Principles and techniques in the use of convexity.

Expected outcomes for a correctly fitted ostomy prosthetic device include sustained, predictable wearing time, protection of the stoma from injury, and maintenance of peristomal skin integrity. To accomplish this, the pouching system must be properly sized and maintain continuous contact with the peristomal skin. Continuous contact is achieved when the faceplate provides a mirror image of the topography of the peristomal plane. Varying degrees of support and convexity of the faceplate are used to fit the unique characteristics of the patient's peristomal plane and stoma. Support can be absent, soft or firm. Convexity is some degree of outward curving of the faceplate. Characteristics of the stoma (i.e., flush, retracted, loop), peristomal plane (i.e., creases, hernia, scarring) and abdomen (i.e., flaccid, soft, or firm) may indicate the need for convexity. Potential problems include mucocutaneous separation, ischemia, laceration, erythema, ecchymosis, and pain if convexity is used inappropriately. Alternatives to convexity include the use of an ostomy belt or surgery. Ongoing, intermittent assessment of the prosthetic is essential to evaluate that the convexity and support have achieved the expected outcomes.