#Punctured wounds# of blood vessels may result from stabs, or they may be accidentally inflicted in the course of an operation.

The division of the coats of the vessel being incomplete, the natural haemostasis that results from curling up of the intima and contraction of the media, fails to take place, and bleeding goes on into the surrounding tissues, and externally.  If the sheath of the vessel is not widely damaged, the gradually increasing tension of the extravasated blood retained within it may ultimately arrest the haemorrhage.  A clot then forms between the lips of the wound in the vessel wall and projects for a short distance into the lumen, without, however, materially interfering with the flow through the vessel.  The organisation of this clot results in the healing of the wound in the vessel wall.

In other cases the blood escapes beyond the sheath and collects in the surrounding tissues, and a traumatic aneurysm results.  Secondary haemorrhage may occur if the wound becomes infected.

The treatment consists in enlarging the external wound to permit of the damaged vessel being ligated above and below the puncture.  In some cases it may be possible to suture the opening in the vessel wall.  When circumstances prevent these measures being taken, the bleeding may be arrested by making firm pressure over the wound with a pad; but this procedure is liable to be followed by the formation of an aneurysm.

Minute puncture of arteries such as frequently occur in the hypodermic administration of drugs and in the use of exploring needles, are not attended with any escape of blood, chiefly because of the elastic recoil of the arterial wall; a tiny thrombus of platelets and thrombus forms at the point where the intima is punctured.

#Incised Wounds.#—­We here refer only to such incised wounds as partly divide the vessel wall.

Longitudinal wounds show little tendency to gape, and are therefore not attended with much bleeding.  They usually heal rapidly, but, like punctured wounds, are liable to be followed by the formation of an aneurysm.

When, however, the incision in the vessel wall is oblique or transverse, the retraction of the muscular coat causes the opening to gape, with the result that there is haemorrhage, which, even in comparatively small arteries, may be so profuse as to prove dangerous.  When the associated wound in the soft parts is valvular the haemorrhage is arrested and an aneurysm may develop.

When a large arterial trunk, such as the external iliac, the femoral, the common carotid, the brachial, or the popliteal, has been partly divided, for example, in the course of an operation, the opening should be closed with sutures—­arteriorrhaphy.  The circulation being controlled by a tourniquet, or the artery itself occluded by a clamp, fine silk or catgut stitches are passed through the outer and middle coats after the method of Lembert, a fine,