Ileocecal valve

After absorption in the small bowel, remaining undigested food passes from the ileum through the ileocecal valve to the colon. A major role of the colon is absorption of fluid. Some of the water and sodium absorption achieved by the colon is facilitated by short-chain fatty acids (SFCAs) formed from digestion of certain dietary fibers by colonic bacterial enzymes. 

Postmortem findings include necrotic lesions in the mouth and nose, congestion of the ileocecal valve, engorgement and blackening of the folds in the cecum, colon, and rectum with "zebra striping," enlarged spleen, edematous lymph nodes, and bronchopneumonia. 

Rendleman, D.F., et al. 1958. Reflux pressure studies on the ileocecal valve of dogs and humans. Surgery 44 640. 

Most of the propulsion in the cecum and ascending colon results from the slow but persistent haustral contractions, requiring as many as 8 to 15 h to move the chyme only from the ileocecal valve to the transverse colon, while the chyme itself becomes fecal in quality and also becomes a semisolid slush instead of a semifluid. 

It is likely that the hormone gastrin, which is secreted by the stomach antral mucosa in response to distension, also plays some role in this effect because gastrin has an excitatory effect on the colon and an inhibitory effect on the ileocecal valve, thus allowing rapid emptying of ileal contents into the cecum. This in turn elicits increased colonic activity. 

Ligate one third of the distal cecum with a 3-0 silk immediately below the ileocecal valve. 

The ileum, pH about 7, with the distal part as high as 8, is the terminal part of the small intestine and has fewer contractions than the duodenum. The ileocecal valve separates the small intestine with the colon... 

Nausea, abdominal cramps, and diarrhea are not uncommon (9). In runners taking daily doses of 1 g of ascorbic acid for reduction of musculoskeletal symptoms, mild diarrhea is common (21). Ascorbic acid stones have been found to obstruct the ileocecal valve (22). 

A 53-year-old man had a side-to-side Ueo-descending colostomy for disseminated carcinoma. FlnoronracU was given in doses of 15 mg/kg for 4 days, then 7.5 mg/kg intravenously on days 6 and 8. He developed severe diarrhea and severe ulceration of the bypassed portion of the colon, resulting in necrosis, and death occurred as the result of bronchopneumonia. Autopsy showed ulcers from the ileocecal valve to the ileo-colostomy site. The mucosa of the stomach, small intestine, and colon distal to the colostomy were not involved. 

The ileocecal valve separates the small intestine with the colon. 

The large intestine extends from the ileocecal valve to the anus. It is wider than the small intestine except for the descending colon, which when empty may have the same diameter as the small intestine. Major functions of the colon are absorption of water, Na+, and other electrolytes, as well as temporary storage of excreta followed by their elimination. The colon harbors large numbers of mostly anaerobic bacteria that can cause disease if they invade tissues. These bacteria metabolize carbohydrates to lactate, short-chain fatty acids (acetate, propionate, and butyrate), and gases (CO2, CH4, and H2). Ammonia, a toxic waste product, is produced from urea and other nitrogenous compounds. Other toxic substances are also produced in the colon. Ammonia and amines (aromatic or aliphatic) are absorbed and transported to the liver via the portal blood, where the former is converted to urea (Chapter 17) and the latter is detoxified. The liver thus protects the rest of the body from toxic substances produced in the colon. Colonic bacteria can also be a source of certain vitamins (e.g., vitamin K, Chapter 36). 

IBD is divided into two major subtypes ulcerative colitis and Crohn s disease. Ulcerative colitis is characterized by confluent mucosal inflammation of the colon starting at the anal verge and extending proximally for a variable extent (e.g., proctitis, left-sided cohtis, or pancolitis). Crohn s disease, by contrast, is characterized by transmnral inflammation of any part of the GI tract bnt most commonly the area adjacent to the ileocecal valve. The inflammation in Crohn s disease is not necessarily confluent, frequently leaving skip areas of relatively normal mucosa. The transmural nature of the inflammation may lead to fibrosis and strictures or, alternatively, fistula formation. 

The small intestine extends from the ileocecal valve at the stomach to the duodenum. The cecum is attached to the duodenum, which is the site where most medication is absorbed. Most foods are also absorbed in the small intestine. 

Fig. 1.73a-c. Crohn s disease. A 14-year-old boy with several previous episodes of abdominal pain. a,b Longitudinal US scans at the terminal ileum and ileocecal valve (arrows) showing diffuse wall thickened. Mural stratification is preserved. The submucosa (S) is enlarged, c Longitudinal US scan shows marked wall thickening of the ascending colon... 

Abdominal tuberculosis (TB) is rare in childhood and usually a diagnostic challenge, particularly in the absence of active pulmonary infection, and because clinical manifestations and results of laboratory studies are nonspecific. Intestinal TB can involve any segment of the gastrointestinal tract, but has a predilection for the ileocecal valve and the adjacent ileum and cecum (Parker 2003 Engin and Balk 2005). 

Laparotomy findings showed that the peritoneal cavity was obliterated with gross thickening and contraction of the parietal and visceral layers of the peritoneum. The small bowel was encased in a rigid tube and usually shortened, but the adverse effect stopped at the ileocecal valve. 

The lesion is endoscopically inaccessible (i.e., localized between the ligament of Treitz and the ileocecal valve). 

Fortunately, the majority of the CAD false-positives - approximately 80-90% of them - can be dismissed relatively easily based on their characteristic locations and appearance, and thus they are not a productivity hindrance (Okamura et al. 2004 Taylor et al. 2003). For example, a falsepositive detection on a thickened fold can be easily dismissed in a 3D endoluminal view, in which the reader can see the global structure of a fold on which a small bump that CAD points to is located. False-positives due to ileocecal valves and the rectal tube can easily be dismissed based on their anatomic location and shape a semi-automated recognition of ileocecal valves (Summers et al. 2004) and rectal tubes (lORDANESCU and Summers 2004 Suzuki et al. 2006) may make this already easy task even easier (Summers et al. 2004). Solid stool can be difficult false-positives to dismiss however, one may distinguish them from polyps by visual correspondence analysis between prone and supine views this relatively elaborate task can also be facilitated by a computerized correspondence between supine and prone data sets (Nappi et al. 2004c). 

Fig. 27.7.a-d Example of CAD false-positives. a Prominent fold. The tip of the fold in the figure (arrow) appears to he a cap-like structure, and thus it was incorrectly identified hy CAD as a polyp, b Solid stool. This polyp-mimicking stool has a cap-like appearance and a solid internal texture pattern, and thus it was detected incorrectly as a polyp, c Ileocecal valve. The tip of the ileocecal valve often has the cap-like appearance of a polyp and thus can be a cause of false-positives in CAD. d Residual materials inside the small bowel and stomach. Although a majority of the small bowel and stomach is removed in the colon extraction step, a small piece of them may be extracted along with the colon, and thus residual materials in the small bowel and stomach can cause false-positives. (Reprint, with permission, from (Yoshida and Dachman 2005)... 

Summers RM, Yao J, Johnson CD (2004) CT colonography with computer-aided detection automated recognition of ileocecal valve to reduce number of false-positive detections. Radiology 233 266-272... 

Contraindication to sedation Obstructing colon mass Post-operative colorectal cancer surveillance High risk patients Scanner weight limitations Pregnancy Hip joint replacement Incompetent ileocecal valve Claustrophobia ... 

---