Blood sampling. View of a woman's arm during venepuncture, the process of removal of a blood sample from a vein. A yellow tourniquet (band) on the upper arm is used to constrict venous blood return, thus enlarging the veins and making them easier to penetrate with a hypodermic needle. The blood is drawn into a vacutainer, a test-tube like container seen here within the barrel of the syringe. This blood sample was taken at Majengo clinic in Nairobi, Kenya.