From The BBC:

Patient bleeds dark green blood

A team of Canadian surgeons got a shock when the patient they were operating on began shedding dark greenish-black blood, the Lancet reports.

The man emulated Star Trek’s Mr Spock - the Enterprise’s science officer who supposedly had green Vulcan blood.

In this case, the unusual colour of the 42-year-old’s blood was down to the migraine medication he was taking.

The man’s leg surgery went ahead successfully and his blood returned to normal once he eased off the drug.

(more here)