HEALTH / Common procedures: Surgical Incisions

A SMALL cut on the finger seems to produce a lot of blood, so what happens when a surgeon makes a cut almost a foot long in the chest or abdomen? Isn't there blood everywhere? The answer is no. For most operations the amount of blood lost is very small; if surgeons are to see what they are doing, they must make sure that they have stopped virtually all the bleeding.

Before the operation starts, the patient is anaesthetised and laid flat on the operating table. The blood pressure is low in these circumstances and this reduces bleeding. The skin is cleaned and often painted with a mixture of alcohol and an antiseptic. A long straight cut is then made through the skin with a scalpel, exposing the fat beneath. Naturally, the edges of the wound bleed, but the surgeon and assistant press gauze swabs on to the wound and this stops the bleeding.

After a minute or so, one of the swabs will be lifted. Some oozing of blood will continue, and there will be brisk bleeding from one or two obvious points where blood vessels have been cut across. These bleeding points are controlled by compressing them between the narrow, rounded tips of Spencer Wells forceps; these have handles with grips like scissors, but with a ratchet so that the blades stay closed. Within a few minutes, both edges of the skin incision will have a dozen or so pairs of forceps in place and bleeding will virtually have ceased.

The forceps are then removed one by one and each bleeding point is sealed either by tying a catgut suture around it or cauterising with an electric current. Once the skin incision is tidied up, the surgeon can cut through the muscle, controlling bleeding in the same way. Eventually, the abdomen or the chest will be opened, the sides of the opening held apart by retractors, and work can commence.

How much blood is lost during the operation depends on what is being done. (For operations on the limbs, the blood supply can be cut off completely by a tourniquet.) The greatest blood loss occurs during operations on the heart and blood vessels. Until recently this blood was simply removed using a suction apparatus and replaced with a blood transfusion into a vein. Despite improvements in screening tests on blood donors, there is still a very small but unavoidable risk of infection, as HIV and some types of hepatitis can be passed on by a blood transfusion. Increasing concern about these risks has led to surgeons making greater use of blood-salvage techniques, in which the blood recovered by the suction apparatus is cleaned and the patient's own red cells are then returned to the circulation.

When the operation is completed, the opening has to be closed; this is done in stages. The cut through the muscle has to be stitched together with material strong enough to resist the considerable pressures caused by coughing and straining. Once the muscle layers have been made secure, the skin edges are brought together with stitches or sometimes clips; these will be removed after 10 days or so, once the skin wound is firmly healed. The scar left by the surgeon will be dramatic at first but will fade with time; the end result depends at least as much on how well the individual's skin heals as on the quality of the surgeon's needlework.