Blood tests for anaemia and blood groupings

Antenatal screening test.

Anaemia: Anaemia is a lack fo red blood cells, which can lead to a lack of oxygen-carrying ability, causing unusual tiredness. Occurs due to a reduced production or an increased loss of red blood cells.

Blood groups: The blood group is determined by the genes you inherit from your parents and is divided into different types, known as blood groups. The 4 main blood groups are A, B, AB and O.

Rhesus factor: Each group can be either RhD positive or Rhd negative, which means that your blood group can be one of eight types.

The usual place for a sample to be taken from is the inside of the elbow or wrists, where veins are relatively close to the surface. The area is cleaned with an antiseptic wipe. 

A tight band (tourniquet) is usually put around your upper arm, squeezing the arm and tempoarily slowing down the flow of blood out of the arm; causing the vein to swell making it easier to take blood.

A needle attached to a syringe is pushed into the vein. 

When the sample has been taken, the needle will be removed and pressure is applied to stop the bleeding and bruising. The sample will be labelled and sent to the lab for analysis.

Anaemia - the results for anaemia would be:

• lower levels of haemoglobin than normal
• fewer red blood cells than normal
• red blood cells may be smaller and paler than usual.

During pregnancy, blood tests are used to ensure the mother has not developed anaemia and to have a record of her blood record of her blood group and rhesus factor in case blood transfusions are required.