The main defect of development to which the rectum is liable, is that represented by atresia ani, or congenital occlusion of the anus. In this case the rectum either has a blind termination, is absent, or opens into the urinary and genital passages (cloaca). In the first case the rectum may reach down to the point where the orifice should be, but the orifice is closed by an expansion of the common integuments over it; these are distended by an effort at defecation, and the meconium may even be seen through them. There may however be a greater deficiency of the rectum, the latter terminating at a higher point, or it may be totally absent, and its place be occupied by dense cellular tissue. In these cases the pelvis appears in an undeveloped state, especially in its antero-posterior diameter; it is very much inclined, and the external genital organs are placed very far back. This affords a valuable aid in the diagnosis, as it allows us to infer a considerable deficiency in the rectum.

Anomalies in the calibre of the rectum are both frequent and important, and appear in the form of dilatations or contractions. The former attain a very considerable extent, presenting sacculated sinuses, and an accumulation of indurated faeces; they are accompanied by considerable thickening of the coats and blennorrhoea. The latter vary much in form and distribution, but more still in respect of their causation. In the first place, the rectum is more liable than any other portion of intestine to be compressed by neighboring viscera, by the pregnant uterus, by tumors developed in the uterine or vaginal parietes, by diseased ovaries, the re-troverted uterus, the hypertrophied prostate, vesical calculi, pessaries, etc. The contractions dependent upon disease of the coats of the rectum are of still greater importance. To these belong contractions from hypertrophy of the coats, accompanied by an accumulation of fat, and induration of the surrounding cellular tissue; contraction consequent upon catarrhal inflammation and suppuration, or gonorrhoeal ulcer; contraction resulting from a dysenteric cicatrix, polypous tumors, and various forms of cancer. Of these the strictures consequent upon dysentery and cancer are the most important.

Hypertrophy of the sphincter is a remarkable affection; it may in rare cases, especially in children, give rise to obstinate constipation and even ileus, but it frequently induces excoriation of the mucous membrane, the so-called fissure of the rectum.

We have already (p. 56) discussed prolapsus ani.

Catarrh and blennorrhoea, accompanied by hypertrophy of the coats, which frequently gives rise to plicated and polypous excrescences of the mucous membrane, are very frequent affections of the rectum. Gonorrhceal catarrh of the rectum represents a peculiar variety: it affects the same uniformly, or in a circumscribed spot: in the former case it is followed by a shrivelling of the rectum, and the mucous membrane gradually disappears; in the latter by a callous induration of the coats of the rectum, and not unfrequently by the formation of an ulcer, which as well as the stricture is placed in the vicinity of the sphincters, and is distinguished by its zonular form, its sinuous circumference, and its callous puckered base.

The hemorrhoidal ulcer is peculiar to the rectum. It results from the irritation of the mucous membrane, produced by lasting congestion in inversion and prolapsus, strangulation by the sphincters, compression of the hemorrhoidal swellings, and undue medicinal interference. It is distinguished by its seat in the vicinity of the sphincters, its irregular shape, its indented and sinuous flabby margin of mucous membrane, and the similar ridges of mucous membrane that surround or pass over it. On account of the absence of reaction in the parts, corrosion of the vessels not unfrequently brings on violent hemorrhage.

An inflammation of cellular tissue resembling perityphlitis, occurs in the rectum, as periproctitis. The remarks made in reference to the former apply to the latter also (vide p. 88). It occasionally becomes chronic, and thus induces hypertrophy and callosity of the cellular and adipose tissues surrounding the rectum, which however differ from the analogous result of cancer. Like the hemorrhoidal ulcer, it may cause fistula recti.

Of intestinal cancerous affections, those occurring in the rectum are the most frequent, especially if we include the scirrhous degenerations which involve it by extension from the female sexual organs, but which we do not allude to at present.

Cancerous disease attacks the rectum in the various forms above described as affecting the intestine at large. The following however are particularly remarkable: a. Erectile tumors developed in the tissue of the mucous membrane, and infiltrated with medullary carcinoma; they assume the shape of broad, sessile, or pediculated fungi. They are commonly placed at the commencement and posterior surface of the rectum, at about three or four inches from the orifice; we find these excrescences only in exceptional cases, at or close to the sphincters.

B. Annular Carcinoma And Stricture Of The Rectum

It occurs almost exclusively at the upper portion of the rectum, and especially at the point at which the sigmoid flexure terminates in the rectum, and which, in its normal condition, presents a distinct contraction. The strictured part is either unattached, or, as is more commonly the case, firmly agglutinated laterally to the promontory; notwithstanding its elevated position, it is, as Cruveilhier correctly remarks, pushed down by the feculent accumulations above, which generally precede the occurrence of ileus, it is therefore easily reached in exploring with the finger.

Y. Scirrhous Degeneration Of The Rectum Over A Large Surface, Or Throughout Its Entire Extent

This primarily affects the submucous cellular tissue, from which it extends through the entire muscular coat to the cellular sheath of the intestine, the cellular and adipose tissue of the pelvic cavity, to the posterior surface of the vagina, and even to the uterus; or it originally attacks one of the last-named tissues, and involves the rectum secondarily. The rectum is firmly attached, from being agglutinated in its entire extent to the sacrum, or adherent to the vagina, or it appears wedged into the pelvis by the surrounding morbid growth; its calibre may be variously diminished, though it sometimes is unaltered; its internal surface is uneven, nodulated, and hard, or it is filled with soft, fungous, bleeding growths; the anus, especially if the morbid product extends to the sphincters, is patent, everted, and varicose; even the perineum appears more or less swollen, protruded, and hardened; and this induration extends to a considerable extent over the nates in consequence of the condensation of the subcutaneous adipose tissue.

The foreign bodies found in the rectum may either have reached it from above, but not proving injurious until they reach this point, or they may have been introduced, per anum, in consequence of morbid sensations or perverted sexual desire. In the latter case they are commonly very singular objects and of alarming size.