Ileo-anal pouch
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The ileal pouch-anal anastomosis (IPAA), also known as an ileo-anal pouch, restorative proctocolectomy, ileal-anal pullthrough, or sometimes referred to as a j-pouch, s-pouch, w-pouch or an internal pouch, is an internal reservoir; usually situated where the rectum would normally be. It is formed by folding loops of small intestine (the ileum) back on themselves and stitching or stapling them together. The internal walls are then removed thus forming a reservoir. The reservour is then stitched or stapled into the perineum where the rectum was.
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[edit] Reasons for pouch construction
Ileo-anal pouches are constructed for people who have had their large intestine surgically removed due to disease or injury. Diseases and conditions of the large intestine which may require surgical removal include:
There is debate about whether patients suffering from Crohn's disease are suitable candidates for an ileo-anal pouch due to the risk of the disease occurring in the pouch, which could make matters even worse. An alternative to an ileo-anal pouch is an ileostomy.
In some cases where the pouch was formed as a result of colitis, inflammation can return to the pouch in a similar way to the original inflammation in the colon. This is known as pouchitis.
[edit] History
The surgical procedure for forming an ileo-anal pouch was developed as an alternative to the ileostomy where, in the absence of a colon, intestinal waste is emptied into a bag attached to the abdomen. This work was pioneered by Sir Alan Parks at St. Mark's Hospital in London in the early 1980's, the pouch was known as Parks' Pouch.
[edit] Surgical Procedure
The entire procedure can be performed in one operation, but is usually split into two or three. When done as a two-step, the first operation involves a colectomy (removal of the large intestine), and fashioning of the pouch. The patient is given a temporary defunctioning ileostomy (also known as a "loop ileostomy"). After a period of usually 3-6 months the second step (sometimes called the "takedown") is performed, in which the ileostomy is reversed. The reason for the temporary ileostomy is to allow the newly constructed pouch to fully heal without waste passing through it, thus avoiding infection.
Some surgeons prefer to perform a subtotal colectomy (removing all the colon except the rectum), since removal of the rectum can lead to complications with the anal sphincters. When a colectomy is performed as an emergency, and/or when the patient is extremely ill, the colectomy and pouch construction are performed in separate stages.
[edit] Pouch behaviour
[edit] Bowel motions
Because the ileo-anal pouch is considerably smaller a reservoir than the colon, patients tend to have more frequent bowel motions; typically 6-8 times a day. Also because the ileum does not absorb as much water as the colon, the stools tend to be less formed, and sometimes fluid. Immediately after the surgery is complete, the patient tends to pass liquid stool with frequent urgency, but this eventually settles down and the normal pouch output is described to be of a consistency similar to porridge. People who find that the consistency remains loose and/or who are experience motions too frequently usually take loperamide or codeine phosphate to thicken the stool and slow the bowel movement.
Because the ileum does not absorb as much of the gastric acid produced by the stomach as the colon did, pouch output also tends to burn the anal region slightly, and many patients find it helpful to wash the area regularly, sometimes using proctective barrier cream.
[edit] Diet
Because more water is lost through pouch output, patients can get dehydrated easily and can also suffer salt deficiency. For this reason, some are encouraged to add extra salt to meals. Persistent dehydration is often supplemented with an electrolyte mix drink.
Many patients choose to eat more white carbohydrates, because this thickens the pouch output and reduces the risk of dehydration or the aforementioned burning of the anal region. It is also common among pouch-owners to eat little and often, or "graze", rather than having three large meals a day. Some patients avoid eating much after 6-7pm to avoid having to get up during the night.
Immediately after surgery, patients are encouraged to eat low fibre, high protein / carbohydrate meals, but after the pouch function has settled, most are able to reintroduce a fully varied diet. There are some foods that are known to irritate the pouch, however, and though they may be introduced carefully, are best avoided immediately following surgery.
- Increased stool output can be caused by fibrous foods (such as pulses, green leaves, raw vegetables etc.) and also by spicy foods, alcohol and caffeine.
- Anal irritation can be caused by nuts, seeds, citric acid, raw fruit and spicy food.
- Increased wind can be caused by fizzy drinks, milk, beer, broccoli, cauliflower, sprouts, cabbage etc.
- Increased odour can be caused by foods such as fish, onions, garlic and eggs.
