Is the order of the blood collection tubes important?
The order of the blood collection tubes is very important, as the wrong order can falsify certain values. The tubes should be collected in the following order: brown, green, red. For the other tubes the order is not important.
The brown tube should be removed first, as prolonged congestion of the veins during collection may increase the potassium value and thus falsify the sample. The green tube should be taken second, as special care should be taken to ensure that it is full up to the calibration mark. This is important because the ratio of blood and additive in the tube is the same for determining the coagulation values.
At the beginning of the blood collection there is always a minimum amount of air in the tube of the collection system and this can cause the green tube not to be full. The green tube should be mixed well after collection. This also applies to the violet tube.
Sources of error during blood collection
Some errors can quickly creep in when taking blood samples. It can happen that blood is taken from the wrong patient or that the samples of patients are mixed up. In order to avoid this, it should be checked before each collection that the information on the tube matches the patient’s name and date of birth.
A second source of error can be incorrect or insufficient disinfection of the puncture site. The sample may be contaminated by skin germs. In addition, the blood sample may be falsified due to the arm being tied too long when taking blood samples.
In particular, potassium increases. Especially with the green tube, an insufficient filling of the tube can lead to falsified coagulation values. This sample should therefore not be the first tube to be taken. A last possible source of error during blood collection is the lack of mixing of the sample. This can lead to unwanted clotting of the blood and the sample can no longer be used.
Taking blood samples from the police – are they allowed to do that?
Blood samples can be taken by the police if there is a suspicion of driving or to determine the blood alcohol at the time of the crime. However, some conditions must be observed. Blood samples may only be taken by a doctor.
The person concerned must not suffer any health disadvantages as a result and must consent to the examination. In the absence of consent, the order of a judge is required. If investigations could be unsuccessful due to waiting for the order, the public prosecutor’s office or, from a certain rank, the investigating police officer can also order the blood withdrawal in exceptional cases. In this case, the blood sample can also be taken against the will of the person concerned.
