Abscesses

A patient with an abscess has severe throbbing pain. The infected part is tender and swollen, and the skin over it stretched, shiny, and red, although this may not be evident on a dark skin. Moving it is acutely painful. If his abscess is large or he has several abscesses, he may be febrile, weak, toxaemic, and anaemic. The usual signs of inflammation and suppuration suggest the diagnosis, but don't necessarily expect to find fluctuation in the sites listed in the previous section.

Severe pain is a useful sign that an abscess is ripe for incision, but pain may be mild when the tissues are loose. So incise it and let the pus flow out; break down any septa in a large cavity and open up any loculi (smaller cavities off the main one). If diagnosis is difficult, try aspirating it with a syringe and a wide bore (1.5 mm) needle; but remember that this is an unreliable test and that pus may be present even if you fail to aspirate any. Never try to treat an abscess by aspiration. There is no need to curette the walls of an abscess, except in the hand where you want inflammation to resolve particularly rapidly and completely.

Abscesses are usually placed at the end of a list of otherwise ''clean' cases, and are often left to very junior staff. Nevertheless, be careful: (1) The diagnosis can be difficult, as with an iliac abscess (5.12). (2) Drainage has its risks, especially severe bleeding when a patient has a large abscess or many of them, so watch blood loss carefully (see below). (3) A superficial abscess over the tibia, femur, or humerus may turn out to be pyomyositis (7.1), or, more seriously, osteomyelitis (7.2). (4) A ''chronic abscess' may turn out to be a solid tumour. Some sarcomas are first treated as infections! (32.8).

Fig. 5-2 INCISION AND DRAINAGE. A, B, and C, show a linear incision being made and its edges spread. D, E and F, show you how to make a cross-shaped incision, cut off the edges of the skin, and so remove the roof of the abscess. After Hill GJ, ''Outpatient Surgery', Fig. 5.12. WB Saunders, with kind permission.

THE GENERAL METHOD [s8]FOR ABSCESSES EXAMINATION. Assess the patient's general condition carefully, especially if he has many abscesses, or large ones. Look for anaemia.

SPECIAL TESTS. (1) If his infection is severe, take blood cultures. You may be able to isolate the causative organism (this is important in osteomyelitis). (2) Test his urine, he may be diabetic[md]always do this if he has had more than one septic infection. Your work load will probably be too heavy to test the urines of all patients with abscesses. (3) If he has a particularly large or unusual abscess, or recurrent ones, test for HIV.

ANTIBIOTICS are not usually needed. Give them if: (1) He has a severe constitutional disturbance with high fever and toxaemia. (2) There are signs that his infection is spreading[md]increasing erythema, cellulitis, lymphangitis, severe lymphadenitis, or fever. (3) Rapid resolution is important, for example, in a deep infection of a hand or finger, or in a woman with a breast abscess where the re-establishment of breast feeding is critical.

If you decide to give him an antibiotic and you can culture the pus, give the first dose in the theatre immediately after drainage. If you cannot culture the pus, give it with the premedication, or an hour before the incision (2.7).

DRAINAGE [s7]OF AN ABSCESS INDICATIONS. A collection of pus anywhere. If you suspect that there is a foreign body in an abscess this is an added reason for exploring it.

If you are not sure if pus is present or not, aspirate the lesion with a needle to see if you can withdraw pus. If pus is present drain it. If you fail to aspirate pus with a needle, this does NOT mean that there is no pus present!

Signs that an infection is spreading are not a contraindication to drainage[md]if you think pus is present, drain it.

ANAESTHESIA. (1) You don't need muscular relaxation, so ketamine will do (A 8.1). (2) If an abscess is already pointing, you can infiltrate the site of the incision with a local anaesthetic solution (A 5.7). (3) Intravenous thiopentone with pethidine (A 8.8). (4) Morphine. (5) Ethyl chloride local spray is the least satisfactory, but you can use it for very superficial abscesses. It makes the tissues hard and difficult to incise.

