Alex, I am so sorry that this is happening to your family. You don't have much information, so I'll discuss with you what I know from my experience as an OR nurse. When removing cancerous tissue, the surgeon knows he must get as much of the cancerous tissue as possible. In order to improve her chance of beating the cancer, he may have removed much cancerous tissue. Ovaries are very vascular, and bleeding is highly likely. The blood vessels might have been already damaged by the cancer, with an increase in bleeding from the surgery. Also, bleeding might be increased due to medications and from the cancers affects on her body. Sometimes the clotting factor is inhibited due to certain cancers, and bleeding is expected. Ovarian cancer is a difficult cancer to beat, it is very aggressive and spreads quickly to other parts of the body. I hope this helps you, My heart goes out to you and your family.