About two-thirds of all cases of appendicitis occur in males. The reason for such a disparity is due to several factors. Females are less ex posed to inclemencies of the weather and other deleterious influence; they undergo less mus cular exertion and the female appendix in the majority of instances, has a better blood supply. Of diseases that predispose to appendicitis may be mentioned: constipation, gastro-enteritis, dysentery, typhoid fever, influenza, etc. Con stipation exerts an influence by causing slug gishness of the bowels, resulting in poor drain age of the appendix. Noxious materials may be retained and thus favor an increase in the viru lence of bacteria, especially the Bacillus con communis. Gastro-enteritis, or inflammation of the stomach and intestines, is a very important etiological factor in appendicitis. In this disease the cecum may become inflamed and by exten sion involve the appendix. In many instances the alterations in the walls of the appendix are slight and fail to produce any clinical mani festations. At times, however, the lining mem brane of the appendix is directly attacked, with acute appendicitis as the result. Under other circumstances, catarrhal changes of mild degree persist and lead to chronic appendicitis. Dysentery and typhoid fever are among the more remote causes of appendicitis. They cause catarrhal alterations, swelling, congestion and oedema of the adenoid (glandular) follicles of the organ. Not uncommonly ulcerations occur, and the resulting scar is one of the most im portant factors in the subsequent development of appendicitis by causing a stricture in the lumen of the appendix, obstructing the drainage of the organ, and thereby favoring the reten tion of irritating material. Influenza owing to the intestinal lesions to which it gives rise may also favor the development of appendicitis.
In general it may be stated that the under lying cause of all cases of appendicitis is infec tion. Emphasis has more recently been laid on the role of the streptococcus group of micro organisms which frequently make their way into the circulation through the tonsils, ade noids and foci of suppuration about the teeth, as well as other portals of entry in the respira tory and gastro-intestinal tracts. It is probable, however, that this so-called hematogenous in fection of the appendix is less common than direct infection from its own interior; the latter being favored by local abnormal condi tions, such as kinks, adhesions, torsions, stric tures, and contained concretions.
The most important predisposing cause of appendicitis is the fact that the appendix has already been the seat of one or more attacks of the same affection. The apparently greater num ber of cases of appendicitis observed in recent years is not due to an actual increased inci dence of this disease, but rather to a greater refinement in diagnosis which has enabled phy sicians more readily to recognize the true nature of the malady, which in former years was variously styled inflammation of the bowels, peritonitis, gastritis, obstruction of the bowels, etc. The appendix is less resistant
than other portions of the intestinal tract to the onslaught of bacteria and other deleter ious influences. This is due to several factors: The blood supply may become defective because of the liability to partial or complete obstruc tion of the blood channels, as a result of kink ing, twisting (volvulus), or the formation of external bands of adhesions, etc., secondary to primary inflammation of the appendix. Dis turbances of circulation, and hence of nutrition, may also be produced by active and sometimes ineffectual muscular efforts of the appendix to rid itself of fecal concretions or even inspis sated fecal matter. Defective drainage, which has been referred to, is of great importance in the pathogenesis of appendicitis because of the anatomical and physiological peculiarities of this organ. The average length of the appendix is about 8 to 9 cm. (3% inches), while its diameter is only 3 mm. to 5 mm. (% to % inch), thus forming a long narrow tube not favorable for free drainage. The peritoneal covering forms what is known as the meso-appendix in such a manner as to draw the appendix into a curve and thus aid in any angula tion resulting from disease. Additional fac tors of importance are the relatively large ex tent of mucous membrane presented by the appendix and the large amount of lymphoid (glandular) tissue, not only in the neighbor hood of the valve-like opening into the cecum, known as Gerlach's valve, but also scattered throughout the wall of the appendix. The lat ter is of especial significance in view of the tendency of adenoid tissue throughout the body to inflammation when subjected to even slight irritation by bacteria and their poisons. An analogous condition may be observed in the tonsils, which are so frequently invaded by bacteria with a resulting tonsilitis (quinsy). Owing to this similarity the appendix has fre quently been called the °abdominal tonsil.' In considering the symptomatology of the two forms of appendicitis — the acute and the chronic — it must be borne in mind .that the extent of disease which has actually taken place in the appendix cannot always be determined by the clinical manifestations. While it is true that, in general, the clinical symptoms become more marked with the increased severity of the appendicular and peritoneal lesions,— that is, when perforation, abscess or gangrene super vene— it is also a fact that remission of all symptoms may occur, and yet the disease may be progressing to a fatal termination. It is like wise a fact that the symptoms suggestive of perforation of the appendix with abscess forma tion in one patient may, in another case, he due to the development of an abscess without perforation of the organ. It is better, there fore, to consider acute appendicitis as a clinical entity. Similar reasoning obtains with regard to chronic appendicitis, although in the latter the questions requiring solution are less com plicated.