Treatments & Therapies

Bedside Test – Treatment, Effect & Risks


The bedside test is a blood group determination directly at the patient’s bedside without sample material being sent to a laboratory.

The procedure is mandatory for every doctor before a blood transfusion to prevent any mix-ups of blood supplies. The test serves to directly compare the blood group of the potential recipient with the condition of the canned product intended for use, which has already been classified and labeled accordingly in the laboratory.

What is the bedside test?

The principle of the bedside test was invented by the American doctor and hematologist Reuben Ottenberg (1882-1959), who introduced special blood compatibility tests into practice in 1907.

The test, which is still common today, is carried out on a small card that has two or three test fields with anti-A, anti-B and, if necessary, anti-D serum. A drop of blood is placed on each field and distributed with a special plastic stick. Thus, the blood group in the so-called ABO system and the Rhesus factor can be reliably tested. For example, blood type A with Rhesus factor positive will agglutinate (clump together) on the anti-A and anti-D fields, while remaining unchanged on the anti-B.

On the anti-B field, drops of blood from groups B and AB clump together, while blood from groups A and 0 does not change. So that there are no erroneous determinations, each individual serum is assigned to the colors usually used in the laboratory. The test field with anti-A serum is always colored blue, that with anti-B serum yellow. The test result is documented in the patient card over the long term, and the test card with the dried drops of blood is destroyed after a few days for hygienic reasons. The procedure is also called the ABO identity test after the relevant blood groups.

Function, effect & goals

Agglutination is the result of the mixing of two or more blood types that do not match. The human body rejects what it doesn’t know, so foreign blood of a different blood group than the body’s own blood type clumps together.

This intolerance results from the different protein substances that are found in each blood group. The proteins are denoted by A and B as well as the Rhesus factor. Blood group A Rhesus positive (A+) means that protein A occurs in the blood and positive evidence for the Rhesus factor is given. Rhesus negative means that this protein is not present in the specific blood group. Anyone who belongs to blood group AB Rh-positive therefore has all three proteins. In contrast, all known protein groups in the blood are missing in group 0 Rhesus negative.

Therefore, this blood group can be used universally as donor blood for emergencies. However, all other blood types must match when transferring blood from a donor to a recipient. The bedside test can be used to determine immediately before a transfusion whether this match actually exists. In order to rule out all risks as far as possible, both the recipient blood and the donor blood are usually examined using the bedside test.

Risks, side effects & dangers

All possible types of transfusion blood have to undergo the test, including and especially the frequently used erythrocyte and granulocyte concentrates .

The bedside test is also mandatory in an emergency if the patient’s life is in danger. The patient’s blood must always be taken directly on site. Recourse to the patient’s stored blood samples of any kind is categorically excluded. Even in the case of a transfusion of autologous blood, the patient’s and canned blood must always be freshly subjected to the bedside test. Immediately after the test has been carried out, the blood data collected from the recipient and the donor must be compared in detail. In the event of the slightest deviation, the forthcoming transfusion process must definitely be avoided.

If several transfusions are carried out in succession, the bedside test must be carried out again for each individual transfusion. This also applies to any change in the medical and medical staff involved. In addition, the bedside test must always be carried out personally by the transfusing doctor. The doctor may not delegate its implementation to any other person. If he wants to teach the test to an inexperienced colleague, the transfusion physician must exercise direct supervision.

Greatest possible caution and vigilance in connection with blood transfusions are necessary because there are extremely diverse possibilities of confusion and in the past this has repeatedly become a reality that no transfusing doctor can overlook. The mix-ups can arise when blood is taken and extend to mixed-up canned goods on a ward or in the operating room. In all of these cases, there can be serious consequences for recipients of blood products, which are often life-threatening. For these reasons, the various conventional methods of bedside testing are constantly under scrutiny.

Imponderables are primarily associated with the sticks with which the drops of blood are placed on the test fields of the small cards with the serum samples. Therefore, in a newly developed procedure, the blood is applied to the respective antiserum through an elastic cover film with the aid of a syringe with a cannula. Because the film encloses the needle tightly, it is guaranteed that neither blood nor serum can be carried over or get into other test fields. In addition, the small opening in the foil is closed again immediately after the puncture. After shaking, the reaction of the blood with the serum can be perceived immediately. This modern form of the bedside test only takes a maximum of ten seconds. This short period of time can be of inestimable value for the patient in emergency situations.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.