What are some reasons that the doctor might tell me to have a splenectomy?

Cause/symptoms: It depends on why it is enlarged and if it is causing symptoms. The mere presence of an enlarged spleen does not necessarily mean an operation is required. A discussion on the pros and cons with your surgeon is advised.

Tumors or bleeding : Most of the times spleens are removed its for large tumors or bleeding issues from low platelets or direct trauma and bleeding from the spleen itself.