What is the first action a nurse should take when admitting a child with Wilms' tumor?

Placing a "no abdominal palpation" sign over the bed is the appropriate first action when admitting a child with Wilms' tumor. This is crucial because Wilms' tumor is a type of kidney cancer most common in children, and it is often encapsulated within the kidney. Palpating the abdomen can increase the risk of rupturing the tumor, which could lead to spillage of tumor cells into the abdominal cavity, worsening the patient's prognosis and complicating the treatment.

Preventing any unnecessary abdominal manipulation is vital in safeguarding the child's condition and ensuring that the treatment plan can proceed without additional complications. While starting IV fluids, administering pain relief, and preparing for surgery are important actions in the overall care of the patient, the immediate priority upon admission is to protect the integrity of the tumor and avoid any risk of rupture.