This section is from the book "Diseases Of The Intestines", by Max Einhorn. Also available from Amazon: Diseases Of The Intestines A Text-Book For Practitioners And Students Of Medicine.
Ileus, miserere, passio iliaca.
An acute stoppage of the passage of the intestinal contents. This may be caused either by a mechanical occlusion at a certain part of the intestinal canal (mechanical ileus) or by an entire absence of motor power in a portion of the bowel (dynamic or paralytic ileus) or sometimes by both (mechano-dynamic ileus).
The etiology of ileus is quite complicated, and it will be best to analyze separately the different factors producing it.
Compression of the Intestines. Compression of the intestines can occur: (1) by strangulation through adhesions, bends or pseudo-ligaments, by Meckel's diverticulum, by normal structures abnormally attached, by slits and apertures in the mesentery and omentum, and by incarcerations into herniae; (2) by torsions (volvulus); and (3) by tumors from without.
The primary factor in producing isolated adhesions (bands or pseudo-ligaments) is a preceding localized peritonitis. In some cases these bands may have been congenital and due to intra-uterine peritonitis. The band may have the form of a firm fibrous cord or it may be very slender and may appear as a tough, rigid thread. Occasionally it may be of comparatively large size. Seldom the constricting ligament has the appearance of an actual band, having a width of half an inch or more.
The strangulation of the intestine by an isolated peritoneal adhesion takes place in two ways: first, the intestine may be strangulated under the band as beneath a shallow and narrow arch; secondly, it may become snared and constricted by a noose or knot formed by the false ligament itself. Strangulation from bands occurs when these are comparatively short and tightly stretched over a firm surface. The arch beneath which the implicated bowel passes is usually large enough to admit one to three fingers. Strangulation by a noose or knot requires the presence of a long false ligament which must lie loose and free in the abdominal cavity, being attached only at its two ends. The most common way in which a coil of intestine becomes snared is where a lax band forms a ring or spiral between its fixed points. Through this ring a loop of the small intestine slips; the protrusion becoming larger the implicated coil cannot free itself from the noose and is strangulated.
Strangulation by the formation of a knot is described by Leichtenstern in the following manner: "There are several kinds of this knotting. The most frequent is the following: A long and loose ligament is fastened at one end to a loop of the small intestine, and hangs in the form of a simple coil (Fig. 29); if the top of the intestinal loop passes directly through the coil a simple knot is formed about the piece of the intestine, as is shown in Fig. 30. It is evident that the same result can be produced by the fig. 30
Figs. 29-32 - Types of Constricting Peritonitic Bands. (After Leichtenstern and Treves.) coil being drawn over the top of and around the intestinal loop. Another and rarer form of knot is produced as follows: A long and perfectly loose false ligament forms a simple coil between its points of attachment. If now one leg of the so-called primary noose passes through it we have a knot like that shown in Fig. 31, and if now the intestinal loop passes directly through (Fig. 32), it becomes firmly caught and strangulated. A common characteristic of all described knots is that when the strangulated intestine is freed, the ligament can immediately be drawn out straight."
Strangulation by Meckel's Diverticulum. Meckel's diverticulum is due to the persistence or incomplete obliteration of the vitelline duct. Most commonly it exists as a blind tube, given off from the ileum. Its length is about three inches. As a rule, it is cylindrical in shape, with a conical extremity. Occasionally it presents a globular shape and is then called "clubbed." Meckel's diverticle is always single and is attached to the ileum one to three feet above the ileo-caecal valve. As a rule, the end of the diverticulum is free. In some instances it is attached to the umbilicus or to the abdominal wall. Sometimes the end attached to the abdominal parietes may give way and form fresh adhesions with some points of the peritoneal surface. The latter occurrence is of great importance with reference to strangulation of the intestine, which frequently takes place under these conditions. By means of the new adhesion of the diverticulum a loop is formed in which some portion of the intestine is liable to engage. Another possibility for strangulation by the diverticulum is afforded when its end is free and club-shaped. The diverticulum forms a ring into which its own free end projects.
A loop of the intestine entering the centre of this ring may push the clubbed end of the process before it and so tie the knot, thus leading to obstruction. Again the diverticulum may surround the pedicle of an intestinal loop in such a way as to encircle it with a single knot (see Figs. 33, 34, 35).
Figs. 33-35. - Knotting of a Meckel's Diverticulum which has a Button-like Swelling of its Extremity. (Treves.) hernia intrasigmoida, hernia bursae omentalis, formed by the foramen of Winslow, diaphragmatic hernia).
In a similar manner as Meckel's diverticulum some normal structures may act when they are abnormally attached.
Thus the vermiform appendix may become adherent to some point of the neighboring peritoneum and so form an arch under which a loop of the intestine may b e strangulated. The Fallopian tube may likewise become adherent to the adjacent peritoneum situated in the iliac fossa and thus form an arch into which a portion of the intestine may slip and become incarcerated. Other internal organs ab-normally attached may form similar traps for intestinal strangulation.
Of great clinical importance is the strangulation of the intestine in slits and apertures of the mesentery or omentum. These may be either congenital or of traumatic origin. Similar to the action of slits in the production of strangulation are also the various internal herniae (hernia duodeno-jejunalis, hernia retroperitonealis anterior,
In all these cases the mechanism of the obstruction is as follows: A coil of gut may be driven with sudden severe force beneath the band or through an aperture and become practically strangulated at once, as is often the case in strangulated hernia. There being no natural force to drive the coil out of its place of imprisonment, it remains firmly gripped. In other cases the involved intestine may not be strangulated at first, but the band pressing upon the mesenteric vessels produces a congestion in the implicated coils, which become engorged and distended by an increased accumulation of gas, and thus complete strangulation is the result. In other cases, again, the final cause of a strangulation is a twisting of the bowel. All the varieties of intestinal strangulation just mentioned occur in the small intestine, the lower portion of the ileum being principally affected, less frequently its upper portion or the jejunum.
The occlusion may in some cases be due to kinking of the intestine through a band attached to the bowel and dragging upon it. Adhesions may also obstruct the bowel, compressing its lumen. This occurs when false membranes are situated around the bowel and have undergone shrinking. They then compress the intestine seriously and narrow its lumen. The same process of shrinking may also effect an obstruction of the bowel if it takes place in the mesentery after inflammation.