Recently, Surgeons operating on a man were shocked to find he had green blood.

Yes this is not Dr. Spock the Vulcan in the famous TV series Star Trek but a real medical case.

This 42-year-old Canadian patient began oozing dark green blood out of the catheter, while the doctors were operating him in a Vancouver hospital.
Dr. Stephan Schwarz and Dr. Alana Flexman presented their unusual case in a recent edition of The Lancet.

Occasionally this kind of discolouration occurs and is caused by sulfhaemoglobin, which forms when a sulphur atom is incorporated into the haemoglobin molecule, and can be caused by medications, including sulfonamides.

The authors say: "It is possible that our patient's arguably excessive intake of sumatriptan, which contains a sulfonamide group, caused his sulfhaemoglobinaemia."

This sumatriptan was from the excessive use of migraine medication.