A sentinel lymph node biopsy uses a small amount of radioactive material (radioisotope) which does not affect the pregnancy. However, the blue dye that is used alongside the radioisotope to identify the sentinel node is generally not recommended during pregnancy. Your surgeon will discuss whether sentinel node biopsy is a suitable option for you.
Whichever type of surgery you have, it will involve having a general anaesthetic. This is generally considered safe during pregnancy, but there may be a slightly increased risk of miscarriage, especially early on in the pregnancy.
Certain combinations of chemotherapy can be given during pregnancy. However, it should be avoided during the first trimester as it may cause harm to the unborn baby or cause miscarriage. Generally, chemotherapy during the second and third trimesters is safe.