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Common unqualified blood samples

Commonly unqualified blood samples fall into the following categories:
1. Coagulation blood sample
2. Hemolyzed blood sample
3, blood cells attached to the wall

A. Coagulated blood sample: refers to the sample with different degrees of fibrin precipitation or blood clot after the blood sample is collected by the anticoagulant blood collection tube.
1. Overt coagulation specimens: Specimens with visible blood clots or fibrin clusters in the blood samples are called overt coagulation specimens
2. Substance coagulation specimens: Specimens with fibrin in whole blood samples are called subclinical coagulation specimens

Cause analysis and solution:
When using a syringe to collect blood, the amount of aliquots exceeds the nominal capacity of the blood collection tube, resulting in insufficient dose of anticoagulant.
——- When it is necessary to pack blood samples under special circumstances, the nominal capacity of the blood collection tube shall prevail.
The anticoagulation tube is not mixed or not mixed in time, the mixing method is wrong, etc.
——-Invert and mix for more than 8 times immediately after blood collection.
For patients with high blood viscosity, the size of the blood collection needle is too small and the blood collection speed is too slow.
——-Choose a suitable blood collection needle, or when the blood collection volume is large, use the butterfly wing type blood collection needle to shake while collecting.
Abnormal unplugging operation (the anticoagulant of the liquid agent is adsorbed on the rubber stopper, and the rubber stopper will bring out part of the pre-added anticoagulant after the stopper is abnormally opened, resulting in insufficient anticoagulant dose).
——- When it is necessary to unplug the blood collection tube, first gently shake the blood collection tube to make the anticoagulant adsorbed on the rubber stopper of the blood collection tube fall off. After the unplugging operation is completed, cover the rubber stopper and mix it upside down for more than 8 times.

B. Hemolyzed blood sample: refers to the blood sample in the process of collection, anticoagulation, storage, and transmission of red blood cells and white blood cells rupture, resulting in the release of blood cell components into plasma or serum.
1. Overt hemolytic specimens: Specimens with red blood serum due to red blood cell rupture and heme release are called overt hemolytic specimens.
2. Occult hemolytic specimens: Specimens with mild turbidity of serum due to the destruction of white blood cells and platelets are called occult hemolytic specimens.
Whether it is a dominant hemolytic specimen or a latent hemolytic specimen, the composition of the serum or plasma will be changed, thereby affecting the accuracy of the test results.

Reason:
The blood collection volume is insufficient, and the residual negative pressure in the blood collection tube causes the blood cells to be compressed and ruptured.
Specimens were collected according to the nominal capacity of the blood collection tube.
Solution:
When using insufficient samples, open the tube plug after blood collection and release the excess vacuum in the blood collection tube.

Reason:
When using a syringe to collect blood and transfer it to a vacuum blood collection tube, the needle of the syringe is not removed. Under a certain pressure, the blood cells are squeezed when they pass through the narrow needle tip, and the blood cells are deformed or ruptured.
Solution:
When it is necessary to collect blood with a syringe and dispense the blood samples into a vacuum blood collection tube, remove the needle, open the tube plug of the blood collection tube, and inject blood along the tube wall.

Reason: When the anticoagulant tube mixes the anticoagulant, the mixing method is wrong or the mixing range is too large, so that the impact force on the blood sample is too large and the blood cells are damaged.
Solution:
Gently invert and mix 8 more times.

Reason:
When using a dry powder blood collection tube, the mixing is not timely, and the heat of dissolution and reaction heat at the contact surface of the blood and the anticoagulant is too high, resulting in cell rupture.
Solution:
Invert and mix 8 times in time.

C. Blood cell attachment: Refers to the fact that after the blood sample is centrifuged, part of the fibrinogen is activated, and the formed fibrin gathers some blood cells in a network structure and adheres to the test tube wall.
Cause analysis and solution:
The centrifugal force is relatively too small and the centrifugation time is too short.
It is recommended to increase the centrifugal force (≥1100gn) and prolong the centrifugation time appropriately.