CHAPTER I.

RELATIVE FREQUENCY—AGE AND SEX AFFECTED—ETIOLOGY—CLASSIFICATION.

FISTULA IN ANO which is not due to ulceration and perforation of the rectal wall from within is the result of a previous abscess. Such an abscess forms in the ischio-rectal fossa, and, although opened early by a free incision even before the cavity becomes distended with pus, it frequently fails to heal. It may fill up and contract to a certain extent, but it does not become entirely obliterated; a narrow track remains, which constitutes the affection designated fistula in ano.

There are several reasons why rectal abscesses so frequently degenerate into fistulæ. One is, that, owing to an internal opening within the bowel, small particles of fecal matter find their way into the sinus, and, acting as foreign bodies, prevent the healing; another, that, owing to the frequent movement of the parts by the sphincter muscles, sufficient rest is not obtained for the completion of the reparative process; and, finally, the vessels near the rectum are not well supported, and the veins have no valves, hence there is a tendency to stasis, which is unfavorable to rapid granulation.

According to the authority of Mr. Harrison Cripps,[33] if the fistula be divided its surface will be seen to be lined with a smooth, gelatinous membrane, which when examined under the microscope is found to consist of granulation-tissue exactly analogous to that which lines the interior of a chronic abscess. The leucocytes constituting the outer wall of this membrane are but loosely adherent, and constantly becoming free they form the chief part of the pus which drains from the fistula.

RELATIVE FREQUENCY OF THIS AFFECTION.—In point of frequency, compared with other rectal diseases, fistula is next to hemorrhoids. This statement is contrary to the showing made by the published statistics of St. Mark's Hospital, as quoted by Allingham.[34] This table shows that out of four thousand cases taken consecutively from the out-patient department of the hospital there were one thousand and fifty-seven persons suffering from fistula and one hundred and ninety-six from abscess, of which latter number one hundred and fifty-one subsequently became fistulæ, so that more than one-fourth of the whole number of cases treated were fistulæ. Allingham also states that a recent examination of the records of the in-patients of the same institution, covering a period of several years, shows that two-thirds of those operated upon were cases of fistula.

Mr. Allingham[35] justly calls attention to one source of error in drawing conclusions from statistics—namely, the fact that many patients suffer from more than one malady. He states that it constantly happens that a fistula is found in connection with hemorrhoids, either as the substantive disease or as a complication. Again, a fissure or circular ulcer often has a sinus running from it, so that it may fairly be considered as the opening of an internal fistula, and the case called a fistula; or the sinus is not detected, and the case is called ulcer or fissure.

Another fallacious element in the statistics of Mr. Allingham, which should not be overlooked, is pointed out by Mr. Chas. B. Ball.[36] St. Mark's has a special reputation for the cure of fistula, so that many persons suffering from this disease go there, and in this way the records show an apparent greater frequency of fistula. Mr. Ball also states[37] that at the Dublin General Hospital, although fistula is common, it is by no means the commonest of rectal diseases; and in his own practice this affection has not furnished more than one-sixth of rectal operative cases.

AGE AND SEX AFFECTED.—This disease is commonly met with during middle age, but it is by no means restricted to that period of life. Allingham states[38] that he has operated upon an infant in arms, and upon a man over eighty years old. Dr. Henry R. Wharton[39] mentions having seen a number of cases at the Children's Hospital, Philadelphia, among which he records one of complete fistula in a child a few months old.

CAUSES.—Fistula in ano may originate in ulceration and perforation of the mucous membrane of the bowel—the result of the irritation produced by fecal accumulations (arising from any cause, such as atony of the intestines, irregularity of habits, rectal stricture, etc.), or by foreign bodies, such as fish- or rabbit-bones, grape- or fig-seeds, etc.; more frequently it owes its origin to an abscess caused by injuries, such as blows or kicks upon the anus, or by exposure to cold, as from sitting upon damp seats—especially after exercise, when the parts are hot and perspiring; it may also arise from excessive irritation of the rectum occasioned by the presence of any of the forms of parasites which infest the anus and its immediate neighborhood. Other predisposing causes are thrombosed veins and suppurating hemorrhoids. Abscess, and then fistula, may likewise supervene in fevers and certain depressed conditions of the blood, such as frequently give rise to boils or carbuncles.[40]

