost purple colour, depending on the extent of hemolysis (i.e., a higher degree of hemolysis will result in a darker discolouration).
Note that segments do not accurately reflect hemolysis in the unit and should not be used to assess for hemolysis.

Red blood cells: Bacterial contamination

abby.wolfe — Fri, 17 May 2024 15:02:27 +0000

Red blood cells: Bacterial contamination

Bacterial contamination is the presence of bacteria in the blood. Blood should be free of bacteria. Blood donations are collected and processed under sterile conditions to maintain this aseptic state. Bacterially contaminated RBC units should NOT be transfused and any components suspected of bacterial contamination based on a visual inspection must be reported to Canadian Blood Services using the feedback form on blood.ca. Contact the nearest distribution centre to report potential contamination and receive further instructions.

Bacterial contamination may be related to the donor or subsequent manufacturing processes.

Donor with asymptomatic bacteremia (i.e., bacteria in blood)
Inadequate cleansing of skin prior to venipuncture. To minimize bacterial contamination, Canadian Blood Services uses a diversion pouch for the first portion of the blood donation. This captures the skin plug and skin bacteria and prevents them from entering the main unit.
Loss of sterility during component manufacturing or handling.

Visual appearance

Growing bacteria within an RBC unit may consume the oxygen and cause a dark purple to black discolouration.
The presence of bacteria may produce gas resulting in excessive air bubbles.
The presence of bacteria may activate clotting, resulting in clots and fibrin strands.
Cloudiness
Because bacterial contamination can cause hemolysis, a pink to red discolouration may be seen in the supernatant.

Red blood cells

Red blood cells: Particulate matter

Red blood cells: Particulate matter

Typical RBC unit

RBC unit with cellular aggregates

RBC unit with white particulate matter

RBC units with clots

RBC unit with cold agglutinins

Red blood cells: Lipemia

Red blood cells: Lipemia

Visual appearance

Typical patient sample after centrifugation

Patient sample with gross lipemia after centrifugation

Red blood cells: Hemolysis

Red blood cells: Hemolysis

Visual appearance

Typical RBC unit

RBC units with hemolysis

Typical patient sample after centrifugation

Patient sample (L) with hemolysis after centrifugation

Red blood cells: Bacterial contamination

Red blood cells: Bacterial contamination

Visual appearance

Typical RBC unit

RBC units with bacterial contamination

RBC units with bacterial contamination

RBC units with clots