Final answer:
A 7 month pregnant woman with painless vaginal bleeding should receive an immediate abdominal ultrasound, which is the safest and most informative procedure in this scenario.
Step-by-step explanation:
A 7 month pregnant woman admitted with painless vaginal bleeding should be prepared for an immediate Abdominal ultrasound. This is because ultrasounds are the safest imaging studies during pregnancy and can be used to assess the presence of conditions like placenta previa or abruption, which can be causes of painless vaginal bleeding in the second or third trimester. A pelvic exam is generally avoided as it could potentially cause more harm if placenta previa is the cause. X-rays are not preferred due to the radiation risk to the fetus, and a non-stress test would not be the immediate diagnostic tool for vaginal bleeding.