INCISION. Drain the abscess at the site of maximum tenderness and try to follow Lange's lines (61-3). This is safer than following any set rule or the dotted line on a diagram. If an abscess is superficial, use a pointed (No. 11) blade, as in Fig. 5-2.

CAUTION ! (1) If the abscess is deep, try to incise parallel to any nerves or vessels, not across them. (2) The common mistake is not to make the incision large enough.

HILTON'S METHOD should always be used if there is anything near the abscess which you might possibly injure. Incise the tissues down to the deep fascia, then push blunt scissors or a haemostat into the softest or most prominent part of the swelling. Open them out inside the abscess. If necessary, enlarge the wound by blunt dissection inside the tissues.

DRAIN THE PUS by putting your finger into the abscess, and breaking down all loculi, so that there is only one cavity. Use your little finger if the abscess is small. If there is much pus, suck it out or clean out the cavity with a swab. Make sure you remove it all.

PROVIDE FREE DRAINAGE. Make sure that any more pus which forms can drain from the bottom of the cavity.

If the abscess you are draining has a tendency to heal over and leave a cavity, deroof it, as in F, Fig. 5-2. This is especially necessary with perianal abscesses and Bartholin's abscesses. Cut away some skin, particularly any dead skin. Then pack it to make sure that the opening remains wider than the base and allows it to granulate from the bottom up. Gently fill the cavity with gauze. Replace this on the second or third day, and continue renewing it until pus no longer discharges. If the cavity is large, use ribbon gauze or bandage. If you use separate pieces of gauze, tie them together. Small pieces are easily lost in a deep cavity. Even a large one will quickly contract and disappear.

If an abscess is deep, push a corrugated rubber drain down to its deepest extension. This cannot block, and is better than a tube drain.

If pus has to drain downwards, as in the breast, try to incise the lowest part of the abscess. This is better than making a counter incision at its lowest point, and it also avoids making two incisions.

IF AN ABSCESS BLEEDS, pack the cavity (3.1). If necessary, set up a drip and give him 0.9% saline. Blood is seldom needed.

GENERAL MEASURES. If his abscess is in some critical place, such as his lateral pharyngeal space, or his mid palmar space, admit him. Make sure his fluid intake is adequate, and don't forget to give him an analgesic[md]abscesses are painful!

POSTOPERATIVE CARE. Rest the part, and where possible raise it. For example, put his hand in a St John's sling (71-1), or, if he is an inpatient, raise his hand in a roller towel, as in Fig. 75-1. If his foot is infected, raise the foot of his bed (81-1).

DIFFICULTIES [s7]WITH ABSCESSES If he has NO FEVER BUT IS OBVIOUSLY ''ILL', suspect that his resistance to infection is low and treat him with particular care.

If he has MANY ABSCESSES, he has pyaemia, multiple pyomyositis, or septicaemia. He may bleed much when you drain them. If he is very anaemic, transfuse him first, and, if necessary, again during the operation. Draining multiple abscesses is a major procedure, particularly if a child is anaemic or malnourished, so be careful before you incise too many abscesses at once[md]children have bled to death!

If he is VERY ILL AND HAS HUGE ABSCESSES, he will not tolerate an extensive procedure. It may occasionally be necessary to take him to the theatre several days in succession and drain a few abscesses at a time.

If an abscess FAILS TO HEAL, don't forget the possibility of tuberculosis (29.1) or HIV (28a.2).

If a child has abscesses, FAILS TO THRIVE, and is miserable, malnourished, and backward with his milestones, suspect HIV and examine his mother for palpable nodes (28a.2).

ALWAYS INCISE AT THE POINT OF MAXIMUM TENDERNESS Fig. 5-3 EXPLORING AN ABSCESS BY HILTON'S METHOD. A, incise the abscess at its lowest point, if this is practicable. B, push blunt scissors or a haemostat into it. C, open the haemostat. D, explore the abscess with your finger. E, insert a drain.