"The late Dr. W. E. Horner, Professor of Anatomy in the University of Pennsylvania, used to describe an arrangement of pouches opening upward, in the mucous membrane of the rectum, by which the entanglement of seeds, bits of bone, etc., contained in the feces was favored. His account may be found in his 'Special Anatomy and Histology,' vol. ii, p. 46 (edition of 1851), where he quotes a paper on Fistula in Ano, by Ribes. He says, also, that Glisson and Ruysch had described them as valves, and that Winslow was acquainted with them. The latter author (Douglas's Transl., 1743, vol. ii, p. 149) says, 'They form little bags or semilunar lacunæ.' Another American writer, Bushe ('Malformations, Diseases, and Injuries of the Rectum and Anus,' 1837, p. 15), speaks of these pouches, and confirms Winslow's description. They are also mentioned in the treatises of Leidy and S. G. Morton. Hyrtl (Handb. der Topogr. Anatomie, 1871, bd. ii, p. 142) describes them quite fully, and speaks of their agency in the development of fistulæ.

"Mr. W. T. Clegg, of Liverpool, says (Lancet, Feb. 5, 1881) that Mr. Bickersteth has for four years been describing these anal pouches, which 'are not mentioned in any of the books he has consulted.'

"It is certainly strange that this arrangement, so clearly pointed out, should have been passed over in silence, not only by many anatomists, but by late writers on rectal surgery; yet it is undoubtedly a frequent cause of fistula. In Fig. 14 these pouches are shown, with a fistula, probably formed by a foreign body lodging in one of them. Over the fistula the mucous membrane has been removed, and a bougie has been passed through the canal."[41]

Finally, a tubercular or strumous diathesis seems to be as potent a factor in the causation of fistula as it is in other suppurative troubles. The appearance of a fistula in a tubercular subject is characteristic of the constitutional malady. It is thus described by Messrs. Alfred Cooper and F. Swinford Edwards:[42] "The part is, as a rule, unusually hirsute; the ischio-rectal fossæ are drawn in, owing to absence of fat; the sphincter is weak and offers no resistance to the introduction of the finger. The skin around the orifice is bluish and often considerably undermined, and the discharge is thin and watery. The internal orifice is often large, and the mucous membrane around it is also undermined."

The tendency to the occurrence of abscess and fistula in phthisical patients has long been recognized, and has given rise to some doubts as to the propriety of resorting to operative measures in such cases. This point will be considered in the chapter on Treatment. According to Messrs. Cooper and Edwards,[43] about five per cent. of phthisical subjects also suffer from fistula, and about twelve per cent. of fistulous patients are the subjects of tuberculosis.

VARIETIES.—For all practical purposes we may divide fistulæ into the following four forms: (1) the _complete_ fistula, in which there are two openings, one in the rectum and one on the skin more or less remote from the anus (Fig. 15); (2) the _incomplete internal_ fistula, in which there is a communication with the cavity of the rectum by means of an opening in the mucous membrane, but none with the external surface of the body (Fig. 16); (3) the _incomplete external_ fistula, in which there is an external opening through the skin, but no communication with the bowel (Fig. 17); and (4) the _complex_ fistula, in which there are many sinuses and numerous external openings (Figs. 18 and 19). Some of these tracks run outward; some extend up the bowel beneath the mucous membrane; whilst others travel round the bowel and open in the other buttock, giving rise to the so-called _horseshoe_ fistula. The second and third varieties named are often spoken of as _blind_ fistulæ.

[Illustrations]

FISTULÆ WITH DOUBLE TRACKS (MOLLIÉRE).

Fig. 18—A, B, deep submuscular track resulting from an ischio-rectal abscess; A, I, submucous track running up and down the bowel.

Fig. 19—D, E, subtegumentary and submucous fistula with internal and external opening; D, F, deep submuscular track, having same internal but separate external opening.

Footnote 33:

_Op. cit._, p. 152.

Footnote 34:

_Op. cit._, p. 13.

Footnote 35:

_Op. cit._, p. 13.

Footnote 36:

_Op. cit._, p. 66.

Footnote 37:

_Op. cit._, p. 67.

Footnote 38:

_Op. cit._, p. 13.

Footnote 39:

Keating's "Cyclopædia of the Diseases of Children," vol. iii, p. 341.

Footnote 40:

Allingham, _op. cit._, p. 14.

Footnote 41:

Article on Diseases of the Rectum, by Henry Smith, Esq., revised by John H. Packard, M.D., in Holmes' "System of Surgery" (Packard, editor of American edition), vol. ii, pp. 643-644.

Footnote 42:

"Diseases of the Rectum and Anus," second edition, London, 1892, p. 126.

Footnote 43:

_Op. cit._, p. 126.