The human body consists of numerous systems that work simultaneously. This system is made to work by cells and organs. This ensures that humans are able to live and survive in the many environments or conditions affecting a human’s life. One of the systems known as the blood circulation system provides oxygen and nutrients on cellular level in the body. It also eliminates waste products from the body. The blood systems do not only involve the 10 000 kilometres long of blood vessels but certainly the heart that can be considered as the engine. In this DoctorOnCall’s article, we will be learning about Coombs test that is associated with evaluating the blood system.
To understand what Coomb test does, you may want to know a bit more on antibodies first. Antibodies are part of the immune system. Antibodies are produced when the body encounters infection. This helps the immune system to protect the human body from diseases. However, in some cases, the immune system may go haywire and act abnormally to the extent of attacking the body’s healthy cells. Thus, Coombs test is a test used to detect such antibodies, specifically the one that attacks red blood cells.
Coombs tests are also known as antiglobulin tests or red blood cell antibody screening. The coombs test detect antibodies that act against the surface of the red blood cells. Presence of these antibodies indicates a condition known as hemolytic anaemia where the blood is destroyed prematurely and causes the body to not have enough red blood cells.
Haemolytic anaemia is a class of anaemia caused by the destruction of the red blood cells and a decrease in haemoglobin level. The World Health Organization (WHO) criteria for anaemia in men is less than 13 g/dL whereas it is less than 12 g/dL for women. It is worth noting that there are revised criteria for anaemia in both men and women with ages, race and lifestyle or medical conditions. There are a number of causes leading to haemolytic anaemia including autoimmune, certain drug or medications, hemoglobinopathies such as sickle cell disease and thalassemia, blood transfusion reactions and infection such as malaria and babesiosis. Symptoms of haemolytic anaemia include fatigue, dizziness and enlargement of spleen or liver.
There are 2 types of Coombs test which are direct and indirect tests. Direct Coombs test identifies the presence of antibodies attached directly to the red blood cells whereas indirect Coombs test detects the unbound antibodies to red blood cells or in other words the antibodies is present in the patient’s serum (the liquid part of blood) instead. The choices of the test used will depend on what needs to be found out by doctors. For example, direct Coombs test is often used to detect the possibility of haemolytic anaemia after receiving blood transfusion and indirect Coomb test is often used in every pregnant woman to check for antibodies against Rh-positive blood.
Thus, if you have a positive Coombs test, does that mean anything serious? This will always depend on the aim of the test itself. In general, a positive Coomb test often means there is presence of anaemia. Autoimmune hemolytic anaemia is traditionally the most recognized cause for positive antiglobulin testing. A positive result of Coombs test can be serious as it indicates the birthing parent’s blood type is incompatible with the baby’s blood types. If these blood mixes during pregnancy or birth, it can cause serious complications for the birthing parents, baby or both. A positive Coombs prior to a transfusion means the blood types are incompatible. This means that serious complications can occur to those receiving the blood. Hence, Coombs test ensures that both donor and recipient blood types match.
Coombs’ test is a relatively simple procedure. Patient does not need to have special preparations but may be advised by doctors to stop taking certain medications before the test is performed. Once the blood is collected, the patient may feel slight pain due to the blood withdrawal process but it is often only for a short time. Applying bandage to the site where the needle has been removed can help to stop the bleeding faster. Patients are advised to avoid using the arm for heavy lifting for the day.
It can be concluded that Coombs test is a test that detects the presence of antibodies against the red blood cells. An indirect Coombs test can help identify potential complications in pregnancies and transfusions. A direct Coombs test can help confirm that antibodies are responsible for damaging red blood cells. Coomb tests may not provide complete information needed. Doctors usually need to order other tests to help confirm a diagnosis. Positive Coombs test does not necessarily mean serious as it will always depend on what the doctor looks for and the patient’s condition. Do have further discussion with your doctor if you are concerned with your Coombs test result.