Your child's doctor will ask about signs and symptoms, other medical problems and the mother's pregnancy. He or she will ask if there's a family history of cancer or congenital defects, particularly those of the genitals and urinary system.

Your child's doctor will perform a physical examination and order laboratory tests of blood and urine. Imaging tests are essential to help locate the tumor. They include:

• Ultrasound. This noninvasive technique uses sound waves to create images of organs.

• Computerized tomography (CT). This imaging method uses X-rays to produce detailed, cross-sectional images of the body.

• Magnetic resonance imaging (MRI). This approach uses a magnetic field and radio waves to create cross-sectional images of the body.

In addition, your child's doctor may order a chest X-ray, chest CT scan, chest MRI and bone scan to determine whether the cancer has spread beyond the kidneys.

With this information, your child's doctors can assess the extent (stage) of the cancer. Staging helps guide treatment decisions. The various stages of Wilms' tumor are:

• Stage I. The cancer is found only in the kidney.

• Stage II. The cancer has spread to the tissues and structures near the kidney, such as fat or blood vessels, but it can be completely removed by surgery.

• Stage III. The cancer has spread beyond the kidney area to nearby lymph nodes or other structures within the abdomen, and it can't be completely removed by surgery.

• Stage IV. The cancer has spread to distant structures such as the lungs, liver or brain.

• Stage V. Cancer cells are in both kidneys.