ABSCESS ([Latin] abscedo, I depart). SYNON. Fr[ench] abcés; Ger[man] Eiterbeule; Geschwür.
DEFINITION.--A collection of purulent matter, one of the results of inflammation. See PUS and INFLAMMATION.
PATHOLOGY.-- If the material which collects in a tissue as the consequence of inflammation softens and becomes liquid (suppuration), it does so either rapidly or slowly; if the former, the result is an acute abscess; if the latter, the abscess is termed chronic or cold. If the material thus softened and forming pus, often mingled with fragments of dead tissue, is limited by condensation of the parts around, which are usually consolidated by the products of inflammation, the abscess is said to be circumscribed; but if the surrounding parts in their turn soften, so as practically to offer no barrier to the pus, then the abscess spreads and is said to be diffused. In an acute circumscribed abscess the lymph which collects around it as the result of inflammation becomes organised and forms a sac (pyogenic membrane); and this, with the compressed tissue about it, is the wall of the abscess, consisting therefore of contents (pus), of a limiting sac, and of condensed tissue around. The resistance offered to the extension of the suppuration is greatest when the parts adjacent are dense and tough, such as bone and fascia; yet, as the pus in an abscess increases in quantity, probably by breaking down of the pyogenic layer, sufficient pressure is exerted to cause the most dense structures to yield, and an abscess will thus make its way even through osseous tissue. As might be expected, an abscess always advances in the direction of least resistance, and this extension is spoken of as its pointing. This pointing may be towards the surface of the body, but an abscess may direct itself towards a serous cavity, such as the peritoneum, or along a track of cellular tissue, as when pus beneath the deep cervical fascia points into the mediastinum. On the side at which the abscess is pointing, its wall, as the resistance lessens, projects; and by ulcerative absorption the parts covering it become quickly thinner, until they and the abscess-wall give way and the pus escapes. In by far the greater number of cases this absorption of tissue before the pointing abscess is towards the surface, and it is by ulceration of the skin that the opening for the discharge of the matter is effected. The wall of the abscess then contracts, pus continuing for a time to be discharged; and in the end, aided by the resilience of the tissues around, the sac of the abscess is obliterated, and the orifice through which its contents were discharged heals by granulation process. To ensure this result the walls must be left at rest, or the granulations which cover them will fail to unite, and the obliteration of the sac will not then take place, as happens for example in the case of an abscess situated between the moveable rectum on the one side and the ischium on the other, where the opposite abscess-walls are prevented form joining by muscular movements on the side of the bowel, and will only unite after such movements have been stopped by cutting across the muscular fibres which occasion them. The track which results from such failure of the healing of an abscess is called a sinus or fistula.
In a diffused abscess the inflammation of the parts around does not limit the suppuration by organisation of the effused lymph, but such lymph, itself degenerating, forms more pus, and so the abscess extends rapidly and widely, unless checked by some barrier of dense tissue. In this way matter often spreads along tracks of cellular tissue, as along the course of veins, and in the subcutaneous structures. An abscess when formed between bone and periosteum, or otherwise hindered from reaching the surface by pointing, also tends to diffuse itself by following the course of least resistance. In most of these cases by direct pressure upon the resisting tissue or by cutting off the blood supply (as of the skin when its subcutaneous tissue is infiltrated with pus), sloughing of the parts covering in the abscess ensues, oftentimes to a considerable extent, and so the pus eventually makes its way to the surface. It is these abscesses, spreading along tracks of tissue before they can reach the surface, which are apt, however, when involving certain parts, such as the course of some of the lumbar nerves, to burst into a serous cavity with fatal consequences.
A chronic abscess begins in some local inflammation without active symptoms, such as results in the deposit of aplastic lymph and subsequent ulcerative changes, as caries of bone, the irritation leading to suppuration. The formation of matter proceeds in a languid manner, so that it is only by slow degrees that it collects in any considerable quantity, although eventually these chronic abscesses may acquire great size. They slowly point, and in their tardy advance occasionally traverse even serous cavities, which have been first obliterated in the line of transit by adhesive inflammation of their opposed surfaces: in this way an abscess formed in the liver (and this holds good also for those of a more acute character) may travel through the layers of the peritoneum, and may point through the anterior wall of the abdomen.
