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An introduction to stomas: Reasons for their formation

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VOL: 101, ISSUE: 29, PAGE NO: 63

Penny Taylor, RN, SCM, Dip Aromatherapy, Cert. Counselling, is clinical nurse specialist, Stoma Care Service, South Birmingham Primary Care Trust, Springfield’s Centre, Birmingham

The word ‘stoma’ comes from the Greek word meaning ‘mouth’ or ‘opening’. Three types of stoma are discussed in this article: colostomy, ileostomy and ileal conduit. All are involved in the elimination of either faeces or urine.

A stoma is an artificial opening in the bowel that has been made deliberately in order to bring the bowel onto the surface of the abdomen so as to divert the flow of faeces or urine.

At any one time there are approximately 80,000 people in the UK with a stoma (Department of Health, 1998).

There are three main types of eliminating stomas:

- Colostomy - an opening into the colon;

- Ileostomy - an opening into the ileum;

- Urostomy - an opening into the urinary tract.


A colostomy can be either permanent or temporary and is described as either an end or a loop colostomy.

The output from a colostomy depends on the part of the colon that has been fashioned as a stoma. Faeces will be either semi-formed or a formed stool. The more proximal the stoma, the softer/more fluid the stool.

- End colostomy: this is formed by passing a resected functioning end of the colon through an incision in the abdominal wall onto the surface of the abdomen. The stoma is then fashioned and sutured to the skin.

An end permanent colostomy is formed following an abdoperineal resection of rectum (removal of the bowel below the colostomy).

An end colostomy is also formed during a Hartmann’s operation, and this can be reversed. The procedure involves resection of the distal (lower end) of the colon and its proximal (upper end). The distal colon is closed off and the upper end of the colon is then brought out onto the surface of the abdomen to form a colostomy.

- Loop colostomy: this is usually fashioned to protect an anastomosis; to aid healing of colonic or anorectal disease; or to divert faecal flow in an emergency.

It is formed by bringing a loop of colon to the surface of the abdomen by means of an incision in the abdominal wall. Initially, the loop is held in place outside the abdomen by a plastic rod. Next, an incision is made in the bowel to allow the passage of stool through the colostomy. The supporting rod is removed from about seven to 10 days after surgery, when healing will have occurred, which will prevent the loop of bowel from retracting into the abdomen. A loop colostomy is bulky and can be difficult to manage.


Ileostomies can be permanent or temporary and are either an end or a loop in formation. An end permanent ileostomy is formed following total excision of the colon, rectum and anus (panproctocolectomy).

Loop ileostomies are usually temporary and are formed to:

- Protect a distal anastomosis;

- Protect the anastomosis of an ileal-anal pouch or a colo-anal pouch during the healing process;

- Aid healing in Crohn’s disease, which affects the colon and the anus;

- Aid healing of fistula tracts (the result of underlying pathology; for example, abscess, malignancy, Crohn’s disease, trauma, sepsis).

Ideally, the output from an ileostomy will have the consistency of porridge, and will produce on average 500-700ml a day.


Urostomies are usually permanent and it is now possible to form a continent urinary diversion; for example, a Mitrofanoff stoma. This is a surgically created pouch usually formed from a piece of large bowel, for example, the appendix, that connects the abdominal wall to the urinary bladder. Self-catheterisation via the stoma is required in order to empty the bladder of these patients.

An ileal conduit is formed when the ureters are anastomosed to an isolated segment of ileum, which is brought out onto the surface of the abdomen. The ileum then acts as a conduit for the passage of urine. Urine draining from the ileal conduit will contain flecks of mucus from the ileum that was used for its construction. The patient cannot control the output from the stoma and requires a urostomy pouch.

Why is a stoma necessary?

There are a number of conditions that may necessitate the formation of a stoma (Box 1). Further details of some of these are highlighted below.

Pelvic cancers - Cancers arising in the pelvis can result in the patient requiring a stoma:

- Colorectal cancer: This is the third most common cancer in men, and the second most common cancer in women in the UK. Each year, there are 18,500 new cases in men, and over 16,000 cases in women (Cancer Research UK, 2005).

The primary treatment remains excision of the tumour. The survival rate of a person with colorectal cancer depends on the stage of the disease at presentation. Ten per cent of all cancer deaths in the UK are attributed to cancers of the large bowel (Cancer Research UK, 2002).

- Bladder cancer: In England and Wales, bladder cancer accounts for four per cent of male cancers and two per cent of those in females (Cancer Research UK, 2002).

It is related to some environmental factors; for example, certain industrial chemicals, and smoking.

- Other pelvic cancers: to obtain a potential cure for someone with a pelvic cancer, including that of the prostate, uterus and cervix, it may be necessary to remove adjacent organs because of the close proximity of the pelvic organs in both males and females. This surgery can result in the patient requiring both a urostomy and a colostomy or ileostomy.

- Familial adenomatous polyposis (FAP): this is a clearly defined pre-cancerous disease. It is an autosomal dominant disease, the main characteristics of which are multiple colonic polyps. However, there is also a variety of extra colonic features.

Diverticular disease - Diverticular disease results in the formation of herniations of the mucosa into the muscle layer of the colon. It is thought that sigmoid diverticular disease is the consequence of a deficiency in vegetable fibre in the diet (Painter and Burkitt, 1975).

Complications of diverticular disease include:

- Acute diverticulitis;

- A fistula; for example, rectovaginal or rectovesicule (between the rectum and the bladder);

- Abscess formation;

- Haemorrhage;

- Obstruction.

Incontinence - Faecal incontinence is socially disabling. Its true incidence is largely under-estimated because of embarrassment and failure to seek help. It is more common in women than men. The ability to retain faeces in the rectum depends on a number of factors:

- Stool consistency;

- The capacity and compliance of the rectum;

- A normal recto-anal reflex;

- Normal internal and external sphincter function;

- Normal sensation in the anal canal.

There are a number of reasons for the occurrence of faecal incontinence: obstetric injury, trauma, rectal prolapse, spina bifida.

A stoma may also be formed to manage urinary incontinence; for example, patients with multiple sclerosis or an obstetric injury.

Ulcerative colitis - Ulcerative colitis is a disease of unknown aetiology, which is confined to the colon and is characterised by mucosal inflammation. It affects the young and has an equal sex distribution (Nicholls, 1998).

Crohn’s disease - Crohn’s disease is a chronic transmural inflammatory process that can affect the gastrointestinal tract anywhere from the mouth to the anus and may be associated with extra intestinal manifestations.


There are three main types of eliminating stomas and a number of different reasons why patients may need to have surgery that requires a stoma. Nurses will care for patients with all types, and must be able to provide appropriate care for each.

- Topics of future articles in this series:

Stomas and cultural issues

Managing stomas at home.

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