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A colostomy is nothing more than an anastomosis between the colon and the skin.
Colostomies may be temporary or permanent, depending on the underlying disease and conditions for which they are created. They can also be end colostomies (one terminal stoma) or loop colostomies (2 side stomas, afferent and efferent).
Appropriate planning and careful technical consideration should be given to the creation of any colostomy.
The number of colostomies performed has been decreasing in recent decades, mainly because the number of abdominoperineal resections is decreasing, as the number of ultra-low anastomoses is consistently growing.
There are some considerations a surgeon must keep in mind when performing a colostomy. The more proximal the colon, the more likely stoma effluent will be liquid and foul-smelling and the higher the likelihood of prolapse through the stoma.
Transverse colostomies should always be regarded as temporary, since with time, the tendency is for the posterior layer to retract and for the diversion to cease to be complete.
When a colostomy is predicted in the preoperative setting, is very helpful to send the patient to a consultation with an enterostomal therapist, where the patient will be be educated and counselled and the site of the stoma can be selected and marked.
The preferred stoma location is through the rectus muscle, slightly inferior to the umbilicus, at the apex of the naturally occurring tissue mound of the abdomen, in the anterior abdominal wall, where the skin has no creases, and which the patient can see and easily access.
The most distant colon with adequate vascularization should be used, in order to avoid complications.
There is a significant rate of complications related to colostomy construction, ranging from 10 to 60% according to some publications. These complications are usually related to technical errors and can be early, when they occur in the first month after the surgery, or late, if they occur after one month.
Early complications include edema and necrosis, stoma retraction, incomplete derivation, hemorrhagic complications, peristomal evisceration, obstruction, fistulae, and peristomal infection. Late complications develop with time, and include prolapse, stenosis, peristomal hernia, stoma perforation, hemorrhage, and tumors and pseudotumors.
Of these, necrosis, stoma retraction, obstruction, prolapse and peristomal hernia are some of the most common complications, and the ones we will discuss in this lecture.
Edema and necrosis are the most common early complications of colostomies. They could result from primary ischemia – when the mesocolon is excessively devascularized - or from secondary ischemia, due to excessive traction of the colon or constriction of a tight orifice.
When this traction is transitory, the stoma will evolve into an edema. When the traction and constriction are maintained, necrosis will appear, which can be superficial or profound.
These patients must quickly undergo re-intervention and a new colostomy should be performed.
Stoma retraction happens in 2 to 3% of colostomies. Obese patients, patients with postoperative ileus, and where a surgical site infection was present are the most prone to this type of complication. Diagnosis is done in the immediate postoperative period through clinical evaluation.
Quick re-intervention will avoid infectious complications.
Obstruction is another frequent complication in colostomies.
It can be an obstruction of the small intestine or the colon. The most common form of obstruction occurs when a loop of small intestine is incarcerated in the parietal orifice, creating an internal hernia.
Patients with intestinal obstruction should undergo re-intervention.
The intervention can be through the stoma orifice or through laparotomy.
If the stoma is intact, there is no need to redo it.
Prolapse is the second most common late complication of colostomies, surpassed only by peristomal hernia.
A stoma prolapse can be of the colon mucosa only or of the total length of the wall, and it can happen in end or in loop colostomies.
When does it happen? When the calibration of the parietal orifice is not well done and there is a significant difference between the parietal orifice and the skin incision; when the stoma is fashioned with a long and mobile segment of colon; and when proximal colon is used.
Peristomal hernia is without a doubt the most common complication with colostomies.
Most publications talk about a prevalence of 10 to 50%, but hernia is said to complicate virtually all colostomies. Although common, it is a very well tolerated situation and does not require re-intervention.
There are some factors that predispose to hernia formation, such as the presence of a large parietal orifice.
Risk-reducing factors include construction of the colostomy through the rectus muscle and building a subperitoneal tract.
The surgeon must keep in mind that creating a colostomy is not a simple procedure and should be done with care. Although it usually the last part of a surgical intervention, it should not be neglected.
About 50% of colostomies will develop a complication, some of them severe and disabling for the patient.
The best way to treat a colostomy complication is to prevent it by following a rigorous technique.