Surgery for abscesses and fistulas
In approximately one in four people with Crohn's disease, the disease affects the anus. This is called perianal disease and includes abscesses and fistulas (abnormal openings and weeping tracts leading to the skin). Perianal disease does not occur in ulcerative colitis (although ulcerative colitis patients may develop significant irritation of the anal area as a result of frequent diarrhea).
Abscesses and fistulas in Crohn's disease develop when there is a microscopic break in the intestinal lining which allows bacteria to spread beyond the bowel. An anal abscess may begin as a pimple-like boil that may enlarge and become quite painful. Surgery for an abscess involves an "incision" or surgical cut into the abscess which allows the pus inside to drain away.
A fistula is an abnormal opening, or tract, that directly connects the rectum to the skin (an external fistula), or connects the rectum to an organ, such as the bladder or the vagina (an internal fistula). Fistulas are the result of abscesses that track from one area to another and leave a passageway behind. If fistulas occur in the abdomen in patients with Crohn's disease, surgery is usually warranted. If they develop in the anal area however, they should rarely be managed with surgery since surgery can sometimes make matters much worse. More often, medical treatment using metronidazole is more appropriate.
Surgery for small-bowel obstruction
The most common abdominal surgical procedure for Crohn's disease involves removing a blockage or obstruction in the small bowel. Obstructions happen because, as the disease progresses, inflammation causes the wall of the small bowel to thicken so that the passageway within the bowel (the lumen) narrows. Eventually, the bowel becomes so narrow that foodstuffs can no longer pass through it. This leads to cramps and sometimes complete obstruction of the intestine.
An area of narrowed bowel is called a "stricture." Strictures can be temporary (swelling that will resolve with anti-inflammatory medications and time) or permanent (due to scaring). Strictures that cause significant symptoms and that do not respond to medications will require surgical treatment.
At operation, a stricture may be corrected by either making it wider ("strictureplasty") or by removing the segment of bowel containing the stricture ("resection"). When strictureplasty can be done, it is generally favored because it doesn't involve removing part of the small bowel. However, if the stricture is more than 2 to 3 inches in length, strictureplasty may not be possible. In a resection, the diseased area is removed and the remaining ends of bowel are joined.
The farther down the small bowel, the more important the intestine is for absorbing nutrients and fluid, so that removing sections of the upper small bowel (jejunum) may not be as significant as removing portions of the lower small bowel (ileum).
If too much small bowel is removed, the patient can develop what is known as "short bowel syndrome" in which a number of symptoms occur as a result of malabsorption of nutrients. Surgeons try everything they can to prevent their patients from developing short bowel syndrome and when the strictureplasty operation was first described at the Radcliffe Infirmary in Oxford, England in the 1970s it spread rapidly amongst intestinal surgeons throughout the world. The bowel is opened along its length right through the narrowed area and is then sewn closed in the opposite direction. This results in a wider segment of bowel.
Strictureplasty now appears to be an effective option and the results seem long-lasting. If further strictures develop, they are generally new ones or ones that were not treated by strictureplasty. In some case however, the development of short bowel syndrome is often unavoidable since some individuals will continue to develop strictures over the years, necessitating repeated operations and inevitable resections. Even experienced, conservative intestinal surgeons will have a few short bowel patients in their practice. Symptoms of short bowel syndrome include chronic diarrhea and difficulty maintaining appropriate fluid and nutritional balance within the body.
Surgery for Crohn's disease of the colon
A short portion of the first part of the colon (the cecum) is often involved with Crohn's disease of the end of the small bowel (terminal ileitis). In such cases, the small bowel segment and a small portion of the first part of the colon may be removed in one piece and the ends rejoined. This is called a limited right hemicolectomy.
In general, however, when the colon is involved with Crohn's disease it is usually fairly extensive. Strictureplasties are not done in the colon and multiple small resections of pieces of colon are also not usually performed. Rather, surgeons will generally remove a third, or half or all of the colon. Names of these types of operations are right hemicolectomy if the right side of the colon is removed, left hemicolectomy if the left side is removed, transverse colectomy if the middle third is removed and total colectomy if the entire colon is removed but the rectum is not.
The most troubling consideration is what to do when the rectum (the last 12 inches of bowel above the anus) is involved. The rectum is the most difficult part of the intestine to remove and, if it is removed, the patient will need a new means of expelling stool, usually through an opening on the abdominal wall called a stoma (meaning mouth). If all of the colon has been removed in addition to the rectum, the operation is called a proctocolectomy (procto means rectum). After a proctocolectomy, the stoma will consist of the end of the small bowel and will be called an ileostomy since the end of the small bowel is called the ileum.
Proctocolectomy and ileostomy is the standard procedure for extensive and debilitating Crohn's disease of the colon and rectum. The results are generally very good. The small intestine adjusts over time to take over most of the functions of the large intestine. An ileostomy is created to permit the elimination of waste through the abdominal wall. An appliance (plastic device) is fitted over the opening to collect waste material. The patient with an ileostomy can't control the passing of stool, however, he or she can empty the collection bag when convenient - usually 3 or 4 times a day. There are some fancier alternatives to the conventional ileostomy called internal ileostomies and pelvic pouches, but these are rarely successful in patients who have Crohn's disease.
If the rectum is still reasonable healthy, a total proctocolectomy may not be necessary. The alternative is the colectomy with ileorectal anastomosis, in which only the diseased colon (but not the rectum or anus) is removed, and the ileum is joined directly to the rectum. Waste can be eliminated through the anus. About 5% of cases are eligible for this procedure. There is a chance that the disease will flare-up in the rectum. If the rectum becomes badly diseased later, it may have to be removed and a conventional ileostomy will then be needed. It is difficult to predict how the patient will do after a colectomy and ileorectal anastomosis. It depends very much on the status of the remainder of the bowel. If the rectum is reasonably healthy and most of the small bowel remains, it is worth a try since it preserves the normal route of stool elimination and the operation is much less surgery if the rectum can be left alone. If there is significant perianal disease with abscesses or fistulas, however, a colectomy and ileorectal anastomosis is not a good choice since the anal problems will often get worse following the operation.