Removal of ovary

43 yr old, 3 children, 1 tubal pregnancy with removal of tube.  Have had constant right side ovarian/pelvic pain for 1 year now with constant tiredness. Periods have always been regular up until last month, had only 3 light days, very unusual for me.

Went to ER last Sept due to severe pain and had transvaginal ultrasound done however only saw small cyst on left ovary.  Had follow up with my gyn and watched for a couple of months.  Had laparoscopy done in Jan due to constant pain.  During lap found several adhesions and basically cleaned up the area, however the right ovary was difficult to see due to several adhesions.  Pain still persisted after surgery and watched and waited a couple of more months.  I am now scheduled for removal of right ovary next week via lap if dr can get to ovary, if not I will have abdominal surgery with possible hysterectomy, depending on what is seen during surgery.  My question is are all tumors seen during ultrasounds and/or laparoscopy or can there be internal turmors inside the ovary which can only be detected by removal or biopsy of ovary?