A stoma, literally meaning 'mouth' when translated from Greek, is a surgical bypass of a natural conduit, allowing diversion of the faecal or urinary stream to the anterior abdominal wall. The effluent is then collected in a plastic bag attached to the abdominal skin.
Stomas may be permanent or temporary and are classified according to the part of the bowel that opens on to the anterior abdominal wall.
Once the diseased portion of bowel or urinary system is removed and there is no distal bowel segment after resection or it is impossible to rejoin the remaining tissue, a permanent stoma is formed. Permanent stomas are usually end stomas formed from the colon or the ileum.
End stomas have one opening. An example of an end stoma is an end colostomy. This is required after abdomino-perineal resection of a low rectal or anal canal tumour, and occasionally for diverticular disease. It is virtually impossible to resect such low lying tumours (or diseased bowel) and then to rejoin the bowel to the anal area. Thus end colostomies involve resiting the anus onto the abdominal wall after resection of the rectum and anal sphincter. Colostomies are usually found in the left iliac fossa, the contents of which will be solid.
Used in pathology involving the lower parts of the rectum and anus. Diseased bowel is removed distally and as there is not enough, or no, remaining distal bowel, the proximal healthy bowel is mobilised through the anterior abdominal wall as an end colostomy
This procedure is carried out after emergency resection of rectosigmoid lesions where primary anastomosis is unfavourable due to possible inflammation, faecal contamination or obstruction. Once the diseased segment is resected, the proximal end of bowel is made into an end colostomy while the distal segment of cut bowel, or rectal stump, is oversewn to remain closed. Secretions from the remaining distal rectal stump can still pass through the anus. Some months later, once the inflammatory process has subsided, the two ends of bowel may be rejoined. However, often the colostomy is well tolerated that another major rejoining operation is avoided.
Diseased large bowel (eg. colorectal tumours) is removed leaving the proximal segment of bowel as an end colostomy while the remaining distal bowel is oversewn as a rectal stump.
An ileostomy is also an example of an end stoma that uses distal ileum. It is often created after resection of the colon and rectum, a pan-proctocolectomy often for IBD. Ileostomies are usually found in the right iliac fossa, the contents of which will be liquid. Once the segment of ileum is brought through the abdominal wall in the RIF, the small bowel is then everted and so turned inside out to create a spout, protecting the anterior abdominal wall skin from the irritating ileal contents.
As well as being end stomas, ileostomies can later be reconstructed to form a pouch of several loops of ileum sutured side-to-side which is then connected to the anus-ileo-anal pouch anastomosis.
Resection of the colon, rectum and anus results in only the ileum being left. This is mobilised through the anterior abdominal wall in the RUQ (usually) to form an ileostomy.
type: temporary (as a loop ileostomy) or permanent
indications: IBD, inherited polyposis coli syndrome
appearance: spout of mucosa
effluent: continuous, liquid
type: temporary (as a loop, but largely replaced by loop ileostomy) or permanent (an as end)
appearance: flush with the skin, mucosa sutured to skin
location: permanent: LIF, temporary, LIF or right hypochondrium
effluent: intermittent and solid
Temporary stomas are used in the emergency setting, to defunction part of a bowel and for bowel rest. They are fashioned more commonly from distal ileum, but the colon may also be used, forming a loop transvere colostomy.
Temporary stomas are usually loop stomas. A loop of bowel is exteriorised to the body surface through a skin incision. The loop of bowel is supported by a rod beneath it (between bowel and skin) to prevent the loop of bowel from slipping back into the abdomen through the incision. The rod is usually removed after a couple of days when the wound has healed enough to prevent retraction of the visible part of the bowel.
The bowel wall is partially cut to create two openings: an afferent limb and an efferent limb. The afferent limb leads to the functioning part of the bowel and allows stool and gas to pass out. The efferent limb leads into the non-functioning part of bowel and secretes mucus. This is called the mucous stoma. There are thus two stomas very close together.
If colon is used to create a loop colostomy, the stoma site will be high on the abdominal wall as the transverse colon is commonly used. However, it is more common to see a loop ileostomy as this is easier to fashion than a loop colostomy.
A loop ileostomy with the afferent loop acting as the functional bowel excreting faeces and gas and the efferent loop aslo known as a mucous stoma. As can be seen from the diagram, the two loops are very close to each other.
There are two other main types of stomas that are important to know about:
Double barrelled stomas, like loop stomas, involve two stomas beside each other. However, unlike the loop stoma, the two stomas are seperate from each other. One stoma acts as an end ileostomy and so uses the small bowel, whereas the other stoma is made by the remaining colon. This secretes mucus and is also known as a mucous fistula. Only the end ileostomy requires a drainage bag. It is often a temporary stoma and has largely been superseeded by the loop stoma.
Urostomies are used for the surgical diversion of the urinary system. They are employed for bladder cancers, urinary incontinence not anemable to other treatments, and neuropathic bladders.
Formation of a urostomy requires an ileal conduit, a segment of ileum open at one end and closed at the other. The ureters are implanted into this isolated segment of small bowel. The open end of the conduit is everted to create a spout similar to an ileostomy, and allows the diversion of urine from the kidneys to the outside world, to be collected by a stoma bag.
Complications are traditionally grouped into 5 areas:
Stomas impact every aspect of a patient's life and can have medical, psychological and social effects. Thorough counselling by the multidisciplinary team, and in particular by experienced stoma nurses is crucial.
These are examples of a stoma bag. A hole is cut out where the circular marking is according to the size of the stoma. Variations in the size of the stoma hole allow the stoma bag to be tailored to each patient.
Stomas are important in the surgical management of a variety of conditions, ranging from intestinal cancers to inflammatory disorders. It is essential that the patient is counselled thoroughly about what it will be like to live with a stoma and how to care for their stoma in order to avoid the medical complications and to be able to function with their stoma with ease.
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