Bleeding resulting from a standard gynecological exam typically does not make a woman niddah or invalidate her clean days. Even so, we recommend taking measures to prevent a halachic question from arising.
In this case, be sure to perform your morning bedikah of the seventh day before your doctor’s appointment. In order to head off questions, you may also switch to colored undergarments after that morning bedikah.
If the appointment is scheduled for the afternoon, you should perform your second bedikah before the appointment as well. If the appointment is scheduled for earlier in the day, you may in this case omit your second bedikah.
Please write back with any further questions.