The word stoma comes from Greek to mean "an opening". There are many types which are formed for a variety of reasons, but here we will focus on diversions of the urinary or gastrointestinal tract to the abdominal wall. These can be temporary or permanent and their purpose is predominantly the diversion of waste products.

Beware though that a stoma bag may not be a true stoma, but instead could be collecting drain output, a fistula or serous discharge from an open wound. 

Different types of stomas



Colostomy
It can be formed from any part of the colon, but typically the descending colon is most commonly used. Thus, colostomies frequently lie on the left side of the abdomen. As the stoma occurs towards the end of the bowel, the stool should appear normal. As the waste produced isn't irritating to the skin, the stoma can be flush to the skin.

The two forms include loop & end colostomies:
  • End colostomy: the colon is completely cut through with the resulting tube being brought to the skin surface. This may be performed when the rectum has been removed or the remaining bowel is sewn shut (making the colostomy permanent) or to rest the remaining bowel (making the colostomy temporary). A Hartmann's procedure is an example where the rectosigmoid colon is resected and the anorectal stump is closed with the formation of an end colostomy. 
  • Loop colostomy: the side of the bowel is cut to form a hole which is brought to the skin surface. This makes it more easily reversible. Beneath the skin, you should expect two openings.
Ileostomy
This is a stoma created from the small intestine (ileum). An indication could be to de-function the large bowel (not allowing content to pass through) to allow it to heal following resection or to relieve inflammation secondary to inflammatory bowel disease. It is also a choice in patients who undergo complex rectal surgery for diversion of waste products. End or loop ileostomies exist (similar to above).

The content is more liquid and can irritate the skin and hence ileostomies are spouted. Many ileostomies are on the right side of the abdomen, but not all. The spout is usually the most helpful feature to differentiate the two stomas.

Urostomy
This allows the patient to pass urine when it is otherwise not possible to pass urine via the bladder e.g. following a cystectomy for malignancy. Ileal conduits are the most common, but they can be differentiated from GI stomas due their size and as they are flush to the skin.

Feeding tubes
Formation of a tract to the stomach (gastrostomy) or the small bowel (jejunostomy) for feeding patients who have swallowing difficulties secondary to obstruction or stroke or patients undergoing radiotherapy.

Examination of a stoma
Inspect
  • Patient - fit and well, any pain, discomfort etc
  • Site - may help indicate the stoma type
  • Spout - spouted, retracted, prolapsed, tissue viability
  • Output - thickness, colour, volume
  • Wound - any infection, dehiscence or granulation
Palpate
  • Abdomen generally for tenderness, masses etc
  • Parastomal region with cough reflex
  • Digitate (if trained and patient gives permission!) to assess obstruction, tension and stenosis
Auscultate the abdomen
  • For general and local bowel sounds
Complications

Short term
  • Ileus or mechanical bowel obstruction often due to adhesions (see bowel obstruction
    • Management includes imaging, IV fluids, NG tube & correcting electrolyte abnormalities
  • Necrosis - due to poor blood flow or stoma siting causing tension on the bowel or vessels
    • Occurs usually within the first 48 hours with a dusky, ischaemic and sometimes ulcerated appearance
    • Escalate urgently! 
    • A trained person (e.g. stoma nurse or senior colleague) can examine internally to assess the degree of necrosis
  • High output stoma
    • Often defined as >2L, with electrolyte disturbances & AKI from the dehydration
    • Manage as per diarrhoea with appropriate history/examination/investigations, particularly excluding any infectious cause before starting antimotility agents (e.g. loperamide, codeine) & omeprazole
    • Hospital guidelines often exist. See the one below from Doncaster Hospital
Long term
  • Psychological - body image and psychosexual issues are common. Involve stoma care nurses!
  • Stomal - high output, dehiscence, prolapse, retraction, stenosis, obstruction, incontinence/leakage, these are often managed by stoma nurse specialists
  • Peristomal - skin irritation, herniation, fistula formation
Basic stoma care
Having a stoma is a big change for patients, thus ensure you support them in coming to terms with it & empower them to look after their stoma. The stoma nurses are outstanding as they will discuss the situation with patients pre-operatively, helping them mentally prepare & educating them on lifestyle changes, what products to use & often give them a supply of things to try.

A dietician & stoma nurse may also advise a reduction in fibre intake for a few months to reduce the risk of complications. In particular, they may advise avoiding foods with husks (e.g. sweetcorn) or tough stems (e.g. broccoli, celery) to avoid bezoar obstruction.

Useful Resources
Written by Dr Adam Foster (FY1)
Reviewed by Dr Swati Bhasin (General Surgery SpR)