Stomas

Colostomy

A colostomy is an artificial opening made in the large bowel to divert faeces and flatus to the exterior, where it can be collected in an external appliance. Depending on the purpose for which the diversion has been necessary a colostomy may be temporary or permanent.

Temporary colostomy

This is most commonly established to defunction an anastomosis after an anterior resection, to prevent faecal peritonitis developing following traumatic injury to the rectum or colon, and to facilitate the operative treatment of a high fistula in ano. It is now less commonly used for patients with distal obstruction of the sigmoid colon as a result of carci­noma or diverticular disease.

A temporary colostomy is made bringing a loop of colon to the surface (loop colostomy) where it is held in place by a plastic bridge passed through the mesentery. Once the abdomen has been closed the colostomy is opened and the edges of the colonic incision are sutured to the adjacent skin margin (Fig. 57.52). When firm adhesion of the colostomy to the abdominal wall has taken place, after 7 days the bridge can be removed.

A loop of colon can most easily be brought to the surface using large bowel that has a mesentery. Most loop colostomies are made in the transverse colon but the sigmoid colon can also be suitable. Following the surgical cure or healing of the distal lesion for which the temporary stoma was constructed, the colostomy can be closed. It is usual to perform a contrast examination (distal loopogram) to check that there is no distal obstruction or continuing problem at the site of previous surgery. Colostomy closure is most easily and safely accom­plished if the stoma is mature, that is, after the colostomy has been established for 2 months. Closure is usually performed by an intraperitoneal technique which is accompanied by fewer closure breakdowns with faecal fistulae.

Double-barrelled colostomy

This colostomy was designed so that it could be closed by crushing the intervening ‘spur’ using an enterotome or a stapling device. It is rarely used now but occasionally the colon is divided so that both ends can be brought separately to the surface ensuring that the distal segment is completely defuntioned.

Permanent colostomy

This is usually formed after excision of the rectum for a carcinoma by the abdominoperineal technique.

It is formed by bringing the distal end (end colostomy) of the divided colon to the surface in the left iliac fossa, where it is sutured in place joining the colonic margin to the surrounding skin.

The point at which the colon is brought to the surface must be carefully selected to allow a colostomy bag to be applied without impinging on the bony prominence of the antero­superior iliac spine. The best site is usually through the lateral edge of the rectus sheath, 6 cm above and medial to the bony prominence (Fig. 57.53).

An important point after the colostomy has been made is to close the lateral space between the intraperitoneal segment of the sigmoid colon and the peritoneum of the pelvic wall, to prevent internal herniation of strangulation of loops of small bowel through the deficiency. Alternatively a retroperi­toneal tunnel for the colostomy avoids creating lateral space.

Colostomy bags and appliances (Fig. 57.54)

Faeces from a permanent colostomy ate collected in disposable adhesive bags. A wide range of such bags is currently available. Many now incorporate a stomahesive backing, which can be left in place for several days. In most hospitals a stoma care service is available to offer advice to patients and to acquaint them with the latest appliances, and the appropriate psychological and practical help.

Complications of colostomies

The following complications can occur to any colostomy but are more common after poor technique:

prolapse;

retraction;

necrosis of the distal end;

stenosis of the orifice;

colostomy hernia;

bleeding (usually from granulomas around the margin of the colostomy);

colostomy ‘diarrhoea’: this is usually an infective enteritis and will respond to oral metronidazole 200 mg three times daily.

Many of these complications require revision of the colostomy. Sometimes this can be achieved with an incision immediately around the stoma but on occasion reopening the abdomen and freeing up the colostomy may be necessary. Occasionally transfer to the opposite side of the abdomen may be necessary.

Loop ileostomy

An ileostomy is used by some surgeons as an alternative to colostomy, particularly for defunctioning a low rectal anastomosis. The creation of a loop ileostomy from a knuckle of terminal ileum has already been described. The advantages of a loop ileostomy over a loop colostomy are the ease with which the bowel can be brought to the surface and the absence of odour. Care is needed, when the ileostomy is closed, that suture line obstruction does not occur.

Caecostomy

This is rarely used now. In desperately ill patients with advanced obstruction, a caecostomy may be useful. In late cases of obstruction the caecum may become so distended and ischaemic that rupture of the caecal wall may be anticipated. This can occur spontaneously giving rise to faecal peritonitis or at operation when an incision in the abdominal wall reduces its supportive role and allows the caecum to expand. In such a situation it should be decompressed by suction as soon as the abdomen is opened. In thin patients it may then be possible to carry out direct suture of the incised or perforated caecal wall to the abdominal skin of the tight iliac fossa, although a resection of this area is really the best treatment. Following on-table lavage, via the appendix stump the irrigating catheter can be left in place as a tube caecostomy. Caecostomy is only a short-term measure to allow a few days for the condition of the patient to improve. Reoperation should normally follow fairly soon thereafter and a proper surgical procedure carried out.