By the term volvulus is understood an obstruction of the bowel by a twist about its mesentery, or its own axis, or the intertwining of an intestinal coil within another. Twisting of the bowel occurs most often in the sigmoid flexure. The usual cause of this trouble is chronic constipation, for in this condition the flexure is more or less constantly distended. Its walls become partly paralyzed and hang down into the pelvis, like an inert heavy mass, being filled with fecal matter. Traction is thereby exerted upon the mesocolon and a loop is soon formed. A twisting of the latter is brought about either by some displacement of the bowel or by a sudden change in the position of the body. The ascending colon, caecum, and the small intestine may also be affected in the same manner, although less frequently. Intertwining of the intestine is here more often met with.

Obturations of the Intestine. Intestinal occlusion often takes place in consequence of obturation of the lumen of the gut through foreign bodies lodging therein. Accumulations of fecal matter may give rise to such an occurrence. The hard fecal tumor is then situated either in the caecum or in the colic or sigmoid flexures. In these cases chronic constipation has existed for a long time.

Gall stones, although rarely, give rise to intestinal occlusion. In order to do this they must be of considerable size. "The puzzle as to how the camel could go through the eye of the needle, i.e., how these enormous gall stones could reach the bowel, has been solved, by the assumption on fair evidence that an ulcerative process opens the way from the gall bladder to the bowel, though doubtless very large stones occasionally find their passage through the ducts" (E. D. Ferguson1 )

In a similar manner enteroliths may also cause obstruction of the bowel. This happens especially if an enterolith situated in an intestinal diverticulum has been dislodged and found its way into the canal of the gut.

1 E. D. Ferguson: Transactions of the New York State Medical Association, 1898, p. 233.

Foreign bodies which have been accidentally or intentionally swallowed may under favorable conditions reach some part of the bowel and here obstruct the lumen. This will occur if the foreign body is of considerable size, or if it is not smooth but provided with sharp points. The latter catch in a fold of mucous membrane and prevent its further passage. The most varied substances have thus been found to be the cause of intestinal obstruction: marbles, stones, coins, glass stoppers, corks, spoons, knives, forks, keys, needles, pins, buttons, false teeth with the plate. Kernels of fruit like cherries, prunes, etc., may accumulate in the bowel and by means of fecal matter be kept together, forming a large conglomeration, completely obstructing the canal.

Recently Murphy's button has also been found in a few instances to cause obstruction of the bowel.

Intestinal parasites (tapeworms, ascaris lumbricoides), if present in large numbers, may also form a mass obstructing the canal. This occurs especially after a vermifuge has been administered and the dead parasites have remained within the canal.

Similar to the action of foreign bodies are also tumors (polypi, fibroma, myoma, etc.) connected by a pedicle with the intestinal wall, filling up its lumen.