Clinical trials have shown that sentinel node biopsy is associated with a lower risk of arm problems than axillary dissection. This means that the risk of numbness, shoulder stiffness and lymphoedema is lower than with axillary dissection.

There’s a small risk of allergic reaction to the radioactive fluid or blue dye used to find the sentinel node. Allergic reactions are usually mild and easily treatable.

Rarely, women may experience a severe allergic reaction (less than 1 in 5000 cases). A doctor may decide not to use the blue dye for sentinel node biopsy if there’s reason to think a woman may be at significant risk of allergy to the blue dye.

If blue dye is used to find the sentinel node, the urine may turn blue for 24 hours after surgery. The skin of the breast may also become blue but this will fade with time.

There will be some pain associated with sentinel node biopsy, and injection of the radioactive isotope sometimes stings.