The gastrointestinal system begins with the mouth, esophagus and stomach. The stomach connects to the small intestine which transitions to become the colon, part of the large intestine. Finally, the large intestine terminates as the rectum. Food and liquid pass through these structures in the process of digestion as nutrients are removed and stool is formed. The segments of the GI system perfom specific, but sometimes overlapping, functions, as explained in detail in "Sabiston Textbook of Surgery, 18th edition."
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Breakdown of food occurs in the stomach and small intestine. Most nutrient absorption, likewise, occurs in the small intestine. The colon also absorbs additional nutrients and electrolytes with the help of the beneficial bacteria that populate the organ. The waste enters the colon in liquid form and is processed into semi-solid form as the colon performs its main function of reabsorbing water into the body.
Indications for partial colon resection include limited colon cancers and other pathology that affects only part of the colon. Diverticulitis -- a weakened outpouching of the colon wall -- sometimes requires partial colon removal as well. After partial colon resection, the ends of the colon on either side of the removed segment are sewn or stapled back together.
Removal of the entire colon, a total colectomy, cures ulcerative colitis and familial polyposis, a genetic condition in which precancerous polyps develop throughout the large intestine. After a total colectomy, the end of the small intestine--the ileum--can be sewn back to the rectum. The other option uses an ileostomy, either temporarily or permanently. With an ileostomy, the end of the small intestine is connected to the outside of the body through an opening created in the abdominal wall and waste is collected in special bags that attach to this opening.
Removing any part, or all, of the five-foot long colon leads to changes in the process of stool formation. Nutrition, both in the immediate post-operative period and the long term requires special consideration.
In the days after surgery, a liquid diet ensures that the suture or staple line begins to heal properly without disruption from irritating food substances. Usually within a few days, introduction of soft foods begins. If this progresses as expected, significant nutritional deficits rarely occur, especially with partial resection. If advancing the diet proves difficult, nutrition temporarily comes from intravenous solutions that contain essential nutrients such as proteins and fats, explains the American Society of Colon and Rectal Surgeons on its website.
Stool frequency after surgery sometimes tops 20 watery bowel movements a day. Because electrolytes and water are eliminated in this liquid stool, disturbances of electrolyte balance and dehydration present the most significant risks in the days after colon surgery. Sodium, potassium, calcium and magnesium levels warrant daily testing in the initial post-operative period.
Avoiding dehydration presents the biggest challenge in the immediate days after surgery. Intravenous fluids replace losses until oral intake of water catches up.
Over time, the body adapts to the loss of part or all of the colon. The small intestine takes over the function of absorbing water and dehydration becomes less of an issue. Electrolyte salvage also becomes more efficient in the small intestine. With total colectomy, nutritional risks persist for weeks or months.
Any abdominal surgery leaves the risk of adhesions and obstructions for a lifetime, states the Nov. 1, 2006 issue of "Annals of Surgery." Adhesions, essentially scar tissue, may constrict and bind structures in the abdomen together. Obstruction of the intestine, sometimes a medical emergency, becomes more likely with adhesions. Many doctors and patients find that this has nutritional implications. Foods, such as raw vegetables, mushrooms, nuts and seeds that digest and break down less easily, cause obstructions and sometimes require elimination from the diet. After colon surgery, supplements and vitamins can help to make up these deficits.
The main objectives of avoiding dehydration and maintaining a balanced diet challenge patients and surgeons. Referral to a nutritionist or dietitian prior to elective surgery allows patients to plan ahead for expected dietary and nutritional changes. Especially after total colectomy, reintroduction of foods occurs very slowly in some cases, and working with the nutritionist provides the best method of assessing and supplementing any deficits. Following the recommendations of the doctors and nutrition experts ensures the smoothest recovery possible.