It appears your sister's cervix
or birth canal is bulky. This is because of a cyst called Nabothian cyst
. This cyst can come due to inflammation of cervix due to infection in most cases. This may prevent menstrual blood from coming out of the uterus which means she may be getting less volume of menses.
There is also another mass in the cervix which the Doctor believes could be a polyp. This needs to be investigated to rule out possibility of neoplasm
Kindly get her a PAP smear
done. Also get the polyp biopsied to find out it's nature. Usually Nabothian cysts disappear by themselves but sometimes may require cauterization
to get them removed.
Kindly consult her Gynecologist on all these aspects.
Wishing good health.