In most situations, fibroids shrink after menopause. Sometimes they grow. Most of the time it is for a benign (not cancer) reason. Malignant changes in fibroids are rare, occuring in less than one percent of the cases. So that is good although it doesn't mean it can't happen.
Usually an ultrasound of the uterus can see the problem and make the diagnosis. If not, an MRI can be done. If it keeps growing after menopause, it should probably be evaluated by surgery. Ideally it would be removed.
It may be possible to remove the fibroid and not have a hysterectomy. Sometimes that can be done (once you are asleep with general anesthesia) by putting a telescope into the opening of the uterus from below and taking it out. If they cannot get through the cervix, it is necessary to make an incision in the abdomen and remove it through the top of the uterus. But if it keeps growing, most doctors would likely remove it.
If the doctors feel confident that it is a fibroid after the ultrasound or the MRI, they might consider a trial of medication to shrink the fibroid. A common choices is lupron. There are also radiology procedures where a catheter is threaded through a vein to a location near the fibroid and a substance injected to shrink the uterus. This might not be the best situation for doing such an approach, but it is hard to say for sure from your history provided.
Talk with your doctor about these options. Have him/her explain why one or the other is best for you based on your body, age and health. Then strongly consider having it treated. If your doctor doesn't explain these options or what they think is best, it might be helpful to get a second opinion.
Machelle M. Seibel, MD