Several things can happen if the blood from an injured artery cannot escape to the surface: (1) It may track widely in the patient’s tissues. (2) It may form a tense local arterial haematoma, which may press on the collateral vessels, obstruct them, and cause gangrene. (3) The outer layers of the haematoma may later become organized and form a traumatic (false) arterial aneurysm. (4) If this aneurysm communicates with a vein, it will form an arteriovenous aneurysm. Initially, this may be difficult to diagnose. Suspect that such an an aneurysm is forming whenever a pulsating haematoma overlies a major artery and vein, particulary in the groin.
An arterial haematoma can form when an artery is injured by a penetrating wound or by a fracture. If it is rapidly expanding, it must be explored before it becomes an arterial aneurysm or an arteriovenous aneurysm, both of which are even more difficult to treat.
The patient has a pulsating swelling after an injury, perhaps only a minor one. If you cannot refer him, proceed as follows.
Where possible, apply a tourniquet proximally, to control bleeding. Then make an adequate incision to explore his wound. Expose the artery proximal to the injury, and control the flow of blood through it with an arterial clamp, or one of the other methods described below. Explore the haematoma, remove the clots, and tie his bleeding vessel. Finally, release the clamp or tourniquet cautiously to see if you have been successful.
If the haematoma is below his elbow or knee, tie the injured artery.
If the haematoma is above his elbow or knee, try to repair his injured artery (55.6). If you feel you cannot do this, or you don’t have the necessary equipment, tie it as close to the injury as you can, and hope for the best. He may be lucky.