Staging Evaluation

The following procedures are used to determine the extent of the cancer:

Procedures used for determining the stage of breast cancer are modified for pregnant women to avoid radiation exposure to the fetus. Nuclear scans cause fetal radiation exposure.[1] If such scans are essential for evaluation, hydration and Foley catheter drainage of the bladder can be used to prevent retention of radioactivity. Timing of the exposure to radiation relative to the gestational age of the fetus may be more critical than the actual dose of radiation delivered.[2] Radiation exposure during the first trimester (>0.1 Gy) may lead to congenital malformations, intellectual disability, and increased relative risk of carcinogenesis.

Chest x-rays with abdominal shielding are considered safe, but as with all radiological procedures, they are used only when essential for making treatment decisions.[1,3] A chest x-ray delivers 0.00008 Gy.[4]

For the diagnosis of bone metastases, a bone scan is preferable to a skeletal series because the bone scan delivers a smaller amount of radiation and is more sensitive. A bone scan delivers 0.001 Gy.[5]

Evaluation of the liver can be performed with ultrasound, and brain metastases can be diagnosed with an MRI scan. Data on MRI during pregnancy are not available, but gadolinium crosses the placenta and is associated with fetal abnormalities in rats.[5]