When an abscess discharges, its contents are seen to be either a thick yellow (laudable) pus, or pus stained with blood, or otherwise coloured, such as black or bluish-green; or the pus may be thin, almost watery, mingled with flakes of lymph; it may inodorous or foetid, or irritating to the touch (ichorous). Abscesses may also contain sloughs of tissue, or foreign bodies, or masses of inspissated pus, as hard occasionally as calculi, or fragments of dead bone, or calculi of various kinds. Sometimes a chronic abscess ceases to enlarge and if the irritation which occasioned it comes to an end, it may diminish by absorption of the fluid part of its contents, the solid drying up into a shrunken putty-like mass. It may remain in this state without giving rise to trouble, or it may become again the seat of suppuration by the formation of what under such circumstances has been termed by Sir James Paget a residual abscess.
The progress of any abscess is largely influenced by the state of the general health. In persons otherwise robust an abscess commonly runs an acute course; in those weakened by acute illness, such as scarlet fever or typhus, they form quickly, but are slowly recovered from, and severely tax by an exhausting discharge the powers of the patient. Persons in feeble health, hereditary or acquired, usually suffer form the chronic and diffused forms; and chronic affections of internal organs, as of the liver or kidneys, are not unfrequently associated with the development of such abscesses.
ÆTIOLOGY.-- The cause of an acute abscess may be an injury, such as a blow or pressure, as often happens in persons weakened by continued fever; exposure; or the irritation of a foreign body, or that of a poison introduced from without. In the last case the abscess is often diffused. Abscess running an acute course may also be due to a foreign body or to an irritant from within, as when it follows necrosis of a portion of bone, or the escape of urine into the tissues of the perineum. It also arises in connection with blood-poisoning, as in various fevers, and affections distinguished as septic. The cause of a chronic abscess is usually found in changes which go with deposits of a tuberculous character; or it is found in the changes which slowly occur around an irritating body, such as a renal calculus; or chronic inflammatory changes may culminate in one of these collections of matter. They may also form in parts which are long congested in connection with obstructed vein circulation (varix); and they may follow, or conditions closely allied may follow, the occlusion of a main artery and the consequent cutting off of the supply of blood to a particular region.
SYMPTOMS.-- The symptoms of an acute abscess are those of a local inflammation, with constitutional disturbance if the abscess is of any size; followed by a sense of cold or actual shivering, with increase of pain and swelling, tenderness, and throbbing. The tenderness can be recognised in the case of most abscesses; and, if pus is formed anywhere near the surface, the presence of the fluid is detected by its fluctuation. The severity of the pain is much influenced by the site of the abscess, as when the pus is held down and hindered from pointing by dense structures, such as fasciæ. Special symptoms may also arise in connection with the situation of the suppuration, as when urgent dyspnoea is caused by the pressure on the larynx of an abscess deeply seated at the base of the tongue. A diffused abscess, if subcutaneous, is recognised by its rapid spreading, and may be suspected if other signs point to a part as the site of the abscess in which diffusion is the rule, as, for instance, by the side of the rectum in the ischio-rectal fossa.
Of chronic abscess there is seldom in its early stage any evidence. The symptoms, if any, are those of failing health, and for the rest are marked by those of other changes from which the abscess is an outcome. Thus in disease of the hip joint or of the spine, unless an attack of shivering chances to attract attention, an abscess is not as a rule suspected until it has broken through its first limits, and has attained considerable size. It is not worth while to attempt to distinguish between chronic abscess and other swellings, such as extravasated blood or soft tumours, especially malignant tumours, for if a doubt in any case arises, it can be at once solved by the introduction of a grooved needle or of a fine trochar into the swelling. The true pulsation in an aneurism sufficiently tells its nature, and is not easily mistaken for the impulse sometimes given to an abscess by an adjacent artery.
VARIETIES.-- The chief local varities of abscesses which are likely to be met with in medical practice may be thus arranged: --
1. Subcutaneous or more deeply seated abscesses in the limbs, in connection with low fevers, erysipelas, pyæmia, &c.
2. Abscesses of local origin in the walls of the abdomen or chest.
3. Abscesses originating in serous membranes.
4. Certain special abscesses associated with diseased bone, e.g., psoas and lumbar abscess.
5. Abscesses formed in the cellular tissue around organs, e.g., peri-nephritic, peri-cæcal, &c.
6. Abscesses originating in inflammation of organs, the chief of which include hepatic, renal, pyelitic, pulmonary, mammary, cerebral, splenic, pancreatic.
