How do they decide whether to sample lymph nodes during a hysterectomy for uterine cancer?

They usually just do: Most surgeries where the uterus is removed for uterine cancers will have some lymph node sampling. This sampling is not usually done when the pre-operative diagnosis is a pre-cancerous condition, even though cancer may be found on the final pathology evaluation. Surgeries to place radioactive implants to treat cancer do not involve lymph node sampling.

Depth of cancer: A pathologist is asked to examine the uterus during surgery to assess how deep the cancer invades in to the uterus. If the invasion is more than half the uterine thickness or if the tumor is very high grade, lymph nodes are sampled from the pelvis.