When a patient is put on an anticoagulant, bleeding can give rise to some serious troubles. If a patient has got a brittle arterial system and an artery ruptures in the brain, bleeding will go on for a long time and brain cells will 'drown' in blood.
Occasionally, a patient on anticoagulants will pass blood in the urine. In the kidneys the blood is only held in the arteries by very thin membranes to allow the passage through the latter of unwanted materials. Blood with a very prolonged clotting time can leak through these membranes and into the urine.
All this means that when a patient is given anticoagulants, a careful check has to be kept on the dosage and the effect they have on the clotting time or 'prothrombin' time. It necessitates a blood sample being taken and sent to the "lab" for testing.
Many articles taken from 'A word with the doctor', by Dr. John Windsor.