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.

 

Classification of Stomas

 

Stomas may be permanent or temporary and are classified according to the part of the bowel that opens on to the anterior abdominal wall.

 

PERMANENT STOMAS

 

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 colostomy

 

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.

 

Figure 1: End colostomy

 

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

 

HARTMANN's PROCEDURE: end colostomy and rectal stump

 

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.

 

Figure 2: Hartmann's procedure

 

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.

 

End ileostomy

 

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.

 

Figure 3: Ileostomy

 

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.

 

Difference between an ileostomy and colostomy

 

ILEOSTOMY

type: temporary (as a loop ileostomy) or permanent

indications: IBD, inherited polyposis coli syndrome

appearance: spout of mucosa

location: RIF

effluent: continuous, liquid

 

 

COLOSTOMY

type: temporary (as a loop, but largely replaced by loop ileostomy) or permanent (an as end)

indications: colorectal cancer, diverticular disease

appearance: flush with the skin, mucosa sutured to skin

location: permanent: LIF, temporary, LIF or right hypochondrium

effluent: intermittent and solid

 

TEMPORARY STOMAS

 

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.

 

    • Emergency procedures: A temporary stoma is constructed in the emergency setting to bypass a diseased or injured part of the bowel or urinary system to relieve obstruction.  For example. in a large bowel obstruction, if the ileo-caecal valve remains competent, the distended caecum is at risk of rupturing and causing peritonitis.  Creating a diverting stoma reduces the risk of peritonitis.

       

      • Defunctioning stoma: Temporary stomas are also created to protect a more distal anastomosis at particular risk of leakage or breakdown.  By diverting the faecal stream and so lowering intraluminal pressure, the anastomosis is afforded time to heal.  This is known as a defunctioning stoma.  Common situations for the use of a defunctioning stoma include difficult low rectal anastomoses where there is a risk of flatus and faeces leaking and emergency resection where there is no time for bowel preparation. Reversal of the temporary stoma is usually at about 3-4 months, however patients can have temporary stomas for weeks, months or even years. 

         

        • Bowel rest: A temporary stoma can also be used to allow the inflammatory process in a distal segment of bowel or perineum to subside by diverting the harmful faecal stream such as in pericolic abscesses and anorectal fistulae.

         

        Loop stoma

         

        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.

         

        Loop stoma

         

        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. 

         

         

        OTHER TYPES OF STOMAS

         

        There are two other main types of stomas that are important to know about:

        • Double barrelled stoma
        • Urostomy

         

          Double barrelled stoma

           

          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.

           

          Urostomy

           

          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.

           

           

          Figure: 6 Urostomy

          Complications of Stomas

           

          Complications are traditionally grouped into 5 areas:

            • Poor siting - Poor siting is when the stoma has been created in a site that makes it impossible for the patient to manage the stoma.  This can range from an inability to change the stoma, dermatitis due to leakage of the effluent to the stoma being difficult to conceal.   It is essential that stomas are sited in areas of the body away from bone, old scars or the umbilicus.

               

              • Stoma proper - This involves problems with the stoma itself and include necrosis, retraction, prolapse, bleeding and luminal stenosis, functional disorders such as diarrhoea and constipation.

                 

                • Peri-intestinal area - Complications at the peri-intestinal area is a parastomal hernia.  Loops of intestine protrude through the opening into the subcutaneous tissue around the stoma. It is a late complication and can be due to poor surgical technique or a gradual enlargement of the fascial defect. 

                 

                • Mucocutaneous junction - Complications at the mucocutaneous junction involve separation of the stoma from the peri-stomal skin.  This manifests initially as erythema and can be a complication of poor surgery or secondary to retraction or necrosis.  It is common in the immunocompromised state such as patients receiving steriods, diabetics and the malnourished patient.

                 

                • Iatrogenic - Iatrogenic complications include belts that rub the stoma, razors when shaving peri-stomal skin.  Injury to stomas often goes unnoticed as stomal mucosa has no nerve endings.

                   

                   

                  Stoma Care

                   

                  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.

                   

                  • Stoma bags: There are two main types of stoma bag. Traditional single piece bags stick directly onto the patient’s skin. Two piece bags, on the other hand, have a flange that sticks to the skin. The stoma bag then attaches to the flange, allowing the bag to be changed without removal of the flange. Stoma bags can also have an additional hole at the bottom of the bag or they can be closed.  The presence of the second hole allows the regular drainage of the stoma bag. Closed bags are useful for patients who only need to change their stoma bag once or twice a day.  Some of the newer stoma bags have a carbon or charcoal flatus filter allowing gas to escape thereby stopping the bag from ballooning up.

                   

                  • Diet: If a patient is experiencing wind, they are sometimes advised to avoid beans, broccoli and cabbage or fizzy drinks. In addition, eating slowly and not talking and eating at the same time may also be advised as this helps to prevent  aerophagia which can cause excessive wind.  Apple sauce, cranberry juice and buttermilk are also said to help reduce odours.

                   

                  • Skin care: Pastes, membranes and powders are available to protect the peri-stomal skin and this is one important aspect of counselling to allow patients to be comfortable with their stoma.

                   

                  Figure 7: Stoma bags

                   

                  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.

                   

                  Conclusion

                   

                  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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