7. Obscure abscesses formed in the deep cellular tissue, e.g., retro-pharyngeal, ischio-rectal, mediastinal.
8. Glandular abscesses, whch are usually chronic and of scrofulous nature.
TREATMENT.-- The treatment of an acute abscess consists in rest, soothing local applications, and the use of remedies to allay pain and constitutional disturbance, if the latter exists. As soon as the presence of pus is recognised the abscess must be opened, if possible where the matter is most dependent; and as soon as its contents have escaped all troublesome symptoms will usually disappear. The opening is needed to relieve pain, and to prevent in some cases diffusion, and sometimes to relieve urgent distress, as when dyspnoea is caused by the pressure of an abscess upon the air-passages. It is also desirable to open an abscess to avoid the considerable scar which must result if the matter is left to escape by ulceration and sloughing of the superficial tissues. If it is important to avoid the scar of an incised wound, an abscess may be punctured in several places with a grooved needle, when the punctures, if kept open, will effectually drain off the pus, and the marks left will in the end be scarcely discernible. In most cases, however, it is necessary to open an abscess by an incision: a narrow double-edged knife should be used; and if the matter is deeply seated, the superficial parts only need be cut, the deeper being torn through, as Mr. Hilton recommends, by dressing forceps: the risk of dividing important structures, as in the neck, is thus avoided. After the pus has escaped, the wound should be kept open by means of a drainage tube (unless the abscess is of insignificant size), which is conveniently made by introducing a twisted slip of thin gutta-percha tissue or of oiled silk, and should be covered with carbolised oil on lint, or with a poultice of linseed and ferralum. Some surgeons protect the wound whilst operating by means of the carbolic spray or by a piece of linen steeped in carbolic lotion (1 in 20), or take other antiseptic precautions. The drainage tube should be withdrawn after the first day if the abscess is superficial, but if the pus has been deeply seated it should be only gradually withdrawn, portions being cut off as the abscess contracts. If a foreign body has caused the formation of the abscess, it must be sought for and removed before the suppuration can be expected to cease. Occasionally the vascular wall of an abscess bleeds freely, or a vessel is opened in the progress of the affection: the hæmorrhage usually ceases on laying the abscess freely open; but if this does not suffice it may be permanently controlled by pressure, and the cases are rare in which further operative interference is called for. Inflammation of the sac used not infrequently to follow the discharge of its contents, but under the treatment now employed such an occurrence is unknown. During the healing of any considerable abscess the general health should be attended to, and tonics and change of air may be useful to expedite recovery.
Diffused abscesses, whether subcutaneous or more deeply seated, require free incisions as soon as suppuration is even suspected, so as to avoid the damage which results from their spreading and from the sloughing of tissue, as of the skin, which will otherwise occur, especially with those due to poison introduced into the system or those caused by infiltration of urine. These abscesses sometimes lead to fatal results.
A chronic abscess may have its contents drawn off by the apirator; or it may, when it has come near the surface, be opened, drained, and dressed with carbolised oil on lint, without any risk of constitutional disturbance, but its ultimate closing will depend upon the removal of the cause; if, for example, it is due to disease of a joint, it cannot be cured until the disease in which it has originated has in some way ended.
SINUS.-- An abscess after being opened may contract until it forms a narrow track, sinus or fistula, leading to the site of primary irritation. Such a track has a dense fibrous wall from which muco-purulent fluid escapes: it may also convey secretions, as from the liver (hepatic fistula) or stomach (gastric fistula), or excretion, as from the kidneys; or it may simply carry out the pus which forms around some irritant at the deep extremity, such as a foreign body, a portion of carious or of necrosed bone. Some such fistulæ are due to the movements of adjacent muscles preventing union of the abscess walls. Unless the cause of the sinus can be removed, as by extracting necrosed bone, these fistulous tracks are difficult to manage, requiring especial treatment according to their situation. Other fistulæ are those forming communications between mucous canals (recto-vesical, vesico-vaginal fistulæ), and these need special treatment, such as plastic operations and operations diverting the course of excreta escaping through unnatural channels.
The tissue about healed abscesses, scar-tissue generally, and tissue spoiled by inflammation, are apt on slight provocation to inflame and suppurate, and to those collections of matter the term 'residual' has been applied. The treament of such abscesses in no way differs from that of others, and they usually heal in the ordinary manner.
-- G.W. Callender.
