This seems to be malingering but any organic cause should be excluded first. Doctor too might have said it to scare the patient and be extrovert enough to tell his problem. Since you are his friend,You must try to take him in confidence and try to find out any underlying cause of unhppinessor sorrow ,so as to make him so violent that he cut his vein even . Be a good friend  and try. All the best.

Hello This may happen but possibility is rare Having said that kindly share his case file and details of surgery so that i may guide you better