The "Visual Window" of Blood Bags: How to Observe the State of Blood through the Transparent Area

The "visual window" of the blood bag, that is, the transparent area on the blood bag, is mainly designed to enable medical staff to directly observe the state of the blood without opening the blood bag, ensuring the quality and safety of the blood and thus guaranteeing the safety of blood transfusion for patients.

1. Specific points for observing the state of blood through transparent areas

1. Observe the color of blood

Normal situation: The color of normal blood varies depending on the oxygen content. Arterial blood has a high oxygen content and is bright red; venous blood has a low oxygen content and is dark red. In the blood bag, whole blood after anticoagulation usually presents a uniform dark red color. This is because red blood cells account for a large proportion of the blood and are in a relatively static state with a low oxygen content.

Abnormal situation and analysis
Too light color: If the blood color is obviously lighter, it may indicate a decrease in the number of red blood cells in the blood, such as hemolysis. During hemolysis, red blood cells rupture and hemoglobin is released into the plasma, which will make the blood color lighter, and the plasma may appear light red or pink. This situation may be caused by mechanical damage during blood collection, storage or transportation, excessively high or low temperatures, bacterial contamination and other factors.
Too dark color or black: If the blood color is too dark or black, it may be due to the presence of methemoglobin or other abnormal substances in the blood. In methemoglobinemia, the methemoglobin content in the blood increases, which makes the blood darker. In addition, long-term storage of blood or the influence of certain chemicals may also cause abnormal color.

2. Observe the stratification of blood

Normal situation: In the blood bag, stratification will occur after a certain period of standing. The upper layer is pale yellow plasma, which mainly contains water, protein, electrolytes, nutrients, etc.; the lower layer is dark red red blood cells, and there may be a thin layer of white blood cells and platelets in the middle, which is called the white blood cell and platelet buffer layer. This stratification phenomenon is a normal physical property of blood, indicating that the composition of blood is relatively stable.

Abnormal situation and analysis
No obvious stratification or no stratification: If the blood stratification is not obvious or no stratification, it may be because the blood is subjected to severe shock during collection or storage, resulting in the rupture of red blood cells and the mixing of plasma and red blood cells. This situation will affect the quality of blood and the effect of transfusion, because the broken red blood cells will release substances in the cells, which may cause transfusion reactions.
Abnormal stratification, such as the appearance of flocs or precipitation: The appearance of flocs or precipitation may be due to the presence of fibrinogen precipitation, bacterial contamination or immune complex formation in the blood. Fibrinogen plays an important role in the blood coagulation process. When the blood is affected by certain factors, fibrinogen may precipitate to form flocs. Bacterial contamination can cause blood deterioration, precipitation and odor. Immune complex formation may be related to transfusion-related immune reactions.

3. Observe whether the blood has clots

Normal situation: In a qualified anticoagulant blood bag, the blood should remain in a uniform liquid state without clot formation. This is because the anticoagulant can prevent blood coagulation and maintain blood fluidity.

Abnormal situation and analysis: If clots are found in the blood, it means that the anticoagulant may fail, or there is improper operation during blood collection, such as incorrect ratio of anticoagulant to blood, too fast collection speed leading to local coagulation of blood, etc. Infusion of blood containing clots may cause blood vessel blockage, cause serious transfusion reactions, and even endanger the patient's life.