Intersigmoid Hernias

The intersigmoid fossa is a peritoneal pouch formed between the two loops of the sigmoid colon and its mesentery. This pocket is found in 65% of cadavers and serves as a potential site for an intersigmoid hernia.9'16'18 This is usually a reducible hernia containing a few small bowel loops. Incarceration is uncommon.

The radiologic diagnosis of intersigmoid hernia is best made by retrograde filling of the small intestine during barium enema examination. Figure 16-37 shows the encapsulated ileal loops in a characteristic relationship to the sigmoid colon.

Two other similar, but rare, entities are (a) the intra-mesosigmoid hernia' which involves a defect of only one of the constituent mesenteric leaves, the separation of which forms the hernial sac;18 and (b) the transmesosig-moid hernia, in which a usually large defect in both layers of the sigmoid mesentery allows herniation of the small bowel loops toward the left lower abdomen pos-terolateral to the sigmoid colon1819 (Fig. 16-38).

Radiologic differentiation of the three types of hernia involving the mesosigmoid is often difficult and irrelevant in terms of their ultimate surgical management. Observation of an intimate relationship between the sig-moid colon and intestinal loops clumped or fixed posterior and lateral to it can serve as a useful criterion to indicate the probability of an internal hernia involving the mesosigmoid.16

Fig. 16—38. Transmesosigmoid hernia.

The postevacuation film of a barium enema study demonstrates herniated small bowel loops occupying the left lower abdomen. The sigmoid colon (arrows) is elevated and displaced to the right. (Reproduced from Ghahremani and Meyers.16)

Fig. 16—38. Transmesosigmoid hernia.

The postevacuation film of a barium enema study demonstrates herniated small bowel loops occupying the left lower abdomen. The sigmoid colon (arrows) is elevated and displaced to the right. (Reproduced from Ghahremani and Meyers.16)

The findings are to be distinguished from a persistent descending mesocolon7'18'60 that may occasionally contain defects involving both layers; small bowel loops may then pass behind the descending colon and fill the left paracolic gutter (Fig. 16-39).

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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