In order to begin the Borderlands 2 Do No Harm mission, we need to go to talk to Dr. Zed (another returning character from the first Borderlands game) in his shop located in the west side of Sanctuary.
Speaking with him reveals the fact that he needs somebody to help him with a surgery.
Dr. Zeds patient needs surgery badly. Dr. Zed asked you to help him with the procedure.
Experience: 483 XP
Helping Dr. Zed with his surgery means that we need to perform a melee attack on the patient we see on the table, an attack which will obviously kill him.
The victim will drop an Eridium Shard, but its unrefined, so Zed instructs us to go and speak with Patricia Tannis (located in Crimson Riders HQ). He also tells us that he has other jobs for us.
Speaking with Tannis will complete the current mission, and will also unlock the Medical Mystery optional mission which can be acquired from Dr. Zed.
After we finish the Borderlands 2 Do No Harm mission, we attend other quests in Sanctuary and try to complete as many as we can.